Co-reporter:Xu Pan;Yingtong Tang;Changneng Zhang;Fantai Kong;Yifeng Sui;Linhua Hu
The Journal of Physical Chemistry C March 11, 2010 Volume 114(Issue 9) pp:4160-4167
Publication Date(Web):Publication Date (Web): February 11, 2010
DOI:10.1021/jp910055c
The reaction mechanisms of a triiodide/iodide redox couple at the platinized FTO glass electrode/electrolyte interface with different electrolytes were studied by cyclic voltammetry, steady polarization curve, and chronocoulometric methods. It was found that the reaction process of the triiodide/iodide redox couple in electrolytes without nitrogenous heterocyclic additives was controlled by adsorption, and different iodide concentrations could affect the reaction mechanism of the triiodide/iodide redox couple on the platinized FTO glass electrode by changing the adsorption characteristic of iodide (triiodide). After nitrogenous heterocyclic additives were added into the electrolytes, the reaction process was controlled by a diffusion process. The nitrogenous heterocyclic additives can absorb on the electrode and change the reaction mechanism of the triiodide/iodide redox couple by forming complex compounds with triiodide. The radius of the redox active species in the electrolyte with nitrogenous heterocyclic additives was bigger than that in electrolytes without nitrogenous heterocyclic additives.
Co-reporter:Zhipeng Huo, Lu Wang, Li Tao, Yong Ding, Jinxin Yi, Ahmed Alsaedi, Tasawar Hayat, Songyuan Dai
Journal of Power Sources 2017 Volume 359(Volume 359) pp:
Publication Date(Web):15 August 2017
DOI:10.1016/j.jpowsour.2017.04.099
•A supramolecular gel electrolyte was prepared by two-component amide based co-gelator.•The supramolecular gel electrolyte provides a fast electron kinetic process.•The QS-DSSC with supramolecular gel electrolyte exhibits boosted performance.A supramolecular gel electrolyte (Tgel > 100 °C) is formed from N,N′-1,8-octanediylbis-dodecanamide and iodoacetamide as two-component co-gelator, and introduced into the quasi-solid-state dye-sensitized solar cells (QS-DSSCs). The different morphologies of microscopic network between two-component and single-component gel electrolytes have influence on the diffusion of redox couple in gel electrolytes and further affect the electron kinetic processes in QS-DSSCs. Compared with the single-component gel electrolyte, the two-component gel electrolyte has less compact gel network and weaker steric hindrance effect, which provides more effective charge transport channel for the diffusion of I3/I− redox couple. Meanwhile, the NH2 groups of iodoacetamide molecules interact with Li+ and I3−, which also accelerate the transport of I3−/I− and decrease in the I3− concentration in the TiO2/electrolyte interface. As a result, nearly a 12% improvement in short-circuit photocurrent density (Jsc) and much higher open circuit potential (Voc) are found in the two-component gel electrolyte based QS-DSSC. Consequently, the QS-DSSC based on the supramolecular gel electrolyte obtains a 17% enhancement in the photoelectric conversion efficiency (7.32%) in comparison with the QS-DSSC based on the single-component gel electrolyte (6.24%). Furthermore, the degradations of these QS-DSSCs are negligible after one sun light soaking with UV cutoff filter at 50 °C for 1000 h.Download high-res image (253KB)Download full-size image
Co-reporter:Yingke Ren 任英科;Bin Duan 段滨;Yafeng Xu 徐亚峰;Yang Huang 黄阳
Science China Materials 2017 Volume 60( Issue 5) pp:392-398
Publication Date(Web):17 April 2017
DOI:10.1007/s40843-017-9027-1
The anti-polar solvent technique is an effective way to improve the film quality in a perovskite solar cell. In this work, we reveal the reason why chlorobenzene (CBZ) plays an important role in controlling the crystallization process. By investigating the formation of intermediate phases in the precursor solution, we observed that the CH3NH3I (MAI)-PbI2-dimethylformamide (DMF) or MAI-PbI2-dimethylsulphoxide (DMSO) adducts have not yet formed until washed with non-polar solvent. The accelerated formation of intermediate phase yields high crystalline perovskite layers. Rapid solvent evaporation and retarded perovskite crystallization in one-step method are efficient to obtain high-quality perovskite films. Consequently, MAI-PbI2-DMSO intermediate shows neat rod-like structure with high crystallinity, which eventually transforms extremely dense and uniform perovskite films.反溶剂技术可以有效改善钙钛矿薄膜的质量. 本文揭示了氯苯(CBZ) 在结晶过程中起的重要作用. 通过研究前体溶液中配合物的结 构变化, 我们观察到, 在滴加反溶剂之前, MAI-PbI2-DMF或MAI-PbI2-DMSO尚未形成. 快速去除多余溶剂后形成中间相, 延缓钙钛矿结晶是 得到高质量钙钛矿薄膜的关键. 其中MAI-PbI2-DMSO中间体表现出了高结晶的棒状结构, 因此最终转变成非常致密和均匀的钙钛矿薄膜.
Co-reporter:Jiajiu Ye;Xuhui Zhang;Liangzheng Zhu;Haiying Zheng;Guozhen Liu;Hongxia Wang;Tasawar Hayat;Xu Pan
Sustainable Energy & Fuels (2017-Present) 2017 vol. 1(Issue 4) pp:907-914
Publication Date(Web):2017/05/30
DOI:10.1039/C7SE00036G
Since solvent engineering methods were applied to the treatment of perovskite films, the performance of perovskite solar cells (PSCs) has shown rapid growth and remarkable achievements have been made. Here we report a highly reproducible method for controlling perovskite crystal growth by a spraying anti-solvent process, which is quite different from conventional dripping methods. The results showed that the change of the method by which the anti-solvent is used has a significant impact on the morphology and formation of the perovskite. It has a high probability to form a mirror-like surface without wave-circle or ring defects, and to obtain a longer carrier lifetime than crystals formed by by dripping. After optimizing the spraying operating conditions, the optimal device based on FA0.81MA0.15Cs0.025PbI2.5Br0.45 obtained a PCE of 19.21%. Particularly, this method exhibited good reproducibility and a high fill factor due to the reduced crystal defects in the film. The champion cell obtained a fill factor as high as 80.84%, measured at AM 1.5G, 100 mW cm−2. It is expected that these findings can be beneficial for the future integrated applications of these perovskites.
Co-reporter:Ying-Ke Ren;Xi-Hong Ding;Ya-Han Wu;Jun Zhu;Tasawar Hayat;Ahmed Alsaedi;Ya-Feng Xu;Zhao-Qian Li;Shang-Feng Yang;Song-Yuan Dai
Journal of Materials Chemistry A 2017 vol. 5(Issue 38) pp:20327-20333
Publication Date(Web):2017/10/03
DOI:10.1039/C7TA06334B
The nucleation stage has an important influence on the lead halide perovskite film morphology, and therefore the solar cell performance. Here, we introduce a facile temperature-assisted rapid nucleation (TRN) method to improve the film crystallization process and the film morphology. By employing low temperature anti-solvents (diethyl ether, chlorobenzene and toluene), we stimulate homogeneous nuclei growth, resulting in a highly dense perovskite thin layer. The TRN method prepared (FAPbI3)0.85(MAPbBr3)0.15 devices exhibit a power conversion efficiency up to 19.2% and maintain over 85% of the original efficiency after 40 days of storage at room temperature under a relative humidity of 10–40%.
Co-reporter:Bin Duan;Yingke Ren;Yafeng Xu;Wenyong Chen;Qing Ye;Yang Huang;Jun Zhu
Inorganic Chemistry Frontiers 2017 vol. 4(Issue 3) pp:473-480
Publication Date(Web):2017/03/14
DOI:10.1039/C6QI00492J
High quality perovskite films were fabricated from different precursor solutions containing a certain proportion of different hydrogen halides. An anti-solvent, toluene, was used here to isolate an intermediate from the perovskite precursor solution to reveal the impact of the hydrogen halides on the crystallization of perovskite films. From the Fourier transform infrared spectra we found that the stretch vibration of CO for pure N,N-dimethylformamide (DMF) appeared at 1663 cm−1, which was shifted to a smaller wavenumber while reacting DMF with CH3NH3I (MAI) + PbI2 and MAI + PbI2 + HX (X = Cl, Br, I). Moreover, the appearance of X-ray diffraction (XRD) peaks at low angles (near 8 degrees) as well as some small angle shift showed that the MAI–PbI2–DMF–xHX (X = Cl, Br, I) intermediate was formed, which benefits perovskite crystallization because the formation of the intermediate will avoid a rapid reaction between MAI and PbI2. What's more, the solubility of the precursor can be improved by adding hydrogen halides. By adding a certain amount of hydrogen halide into the one-step perovskite precursor solution we can obtain pin-hole free and almost no defect films. Transient absorption (TA) was carried out to investigate the charge recombination in intrinsic perovskite films and perovskite devices, giving some reasonable interpretations.
Co-reporter:Jiajiu Ye, Haiying Zheng, Liangzheng Zhu, Xuhui Zhang, Ling Jiang, Wangchao Chen, Guozhen Liu, Xu Pan, Songyuan Dai
Solar Energy Materials and Solar Cells 2017 Volume 160(Volume 160) pp:
Publication Date(Web):1 February 2017
DOI:10.1016/j.solmat.2016.10.022
•Perovskite film was annealed at 220 °C.•The perovskite film was shaped in 15 s.•High-temperature promote the formation of larger crystal grain.•Perovskite solar cell treated with high temperature have higher stability.Recent developments of PSCs have achieved great progress with power conversion efficiency reached to 22.1%. The crystal growth process as an important factor will significantly influence the quality of perovskite films and the device performance. In this paper, we demonstrate a simple approach for fast preparation based on the precursor compositions of (FAPbI3) 0.85 (MAPbBr3)0.15 by regulating the temperature during annealing process for transition from FAI, PbI2, MABr, and PbBr2 to perovskite. The film will be shaped in 15 s for one-step deposition at annealing temperature of 220 °C. It has been found that higher temperature will induce perovskite to form larger size and oriented crystal grains rapidly. This will contribute to longer carrier lifetime and smaller carrier recombination which, are beneficial for solar cell device. The champion cell with PCE of 17.1% had been obtained measured under conditions of AM 1.5 G, 100 mW/cm2. Furthermore, this method exhibits good stability which is benefited from large size crystal, the device will not be deteriorated and the PCE maintained over 90% after 3 months.we demonstrate a simple approach for fast preparation at annealing temperature as high as 220 °C, and the film will be shaped in 15 s based on the precursor compositions of (FAPbI3) 0.85 (MAPbBr3)0.15 for the one-step deposition.Download high-res image (165KB)Download full-size image
Co-reporter:Fu-Ling Guo;Zhao-Qian Li;Xue-Peng Liu;Li Zhou;Fan-Tai Kong;Wang-Chao Chen;Song-Yuan Dai
Advanced Functional Materials 2016 Volume 26( Issue 31) pp:5733-5740
Publication Date(Web):
DOI:10.1002/adfm.201601305
The anchoring group in dye-sensitized solar cells (DSSCs) profoundly affects the electron injection and durability on TiO2 films interface. Here, the hydantoin acceptor is introduced as anchoring group for DSSCs. The hydantoin based sensitizer achieves a photovoltaic efficiency of 7.66%, compared to 4.90% for sensitizer containing the conventional cyanoacrylic acid as anchoring group. Remarkably, the hydantoin anchoring group significantly enhances the electron-injection efficiency (Φinj) and photocurrent (Jsc). The time dependent adsorption and desorption data indicate the strong binding strength and the superiority of stability for hydantoin based sensitizers. The Fourier transform infrared measurements investigate the adsorption mechanism of hydantoin on TiO2 interface. These results strongly corroborate the advantages of incorporating hydantoin as acceptor and anchoring group. As a consequence, the sensitizer HY-4 with hydantoin approaches the photovoltaic efficiency of 8.32% under 0.1 sunlight illumination. These observations offer a new route to design and develop efficient sensitizers for DSSCs.
Co-reporter:Feng Liu, Jun Zhu, Yafeng Xu, Li Zhou and Songyuan Dai
Nanoscale 2016 vol. 8(Issue 19) pp:10021-10025
Publication Date(Web):21 Apr 2016
DOI:10.1039/C6NR02505F
Phosphine-free synthesis of CISe quantum dots (QDs) is highly desirable, yet it has been challenging. The main difficulty lies in achieving phosphine-free Se precursors. Most reported protocols for the synthesis of size-confined CISe QDs highly depend on the use of air-sensitive, toxic, and expensive alkylphosphines to prepare reactive Se precursors and to confine particle growth. Herein, we present a new amine/thiol combination-based route to Se precursors that may enable a general synthesis of phosphine-free selenide QDs. What's more, instead of the traditional “hot-injection” method, we also report the first one-pot noninjection synthesis of high quality CISe QDs enabled by our strategy. A very high chemical yield of ∼95% is demonstrated, as well as the facile gram-scale production of monodisperse CISe QDs. By simply adjusting the amount of 1-dodecanethiol used in the synthesis, we are able to produce CISe QDs with continuous tunability of the particle size from ∼2 nm to ∼10 nm, and hence their intrinsic optical properties.
Co-reporter:Liangzheng Zhu, Zhipeng Shao, Jiajiu Ye, Xuhui Zhang, Xu Pan and Songyuan Dai
Chemical Communications 2016 vol. 52(Issue 5) pp:970-973
Publication Date(Web):10 Nov 2015
DOI:10.1039/C5CC08156D
One of the limitations of TiO2 based perovskite solar cells is the poor electron mobility of TiO2. Here, perovskite oxide BaSnO3 is used as a replacement. It has a higher electron mobility and the same perovskite structure as the light harvesting materials. After optimization, devices based on BaSnO3 showed the best performance of 12.3% vs. 11.1% for TiO2.
