Co-reporter:Yanqiang Li, Haibin Xu, Huiyong Huang, Liguo Gao, Yingyuan Zhao, Tingli Ma
Electrochimica Acta 2017 Volume 254(Volume 254) pp:
Publication Date(Web):10 November 2017
DOI:10.1016/j.electacta.2017.09.143
•A dual ligand metal organic framework was facilely synthesized via solid grinding method and transferred to N, S co-doped porous carbons (NSCs) by thermal annealing.•The NSCs show interconnected hierarchical structure, high surface area, high graphitic N and pyridinic N content.•The NSCs show high ORR activity comparable to Pt/C both in alkaline and acidic medium and excellent stability.Heteroatom doped porous carbons have been regarded as one of most promising candidates for Pt-free oxygen reduction reaction (ORR) catalysts. The proper heteroatom bonding configuration and synergistic effect of multiple atom co-doping are very important for improving their catalytic activity. In this work, a series of N, S co-doped porous carbons (NSCs) with excellent ORR performance were prepared by rationally using a dual-ligand metal organic framework as a carbon precursor. The interconnected porous structure, high surface area, N, S co-doping and high graphitization-N dopant, significantly contribute to the enhanced catalytic performance of ORR. The electrocatalyst studies indicated that the obtained materials have comparable ORR activity to that of the commercial Pt/C in both alkaline and acidic media, and superior long-term durability than that of Pt/C. This work can provide some guidance for synthesizing other multiple atom co-doping carbons for energy storage and conversion applications through target oriented synthesis of metal organic frameworks with different ligands.N, S co-doped porous carbons (NSCs) was prepared via directing thermal annealing of a dual ligand metal organic framework. The NSCs show interconnected network, hierarchical structure, high surface area, high graphitic N and pyridinic N content. When used as ORR catalyst, the NSC-1000 show high ORR activity comparable to that of Pt/C both in alkaline and acidic medium and excellent stability.Download high-res image (82KB)Download full-size image
Co-reporter:Xiaogong Bai, Yantao Shi, Jiahao Guo, Liguo Gao, Kai Wang, Yi Du, Tingli Ma
Journal of Power Sources 2016 Volume 306() pp:85-91
Publication Date(Web):29 February 2016
DOI:10.1016/j.jpowsour.2015.10.081
•Abundant structural defects on graphene enhance the ORR activity.•Balanced N distribution on graphene could also improve the ORR activity.•Structural defects and N distribution are adjusted by regulating temperature.•NG-1000 shows notable ORR activities in both alkaline and acid media.N-doped graphene (NG) is a promising candidate for oxygen reduction reaction (ORR) in the cathode of fuel cells. However, the catalytic activity of NG is lower than that of commercial Pt/C in alkaline and acidic media. In this study, NG samples were obtained using urea as N source. The structural defects and N distribution in the samples were adjusted by regulating the pyrolysis temperature. The new NG type exhibited remarkable catalytic activities for ORR in both alkaline and acidic media.
Co-reporter:Mingxing Wu, Xiao Lin, Yudi Wang and Tingli Ma
Journal of Materials Chemistry A 2015 vol. 3(Issue 39) pp:19638-19656
Publication Date(Web):05 Aug 2015
DOI:10.1039/C5TA03682H
Dye- or quantum dot-sensitized solar cells (DSCs or QDSCs) comprise a sensitizer, a semiconductor, an electrolyte containing redox couple, and a counter electrode (CE), which have inspired a new wave of research. The challenges in realizing the practical application of such photovoltaic devices are the enhancement of photovoltaic performance, stability, and the reduction of fabrication costs. The CE is an important component, and the exploration of low cost CE catalysts to match the redox couples has become a feasible route in the pursuit of high power conversion efficiency and low production cost of the devices. This article reviews the development of CE catalysts for the regeneration of each type of iodide-free redox couple, including inorganic, organic, and transition metal complex-based redox couples, among others.