Co-reporter:Yang Huang, Jun Zhu, Yong Ding, Shuanghong Chen, Changneng Zhang, and Songyuan Dai
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 12) pp:8162
Publication Date(Web):March 8, 2016
DOI:10.1021/acsami.5b08421
TiO2 sub-microspheres composed of anatase granular-like nanocrystallines with an average diameter ∼250 nm are synthesized using sol–gel method and employed as the scaffold layer for efficient mesocopic perovskite solar cells. Compared with mesoporous TiO2 films composed of ∼18 nm nanoparticles, the sub-microsphere films show superior light-trapping characteristics and significantly improve the light-harvesting capability of the solar cells. In addition, the charge-transport performance is also dramatically improved according to the transient photocurrent decay despite there being no significant difference in the perovskite layer surface morphology. As a result, an average power conversion efficiency of 15% with a highly uniform distribution is achieved for the solar cells with TiO2 sub-microsphere films, 12% higher than those with TiO2 nanoparticle films. The combination of light-harvesting capability and fast charge transfer make the TiO2 sub-microsphere film a good candidate as the scaffold layer for efficient perovskite solar cells.Keywords: charge transport; light-harvesting capability; perovskite solar cells; scaffold layer; sub-microspheres; TiO2
Co-reporter:Jiajiu Ye, Liangzheng Zhu, Li Zhou, Xuepeng Liu, Xuhui Zhang, Haiying Zheng, Guozheng Liu, Zhipeng Shao, Xu Pan, Songyuan Dai
Solar Energy 2016 Volume 136() pp:505-514
Publication Date(Web):15 October 2016
DOI:10.1016/j.solener.2016.07.034
•PCL was shaped by weak corrosive anti-solvent and ultra-dry gas flow.•High-quality perovskite films was prepared with low defects.•The PCE was boosted from 8.79% to 18.25% with the fill factor as high as 80.91%.•The PCE of the best device was able to maintain 80% after 60 days.•This method can be used as general approach for boosting the efficiency of PSCs.Recent development of perovskite solar cells have achieved great progress with power conversion efficiency reach to 22.1%. In this paper, we focus our attention on shaping perovskite capping layer (PCL) by adopting weak corrosive mixed anti-solvent to precisely control the capping layer thickness and crystallization. Ultra-dry gas flow was used for protecting perovskite film and inducing the formation of low defects perovskite crystal grain. The device performance is greatly enhanced after modifying the quality of CH3NH3PbI3 films with suitable PCL thickness and crystalline grain. The power conversion efficiency was boosted from 8.79% to 18.25% for the champion cell with the fill factor as high as 80.91% measured under conditions of AM 1.5G, 100 mW/cm2. It is expected that this method can be used as a general approach for boosting the perovskite solar cell efficiency with different type of precursor material (MA,FA group and diverse combination with each other), such as MAPbX3, FAPbX3 and (FAPbI3)x (MAPbBr3)1−x. Furthermore, the method exhibit good reproducibility and device stability due to high-quality perovskite films and the device of the best one will be not deteriorated with the PCE maintaining over 80% after 60 days.The PCL was shaped by changing the volume of weak corrosive mixed anti-solvent (8% acetonitrile in chlorobenzene, volume ratio), and ultra-dry gas flow was used for protecting perovskite film as well as inducing the formation of low defects perovskite films with high fill factor.
Co-reporter:Feng Liu, Zhongxiu Jin, Jun Zhu, Yafeng Xu, Li Zhou, Songyuan Dai
Chemical Physics Letters 2016 Volume 653() pp:173-177
Publication Date(Web):1 June 2016
DOI:10.1016/j.cplett.2016.04.089
Highlights
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A general surface engineering approach is designed to modify QD surface loading.
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S2− treatment/QD re-uptake process results in up to a 60% increase in QD loading.
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QDSCs exhibit efficiency of 3.66%, 83% higher than those with standard procedures.
Co-reporter:Lu Wang, Zhipeng Huo, Li Tao, Jun Zhu, Changneng Zhang, Shuanghong Chen, Songyuan Dai
Journal of Photochemistry and Photobiology A: Chemistry 2016 Volume 329() pp:139-145
Publication Date(Web):1 October 2016
DOI:10.1016/j.jphotochem.2016.05.027
•An intrinsic stable gel electrolyte based on LMOG with high Tgel was prepared.•N,N'-1,4-butylenediylbis-dodecanamide was used to gelate the liquid electrolyte.•The influence of gelation on the performance of QS-DSSC was investigated in detail.•The QS-DSSC exhibites notably improved stability during the accelerated aging test.Quasi-solid-state dye-sensitized solar cell (QS-DSSC) were fabricated using N,N'-1,4-butylenediylbis-dodecanamide as low molecular mass organogelator (LMOG). The gel to solution transition temperature (Tgel) of this gel electrolyte is 115.8 °C which ensures a good intrinsic stability of the gel electrolyte at the QS-DSSC operating temperature. The kinetic processes of electron transport and recombination of DSSCs influenced by the gel electrolyte are investigated in detail. Due to the diffusion of redox species in the gel electrolyte is hindered by the crosslinked network and the electron recombination at the interface of the TiO2 photoanode/electrolyte is accelerated, the incidental photon-to-electron conversion efficiency (IPCE) and the short circuit photocurrent density (Jsc) of the QS-DSSC are slightly decreased compared with those of liquid electrolyte based DSSC (L-DSSC). Remarkably, the QS-DSSC exhibits excellent thermal and light-soaking stabilities during accelerated aging tests for 1000 h. The QS-DSSC retains 90% of its initial photoelectric conversion efficiency, whereas that of L-DSSC only retains 83% under successive one sun light soaking with UV cut-off filter at 50 °C for 1000 h.An amide derivative, N,N'-1,4-butylenediylbis-dodecanamide was synthesized and used as LMOG to fabricate a novel gel electrolyte with gel to solution transition temperature (Tgel = 115.8 °C). This high Tgel ensures the gel state of the electrolyte at operating temperature of the devices by retarding evaporation and leakage of the organic solvent in the electrolyte, which is crucial for the long-term stability of the DSSC. The influence of gelation on the kinetic processes of electron transport and recombination and the photovoltaic performance of the quasi-solid state dye sensitized solar cell (QS-DSSC) were investigated in detail.
Co-reporter:Changneng Zhang, Ling Jiang, Li 'e Mo, Li Tao, Yang Huang, Linhua Hu, Shuanghong Chen, Zhipeng Huo, Songyuan Dai
Journal of Photochemistry and Photobiology A: Chemistry 2016 Volume 321() pp:19-23
Publication Date(Web):1 May 2016
DOI:10.1016/j.jphotochem.2016.01.006
•The doped Mg ions as a major recombination channels in dyed Mg2+-doped TiO2 solar cells with Li+ electrolyte.•The increase in IPCE at long wavelengths for DSCs with increasing Li+ concentration in the electrolytes.•The improved stability of dyed Mg2+-doped TiO2 solar cells with LiI electrolyte under room temperature.This work mainly studies the effect of Li+ ions in the electrolyte on the enhancement of photoelectric performance and stability in the dyed Mg2+ doped TiO2 solar cells. Measurements of dynamic recombination between interface electron lifetime τn and short-circuit current Jsc suggested that the doped Mg ions as recombination channels, rather than Li+ ions, played key role in recombination reaction in Mg2+-doped TiO2 electrodes. The adsorbed Li+ on the surface of Mg2+ doped TiO2 is mainly attributed to the positive shift of the conduction band edge that resulted in the decreased Voc. It is found that the conduction band edge of Mg2+ doped TiO2 electrodes was positively shifted with the increasing concentration of Li+ from 0 M to 0.4 M, which led to the increases of the electron injection efficiency ηinj and the photocurrent density Jsc for Mg2+ doped TiO2 solar cells. And the stability of Mg2+ doped in solar cells showed that the adsorbed and intercalated Li+ ion in Mg2+ doped TiO2 electrode can improve the cell performance and interface stability.
Co-reporter:Bin Pan;ShuangHong Chen;Yang Huang;ZhiPeng Shao
Science China Technological Sciences 2016 Volume 59( Issue 8) pp:1276-1282
Publication Date(Web):2016 August
DOI:10.1007/s11431-016-6085-3
Elevated working temperatures reduce the efficiency of dye-sensitized solar cells (DSCs), and effective temperature regulation protects them from the undesirable efficiency loss. In this work, a semi-transparent DSC module equipped with a cooling system was designed and constructed for application in buildings, the temperature and output performance of the modules with or without cooling treatment were investigated. The test results showed the cooling system could noticeably improve the power generation and reduce the module temperature. Moreover, we established a mathematical model to analyze the modules’ thermal performances, and introduced the concept of cooling efficiency to evaluate the cooling effect. The model accuracy have been validated utilizing measured data, and the effects of channel depth and mass flow rate on the module temperature and cooling efficiency were further theoretically studied. The combined DSC module has been found to have a good application prospect in building integrated photovoltaic (BIPV), and the numerical results are important in system design.
Co-reporter:Yong Ding;Li Zhou;Li'e Mo;Ling Jiang;Linhua Hu;Zhaoqian Li;Shuanghong Chen
Advanced Functional Materials 2015 Volume 25( Issue 37) pp:5946-5953
Publication Date(Web):
DOI:10.1002/adfm.201502224
An optimized configuration of TiO2 microspheres in photoanodes is of great importance to prepare highly efficient dye-sensitized solar cells (DSSCs). In this work, TiO2 microspheres with tunable diameter, pore size, and porosity are synthesized by subtly adjusting the synthesizing conditions, including ratios of deionized water, ammonia, and ethanol, respectively. TiO2 microspheres are obtained with large pore sizes and a high porosity without sacrificing specific surface areas. In addition, the effect of their porosity and pore size on the performance of DSSCs is investigated. As confirmed by the dye-loading ability and electrolyte diffusion resistance, the large mesopores and the high porosity of the TiO2 microspheres can improve dye adsorption and facilitate electrolyte diffusion, giving rise to a high light-harvesting and electron collection efficiency. Consequently, the highest photocurrent of 19.21 mA cm−2 and a power conversion efficiency of 9.98% are obtained by using the TiO2 microspheres with the highest porosity, compared with a 9.29% efficiency demonstrated by the lowest porosity (an improvement of 7.4%). By modifying the interconnection and the external pores of the microspheres photoanode, a high efficiency of 11.67% is achieved for a DSSC based on the most potent TiO2 microspheres.
Co-reporter:Yi Li, Jun Zhu, Yang Huang, Junfeng Wei, Feng Liu, Zhipeng Shao, Linhua Hu, Shuanghong Chen, Shangfeng Yang, Junwang Tang, Jianxi Yao and Songyuan Dai
Nanoscale 2015 vol. 7(Issue 21) pp:9902-9907
Publication Date(Web):28 Apr 2015
DOI:10.1039/C5NR00420A
Lead halide perovskite solar cells have attracted great interest due to their high efficiency and simple fabrication process. However, the high efficiency heavily relies on expensive organic hole-transporting materials (OHTMs) such as 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-MeOTAD), it is preferable to replace these expensive OHTMs by inorganic and low cost materials. Here, we report colloidal PbS quantum dots synthesized by a facile method and used as the inorganic hole-transporting material in a hybrid perovskite solar cell. By controlling the crystalline morphology of the perovskite capping layer, the recombination process is significantly retarded. Furthermore, a pure inorganic solar cell prepared by a two-step process demonstrated a nearly 8% power conversion efficiency due to efficient charge separation by a cascade of junctions and retarding charge recombination by a void-free capping layer. The stability of the inorganic solar cell was also tested with a little decay observed within ca. 100 h.
Co-reporter:Feng Liu, Jun Zhu, Linhua Hu, Bing Zhang, Jianxi Yao, Md. K. Nazeeruddin, Michael Grätzel and Songyuan Dai
Journal of Materials Chemistry A 2015 vol. 3(Issue 12) pp:6315-6323
Publication Date(Web):03 Feb 2015
DOI:10.1039/C5TA00028A
Transition metal chalcogenide crystalline films FeSe2, Cu1.8S, and CuSe have been deposited from solution by drop casting their dissolved inks onto a conductive substrate, followed by a mild thermal treatment. We demonstrate that the resulting chalcogenide films exhibit an excellent catalytic activity and function as highly efficient counter electrodes (CEs) for dye- and quantum dot-sensitized solar cells (DSCs and QDSCs). In particular, the FeSe2 and CuSe films produced herein with novel morphologies show better catalytic activity than that of the conventional Pt coated CE used in DSCs and Cu2S in QDSCs, respectively. Ensuing devices present an improved photovoltaic performance with maximum values of 9.10% for DSCs and 4.94% for QDSCs, comparable to those based on Pt and Cu2S CEs. The efficient CE materials developed here from such a facile and scalable route offer strong potential for a broader solar cell application that requires low-cost and large-scale production.
Co-reporter:Mei Lv, Jun Zhu, Yang Huang, Yi Li, Zhipeng Shao, Yafeng Xu, and Songyuan Dai
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 31) pp:17482
Publication Date(Web):July 17, 2015
DOI:10.1021/acsami.5b05104
To develop novel hole-transporting materials (HTMs) is an important issue of perovskite solar cells (PSCs), especially favoring the stability improvement and the cost reduction. Herein, we use ternary quantum dots (QDs) as HTM in mesoporous TiO2/CH3NH3PbI3/HTM/Au solar cell, and modify the surface of CuInS2 QDs by cation exchange to improve the carrier transport. The device efficiency using CuInS2 QDs with a ZnS shell layer as HTM is 8.38% under AM 1.5, 100 mW cm–2. The electrochemical impedance spectroscopy suggested that the significantly enhanced performance is mainly attributed to the reduced charge recombination between TiO2 and HTM. It paves a new pathway for the future development of cheap inorganic HTMs for the high efficiency PSCs.Keywords: CuInS2; hole-transporting materials; interface recombination; perovskite solar cells; quantum dots
Co-reporter:Zhongguan Liang, Weiqing Liu, Jun Chen, Linhua Hu, and Songyuan Dai
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 2) pp:1100
Publication Date(Web):December 17, 2014
DOI:10.1021/am506101z
After injection of electrolyte, the internal three-dimensional solid–liquid penetration system of dye-sensitized solar cells (DSCs) can take a period of time to reach “mature” state. This paper studies the changes of microscopic processes of DSCs including TiO2 energy-level movement, localized state distribution, charge accumulation, electron transport, and recombination dynamics, from the beginning of electrolyte injection to the time of reached mature state. The results show that the microscopic dynamics process of DSCs exhibited a time-dependent behavior and achieved maturity ∼12 h after injecting the electrolyte into DSCs. Within 0–12 h, several results were observed: (1) the conduction band edge of TiO2 moved slightly toward negative potential direction; (2) the localized states in the band gap of TiO2 was reduced according to the same distribution law; (3) the transport resistance in TiO2 film increased, and electron transport time was prolonged as the time of maturity went on, which indicated that the electron transport process is impeded gradually; (4) the recombination resistance at the TiO2/electrolyte (EL) interface increases, and electron lifetime gradually extends, therefore, the recombination process is continuously suppressed. Furthermore, results suggest that the parameters of EL/Pt-transparent conductive oxide (TCO) interface including the interfacial capacitance, electron-transfer resistance, and transfer time constant would change with time of maturity, indicating that the EL/Pt-TCO interface is a potential factor affecting the mature process of DSCs.Keywords: dye-sensitized solar cell; electrochemical impedance spectroscopy; mature process; microscopic dynamics
Co-reporter:Feng Liu, Jun Zhu, Yafeng Xu, Li Zhou, Yi Li, Linhua Hu, Jianxi Yao and Songyuan Dai
Chemical Communications 2015 vol. 51(Issue 38) pp:8108-8111
Publication Date(Web):10 Mar 2015
DOI:10.1039/C5CC00772K
Solution-deposited SnSe and SnS thin films demonstrate excellent electrocatalytic activity toward the triiodide reduction in dye-sensitized solar cells (DSCs), even better than that of the conventional noble Pt electrode used in DSCs. An enhanced photovoltaic efficiency with the maximum value of 9.4% was thus achieved, higher than that with Pt (9.0%).
Co-reporter:Feng Liu, Jun Zhu, Yi Li, Junfeng Wei, Mei Lv, Yafeng Xu, Li Zhou, Linhua Hu, Songyuan Dai
Journal of Power Sources 2015 Volume 292() pp:7-14
Publication Date(Web):1 October 2015
DOI:10.1016/j.jpowsour.2015.05.038
•A new solution-based route to high crystalline quality CTSe thin film is presented.•Potential viability of CTSe for catalytic use in polysulfide system is demonstrated.•CTSe exhibits excellent electrocatalytic activity for S2−/Sn2− redox couple.•QDSCs using CTSe CE show comparable efficiency relative to Cu2S.We present herein a new facile solution-phase route to the growth of high crystalline quality Cu2SnSe3 (CTSe) thin film on a conductive substrate and demonstrate for the first time its promising application as an efficient counter electrode (CE) in liquid-junction quantum dot-sensitized solar cells (QDSCs). Dissolving Cu2Se and SnSe powders in the thiol-amine mixture forms a homogeneous CTSe molecular precursor solution. High-quality crystalline CTSe thin film electrode can be readily deposited from the above solution via a low-temperature heating step. Powder X-ray diffraction experiment combined with Raman spectroscopy revealed that the resulting CTSe has the monoclinic crystal structure. Electrochemical measurements, impedance spectroscopy, Tafel polarization, and cyclic voltammetry verified that CTSe possesses fascinating electrocatalytic activity for S2−/Sn2− redox couple in aqueous polysulfide electrolyte solution, and is superior to the traditional electrocatalyst, Pt, both in catalytic activity and in electrochemical stability under prolonged potential cycling, rationalizing the improved solar cell device performance, i.e., QDSCs employing CTSe CE showed more than a two-fold improvement in power conversion efficiency relative to that of Pt-based cells. The excellent catalytic performance along with the ease of solution processing of these earth-abundant CTSe materials make them a distinctive choice among the various CEs studied.
Co-reporter:Weiqing Liu, Jun Chen, Minggang Chai, Zhongguan Liang, Linhua Hu, Songyuan Dai
Electrochimica Acta 2015 Volume 165() pp:85-91
Publication Date(Web):20 May 2015
DOI:10.1016/j.electacta.2015.02.238
Composed of sub-micron TiO2 particles, the scattering layer covers the top of the optical active layer composed of nano TiO2 particles to together form the “optical active layer/scattering layer”, the double-layer skeleton microstructure of the photoanode in dye sensitized solar cells (DSCs). This type of photoanode extends the optical path of the incident light and enables repeated absorption of light, resulting in increase in the efficiency of DSCs. Since the optical active layer and scattering layer are integrally sintered and the materials have homogeneity, the study on influence of the scattering layer on the photoanode performance should not be limited to the optical properties. This paper investigates the non-optical properties of the scattering layer in detail, including electronic distribution, charge accumulation, transport/recombination dynamics, as well as the inherent influence of these properties on DSCs. The results show that the scattering layer can not only reflect light simply, but also has unique the electronic properties. Just like the optical active layer, the scattering layer can accommodate electrons. The electron transit time and lifetime in the scattering layer are faster than those in the optical active layer after the influence caused by the conduction band movement is removed. It is reasonable to infer that the main transport process occurs in the optical active layer and the recombination rate of the scattering layer is higher than that of the optical active layer within a certain bias range in a DSCs with the double-layer skeleton microstructure of the photoanode. So, the recombination process of electrons through the scattering layer may be a potential recombination path under the working conditions.
Co-reporter:Yi Li, Jun Zhu, Yang Huang, Feng Liu, Mei Lv, Shuanghong Chen, Linhua Hu, Junwang Tang, Jianxi Yao and Songyuan Dai
RSC Advances 2015 vol. 5(Issue 36) pp:28424-28429
Publication Date(Web):09 Mar 2015
DOI:10.1039/C5RA01540E
Perovskite solar cells with mesoporous metal oxide films as scaffold layers have demonstrated very impressive advances in performance recently. Here, we present an investigation into mesoporous perovskite solar cells incorporating mesoporous SnO2 nanoparticle films as electron-transporting materials and scaffold layers, to replace traditional mesoporous TiO2 films. We have optimized the SnO2 film thickness and treated the surface of the SnO2 film with an aqueous solution of TiCl4. Due to the TiCl4 treatment the recombination process was significantly retarded. The short-circuit current density (Jsc) and open-circuit voltage (Voc) reached nearly 18 mA cm−2 and 1 V, respectively. Consequently, the power conversion efficiency of the device with the SnO2 film exceeded 10%.
Co-reporter:Changneng Zhang, Ling Jiang, Li’e Mo, Yang Huang, Shangfeng Xiao, Linhua Hu, Shuanghong Chen, Zhipeng Huo, Fantai Kong, Songyuan Dai
Journal of Electroanalytical Chemistry 2015 Volume 736() pp:107-111
Publication Date(Web):1 January 2015
DOI:10.1016/j.jelechem.2014.10.029
•The shift of Vfb of TiO2 electrode is obviously dependent on the surface reaction.•The properties of TiO2 thin-film obviously impact on the shift of Vfb.•The mechanism of Vfb shift in substitutional dopant into TiO2 lattice is proposed.•N and Mg2+ incorporation into titania lattice result in the negative shift of Vfb.In this work, conduction band edge (Vfb) shift in the nanostructure TiO2 electrodes was investigated in detail using photoelectrochemical methods. The density of conduction band at a given applied potential was affected by the electrochemical reaction on the nano-TiO2 surface and spectroelectrochemistry techniques could determinate Vfb from the measured absorbance as a function of applied potential for the TiO2 electrodes. It is indicated that the increased thickness of TiO2 electrodes led to the positive shift of conduction band edge (Vfb), which resulted in the increased reaction rate of electrochemical reaction in nanostructure TiO2 electrode. The N and Mg2+ incorporation into the TiO2 lattice resulted in the negative conduction band edge, and an analytical dependence of the photoelectrochemical methods on the TiO2 surface performance found that the negative shift of Vfb could be attributed to the substitutional dopant into TiO2 lattice to decrease the electrochemical surface reaction in the photoelectrodes.
Co-reporter:Yi Li;Jun Zhu;Hui Chu;Junfeng Wei;Feng Liu;Mei Lv
Science China Chemistry 2015 Volume 58( Issue 9) pp:1489-1493
Publication Date(Web):2015 September
DOI:10.1007/s11426-015-5348-3
Semiconductor sensitized solar cells (SSSCs) are promising candidates for the third generation of cost-effective photovoltaic solar cells and it is important to develop a group of robust, environment friendly and visible-light-responsive semiconductor sensitizers. In this paper, we first synthesized bismuth vanadate (BiVO4) quantum dots by employing facile successive ionic layer adsorption and reaction (SILAR) deposition technique, which we then used as a sensitizer for solar energy conversion. The preliminary optimised oxide SSSC showed an efficiency of 0.36%, nearly 2 orders of magnitude enhancement compared with bare TiO2, due to the narrow bandgap absorption of BiVO4 quantum dots and intimate contact with the oxide substrate. This result not only demonstrates a simple method to prepare BiVO4 quantum dots based solar cell, but also provides important insights into the low bandgap oxide SSSCs.
Co-reporter:Meng Wang;Xu Pan;Jian Chen
Science China Chemistry 2015 Volume 58( Issue 12) pp:1884-1890
Publication Date(Web):2015 December
DOI:10.1007/s11426-015-5390-1
In this study, a series of imidazolium salts with different N3-substituents (3-position: methyl, vinyl, ethyl, n-propyl, n-butyl)-based ionic-liquid crystals with iodide as counterion (ILCs) are synthesized and characterized, with the aim of regulating the mesogenic properties of imidazolium salts. The imidazolium salts-based ionic-liquid crystals are characterized by thermal analysis, polarized optical microscopy, X-ray powder diffraction, and single-crystalline diffraction. Liquid crystalline phase with a Smectic A phase interdigitated bilayer structure is observed. The mesophase temperature range decreases with the increase of the alkyl chain length of N3-substituent. While when vinyl is attached to the N3 position, intermolecular π-π interactions are formed in adjacent layers, which exert a positive effect on the formation of mesophase. The layer-spacing of imidazolium salts keeps increasing with the increase of the alkyl chain length attached to both the N1 and N3 positions, and gradually decreases with the increasing temperature in liquid crystalline phase. The 1-alkyl-3-vinylimidazolium salt has the smallest layer-spacing, due to the intermolecular π-π interactions between the vinyl and imidazolium rings in adjacent layers.
Co-reporter:ZhiPeng Shao, Xu Pan, HaiWei Chen, Li Tao, WenJun Wang, Yong Ding, Bin Pan, Shangfeng Yang and Songyuan Dai
Energy & Environmental Science 2014 vol. 7(Issue 8) pp:2647-2651
Publication Date(Web):22 May 2014
DOI:10.1039/C4EE01315H
A novel polymer based photocathode with a secondary porous structure was developed for tandem dye-sensitized solar cells (pn-DSCs). We adopt a narrow band gap polymer PCPDTBT as the light absorber in the photocathode. Complementary absorption was realized in pn-DSCs by sandwiching the photocathode with a typical TiO2 photoanode. The resulting tandem devices achieved a panchromatic absorption and a power conversion efficiency of 1.30%, which demonstrates the great potential of the polymer based photocathode for pn-DSCs.
Co-reporter:Wenjun Wang, Xu Pan, Weiqing Liu, Bing Zhang, Haiwei Chen, Xiaqin Fang, Jianxi Yao and Songyuan Dai
Chemical Communications 2014 vol. 50(Issue 20) pp:2618-2620
Publication Date(Web):28 Jan 2014
DOI:10.1039/C3CC49175G
The FeSe2 films with controllable morphologies (including 3D flower-like and sphere-shaped) have been applied as the counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). It is found that 3D flower-like FeSe2 CEs perform comparably to conventional platinum CEs (power conversion efficiencies of 8.00 and 7.87%, respectively).
Co-reporter:Li Tao, Zhipeng Huo, Songyuan Dai, Jun Zhu, Changneng Zhang, Yang Huang, Bing Zhang, Jianxi Yao
Journal of Power Sources 2014 Volume 262() pp:444-450
Publication Date(Web):15 September 2014
DOI:10.1016/j.jpowsour.2014.03.128
•A diamide derivative is used as LMOG to gelate liquid electrolyte.•A novel and intrinsic stable gel electrolyte with high Tgel is prepared.•The kinetic processes of electron transport and recombination are investigated.•The QS-DSSC exhibits excellent stability during the accelerated aging tests.High stability is a significant target for practical applications of dye-sensitized solar cells. 2-(1-oxododecyl)hydrazide, a diamide derivative, is synthesized and applied in quasi-solid-state dye-sensitized solar cells (QS-DSSCs) as a low molecular mass organogelator (LMOG). It is noteworthy that the transition temperature from gel state to liquid state (Tgel) of this gel electrolyte is 125.2 °C, which ensures the gel state of the electrolyte at the DSSC operating temperature. The influences of the gel electrolyte on the kinetic processes of electron transport and recombination are investigated. The diffusion of redox species in the gel electrolyte is hindered by the crosslinked network, and the decreased electron recombination lifetime indicates an increased electron recombination in QS-DSSC. Significantly, the QS-DSSC exhibits excellent thermal and light-soaking stabilities during accelerated aging tests for 1000 h. Especially, there is almost no change in the short-circuit current density (Jsc) in the QS-DSSC, while the Jsc of the liquid electrolyte based DSSC decreases to 79–90% of their initial values. These results are very important for the application and commercialization of DSSCs.2-(1-Oxododecyl)hydrazide is successfully developed as a low molecular mass organogelator to gelate the 3-methoxypropionitrile based liquid electrolyte. The influence of gelation on the kinetic processes of electron transport and recombination and the photovoltaic performance of the quasi-solid state dye sensitized solar cell (QS-DSSC) are investigated in detail. Significantly, the QS-DSSC exhibits excellent stability during the accelerated aging test.
Co-reporter:Guohua Wu, Fantai Kong, Yaohong Zhang, Xianxi Zhang, Jingzhe Li, Wangchao Chen, Changneng Zhang, Songyuan Dai
Dyes and Pigments 2014 Volume 105() pp:1-6
Publication Date(Web):June 2014
DOI:10.1016/j.dyepig.2014.01.012
•Three triphenylamine dyes with different dual-channel anchoring groups are applied in dye-sensitized solar cells.•The light absorption capacity of TPACR2 is better than that for TPAC1 and TPAR2.•Photovoltaic performance of TPACR2-based DSSC is dramatically enhanced compared with TPAC1 and TPAR2.Three di-anchoring triphenylamine dyes, which were coded as TPAC1, TPAR2 and TPACR2, were designed and synthesized for dye-sensitized solar cell application. The structural modification effect of different anchoring groups on photophysical, electrochemical and photovoltaic properties of the related DSSCs was extensively investigated. With the variation from cyanoacetic acid via rhodanine-3-acetic acid to co-rhodanine units, the molar extinction coefficients of the maximum absorption wavelength for the three dyes gradually increase due to the extension of π system. In comparison with that for TPAC1 and TPAR2, DSSC based on dye TPACR2 with double co-rhodanine groups shows the best overall conversion efficiency of 4.64% with simultaneous enhancement of photocurrent and photovoltage, which is attributed to the higher molar extinction coefficient (6.5 × 104 M−1 cm−1), broader absorption spectra, broader IPCE spectra and longer electron lifetime.
Co-reporter:Jingzhe Li, Fantai Kong, Guohua Wu, Wangchao Chen, Fuling Guo, Bing Zhang, Jianxi Yao, Shangfeng Yang, Songyuan Dai, Xu Pan
Synthetic Metals 2014 Volume 197() pp:188-193
Publication Date(Web):November 2014
DOI:10.1016/j.synthmet.2014.09.023
•Di-n-alkylphosphinic acids were used as coadsorbents with indoline sensitizer D149.•We examine the effect of the different alkyl chains on DSCs performance.•The device performance was obviously enhanced with increasing the alkyl chain length.•The device efficiency was increased by about 10% with DHdPA co-adsorbed.Three di-n-alkylphosphinic acids (DPAs) with different chain lengths (1, 8, 16) were adopted as coadsorbents in dye-sensitized solar cells (DSCs) with organic sensitizer D149. The adsorption behavior of these coadsorbents on nanoporous TiO2 surface through POTi bond was confirmed by FT-IR spectra. And the performance of all devices was detected on the basis of photocurrent–voltage (J–V) characteristics and electrochemical impedance spectroscopy (EIS). It was found that the amount of dye adsorption gradually decreased with increasing alkyl chain length of DPAs, which was contributed to the competitive adsorption between dye D149 and coadsorbents. In spite of this, di-n-hexadecylphosphinic acid (DHdPA) performed best both in the improvement of short-circuit current density (Jsc) and open-circuit voltage (Voc). The increase of open-circuit photovoltage was ascribed to the negative movement of the conduction band edge and the retardation of electron recombination. Although the dye adsorption amount reduced to a great degree, the break up of dye aggregation mainly contribute to the enhancement of short-circuit current density. The overall conversion efficiency was further improved from 5.53% to 6.09% with DHdPA as the coadsorbent for D149 based device.