Co-reporter:Jiahao Guo, Suxia Liang, Yantao Shi, Ce Hao, Xuchun Wang and Tingli Ma
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 43) pp:28985-28992
Publication Date(Web):25 Sep 2015
DOI:10.1039/C5CP04862A
Exploiting an alternative of the Pt-based counter-electrode materials for the triiodide reduction reaction has become a major interest in the fundamental research of dye-sensitized solar cells. Transition-metal selenides have recently been demonstrated as promising non-precious metal electrocatalysts for the triiodide reduction reaction. Herein, we prepared a series of transition-metal selenides via a free-reductant solvothermal method and used them as counter-electrodes in high efficiency dye-sensitized solar cells. The electrochemical results showed that these selenides had excellent catalytic activity for the reduction of the triiodine/iodine couple, and except for MoSe2, the conversion efficiencies of the corresponding dye-sensitized solar cells were comparable to the sputtered Pt counter-electrode. Theoretical investigation clearly revealed that the unsatisfactory performance of MoSe2 mainly originated from the processes of adsorption and charge-transfer. These findings can help to better understand the electrocatalytic processes and thus offer some useful guidelines to develop more efficient electrochemical catalysts.
Co-reporter:Jiahao Guo, Suxia Liang, Yantao Shi, Bo Li, Ce Hao, Xuchun Wang and Tingli Ma
RSC Advances 2015 vol. 5(Issue 89) pp:72553-72561
Publication Date(Web):29 Jul 2015
DOI:10.1039/C5RA13147B
Developing cost-effective and highly electrocatalytic Pt-free counter electrode (CE) materials for triiodide reduction has become a major interest for dye-sensitized solar cells (DSCs). In a heterogeneous catalytic system, iron chalcogenides like FeS2 and FeSe2 have demonstrated excellent catalytic activity when serving as CE materials in DSCs. However, theoretical and experimental studies have yet to be conducted to investigate the catalytic activity of iron chalcogenides in energy conversion and storage devices under the same conditions. In this work, FeS2, FeSe2, and FeTe2 were selected as our research object to systematically investigate and compare the regulatory mechanisms of the changes in the catalytic activity of iron chalcogenides. Theoretical research reveals that the iodine adsorption and charge exchange of these three materials occurred efficiently in heterogeneous catalytic systems. Experimental results further show that these three materials exhibited excellent catalytic activities. The conversion efficiencies of the corresponding DSCs are comparable to those of the sputtered Pt CE. This study also provides a method to rationally screen cost-effective and highly efficient catalytic materials for electrocatalysis applications.
Co-reporter:Yantao Shi
The Journal of Physical Chemistry C 2015 Volume 119(Issue 28) pp:15868-15873
Publication Date(Web):June 22, 2015
DOI:10.1021/acs.jpcc.5b02784
In perovskite solar cells (PSCs), issues of compatibility between the photoabsorber and the cell architecture arise. In this work, we systematically demonstrated the characteristics of PSCs with an organometal halide, CH3NH3PbI3 or CH3NH3PbI3–xClx, in a planar or mesoporous architecture, and the dependence of the cell photovoltaic performance on the architecture was illustrated in detail. In addition to the inherent photoelectric characteristics, CH3NH3PbI3 and CH3NH3PbI3–xClx also differ in other aspects, such as light absorption, crystallinity, surface coverage, and dissociation of the photogenerated electrons. For PSCs with CH3NH3PbI3, the mesoporous ones gave high power conversion efficiencies (PCE) of up to 14.05%, which is much higher than those of the planar ones (up to 6.76%). For PSCs with CH3NH3PbI3–xClx, the planar and mesoporous devices exhibited PCEs of up to 12.67% and 7.87%, respectively, quite in contrast with the case of CH3NH3PbI3.
Co-reporter:Huawei Zhou
The Journal of Physical Chemistry C 2015 Volume 119(Issue 9) pp:4600-4605
Publication Date(Web):February 16, 2015
DOI:10.1021/jp512101d
Carbon-based ZnO/CH3NH3PbI3/C planar heterojunction perovskite solar cells (PHJ-PSCs) were prepared at low-temperature without using organic hole conductor and metal electrode. When measured via reverse bias scan, rigid and flexible PHJ-PSCs achieved power conversion efficiencies (PCEs) up to 8% and 4% on fluorine-doped tin oxide (FTO)/glass substrates and flexible polymer substrates, respectively. The flexible devices were capable of maintaining 80% of their initial PCEs after 1000 times of bending.