Co-reporter:Aiying Pang, Xun Sun, Hongcheng Ruan, Yafeng Li, Songyuan Dai, Mingdeng Wei
Nano Energy 2014 Volume 5() pp:82-90
Publication Date(Web):April 2014
DOI:10.1016/j.nanoen.2014.02.007
•Hierarchical microspheres constructed from TiO2 cores and SnO2 shells have been fabricated.•The products were formed via a self-assembly process accompanied by the Kirkendall effect.•C106 dye sensitized TiO2@SnO2 microspheres exhibited an efficiency of 6.24%.Hierarchical microspheres constructed from a TiO2 core and a SnO2 shell have been successfully fabricated using a one-step solvothermal method. The synthesized products were characterized by XRD, SEM, TEM and FT-IR measurements. It was found that the concentration of precursor Sn4+ in the reaction system plays a key role in the formation of the hierarchical microspheres. The core–shell microspheres of TiO2@SnO2 were formed by a self-assembly process, accompanied by the Kirkendall effect. These core–shell microspheres of TiO2@SnO2 have been used for the first time as the electrode for C106 dye-sensitized solar cells; they exhibited an efficiency of 6.24%. This might be attributed to large surface area and hierarchical structure of the microspheres, leading to light scattering, an increase of dye adsorption, a suppression of charge recombination and prolonging the electron lifetime.Hierarchical microspheres constructed from a TiO2 core and a SnO2 shell have been fabricated using a facile solvothermal method. The concentration of precursor Sn4+ in the reaction system plays a key role in the formation of the hierarchical microspheres. These core–shell microspheres of TiO2@SnO2 have been used for the first time as the electrode for C106 dye-sensitized solar cells, exhibiting an efficiency of 6.24%.
Co-reporter:Yaohong Zhang, Jun Zhu, Feng Liu, Guohua Wu, Junfeng Wei, Linhua Hu, Yang Huang, Changneng Zhang, Junwang Tang, Songyuan Dai
Journal of Photochemistry and Photobiology A: Chemistry 2014 Volume 281() pp:53-58
Publication Date(Web):1 May 2014
DOI:10.1016/j.jphotochem.2014.02.012
•In2S3 sensitized solar cells were prepared by a low cost chemical bath deposition (CBD) methodology.•Amorphous Y2O3 layer was firstly used as a passivation layer in quantum dot sensitized solar cells.•A high FF of 65% was achieved in the solar cell.In2S3 as a semiconductor sensitizer has the advantage of non-toxicity, good stability and high carrier mobility. In this paper, In2S3 sensitized solar cells were firstly prepared by a low cost chemical bath deposition methodology and then fully characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The ZnS passivation layer modified the In2S3 sensitized TiO2 photoanodes and resulted into enhanced Jsc and FF but a lowered Voc compared with the original solar cell under AM1.5, 1 sun. More importantly, we have enhanced all FF, Jsc and Voc when amorphous Y2O3 was used to passivate the In2S3 sensitized solar cells, achieving the highest FF of 65% among the reported similar solar cells.In2S3 sensitized solar cells were prepared by a low cost chemical bath deposition (CBD) methodology. Amorphous Y2O3 layer was used as a passivation layer in the solar cells and dramatically improved the performance.
Co-reporter:Dr. Shuan Wang;Yong Ding;Dr. Sichao Xu; Yunxia Zhang; Guanghai Li; Linhua Hu; Songyuan Dai
Chemistry - A European Journal 2014 Volume 20( Issue 17) pp:4916-4920
Publication Date(Web):
DOI:10.1002/chem.201304963
Abstract
A facile route to synthesize amorphous TiO2 nanospheres by a controlled oxidation and hydrolysis process without any structure-directing agents or templates is presented. The size of the amorphous TiO2 nanospheres can be easily turned from 20 to 1500 nm by adjusting either the Ti species or ethanol content in the reaction solution. The phase structure of nanospheres can be controlled by hydrothermal treatment. The TiO2 nanospheres show excellent size-dependent light-scattering effects and can be structured into a light-harvesting layer for dye-sensitized solar cells with a quite high power conversion efficiency of 9.25 %.
Co-reporter:Guohua Wu ; Fantai Kong ; Yaohong Zhang ; Xianxi Zhang ; Jingzhe Li ; Wangchao Chen ; Weiqing Liu ; Yong Ding ; Changneng Zhang ; Bing Zhang ; Jianxi Yao
The Journal of Physical Chemistry C 2014 Volume 118(Issue 17) pp:8756-8765
Publication Date(Web):April 11, 2014
DOI:10.1021/jp4124265
A series of triphenylamine-based dyes (TPACR1, TPACR2, and TPACR3) with multiple corhodanine derivatives as acceptors were prepared and examined as sensitizers for dye-sensitized solar cells. The overall conversion efficiencies of DSSCs based on these dyes were in the range of 2.63 to 5.31%, in which TPACR2-based DSSC showed the best photovoltaic performance: a short-circuit current (Jsc) of 15.03 mA·cm–2, an open-circuit voltage (Voc) of 552 mV, and a fill factor (FF) of 0.64, corresponding to an overall efficiency of 5.31% under simulated AM 1.5 solar irradiation (100 mW·cm–2). Compared with monoanchoring TPACR1 dye and trianchoring TPACR3 dye, dianchoring TPACR2 dye had a relatively slower charge recombination rate between injected electrons and triphenylamine dye cations, which was indicated by transient absorption kinetics Furthermore, the suppression of the charge recombination between injected electron and the I3– in the electrolyte lead to the longer electron lifetime observed with the DSSC based on the TPACR2 dye. In comparison with the TPACR1 and TPACR3 dye, the TPACR2 dye showed the higher overall conversion efficiency with simultaneous enhancement of photocurrent and photovoltage.
Co-reporter:Li Tao ; Zhipeng Huo ; Songyuan Dai ; Yong Ding ; Jun Zhu ; Changneng Zhang ; Bing Zhang ; Jianxi Yao ; Mohammad K. Nazeeruddin ;Michael Grätzel
The Journal of Physical Chemistry C 2014 Volume 118(Issue 30) pp:16718-16726
Publication Date(Web):March 7, 2014
DOI:10.1021/jp412717y
Stable quasi-solid-state dye-sensitized solar cells (DSCs) were fabricated by using room-temperature molten salts (1-methyl-3-hexyl-imidazolium iodide), and a series of diamine derivatives with different lengths of alkyl chain as low molecular mass organogelators (LMOGs). The number of methylene (−CH2−) units between the two amide carbonyl groups in the gelator molecule has significant influence on the charge transport property of gel electrolyte, and the kinetic processes of the electron transport and recombination. Less compact networks of the ionic liquid gel electrolytes containing odd-numbered −CH2– gelator facilitate the diffusion of I3– and I–. Also, the odd-numbered −CH2– gelators-based DSCs exhibit longer electron recombination lifetime and a higher open circuit potential (Voc) compared with the DSCs based on even-numbered −CH2– gelators; consequently, the photovoltaic performances of DSCs based on odd-numbered −CH2– gelators are much better than those even-numbered −CH2– gelators. Remarkably, the results of the accelerated aging tests showed that the ionic liquid gel electrolyte-based DSCs could retain 93%–99% of their initial photoelectric conversion efficiencies (η) under heat at 60 °C, and 100% of their initial photoelectric conversion efficiencies under one sun light soaking with UV cutoff filter at 50 °C for 1000 h. This excellent long-term stability of quasi-solid-state DSCs is very important for application and commercialization of DSCs.
Co-reporter:Feng Liu, Jun Zhu, Junfeng Wei, Yi Li, Linhua Hu, Yang Huang, Oshima Takuya, Qing Shen, Taro Toyoda, Bing Zhang, Jianxi Yao, and Songyuan Dai
The Journal of Physical Chemistry C 2014 Volume 118(Issue 1) pp:214-222
Publication Date(Web):December 18, 2013
DOI:10.1021/jp410599q
We present an effective way to boost the as-synthesized CdSe quantum dot-sensitized solar cells (QDSSCs) performance by introducing an inorganic ligand exchange strategy into this traditional system. Inorganic ligand exchange, to the best of our knowledge, is designed for the first time for CdSe-based QDSSCs, and it features low-cost, easy operation, and repeatable process. The route involves the direct deposition of the CdSe quantum dots (QDs), which were initially capped with trioctylphosphine (TOP) ligands onto mesoporous TiO2 nanocrystalline electrodes and followed by a post-treatment of the sensitized photoanode films with sulfur ions (S2–) solution. Here, changes in surface chemical status of CdSe QDs during the inorganic ligand exchange process and the influence of ligand exchange on the electron’s ultralfast transfer between nanoparticles were investigated through XPS and femtosecond transient grating techniques, respectively. With the inorganic ligand passivated CdSe QDs, the QDSSCs exhibited a power conversion efficiency of 3.17% (AM1.5G, 100 mW/cm2), 65% higher than that of the organic ligands capped QDSSCs.
Co-reporter:Molang Cai, Xu Pan, Weiqing Liu, Jiang Sheng, Xiaqin Fang, Changneng Zhang, Zhipeng Huo, Huajun Tian, Shangfeng Xiao and Songyuan Dai
Journal of Materials Chemistry A 2013 vol. 1(Issue 15) pp:4885-4892
Publication Date(Web):31 Jan 2013
DOI:10.1039/C3TA00835E
Electron recombination and dye aggregation at the dyed-TiO2/electrolyte interface are still problems in dye-sensitized solar cell (DSC) research. In this paper, tributyl phosphate (TBpp) as a special additive to modify the dyed-TiO2/electrolyte interface was introduced to enhance the photovoltaic performance. The adsorption mode of TBpp and the interaction between cis-dithiocyanate-N,N′-bis-(4-carboxylate-4-tetrabutylammonium carboxylate-2,2′-bi-pyridine) ruthenium(II) (N719) and TBpp were investigated. It was found that one TBpp parent molecule split into several smaller fragments and formed four anchoring modes on the TiO2 surface. It was very interesting that the molecular cleavage of TBpp and adsorption of N719 assisted each other on the sensitized TiO2 surface. The fragments distributed around N719 result in steric hindrance, consequently hydrogen-bonding among N719 molecules was decreased. The unstable type N719 transformed into stable type N719 accompanied by molecular cleavage of TBpp and the N719 aggregation was reduced. Furthermore, these new fragments were multiply adsorbed on the non-sensitized TiO2 surface to form an insulating barrier layer. Therefore, the electron recombination at the dyed-TiO2/electrolyte interface was restrained. Besides the change of surface configuration, the TiO2 band edge negatively shifted and the rate of electron transport in the TiO2 films decreased with the addition of TBpp. As a result, an increase in the photoelectric conversion efficiency (η) was obtained of almost 40%.
Co-reporter:Haiwei Chen, Xu Pan, Weiqing Liu, Molang Cai, Dongxing Kou, Zhipeng Huo, Xiaqin Fang and Songyuan Dai
Chemical Communications 2013 vol. 49(Issue 66) pp:7277-7279
Publication Date(Web):30 Apr 2013
DOI:10.1039/C3CC42297F
A simple solution-processing method was employed to fabricate panchromatic mp-TiO2/CH3NH3PbI3/P3HT–MWNT/Au solar cells. MWNTs in a P3HT–MWNT composite acted as efficient nanostructured charge transport tunnels and induce crystallization of P3HT, hence significantly enhancing the conductivity of the composite. The fill factor of the hybrid solar cells was greatly enhanced by 26.7%.
Co-reporter:Liu Wei-Qing, Liang Zhong-Guan, Kou Dong-Xing, Hu Lin-Hua, Dai Song-Yuan
Electrochimica Acta 2013 Volume 88() pp:395-403
Publication Date(Web):15 January 2013
DOI:10.1016/j.electacta.2012.10.061
The special “sandwich” structure of dye-sensitized solar cells (DSC) provides multiple electron transfer interfaces and two charge transport channels inside the cell. Some processes that take place on such interfaces have generally been left unnoticed when electrochemical impedance spectroscopy was used to study charge transfer process on these interfaces and charge transport process in these channels. In this paper, by dramatically varying the values of parameters of the impedance components of a DSC full-interface equivalent circuit containing 4 interfaces and 2 layers, we have studied the interaction between the charge interface transfer impedance and transport impedance and its effect on the overall impedance of the cell. We have also conducted a detailed study of the impedance characteristics of the internal charge transport, transfer, and collection processes of DSC. The results show that some previously ignored interfaces, such as the TCO/TiO2 and TCO/EL interfaces, as well as Nernst diffusion impedance in the electrolyte solution, can also influence the overall impedance characteristics of DSC under certain circumstances.Highlights► Model the interaction among multiple interface processes of charge transport and transfer in DSC with wide frequency range. ► Diagnostic changes of impedance behavior over a wide range of changing conditions in DSC. ► The TCO/TiO2 and TCO/EL interfaces, as well as Nernst diffusion impedance can also influence the overall impedance characteristics of DSC under certain circumstances.
Co-reporter:Xu Pan;Meng Wang;XiaQing Fang;ChangNeng Zhang;ZhiPeng Huo
Science China Chemistry 2013 Volume 56( Issue 10) pp:1463-1469
Publication Date(Web):2013 October
DOI:10.1007/s11426-013-4904-y
A room temperature ionic liquid crystal, 1-dodecyl-3-ethylimidazolium iodide (C12EImI), and an ionic liquid, 1-decyl-3-ethylimidazolium iodide (C10EImI), have been synthesized, characterized and employed as the electrolyte for dye-sensitized solar cells (DSSC). The physicochemical properties show that a smectic A (SmA) phase with a lamellar structure is formed in C12EImI. Both C12EImI and C10EImI have good electrochemical and thermal stability facilitating their use in DSSC. The steady-state voltammograms reveal that the diffusion coefficient of I3− in C12EImI is larger than that in C10EImI, which is attributed to the existence of the SmA phase in C12EImI. Because the iodide species are located between the layers of imidazolium cations in C12EImI, exchange reaction-based diffusion is increased with a consequent increase in, the overall diffusion. The electrochemical impedance spectrum reveals that charge recombination at the dyed TiO2/electrolyte interface of a C12EImI-based DSSC is reduced due to the increase in I3− diffusion, resulting in higher open-circuit voltage. Moreover, both short-circuit current density and fill factor of the C12EImI based DSSC increase, as a result of the increasing transport of I3− in C12EImI. Consequently, the photoelectric conversion efficiency of C12EImI-based DSSC is higher than that of the C10EImI-based DSSC.
Co-reporter:XueChao Yu;Jun Zhu;Feng Liu;JunFeng Wei;LinHua Hu
Science China Chemistry 2013 Volume 56( Issue 7) pp:977-981
Publication Date(Web):2013 July
DOI:10.1007/s11426-012-4810-8
Cu2S film onto FTO glass substrate was obtained to function as counter electrode for polysulfide redox reactions in CdS/CdSe co-sensitized solar cells by sintering after spraying a metal chalcogenide complex, N4H9Cu7S4 solution. Relative to Pt counter electrode, the Cu2S counter electrode provides greater electrocatalytic activity and lower charge transfer resistance. The prepared Cu2S counter electrode represented nanoflower-like porous film which was composed of Cu2S nanosheets on FTO and had a higher surface area and lower sheet resistance than that of sulfided brass Cu2S counter electrode. An energy conversion efficiency of 3.62% was achieved using the metal chalcogenide complex-mediated fabricated Cu2S counter electrode for CdS/CdSe co-sensitized solar cells under 1 sun, AM 1.5 illumination.
Co-reporter:Dongxing Kou, Weiqing Liu, Linhua Hu, Songyuan Dai
Electrochimica Acta 2013 100() pp: 197-202
Publication Date(Web):
DOI:10.1016/j.electacta.2013.03.105
Co-reporter:Guohua Wu, Fantai Kong, Jingzhe Li, Wangchao Chen, Xiaqin Fang, Changneng Zhang, Qianqian Chen, Xianxi Zhang, Songyuan Dai
Dyes and Pigments 2013 99(3) pp: 653-660
Publication Date(Web):
DOI:10.1016/j.dyepig.2013.06.023
Co-reporter:Huajun Tian, Linhua Hu, Changneng Zhang, Lie Mo, Wenxin Li, Jiang Sheng and Songyuan Dai
Journal of Materials Chemistry A 2012 vol. 22(Issue 18) pp:9123-9130
Publication Date(Web):28 Mar 2012
DOI:10.1039/C2JM16896K
This work reports the preparation of N, B codoped TiO2 (N, B–TiO2) electrodes in dye-sensitized solar cells (DSCs) by a facial modified sol–gel method. After the nitrogen and boron dopants incorporated into the TiO2 electrodes, the cubic-like TiO2 nanocrystallites with diameters of 22∼24 nm were obtained efficiently. The back electron transfer of the DSC based on the N, B–TiO2 electrode was studied by measuring the electrochemistry impedance spectra (EIS) and the EIS for the DSCs showed that the enhanced electron lifetime for the dye-sensitized B, N–TiO2 solar cells could be attributed to the formation of an O–Ti–B–N bond in the TiO2 photoelectrode, which retards electron recombination at the dyed N, B–TiO2 photoelectrode/electrolyte interface after N, B codoping as compared to the undoped DSC. We found that a high efficiency of 8.4% for the DSC (active area:4 cm2) based on the N, B–TiO2 anode under 0.2 sun illumination was received. In particular, the photovoltaic performance of the DSC under high temperature conditions (60 °C) and one-sun light soaking over a time of more than 1100 h showed that the DSC based on the N, B–TiO2 electrode exhibited a better stability compared to the undoped DSC. The excellent photoelectrochemical performance could be attributed to the ideal combination of retarded electron recombination and superior energy band structure from the unique N, B–TiO2 particle structure.
Co-reporter:Meng Wang, Xu Pan, Shangfeng Xiao, Changneng Zhang, Wenxin Li and Songyuan Dai
Journal of Materials Chemistry A 2012 vol. 22(Issue 5) pp:2299-2305
Publication Date(Web):12 Dec 2011
DOI:10.1039/C1JM14790K
In this study, a series of binary systems based ionic liquid crystals (ILCs) C12MIm(BF4)yIx (x + y = 1) are prepared by mixing ILCs 1-dodecyl-3-methylimidazolium iodide (C12MImI) and 1-dodecyl-3-methylimidazolium tetrafluoroborate (C12MImBF4), aiming to combine the properties of both C12MImBF4 and C12MImI. Their mesogenic properties are characterized by thermal analysis, polarized optical microscopy, X-ray diffraction as well as anisotropic ionic conductivity measurements. It is found that the smectic A phase with interdigitated bilayer structure is observed in the C12MIm(BF4)yIx series. The binary system C12MIm(BF4)yIx has a larger mesophase temperature range and interdigitated layer spacing than pure C12MImBF4. And the anisotropic ionic conductivity of the binary system, including parallel and perpendicular to smectic layer, is higher than pure C12MImI. Moreover, in binary system C12MIm(BF4)yIx, with the increasing content of C12MImI the ability of the anion to form three dimensional hydrogen bonds increases, resulting in the increase of the mesophase temperature range, interdigitated layer spacing and the decrease of anisotropic ionic conductivity. Furthermore, multi-component system based ILCs are obtained by introducing iodine to the binary system, and the mesophase temperature range is lowered, which is associated with the weak ability of I3− to form hydrogen bond with cations. All these results suggest that we can regulate the mesogenic properties of ILCs as we need by making binary or even multi-component systems.
Co-reporter:Xuechao Yu, Jun Zhu, Yaohong Zhang, Jian Weng, Linhua Hu and Songyuan Dai
Chemical Communications 2012 vol. 48(Issue 27) pp:3324-3326
Publication Date(Web):06 Feb 2012
DOI:10.1039/C2CC17081G
A kind of molecular metal chalcogenide, (N2H4)3(N2H5)4Sn2Se6 complex, was synthesized in the hydrazine solution and employed as the precursors for SnSe2 deposition on TiO2 nanocrystalline porous films. A power conversion efficiency of 0.12% under AM 1.5, 1 sun was obtained for the SnSe2 sensitized TiO2 solar cells.
Co-reporter:Jiang Sheng;LinHua Hu;Li’E Mo;WenXin Li;HuaJun Tian
Science China Chemistry 2012 Volume 55( Issue 3) pp:368-372
Publication Date(Web):2012 March
DOI:10.1007/s11426-011-4362-3
The mechanism of the conversion of titanate nanotubes into nanoribbons is of considerable interest. The details of the transformation processes involved when nanoribbons are produced from a P25 TiO2 powder precursor by alkaline hydrothermal treatment have been investigated systematically by transmission electron microscopy. A multistep attachment model is proposed for the growth at the early stage of coarsening. The treatment duration has a strong effect on the change in product morphology from hollow nanotubes into nanoribbons, since the nanotubes cannot retain their morphology in the strong alkaline solution for extended periods of time. Most of the nanotubes were etched and dissolved, providing the nutrients for subsequent nanoribbon growth. Some stable nanotubes grew spirally internally to form nanowires or became connected together to form rafts which acted as the grains for nanoribbon growth. With increasing hydrothermal time, a large number of nanotubes and other fragments became attached to the grains which began to grow larger and eventually formed the nanoribbons, in a process in which the stepped faces and kinked faces became fused and were eliminated while the flat faces were retained in the nanoribbon morphology.
Co-reporter:Changneng Zhang, Yang Huang, Shuanghong Chen, Huajun Tian, Li’e Mo, Linhua Hu, Zhipeng Huo, Fantai Kong, Yingwen Ma, and Songyuan Dai
The Journal of Physical Chemistry C 2012 Volume 116(Issue 37) pp:19807-19813
Publication Date(Web):August 27, 2012
DOI:10.1021/jp304911u
The interface structure induced by electrolyte cations was found to play a significant role in determining the performance and stability of dye-sensitized solar cells. The trap state density in the nanostructure TiO2 electrodes was affected by the adsorbed 1,2-dimethyl-3-propylimidazolium cation (DMPI+) or alkali cations, such as Li+, Na+, K+, and Cs+, on the dyed TiO2 electrode and was found to increase with the order of decreasing cation radius DMPI+ < Cs+ < K+ < Na+ < Li+. The change in interface structure resulted from the accumulation of the adsorbed cations to increase trap states in the nanostructure TiO2 electrodes during long-term accelerated aging tests. The size effect of electrolyte cations on the cell performance suggested that the reduced surface cations, when small cations penetrated into titania lattice, resulted in a negative shift of the TiO2 conduction band edge and a weaker interaction of Li+ with dyes to obtain the decline in photocurrent and efficiency. The overall efficiency of dye-sensitized solar cells with large DMPI+ in the electrolyte retained over 110% of its initial value after 2100 h. Also, no obvious differences in the efficiency for dye-sensitized solar cells with electrolyte cations, such as Li+, Cs+, and DMPI+, were observed after 1270 h under one sun light soaking in our experiment. The results suggested that large DMPI+ chemisorbed on TiO2 surface could not intercalate into the TiO2 lattice for the enhanced stability of dye-sensitized solar cells in practical application.
Co-reporter:Huajun Tian, Linhua Hu, Wenxin Li, Jiang Sheng, Shuangying Xu and Songyuan Dai
Journal of Materials Chemistry A 2011 vol. 21(Issue 20) pp:7074-7077
Publication Date(Web):18 Apr 2011
DOI:10.1039/C1JM10853K
A facile process to fabricate highly crystalline mesoporous N,B codoped TiO2 is introduced. The N,B codoped TiO2 nanomaterial, which has controlled crystallographic phase, size and unique nanoshape, is successfully applied to an enhanced device for dye-sensitized solar cells (DSCs) with an open-circuit photovoltage of 0.823 V and yielding a high overall energy conversion of 8.4%. A DSC based on the N,B codoped TiO2 electrode shows a competitive photovoltaic performance compared with the undoped DSC, which is attributed to the ideal combination of superior energy band structure and retarded electron recombination from the unique N,B codoped TiO2 particle structure.
Co-reporter:Huajun Tian, Linhua Hu, Changneng Zhang, Shuanghong Chen, Jiang Sheng, Lie Mo, Weiqing Liu and Songyuan Dai
Journal of Materials Chemistry A 2011 vol. 21(Issue 3) pp:863-868
Publication Date(Web):11 Nov 2010
DOI:10.1039/C0JM02941F
Highly crystallized boron-doped anatase TiO2 nanoparticles are prepared by a facile synthetic route and successfully used as the photoanode of dye-sensitized solar cells (DSCs). We have observed that the boron doping could improve the crystallinity of TiO2. Moreover, the highly crystallized anatase boron-doped TiO2 were analyzed by electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy, and the internal resistances of the boron-doped DSCs were studied by measuring the electrochemical impedance spectra (EIS). The improved photocurrent density of the boron-doped DSCs is due to a significant enhancement of IPCE in the range 370–650nm in comparison with that of the undoped DSC. Meanwhile, the energy-conversion efficiency of the cell based on the B-doped TiO2 electrode is enhanced significantly, by about 9%, compared to that of the undoped DSC. Overall, DSCs based on B-doped electrodes show good stability and remain over 95% of their initial efficiency under visible light soaking for more than 2400 h.
Co-reporter:Jiang Sheng, Linhua Hu, Shuangying Xu, Weiqing Liu, Li'e Mo, Huajun Tian and Songyuan Dai
Journal of Materials Chemistry A 2011 vol. 21(Issue 14) pp:5457-5463
Publication Date(Web):17 Feb 2011
DOI:10.1039/C0JM03112G
The influence of TiO2 nanotubes on the charge collection efficiency and the dynamics of electron transport and recombination in dye-sensitized solar cells (DSCs) based on the TiO2 nanotube/nanoparticle composite films were investigated in this paper. Electrochemical impedance spectroscopy was employed to quantify the charge transfer resistance of DSCs. The different transport and recombination properties of DSCs were studied by frequency-resolved modulated photocurrent/photovoltage spectroscopies. It was shown that the electrons had a longer lifetime in the nanotubes and retarded recombination more significantly than in the nanoparticles. But with increasing the amount of nanotube, the electron pathway was extended seriously in these network structures resulting in increased recombination chances. In addition, the 5 wt% nanotube DSC had the highest charge collection efficiency among all the DSCs, which yielded a high photovoltaic conversion efficiency of 9.79% under simulated AM 1.5 sunlight (100 mW cm−2).
Co-reporter:Meng Wang, Xu Pan, Xiaqin Fang, Lei Guo, Changneng Zhang, Yang Huang, Zhipeng Huo, Songyuan Dai
Journal of Power Sources 2011 Volume 196(Issue 13) pp:5784-5791
Publication Date(Web):1 July 2011
DOI:10.1016/j.jpowsour.2011.02.051
In this study, nematic liquid crystal, 4-Cyano-4′-n-heptyloxybiphenyl, is introduced into the poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF) based polymeric gel electrolyte for quasi-solid-state dye-sensitized solar cells (DSC), aiming to improve the photovoltaic performance of DSC. The effects of liquid crystal on the electrochemical behavior of I3−/I− and photovoltaic performance, dynamic response as well as long-term stability of DSC are studied in detail. It is found that although the addition of liquid crystal would hinder the charge transport in the electrolyte, it could still fulfill the requirements of the photocurrent for DSC. More important, a significant increase in the photocurrent density for DSC is observed when liquid crystal is introduced into PVDF based polymeric gel electrolyte, resulting in the higher photoelectric conversion efficiency. The large increase in short-circuit photocurrent density could be attributed to the higher light harvesting efficiency, which is caused by the effective formation of light trapping scheme in electrolyte due to the addition of liquid crystal. Besides, at-rest long-term stability shows that when liquid crystal is introduced into PVDF based polymeric gel electrolyte, DSC could retain over 92% of its initial photoelectric conversion efficiency value after 1000 h, exhibiting relatively better stability.Graphical abstractHighlights► Light trapping has been extended to the field of polymeric gel electrolyte for DSC. ► Liquid crystal contributes to the formation of light trapping scheme. ► Light harvesting efficiency of DSC is enhanced by trapping light through electrolyte. ► Liquid crystal also contributes to the stability of DSC.
Co-reporter:Yingtong Tang, Xu Pan, Changneng Zhang, Linhua Hu, Fantai Kong, Songyuan Dai
Electrochimica Acta 2011 Volume 56(Issue 9) pp:3395-3400
Publication Date(Web):30 March 2011
DOI:10.1016/j.electacta.2010.11.007
The electrochemical behaviors of the tri-iodide (I3−)/iodide (I−) redox couple of symmetric cells were investigated by cyclic voltammetry, steady-state polarization, chronocoulometry, and electrochemical impedance spectroscopy. 1,3-Dialkylimidazolium cations affected the characteristics of the Pt electrode/electrolyte interface by adsorbing on the Pt electrode, as a result of electrostatic interactions, and further affected the reduction of I3− on the Pt electrode. Capacitance of the double layers of the Pt electrode/electrolyte interface was chiefly determined by capacitance of the compact layer according to the Helmoholtz theory.