Co-reporter:Liang Wang, Yantao Shi, Xiaogong Bai, Yujin Xing, Hong Zhang, Lin Wang, Wei Guo, Ning Wang, Tingli Ma and Michael Grätzel
Energy & Environmental Science 2014 vol. 7(Issue 1) pp:343-346
Publication Date(Web):29 Oct 2013
DOI:10.1039/C3EE42767F
We demonstrated that extracts from sea tangle can serve as a sensitizer, redox couple, as well as a counter electrode material, or even can be fabricated into an “all-natural solar cell”. Especially, the carbon counter electrode from sea tangle has achieved a comparable performance with Pt, favorable for the cost-reduction of DSCs.
Co-reporter:Huawei Zhou, Yantao Shi, Qingshun Dong, Yanxiang Wang, Chao Zhu, Liang Wang, Ning Wang, Ying Wei, Shengyang Tao and Tingli Ma
Journal of Materials Chemistry A 2014 vol. 2(Issue 12) pp:4347-4354
Publication Date(Web):02 Jan 2014
DOI:10.1039/C3TA14345G
Sufficient contact, high catalytic activity, free electron transport and ionic diffusion are desired for liquid–solid heterogeneous electrocatalysis. However, preparing catalysts that simultaneously possess all of these four advantages has proven challenging. Nanostructures originating from anisotropic growth always exhibit specific structural advantages and unique physical, chemical or catalytic properties. Herein, via a facile and template-free solvothermal approach, we synthesized W18O49 nanofibers (NFs) and nanofiber bundles (NFBs), as well as hierarchical spheres (HSs). As catalyst for the counter electrode (CE) of dye-sensitized solar cells (DSCs), W18O49 NFs demonstrated remarkable electrocatalytic activity because: (i) abundant oxygen vacancies offered sufficient active sites for reduction of I3− into I−; (ii) the one dimensional NFs were more beneficial to electron transport; (iii) the two phases, the liquid electrolyte and the solid NFs, could fully contact each other, and meanwhile ions could diffuse freely among the networks constructed by the interlaced NFs. Notably, DSCs using the NF-based semitransparent CE achieved high photoelectric conversion efficiencies (PCEs) up to 8.58%, superior to those based on NFBs or HSs, and comparable to that of 8.78% using Pt as the CE. Furthermore, it was proven that both the electrolytic activity and the PCE deteriorated drastically when the NFs were destroyed. Our work here will be of great interest for both fundamental research and practical applications of W18O49 nanomaterials in other fields.
Co-reporter:Liang Wang, Yantao Shi, Hong Zhang, Xiaogong Bai, Yanxiang Wang and Tingli Ma
Journal of Materials Chemistry A 2014 vol. 2(Issue 37) pp:15279-15283
Publication Date(Web):25 Jul 2014
DOI:10.1039/C4TA03727H
Fe3O4 with hierarchical structures was successfully synthesized and introduced into dye-sensitized solar cells as the counter electrode. A power conversion efficiency of 7.65% based on Fe3O4 was achieved, which is superior to that of pyrolytic Pt (6.88%) and close to that for sputtered Pt (7.87%).
Co-reporter:Liang Wang, Yantao Shi, Yanxiang Wang, Hong Zhang, Huawei Zhou, Ying Wei, Shengyang Tao and Tingli Ma
Chemical Communications 2014 vol. 50(Issue 14) pp:1701-1703
Publication Date(Web):21 Nov 2013
DOI:10.1039/C3CC47163B
A composite catalyst of rosin carbon/Fe3O4 with marvellous morphology was synthesized and applied as a counter electrode (CE) in dye-sensitized solar cells (DSCs), demonstrating notable electrocatalytic activity for the reduction of I3−. Based on this CE, a high power conversion efficiency of 8.11% was achieved, comparable to that of the traditional Pt CE.
Co-reporter:Hong Zhang, Yantao Shi, Feng Yan, Liang Wang, Kai Wang, Yujin Xing, Qingshun Dong and Tingli Ma
Chemical Communications 2014 vol. 50(Issue 39) pp:5020-5022
Publication Date(Web):25 Mar 2014
DOI:10.1039/C3CC49458F
The ionic liquid N-butyl-N′-(4-pyridylheptyl)imidazolium bis(trifluoromethane)sulfonimide (BuPyIm-TFSI) was used as a dual-functional additive to improve the electrical properties of the hole-transporting material (HTM) for perovskite solar cells. BuPyIm-TFSI improved the conductivity of HTM and reduced the dark current of the solar cell simultaneously, thereby greatly increasing the power conversion efficiency.