Co-reporter:Jiang Sheng, Linhua Hu, Wenxin Li, Li’e Mo, Huajun Tian, Songyuan Dai
Solar Energy 2011 Volume 85(Issue 11) pp:2697-2703
Publication Date(Web):November 2011
DOI:10.1016/j.solener.2011.08.009
The morphological evolution of specimen taken out after the different duration in TiCl3 solution was investigated by field emission scanning electron microscopy (FE-SEM). The rutile TiO2 splitting microspheres may be formed by the splitting crystal growth mechanism through the multistep process. The microsphere composed of the 20 nm width nanorods was in the range of 1.5–2.5 μm in the diameter. The dye-sensitized solar cell (DSC) based on the microspheres received 3.57% conversion efficiency under simulated AM 1.5 (100 mW/cm2) solar illumination, which exhibited remarkably higher charge collection efficiency and light scattering compared to that of P25. Electrochemical impedance spectroscopy (EIS) measurement revealed that impedance resistance at the surface of single-crystalline rutile TiO2 splitting microspheres was 6 times larger than that of P25 nanoparticles, indicating electron recombination was significantly retarded.Highlights► Growth of rutile splitting microspheres through multistep splitting and attachment. ► Microspheres efficiently scattered light. ► Electrolyte easily diffused in microsphere film. ► High charge collection efficiency in DSC based on microsphere film. ► Improve photovoltaic performance of DSC made from microsphere film.
Co-reporter:Lei Guo, Xu Pan, Changneng Zhang, Meng Wang, Molang Cai, Xiaqin Fang, Songyuan Dai
Journal of Molecular Liquids 2011 Volume 158(Issue 2) pp:75-79
Publication Date(Web):15 January 2011
DOI:10.1016/j.molliq.2010.10.011
A novel series of hydrophobic room temperature ionic liquids based on six cyclic sulfonium cations with TFSI− were synthesized and characterized. Their physical parameter (density and viscosity), electrochemical and thermal properties (electrochemical windows, conductivity, phase transition behavior and decomposition temperature) had been measured. Most of them showed low melting point (<−60 °C) and low viscosity and good conductivity (52 mPa s and 4.10 mS cm− 1 at 25 °C, respectively). Three kinds of phase transition behavior were observed from differential scanning calorimeter curves for these room temperature ionic liquids. The decomposition temperature of these hydrophobic room temperature ionic liquids was near to 80 °C higher than those hydrophilic ones. The result shows that these ionic liquids are suitable for electrochemical devices such as dye-sensitized solar cells even under some rigorous condition and it is an efficient method for improving ionic liquids' properties by modifying the structure of cyclic sulfonium.
Co-reporter:Shuangying Xu;Linhua Hu;Jiang Sheng
Frontiers of Optoelectronics 2011 Volume 4( Issue 1) pp:72-79
Publication Date(Web):2011 March
DOI:10.1007/s12200-011-0202-5
Micro-structure of TiO2 films in dye-sensitized solar cells (DSSCs) can affect light absorption and electron transportation that impact on the characteristics of currentvoltage (J-V). In this paper, films with different surface area, pore size and porosity were obtained by adding different ratio of ethyl cellulose (Ec-S) to pastes, and a photo-electric conversion efficiency (η) of 7.55% with a short-circuit current density (Jsc) of 16.81 mA·cm−2 was obtained when the ratio of Ec-S was 10:5. BET results showed that film with this optimum ratio had the most suitable pore size and surface area for good properties of photovoltaic, which had a low reflectivity and high transmission rate, and the efficiency of light utilization was improved. Moreover, measurements by intensity-modulated photocurrent spectroscopy (IMPS) and intensity-modulated photovoltage spectroscopy (IMVS) implied that the electron transport time (τd) increased as the content of Ec-S increased, which was related to the larger surface area. Results of steady-state cyclic voltammetry indicated that diffusion-limited current density (Jlim) of I3− in TiO2 film increased with its porosity, which revealed that the transportation of redox mediators in the electrolyte was speeded up.
Co-reporter:Changneng Zhang ; Shuanghong Chen ; Huajun Tian ; Yang Huang ; Zhipeng Huo ; Songyuan Dai ; Fantai Kong ;Yifeng Sui
The Journal of Physical Chemistry C 2011 Volume 115(Issue 17) pp:8653-8657
Publication Date(Web):April 8, 2011
DOI:10.1021/jp111585s
In this work, we investigated the iodine effect on the kinetics of back electron transfer and the band edge shift in the dyed TiO2 semiconductor electrodes. The iodine adsorbed on the TiO2 surface as the recombination centers resulted in the positive shift in band edge of the TiO2 electrode with the increase of I3− concentration. Detailed analysis of the back electron transfer indicated that the higher value of the transfer coefficient under the irradiation condition than in the dark was due to the possible faster recombination channels about the decomposition of I2 and the decomposition of I2 via the triplet-state sensitizers on the TiO2 surface. From impedance spectra of the solar cells, it could be concluded that the smaller charge transfer resistance at the TiO2/electrolyte interface was attributed to the positive shift of band edge in the iodine-adsorbed TiO2 electrode with the increase of I3− concentration in the electrolytes. An analytical dependence of the short-circuit photocurrent density (Jsc) on the illumination intensity found that the increased efficiency of electron injection (Φinj) could be attributed to the positive shift of band edge in the iodine-adsorbed TiO2 electrode, resulting in a slightly increased Jsc.
Co-reporter:Changneng Zhang ; Shuanghong Chen ; Li’e Mo ; Yang Huang ; Huajun Tian ; Linhua Hu ; Zhipeng Huo ; Songyuan Dai ; Fantai Kong ;Xu Pan
The Journal of Physical Chemistry C 2011 Volume 115(Issue 33) pp:16418-16424
Publication Date(Web):July 4, 2011
DOI:10.1021/jp2024318
The effect of Mg2+ ions substituted into the anatase lattice on the charge recombination and band-edge movement in dye-sensitized solar cells was investigated in this study. The HRTEM results indicated that Mg2+ ions incorporation into the TiO2 lattice led to the increased lattice spacing of the (101) plane of the anatase phase. Mg2+-doped TiO2 could produce a blue shift in the optical absorption edge compared with that of the untreated samples. Detailed analysis of the open-circuit photovoltage (Voc) under different surface charge densities showed that the Mg2+-doped TiO2 samples resulted in the negative shift of the TiO2 conduction band about 70 mV in comparison with the untreated samples. From Raman spectra and light intensity-dependent variation of the short-circuit current density (Jsc) of the solar cells, it could be concluded that the decreased efficiency of electron injection for DSCs with Mg2+-doped TiO2 was attributed to the negative shift of the band edge in the Mg2+-doped TiO2 electrode to obtain a decreased Jsc. The electron diffusion coefficient in Mg2+-doped TiO2 was found to be higher than that in TiO2 at the same photoelectron density. We present evidence that the increase of trap states in Mg2+-doped TiO2 as recombination channels to decrease the electron lifetime could compensate for the effect of band-gap widening to obtain a slightly increased Voc for DSCs with Mg2+-doped TiO2. It is suggested that the recombination channels should be suppressed to enhance the performance of dye-sensitized Mg2+-doped TiO2 solar cells.
Co-reporter:Zhipeng Huo, Changneng Zhang, Xiaqin Fang, Molang Cai, Songyuan Dai, Kongjia Wang
Journal of Power Sources 2010 Volume 195(Issue 13) pp:4384-4390
Publication Date(Web):1 July 2010
DOI:10.1016/j.jpowsour.2009.12.107
Quasi-solid-state dye-sensitized solar cells (DSC) are fabricated using tetradodecylammonium bromide as a low molecular mass organogelator (LMOG) to form gel electrolyte with a high solution-to-gel transition temperature (TSG) of 75 °C to hinder flow and volatilization of the liquid. The steady-state voltammograms reveal that the diffusion of the I3− and I− in the gel electrolyte is hindered by the self-assembled network of the gel. An increased interfacial exchange current density (j0) of 4.95 × 10−8 A cm−2 and a decreased electron recombination lifetime (τ) of 117 ms reveal an increased electron recombination at the dyed TiO2 photoelectrode/electrolyte interface in the DSC after gelation. The results of the accelerated aging tests show that the gel electrolyte based dye-sensitized solar cell can retain over 93% of its initial photoelectric conversion efficiency value after successive heating at 60 °C for 1000 h, and device degradation is negligible after one sun light soaking with UV cutoff filter for 1000 h.
Co-reporter:Weiqing Liu, Linhua Hu, Songyuan Dai, Lei Guo, Nianquan Jiang, Dongxing Kou
Electrochimica Acta 2010 Volume 55(Issue 7) pp:2338-2343
Publication Date(Web):28 February 2010
DOI:10.1016/j.electacta.2009.11.065
The influence of the series resistance on the electron transport and recombination processes in dye-sensitized solar cells (DSC) has been investigated. The series resistances induced by some parts of DSC, such as the transparent conductive oxide (TCO), the electrolyte layer and the counter electrode, influence the performance of DSC. By combining three frequency-domain techniques, specifically electrochemical impedance spectroscopy (EIS), intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS), we studied the relationship between the series resistance and the dynamic response of DSC. The results show that the series resistance induced by the TCO or counter electrode predominantly affects the electron transport under short circuit conditions and has no significant influence on the recombination under open circuit conditions. However, the resistance related to the electrolyte layer not only limits the carrier transport but also influences the recombination. Possible reasons for the influence of the series resistance on the electron transport and recombination processes in DSC are also discussed.
Co-reporter:Lei Guo, Xu Pan, Changneng Zhang, Weiqing Liu, Meng Wang, Xiaqin Fang, Songyuan Dai
Solar Energy 2010 Volume 84(Issue 3) pp:373-378
Publication Date(Web):March 2010
DOI:10.1016/j.solener.2009.11.008
A new ionic liquid S-propyltetrahydrothiophenium iodide (T3I) was developed as the solvent and iodide ion source in electrolyte for dye-sensitized solar cells. The electrochemical behavior of the I3-/I− redox couple and effect of additives in this ionic liquid system was tested and the results showed that this ionic liquid electrolyte revealed good conducting abilities and potential application for solar devices. The effects of LiI and dark-current inhibitors were investigated. The dye-sensitized solar cell with the electrolyte (0.1 mol L−1 LiI, 0.35 mol L−1 I2, 0.5 mol L−1 NMBI in pure T3I) gave short-circuit photocurrent density (Jsc) of 11.22 mA cm2, open-circuit voltage (Voc) of 0.61 V and fill factor (FF) of 0.51, corresponding to the photoelectric conversion efficiency (η) of 3.51% under one Sun (AM1.5).
Co-reporter:Changneng Zhang, Zhipeng Huo, Yang Huang, Songyuan Dai, Meng Wang, Yingtong Tang, Yifeng Sui
Journal of Photochemistry and Photobiology A: Chemistry 2010 Volume 213(2–3) pp:87-92
Publication Date(Web):25 June 2010
DOI:10.1016/j.jphotochem.2010.05.004
In this study, the influence of electrolyte on the charge recombination, electron injection efficiency (Φinj) and performance of dye-sensitized solar cells (DSCs) was investigated. A negative shift in the flatband potential (Vfb) of the TiO2 electrode indicated that 1-methylbenzimidazole (MBI) chemisorbed on the TiO2 surface and reduced the Li+ adsorption in the nanostructured electrode. Electrochemical impedance spectra for the DSCs showed that the addition of MBI in the LiI electrolyte could increase the electron lifetime and reduce the rate constant (ket) for I3− reduction with electrons in the TiO2 conduction band. The increase in Voc for solar cells with MBI was mainly attributed to the negative shift in the Vfb of the TiO2 electrode and the decrease of recombination reaction at the dyed TiO2/electrolyte interface. Analysis of the short-circuit current density (Jsc) depended on the light intensity for dye-sensitized solar cells indicated that there was no obvious effect on Φinj when the LiI concentration was up to 0.7 M in the electrolyte. Due to the negative shift in Vfb of the TiO2 electrode by the addition of MBI in the electrolyte, Φinj could be reduced to obtain a decreased Jsc.
Co-reporter:Weiqing Liu, Dongxing Kou, Molang Cai, Linhua Hu, Jiang Sheng, Huajun Tian, Nianquan Jiang and Songyuan Dai
The Journal of Physical Chemistry C 2010 Volume 114(Issue 21) pp:9965-9969
Publication Date(Web):May 7, 2010
DOI:10.1021/jp1003903
In the electrolyte containing Li+ and TBA+ (tert-n-butylammonium), the band edge movement, trap state distribution, electron recombination and electron transport in dye-sensitized solar cells (DSSCs) before and after TiO2 film surface coating with Yb2O3 is studied in this paper. It is found that whether surface coating could improve the performance of DSSCs depends on the compositions of the electrolytes. After surface coating, the band edge shifts negatively in the Li+ electrolyte, but no significant negative shift was observed in the TBA+ electrolyte. The changes of the trap state distribution also depend on the combined effects of the electrolytes and surface coating. In both types of electrolytes, the Yb2O3-coated TiO2 film suppresses the recombination and slows down the electron transport. These findings are important for improving the performance of the DSSC using the surface coating, which could explain the reasons why the photoelectric efficiency could not improve by coating, doping, and core−shell TiO2 in DSSCs.
Co-reporter:Huajun Tian, Linhua Hu, Changneng Zhang, Weiqing Liu, Yang Huang, Lie Mo, Lei Guo, Jiang Sheng and Songyuan Dai
The Journal of Physical Chemistry C 2010 Volume 114(Issue 3) pp:1627-1632
Publication Date(Web):January 5, 2010
DOI:10.1021/jp9103646
In this paper, the photovoltaic performance and charge recombination of the dye-sensitized solar cells (DSCs) based on nitrogen-doped TiO2 electrodes were investigated in detail. A negative shift of the flatband potential (Vfb) of nitrogen-doped TiO2 film was attributed to the formation of an O−Ti−N bond, and it was indicated that the position of the edge of the Vfb is shifted to negative, resulting in the improvement of the open circuit voltage for DSC with nitrogen doping. The UV−vis spectrum of the nitrogen-doped film exhibited a visible absorption in the wavelength range from 400 to 500 nm. The back electron transfer of the nitrogen-doped DSC was studied by measuring the electrochemistry impedance spectra (EIS), and the EIS for DSCs showed that the enhanced electron lifetime for nitrogen-doped TiO2 solar cells could be attributed to the formation of O−Ti−N in the TiO2 electrode to retard the recombination reaction at the TiO2 photoelectrode/electrolyte interface as compared to the undoped TiO2 solar cells. The photovoltaic performance of the DSC under high temperature conditions and one soaking in sun light for more than 1000 h indicated that the nitrogen-doped TiO2 solar cells exhibited better stability. It indicated that the formation of O−Ti−N in the TiO2 electrode influences the performance of the DSC. Especially, the introduction of nitrogen into the DSC can stabilize the DSC system due to the replacement of oxygen-deficient titania by nitrogen-doped TiO2.
Co-reporter:Changneng Zhang, Zhipeng Huo, Yang Huang, Lei Guo, Yifeng Sui, Linhua Hu, Fantai Kong, Xu Pan, Songyuan Dai, Kongjia Wang
Journal of Electroanalytical Chemistry 2009 Volume 632(1–2) pp:133-138
Publication Date(Web):1 July 2009
DOI:10.1016/j.jelechem.2009.04.006
In this work, the effect of benzimidazole on the interface recombination in dye-sensitized solar cells was investigated in detail using Raman spectroscopy and electrochemical impedance spectroscopy (EIS). A strong Raman peak at 143 cm−1 (TiO2) indicated that the electrolyte additive benzimidazole suppressed the recombination reaction at the TiO2 photoelectrode/electrolyte interface. The enhanced electron lifetime for dye-sensitized solar cells with benzimidazole could be attributed to the negative shift in the conduction band edge of the semiconductor. The results from EIS for DSC at different negative potentials indicated that addition of benzimidazole could obviously reduce the rate constant (ket) for the back electron transfer from the conduction band of TiO2 to I3- ions and also retain no influence on the trap distribution in energy below the conduction band. The devices with benzimidazole showed nearly constant in the open-circuit voltage (Voc) after 1000 h at 60 °C in the dark, keeping the dyed TiO2/electrolyte interface stable.
Co-reporter:Changneng Zhang, Yang Huang, Zhipeng Huo, Shuanghong Chen and Songyuan Dai
The Journal of Physical Chemistry C 2009 Volume 113(Issue 52) pp:21779-21783
Publication Date(Web):December 10, 2009
DOI:10.1021/jp909732f
In this study, we investigated the photoelectrochemical effect of guanidinium thiocyanate (GuSCN) in the base electrolyte composed of 1-methylbenzimidazole (0.45 M) and 3-methoxypropionitrile on the efficiency of electron injection (Φinj), interfacial recombination kinetics, and photovoltaic performance of dye-sensitized solar cells (DSCs). A significant increase in the photocurrent for DSCs with GuSCN was observed, which was higher than that for DSCs with the base electrolyte. The dependence of the short-circuit photocurrent density on the illumination intensity indicated that the large increase in Φinjcould be attributed to the positive shift in the flatband potential of the TiO2 electrode and could increase the electron injection yield. The results from electrochemical impedance spectroscopy (EIS) for DSCs indicated that guanidinium cation chemisorbed on the TiO2 surface could passivate the surface recombination sites and enhance the electron lifetime in the nanostructured TiO2 film to give an improved open-circuit photovoltage. The photostability of DSCs with 0.1 M GuSCN could retain over 98% of its initial photoelectric conversion efficiency value under one sun light soaking over the time of 3000 h. It is indicated that GuSCN chemisorbed on TiO2 surface could keep the interface of DSCs stable.
Co-reporter:Songyuan Dai, Jian Weng, Yifeng Sui, Shuanghong Chen, Shangfeng Xiao, Yang Huang, Fantai Kong, Xu Pan, Linhua Hu, Changneng Zhang, Kongjia Wang
Inorganica Chimica Acta 2008 Volume 361(Issue 3) pp:786-791
Publication Date(Web):15 February 2008
DOI:10.1016/j.ica.2007.04.018
To upscale DSC size to commercial size, our group was involved in developing a commercial DSC panel, which could show the industrial way and prospect. The repeatable DSC module with the size of 150 mm × 200 mm and photoelectric conversion efficiency around 6% was reproduced in our laboratory. The DSC panel up to the size of 450 mm × 800 mm was fabricated. This is the high efficiency and industrial production design of a DSC panel, a primary power station with 500 W was installed on our roof for charging the battery. The study on the stability and performance of the DSC module, panel and future production are ongoing in our laboratory. In this article, we will report a systematic study in the test and the design from the single cell, the modules, to the panels, and our design of a 500 W primary DSC power station.To upscale DSC size to commercial size, our group was involved in developing a commercial DSC panel, which could show the industrial way and prospect. The repeatable DSC module with the size of 150 mm × 200 mm and photoelectric conversion efficiency around 6% was reproduced in our laboratory. The DSC panel up to the size of 450 mm × 800 mm was fabricated. This is the high efficiency and industrial production design of a DSC panel, a primary power station with 500 W was installed on our roof for charging the battery. The stability and performance of the DSC module, panel and future production are ongoing in our laboratory. In this article, we will report a systematic study in the test and the design from the single cell, the modules, to the panels, and our design of a 500 W primary DSC power station.
Co-reporter:Zhipeng Huo, Songyuan Dai, Changneng Zhang, Fantai Kong, Xiaqin Fang, Lei Guo, Weiqing Liu, Linhua Hu, Xu Pan and Kongjia Wang
The Journal of Physical Chemistry B 2008 Volume 112(Issue 41) pp:12927-12933
Publication Date(Web):September 18, 2008
DOI:10.1021/jp8052168
Stable quasi-solid-state dye-sensitized solar cells (DSC) were fabricated using 12-hydroxystearic acid as a low molecular mass organogelator (LMOG) to form gel electrolyte. TEM image of the gel exhibited the self-assembled network constructed by the LMOG, which hindered flow and volatilization of the liquid. The formation of less-mobile polyiodide ions such as I3− and I5− confirmed by Raman spectroscopy increased the conductivity of the gel electrolytes by electronic conduction process, which should be rationalized by the Grotthuss-type electron exchange mechanism caused by rather packed polyiodide species in the electrolytes. The results of the accelerated aging tests showed that the gel electrolyte based dye-sensitized solar cell could retain over 97% of its initial photoelectric conversion efficiency value after successive heating at 60 °C for 1000 h and device degradation was also negligible after one sun light soaking with UV cutoff filter for 1000 h.
Co-reporter:Xu PAN;Song-Yuan DAI;Kong-Jia WANG
Chinese Journal of Chemistry 2007 Volume 25(Issue 11) pp:1601-1603
Publication Date(Web):13 NOV 2007
DOI:10.1002/cjoc.200790296
For the fist time the preparation of a mostly solid-state high efficient electro-conductive material comprising 1-methyl-3-propylimidazolium iodide (MPII), benzimidazole (BI), iodine and lithium iodide was reported. In this electrolyte, BI acts as not only additives but also gelators. With its significant electrochemical properties, an overall efficiency of 3.07% was achieved under AM 1.5 (100 mW/cm2).
Co-reporter:Fan-Tai Kong;Song-Yuan Dai;Kong-Jia Wang
Chinese Journal of Chemistry 2007 Volume 25(Issue 2) pp:
Publication Date(Web):7 FEB 2007
DOI:10.1002/cjoc.200790034
Amphiphilic polypyridyl ruthenium(II) complex cis-di(isothiocyanato)(4,4′-di-tert-butyl-2,2′-bipyridyl)(4,4′- dicarboxy-2,2′-bipyridyl)ruthenium(II) (K005) has been synthesized and characterized by cyclic voltammetry, 1H NMR, UV-Vis, and FT-IR spectroscopies. The sensitizer sensitizes TiO2 over a notably broad spectral range due to its intense metal-to-ligand charge-transfer (MLCT) bands at 537 and 418 nm. The photophysical and photochemical studies of K005 were contrasted with those of cis-Ru(dcbpy)2(NCS)2, known as the N3 dye, and the amphiphilic ruthenium(II) dye Z907. A reversible couple at E1/2=0.725 V vs. saturated calomel electrode (SCE) with a separation of 0.08 V between the anodic and cathodic peaks, was observed due to the RuII/III couple by cyclic voltammetry. Furthermore, this amphiphilic ruthenium complex was successfully used as sensitizers for dye-sensitized solar cells with the efficiency of 3.72% at the 100 mW·cm−2 irradiance of air mass 1.5 simulated sunlight without optimization of TiO2 films and the electrolyte.
Co-reporter:Chengwu Shi, Songyuan Dai, Kongjia Wang, Xu Pan, Longyue Zeng, Linhua Hu, Fangtai Kong, Li Guo
Electrochimica Acta 2005 Volume 50(Issue 13) pp:2597-2602
Publication Date(Web):30 April 2005
DOI:10.1016/j.electacta.2004.11.021
In this paper, we studied the influence of different cations on redox behavior of I− and I3− by cyclic voltammetry and electrochemical impedance spectroscopy. It was demonstrated that increasing cation size tends to give rise to higher reductive activity of I− and lower diffusion coefficient of I3− in these cations, alkylimidazolium, [Na ⊂ 15-C-5]+ and [K ⊂ 18-C-6]+. Moreover, we measured the performance of dye-sensitized solar cells (DSCs) with electrolyte containing [K ⊂ 18-C-6]I or 1,2-dimethyl-3-propylimidazolium iodide (DMPII). It was found that dye-sensitized solar cells (DSCs) with [K ⊂ 18-C-6]I give a little higher short-circuit photocurrent density and a little lower fill factor than DSCs with DMPII.
Co-reporter:Chengwu Shi, Songyuan Dai, Kongjia Wang, Xu Pan, Fantai Kong, Linhua Hu
Vibrational Spectroscopy 2005 Volume 39(Issue 1) pp:99-105
Publication Date(Web):15 September 2005
DOI:10.1016/j.vibspec.2005.01.002
In this article, we studied the adsorption of 4-tert-butylpyridine (TBP) on the nanocrystalline TiO2 (anatase) powder by Raman, IR and XPS. In Raman spectra, the free TBP and physisorbed TBP showed the totally symmetric ring breathing mode at 996 cm−1 and the vibration of the trigonal symmetry ring stretching mode was too weak to identify, while the coordinated TBP produced the characteristic trigonal symmetry ring stretching mode at 1022 cm−1 and the vibration of the totally symmetric ring breathing mode shifted from 996 to 1007 cm−1. From Raman spectra of dye-sensitized solar cells in situ, the Raman line at 167–169 cm−1 should be assigned to the formation of TBP·I2 or iodine adsorbed on the dye. Since there were significant differences from 100 to 300 cm−1, we suggested that TBP, besides the adsorption on TiO2, can also remove iodine adsorbed on the dye to suppress the rate of interfacial electron transfer from the conduction band of TiO2 to iodine.
Co-reporter:Shi Cheng-Wu;Dai;Song-Yuan;Wang Kong-Jia;Pan Xu;Guo Li;Hu Lin-Hua;Kong Fan-Tai
Chinese Journal of Chemistry 2005 Volume 23(Issue 3) pp:
Publication Date(Web):4 APR 2005
DOI:10.1002/cjoc.200590251
In this article, the I−3/I− redox behavior in 3-methoxypropionitrile (MePN) containing alkali-metal iodide com-plexes with crown ether and cryptand macrocycles was studied by cyclic voltammetry. It was found that the apparent diffusion coefficient D values of triiodide and iodide ions correlate with cations. D values of triiodide follow the order: 1,2-dimethyl-3-propylimidazolium cation (DMPI+)>[Na⊂15-C-5]+ (the mathematical symbol of inclusion, ⊂, was used to indicate Na+ included in 15-C-5)>[K⊂18-C-6]+>[Na⊂2.2.1-cryptand]+ and those of iodide ions follow the order: [Na⊂2.2.1-cryptand]+>[Na⊂15-C-5]+ ≈[K⊂18-C-6]+ >DMPI+. The photovoltaic performances of dye-sensitized solar cells (DSC) with these complexes were compared with those containing 1,2-dimethyl-3-propylimidazolium iodide (DMPII) in MePN. It shows that DSC with these complexes gave a little higher short photocurrent intensity and lower fill factor than those with DMPII, which is consistent with D values of triiodide and iodide ions. Moreover, solvents played an important role for the photo-electric conversion efficiency of DSC. The photo-electric conversion efficiency of DSC with DMPII is higher than that with [K⊂18-C-6]I in MePN, while in ACN, it shows a little difference.
Co-reporter:Xu Pan;Song-Yuan Dai;Kong-Jia Wang;Lin-Hua Hu;Cheng-Wu Shi;Li Guo;Fan-Tai Kong
Chinese Journal of Chemistry 2005 Volume 23(Issue 12) pp:1579-1583
Publication Date(Web):22 DEC 2005
DOI:10.1002/cjoc.200591579
Photo correlation spectroscopy was used to measure the particle size distribution of TiO2 films. Other parameters, such as porosity, BET surface area, average pore size, crystallite size D101, distribution of pore size etc. were also measured. The effects of these parameters on the ionic liquid based dye-sensitized solar cells (DSC) were studied. It was concluded that the particle size distribution of nanocrystalline TiO2 played an important role on the performance of DSC. The narrow particle size distribution of nanocrystalline TiO2 increased the efficiency of DSC, while the wide distribution decreased the efficiency of DSC. From the result above, it was also concluded that the photo correlation spectroscopy was a good method to identify the performance of TiO2 films. Based on electrochemical impedance spectroscopy, we found that the particle size distribution could affect the electronic contact between the TiO2 layers as well. The narrow particle size distribution made the electronic contact between TiO2 layers better than the wide particle size distribution of the TiO2 films, and then better the electronic contact, higher the efficiency of the DSC.
Co-reporter:Jiang Sheng, Linhua Hu, Wenxin Li, Li’e Mo, Huajun Tian, Songyuan Dai
Solar Energy (November 2011) Volume 85(Issue 11) pp:2697-2703
Publication Date(Web):1 November 2011
DOI:10.1016/j.solener.2011.08.009
The morphological evolution of specimen taken out after the different duration in TiCl3 solution was investigated by field emission scanning electron microscopy (FE-SEM). The rutile TiO2 splitting microspheres may be formed by the splitting crystal growth mechanism through the multistep process. The microsphere composed of the 20 nm width nanorods was in the range of 1.5–2.5 μm in the diameter. The dye-sensitized solar cell (DSC) based on the microspheres received 3.57% conversion efficiency under simulated AM 1.5 (100 mW/cm2) solar illumination, which exhibited remarkably higher charge collection efficiency and light scattering compared to that of P25. Electrochemical impedance spectroscopy (EIS) measurement revealed that impedance resistance at the surface of single-crystalline rutile TiO2 splitting microspheres was 6 times larger than that of P25 nanoparticles, indicating electron recombination was significantly retarded.Highlights► Growth of rutile splitting microspheres through multistep splitting and attachment. ► Microspheres efficiently scattered light. ► Electrolyte easily diffused in microsphere film. ► High charge collection efficiency in DSC based on microsphere film. ► Improve photovoltaic performance of DSC made from microsphere film.