Co-reporter:Huawei Zhou, Yantao Shi, Qingshun Dong, Liang Wang, Hong Zhang and Tingli Ma
RSC Advances 2014 vol. 4(Issue 79) pp:42190-42196
Publication Date(Web):28 Aug 2014
DOI:10.1039/C4RA07906J
Understanding the relationship between the surface of electrocatalysts and the catalytic properties of different redox mediators is beneficial to the rational design of efficient catalysts for use in practical catalytic processes. Previous research observed that surface oxygen vacancies (SOVs) affected the catalytic activity for triiodide/iodide (I−/I3−) and T2/T− (T− = 5-mercapto-1-methyltetrazole ion) redox mediators in dye-sensitized solar cells (DSCs). However, the electrocatalytic properties of larger and steric metal complex redox mediators (cobalt complex, ferrocenium) on SOVs of W18O49 are unclear and have never been reported. In this study, we investigated the electrocatalytic properties of cobalt complex and ferrocenium redox mediators on SOVs of W18O49. Results indicated that the catalytic performance of W18O49 nanowires (NWs) as a counter electrode for cobalt complex and ferrocenium redox mediators was comparable to that of Pt. After SOVs filling, the reduction reaction activity of the cobalt complex decreases slightly whereas it increases slightly for ferrocenium. These findings enrich our understanding of heterogeneous catalytic reactions on the surface of transition metal complexes for different redox mediators.
Co-reporter:Huawei Zhou ; Yantao Shi ; Qingshun Dong ; Jian Lin ; Aiqin Wang ;Tingli Ma
The Journal of Physical Chemistry C 2014 Volume 118(Issue 35) pp:20100-20106
Publication Date(Web):August 5, 2014
DOI:10.1021/jp504368v
Surface oxygen vacancies (SOVs) are the most relevant surface defects in metal oxides (MOs), and they participate in numerous physical and chemical reactions. However, information on the nature, distribution, formation, and reactivity of SOVs, as well as relationships among SOVs, is lacking. Investigating SOVs is difficult because of disturbance by the crystal phase, morphology of bulk materials, and synergistic effect between substrate and catalyst host. Herein, by clarifying the origin of SOVs and their distribution, one-dimensional (1D) tungsten oxide nanowires (NWs) with numerous SOVs were synthesized. Compared with the three-dimensional nanostructure, the high aspect ratio of 1D NW exposed the SOVs on the surface of the nanostructure rather than embedding them in the bulk. To investigate accurately the effect of SOVs on electrocatalytic activity, we clearly identified how SOVs of tungsten oxide catalyst regulate iodide reduction reactions in the solar cell by in situ filling of SOVs in electrodes and maintaining the crystal phase and morphology of NWs. Iodide reduction reaction activity was notably dependent on tungsten oxide catalyst SOVs, which serve as important catalytic site descriptors. These findings may clarify the fundamental features of SOVs on metal oxides and contribute to the rational design of efficient catalysts and supports.
Co-reporter:Huawei Zhou, Yantao Shi, Qingshun Dong, Hong Zhang, Yujin Xing, Kai Wang, Yi Du, and Tingli Ma
The Journal of Physical Chemistry Letters 2014 Volume 5(Issue 18) pp:3241-3246
Publication Date(Web):September 7, 2014
DOI:10.1021/jz5017069
Low cost, high efficiency, and stability are straightforward research challenges in the development of organic–inorganic perovskite solar cells. Organolead halide is unstable at high temperatures or in some solvents. The direct preparation of a carbon layer on top becomes difficult. In this study, we successfully prepared full solution-processed low-cost TiO2/CH3NH3PbI3 heterojunction (HJ) solar cells based on a low-temperature carbon electrode. Power conversion efficiency of mesoporous (M-)TiO2/CH3NH3PbI3/C HJ solar cells based on a low-temperature-processed carbon electrode achieved 9%. The devices of M-TiO2/CH3NH3PbI3/C HJ solar cells without encapsulation exhibited advantageous stability (over 2000 h) in air in the dark. The ability to process low-cost carbon electrodes at low temperature on top of the CH3NH3PbI3 layer without destroying its structure reduces the cost and simplifies the fabrication process of perovskite HJ solar cells. This ability also provides higher flexibility to choose and optimize the device, as well as investigate the underlying active layers.Keywords: carbon electrode; low temperature; perovskite solar cells;
Co-reporter:Yantao Shi, Chao Zhu, Lin Wang, Chunyu Zhao, Wei Li, Kwok Kwong Fung, Tingli Ma, Anders Hagfeldt, and Ning Wang
Chemistry of Materials 2013 Volume 25(Issue 6) pp:1000
Publication Date(Web):March 1, 2013
DOI:10.1021/cm400220q
Zinc oxide (ZnO) hierarchical structures (HSs) have recently demonstrated notable photochemical and photovoltaic performances attributed to their nano/micro combined architectures. In this study, ZnO HSs were synthesized at room temperature using ultrarapid sonochemistry. This novel approach can effectively overcome deficiencies in the synthesis via traditional direct precipitation by promoting nucleation and accelerating diffusion. Only 15 min was needed to complete the formation of highly crystallized and uniformed HSs consisting of interconnected monocrystalline nanosheets using sonochemistry. The formation of HSs through in situ observations was interpreted using a new mechanism based on oriented attachment and reconstruction. In the nonequilibrium synthesis system, thicker, porous, and coarse crystallized ZnO sheets were first constructed via oriented attachment of small-sized nanocrystals. After reconstruction, untrathin, integrated, and monocrystalline nanosheets were obtained. According to the two-dimensional nanosheets to three-dimensional HSs, the formation was much more sophisticated because repeated and parallel heterogeneous oriented attachments with reconstructions dominated the final morphologies of the HSs. The relationships between synthetic conditions and HSs structures were established. Based on the photoanodes in dye-sensitized solar cells (DSCs), the performances of these differently structured HSs were tested. HSs with densely assembled nanosheets exhibited better performances in photoelectric conversions. Systematic investigations were also carried out by selecting two representative HSs to demonstrate the critical factors governing the optical and electrical properties of photoanodes. Finally, under AM 1.5 and 100mW cm–2 light irradiation, high photoelectric conversion efficiencies of up to 6.42% were achieved. These results established a new record for quasi-solid ZnO-based DSCs.Keywords: dye-sensitized solar cell; photovoltaic; quasi-solid; sonochemical synthesis; ZnO hierarchical structure;
Co-reporter:Sining Yun, Huawei Zhou, Liang Wang, Hong Zhang and Tingli Ma
Journal of Materials Chemistry A 2013 vol. 1(Issue 4) pp:1341-1348
Publication Date(Web):13 Nov 2012
DOI:10.1039/C2TA00680D
Hafnium oxygen nitride binary/ternary nanocomposites were prepared by combining Hf7O8N4, HfO2, and amorphous carbon through a simple chemical synthesis. The obtained HfO2 (Hf-R0-U), HfO2–C (Hf-R5-B), and Hf7O8N4–HfO2–C (Hf-R12-T) were characterized by XRD, SEM, FESEM, and electrochemical measurements. Dye-sensitized solar cells (DSCs) with binary Hf-R5-B and ternary Hf-R12-T composites as counter electrode (CE) showed superior electrocatalytic activity for I3− reduction and high power conversion efficiencies (PCE) of 6.71% and 7.85%, respectively, matching the performance of DSCs with Pt CE (7.19%). The design strategy demonstrated is promising for fabricating highly efficient and low-cost composite CE catalysts for DSCs.
Co-reporter:Huawei Zhou, Yantao Shi, Da Qin, Jiang An, Lingling Chu, Chaolei Wang, Yudi Wang, Wei Guo, Liang Wang and Tingli Ma
Journal of Materials Chemistry A 2013 vol. 1(Issue 12) pp:3932-3937
Publication Date(Web):07 Feb 2013
DOI:10.1039/C3TA00960B
Low-cost bendable photoanodes and counter electrodes (CEs), as well as gel electrolytes, are potentially desired for the mass production of completely flexible dye-sensitized solar cells (DSSCs). In this work, via printing at low temperature, we fabricated titanium carbide (TiC)-functionalized conductive-carbon (CC) on flexible polyimide (PI) films to replace traditional and expensive Pt/ITO/PEN CEs. Morphology characterization revealed this composite CE was highly porous and homogeneous. Electrochemical investigations demonstrated that this Pt-and-ITO free flexible CE exhibited a high electro-catalytic activity. Finally, the conversion efficiencies of the all flexible quasi-solid DSSCs using this low-cost TiC-CC/PI CE achieved 86% of that based on a Pt/CC/PI CE. Thus, the facile fabrication process of this novel CE, along with its notable performance, are quite promising for the future roll-to-roll production of completely flexible DSSCs.