Co-reporter:Ying-Ke Ren, Shi-Dong Liu, Bin Duan, Ya-Feng Xu, Zhao-Qian Li, Yang Huang, Lin-Hua Hu, Jun Zhu, Song-Yuan Dai
Journal of Alloys and Compounds (25 May 2017) Volume 705() pp:
Publication Date(Web):25 May 2017
DOI:10.1016/j.jallcom.2017.01.035
•Controllable MAI·PbI2·(DMSO)y adducts were first found via One-Step Spin-Coating.•The controllable morphology of MAPbI3 thin films were obtained.•By optimizing intermediate adduct, a PCE of 16.41% is achieved.In the past two years, the introduction of dimethylsulfoxide (DMSO) has recognized as an effective way to prepare high-quality pervoskite films. During the developed DMSO process, the formation of an intermediate phase has proven to uniform crystal growth rates between CH3NH3I (MAI) and PbI2 in common solvents. In this work, controllable intermediates were obtained in dimethylformamide (DMF) by additional solvent of DMSO, which tend to be closely packed by means of intermolecular self-assembly. In addition, the bond strength and chemical composition of intermediate phase were investigated with FTIR and TGA. The use of different ratios of DMSO leads to four different complexes of MAI·PbI2·DMF and MAI·PbI2·(DMSO)y (y = 0.6, 1.5, 1.9), thus dramatically influencing the crystallization of perovskite films. Of these complexes, optimized MAI·PbI2·(DMSO)1.5 intermediate adduct enables highly dense perovskite thin films with large grain size and enhances efficient perovskite solar cells with high charge carrier lifetime.
Co-reporter:Feng Liu, Jun Zhu, Linhua Hu, Bing Zhang, Jianxi Yao, Md. K. Nazeeruddin, Michael Grätzel and Songyuan Dai
Journal of Materials Chemistry A 2015 - vol. 3(Issue 12) pp:NaN6323-6323
Publication Date(Web):2015/02/03
DOI:10.1039/C5TA00028A
Transition metal chalcogenide crystalline films FeSe2, Cu1.8S, and CuSe have been deposited from solution by drop casting their dissolved inks onto a conductive substrate, followed by a mild thermal treatment. We demonstrate that the resulting chalcogenide films exhibit an excellent catalytic activity and function as highly efficient counter electrodes (CEs) for dye- and quantum dot-sensitized solar cells (DSCs and QDSCs). In particular, the FeSe2 and CuSe films produced herein with novel morphologies show better catalytic activity than that of the conventional Pt coated CE used in DSCs and Cu2S in QDSCs, respectively. Ensuing devices present an improved photovoltaic performance with maximum values of 9.10% for DSCs and 4.94% for QDSCs, comparable to those based on Pt and Cu2S CEs. The efficient CE materials developed here from such a facile and scalable route offer strong potential for a broader solar cell application that requires low-cost and large-scale production.
Co-reporter:Bin Duan, Yingke Ren, Yafeng Xu, Wenyong Chen, Qing Ye, Yang Huang, Jun Zhu and Songyuan Dai
Inorganic Chemistry Frontiers 2017 - vol. 4(Issue 3) pp:NaN480-480
Publication Date(Web):2017/01/09
DOI:10.1039/C6QI00492J
High quality perovskite films were fabricated from different precursor solutions containing a certain proportion of different hydrogen halides. An anti-solvent, toluene, was used here to isolate an intermediate from the perovskite precursor solution to reveal the impact of the hydrogen halides on the crystallization of perovskite films. From the Fourier transform infrared spectra we found that the stretch vibration of CO for pure N,N-dimethylformamide (DMF) appeared at 1663 cm−1, which was shifted to a smaller wavenumber while reacting DMF with CH3NH3I (MAI) + PbI2 and MAI + PbI2 + HX (X = Cl, Br, I). Moreover, the appearance of X-ray diffraction (XRD) peaks at low angles (near 8 degrees) as well as some small angle shift showed that the MAI–PbI2–DMF–xHX (X = Cl, Br, I) intermediate was formed, which benefits perovskite crystallization because the formation of the intermediate will avoid a rapid reaction between MAI and PbI2. What's more, the solubility of the precursor can be improved by adding hydrogen halides. By adding a certain amount of hydrogen halide into the one-step perovskite precursor solution we can obtain pin-hole free and almost no defect films. Transient absorption (TA) was carried out to investigate the charge recombination in intrinsic perovskite films and perovskite devices, giving some reasonable interpretations.
Co-reporter:Huajun Tian, Linhua Hu, Changneng Zhang, Lie Mo, Wenxin Li, Jiang Sheng and Songyuan Dai
Journal of Materials Chemistry A 2012 - vol. 22(Issue 18) pp:NaN9130-9130
Publication Date(Web):2012/03/28
DOI:10.1039/C2JM16896K
This work reports the preparation of N, B codoped TiO2 (N, B–TiO2) electrodes in dye-sensitized solar cells (DSCs) by a facial modified sol–gel method. After the nitrogen and boron dopants incorporated into the TiO2 electrodes, the cubic-like TiO2 nanocrystallites with diameters of 22∼24 nm were obtained efficiently. The back electron transfer of the DSC based on the N, B–TiO2 electrode was studied by measuring the electrochemistry impedance spectra (EIS) and the EIS for the DSCs showed that the enhanced electron lifetime for the dye-sensitized B, N–TiO2 solar cells could be attributed to the formation of an O–Ti–B–N bond in the TiO2 photoelectrode, which retards electron recombination at the dyed N, B–TiO2 photoelectrode/electrolyte interface after N, B codoping as compared to the undoped DSC. We found that a high efficiency of 8.4% for the DSC (active area:4 cm2) based on the N, B–TiO2 anode under 0.2 sun illumination was received. In particular, the photovoltaic performance of the DSC under high temperature conditions (60 °C) and one-sun light soaking over a time of more than 1100 h showed that the DSC based on the N, B–TiO2 electrode exhibited a better stability compared to the undoped DSC. The excellent photoelectrochemical performance could be attributed to the ideal combination of retarded electron recombination and superior energy band structure from the unique N, B–TiO2 particle structure.
Co-reporter:Jiang Sheng, Linhua Hu, Shuangying Xu, Weiqing Liu, Li'e Mo, Huajun Tian and Songyuan Dai
Journal of Materials Chemistry A 2011 - vol. 21(Issue 14) pp:NaN5463-5463
Publication Date(Web):2011/02/17
DOI:10.1039/C0JM03112G
The influence of TiO2 nanotubes on the charge collection efficiency and the dynamics of electron transport and recombination in dye-sensitized solar cells (DSCs) based on the TiO2 nanotube/nanoparticle composite films were investigated in this paper. Electrochemical impedance spectroscopy was employed to quantify the charge transfer resistance of DSCs. The different transport and recombination properties of DSCs were studied by frequency-resolved modulated photocurrent/photovoltage spectroscopies. It was shown that the electrons had a longer lifetime in the nanotubes and retarded recombination more significantly than in the nanoparticles. But with increasing the amount of nanotube, the electron pathway was extended seriously in these network structures resulting in increased recombination chances. In addition, the 5 wt% nanotube DSC had the highest charge collection efficiency among all the DSCs, which yielded a high photovoltaic conversion efficiency of 9.79% under simulated AM 1.5 sunlight (100 mW cm−2).
Co-reporter:Huajun Tian, Linhua Hu, Changneng Zhang, Shuanghong Chen, Jiang Sheng, Lie Mo, Weiqing Liu and Songyuan Dai
Journal of Materials Chemistry A 2011 - vol. 21(Issue 3) pp:NaN868-868
Publication Date(Web):2010/11/11
DOI:10.1039/C0JM02941F
Highly crystallized boron-doped anatase TiO2 nanoparticles are prepared by a facile synthetic route and successfully used as the photoanode of dye-sensitized solar cells (DSCs). We have observed that the boron doping could improve the crystallinity of TiO2. Moreover, the highly crystallized anatase boron-doped TiO2 were analyzed by electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy, and the internal resistances of the boron-doped DSCs were studied by measuring the electrochemical impedance spectra (EIS). The improved photocurrent density of the boron-doped DSCs is due to a significant enhancement of IPCE in the range 370–650nm in comparison with that of the undoped DSC. Meanwhile, the energy-conversion efficiency of the cell based on the B-doped TiO2 electrode is enhanced significantly, by about 9%, compared to that of the undoped DSC. Overall, DSCs based on B-doped electrodes show good stability and remain over 95% of their initial efficiency under visible light soaking for more than 2400 h.
Co-reporter:Molang Cai, Xu Pan, Weiqing Liu, Jiang Sheng, Xiaqin Fang, Changneng Zhang, Zhipeng Huo, Huajun Tian, Shangfeng Xiao and Songyuan Dai
Journal of Materials Chemistry A 2013 - vol. 1(Issue 15) pp:NaN4892-4892
Publication Date(Web):2013/01/31
DOI:10.1039/C3TA00835E
Electron recombination and dye aggregation at the dyed-TiO2/electrolyte interface are still problems in dye-sensitized solar cell (DSC) research. In this paper, tributyl phosphate (TBpp) as a special additive to modify the dyed-TiO2/electrolyte interface was introduced to enhance the photovoltaic performance. The adsorption mode of TBpp and the interaction between cis-dithiocyanate-N,N′-bis-(4-carboxylate-4-tetrabutylammonium carboxylate-2,2′-bi-pyridine) ruthenium(II) (N719) and TBpp were investigated. It was found that one TBpp parent molecule split into several smaller fragments and formed four anchoring modes on the TiO2 surface. It was very interesting that the molecular cleavage of TBpp and adsorption of N719 assisted each other on the sensitized TiO2 surface. The fragments distributed around N719 result in steric hindrance, consequently hydrogen-bonding among N719 molecules was decreased. The unstable type N719 transformed into stable type N719 accompanied by molecular cleavage of TBpp and the N719 aggregation was reduced. Furthermore, these new fragments were multiply adsorbed on the non-sensitized TiO2 surface to form an insulating barrier layer. Therefore, the electron recombination at the dyed-TiO2/electrolyte interface was restrained. Besides the change of surface configuration, the TiO2 band edge negatively shifted and the rate of electron transport in the TiO2 films decreased with the addition of TBpp. As a result, an increase in the photoelectric conversion efficiency (η) was obtained of almost 40%.
Co-reporter:Feng Liu, Jun Zhu, Yafeng Xu, Li Zhou, Yi Li, Linhua Hu, Jianxi Yao and Songyuan Dai
Chemical Communications 2015 - vol. 51(Issue 38) pp:NaN8111-8111
Publication Date(Web):2015/03/10
DOI:10.1039/C5CC00772K
Solution-deposited SnSe and SnS thin films demonstrate excellent electrocatalytic activity toward the triiodide reduction in dye-sensitized solar cells (DSCs), even better than that of the conventional noble Pt electrode used in DSCs. An enhanced photovoltaic efficiency with the maximum value of 9.4% was thus achieved, higher than that with Pt (9.0%).
Co-reporter:Meng Wang, Xu Pan, Shangfeng Xiao, Changneng Zhang, Wenxin Li and Songyuan Dai
Journal of Materials Chemistry A 2012 - vol. 22(Issue 5) pp:
Publication Date(Web):
DOI:10.1039/C1JM14790K
Co-reporter:Huajun Tian, Linhua Hu, Wenxin Li, Jiang Sheng, Shuangying Xu and Songyuan Dai
Journal of Materials Chemistry A 2011 - vol. 21(Issue 20) pp:NaN7077-7077
Publication Date(Web):2011/04/18
DOI:10.1039/C1JM10853K
A facile process to fabricate highly crystalline mesoporous N,B codoped TiO2 is introduced. The N,B codoped TiO2 nanomaterial, which has controlled crystallographic phase, size and unique nanoshape, is successfully applied to an enhanced device for dye-sensitized solar cells (DSCs) with an open-circuit photovoltage of 0.823 V and yielding a high overall energy conversion of 8.4%. A DSC based on the N,B codoped TiO2 electrode shows a competitive photovoltaic performance compared with the undoped DSC, which is attributed to the ideal combination of superior energy band structure and retarded electron recombination from the unique N,B codoped TiO2 particle structure.
Co-reporter:Haiwei Chen, Xu Pan, Weiqing Liu, Molang Cai, Dongxing Kou, Zhipeng Huo, Xiaqin Fang and Songyuan Dai
Chemical Communications 2013 - vol. 49(Issue 66) pp:NaN7279-7279
Publication Date(Web):2013/04/30
DOI:10.1039/C3CC42297F
A simple solution-processing method was employed to fabricate panchromatic mp-TiO2/CH3NH3PbI3/P3HT–MWNT/Au solar cells. MWNTs in a P3HT–MWNT composite acted as efficient nanostructured charge transport tunnels and induce crystallization of P3HT, hence significantly enhancing the conductivity of the composite. The fill factor of the hybrid solar cells was greatly enhanced by 26.7%.
Co-reporter:Xuechao Yu, Jun Zhu, Yaohong Zhang, Jian Weng, Linhua Hu and Songyuan Dai
Chemical Communications 2012 - vol. 48(Issue 27) pp:NaN3326-3326
Publication Date(Web):2012/02/06
DOI:10.1039/C2CC17081G
A kind of molecular metal chalcogenide, (N2H4)3(N2H5)4Sn2Se6 complex, was synthesized in the hydrazine solution and employed as the precursors for SnSe2 deposition on TiO2 nanocrystalline porous films. A power conversion efficiency of 0.12% under AM 1.5, 1 sun was obtained for the SnSe2 sensitized TiO2 solar cells.
Co-reporter:Wenjun Wang, Xu Pan, Weiqing Liu, Bing Zhang, Haiwei Chen, Xiaqin Fang, Jianxi Yao and Songyuan Dai
Chemical Communications 2014 - vol. 50(Issue 20) pp:NaN2620-2620
Publication Date(Web):2014/01/28
DOI:10.1039/C3CC49175G
The FeSe2 films with controllable morphologies (including 3D flower-like and sphere-shaped) have been applied as the counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). It is found that 3D flower-like FeSe2 CEs perform comparably to conventional platinum CEs (power conversion efficiencies of 8.00 and 7.87%, respectively).
Co-reporter:Liangzheng Zhu, Zhipeng Shao, Jiajiu Ye, Xuhui Zhang, Xu Pan and Songyuan Dai
Chemical Communications 2016 - vol. 52(Issue 5) pp:NaN973-973
Publication Date(Web):2015/11/10
DOI:10.1039/C5CC08156D
One of the limitations of TiO2 based perovskite solar cells is the poor electron mobility of TiO2. Here, perovskite oxide BaSnO3 is used as a replacement. It has a higher electron mobility and the same perovskite structure as the light harvesting materials. After optimization, devices based on BaSnO3 showed the best performance of 12.3% vs. 11.1% for TiO2.
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