Co-reporter:Jiahao Guo, Yantao Shi, Chao Zhu, Lin Wang, Ning Wang and Tingli Ma
Journal of Materials Chemistry A 2013 vol. 1(Issue 38) pp:11874-11879
Publication Date(Web):01 Aug 2013
DOI:10.1039/C3TA12349A
Developing Pt-free and highly efficient counter electrodes (CEs) is meaningful and necessary for the cost reduction of dye-sensitized solar cells (DSCs). In this work, via a facile and reductant-free solvothermal approach, we report the controllable synthesis of NbSe2 nanosheets (NSs), nanorods (NRs), as well as the composite NbSe2/C for use as CEs in high efficiency DSCs. The morphology and structure of the three samples were characterized by SEM, XRD and TEM. Meanwhile, by cyclic voltammetry measurements, electrochemical impedance spectroscopy and Tafel polarization, we found some key issues which explain the difference in their electrocatalytic activity in the reduction of triiodide (I3−). Compared with electrodes based on NbSe2 NRs, NbSe2 NS-based CEs demonstrated lower resistances in charge transfer and ionic diffusion. Subsequently, DSCs with NbSe2 NS-based CEs achieved a conversion efficiency of 7.34%. In addition, NbSe2/C composite-based CEs could further reduce the series resistance and finally a conversion efficiency of 7.80% was obtained, comparable to an efficiency of 7.90% for Pt-based CEs. The NbSe2 in our work provides a cost-effective CE alternative to the noble metal Pt in DSCs.
Co-reporter:Hong Zhang, Yantao Shi, Liang Wang, Chaolei Wang, Huawei Zhou, Wei Guo and Tingli Ma
Chemical Communications 2013 vol. 49(Issue 79) pp:9003-9005
Publication Date(Web):01 Aug 2013
DOI:10.1039/C3CC44520H
Pyridyl iodides were synthesized to serve as effective, economical, green and dual function additives for high efficiency and stable DSCs. Using commercial P25 as the photoanode, a high PCE of 7.81% was achieved with a pyridyl iodide-containing electrolyte. Meanwhile, DSCs based on our novel electrolytes demonstrated better stability.
Co-reporter:Xiaojia Zheng, Jiahao Guo, Yantao Shi, Fengqiang Xiong, Wen-Hua Zhang, Tingli Ma and Can Li
Chemical Communications 2013 vol. 49(Issue 83) pp:9645-9647
Publication Date(Web):23 Aug 2013
DOI:10.1039/C3CC45064C
Porous chalcogels CoMoS4 and NiMoS4 made by a facile solution reaction displayed good electrocatalytic activity in the redox reaction of the I−/I3− shuttle. Dye-sensitized solar cells with these ternary compounds as counter electrodes (CEs) showed photovoltaic performance similar to the devices made with noble metal platinum CE (7.46%).
Co-reporter:Jiahao Guo, Yantao Shi, Yuting Chu and Tingli Ma
Chemical Communications 2013 vol. 49(Issue 86) pp:10157-10159
Publication Date(Web):22 Aug 2013
DOI:10.1039/C3CC45698F
Two transition metal tellurides, CoTe and NiTe2, were synthesized and for the first time employed as the counter electrodes (CEs) with high catalytic activity for reduction of I3− in dye-sensitized solar cells (DSCs). Using CoTe and NiTe2-based CEs, photoelectric conversion efficiencies (PCEs) of 6.92% and 7.21% were achieved for DSCs, respectively, comparable to that of 7.04% achieved when using a Pt-based CE. The results indicated that, serving as a CE in DSCs, telluride could be a cost-effective and efficient alternative to the noble metal Pt.
Co-reporter:Huawei Zhou, Yantao Shi, Liang Wang, Hong Zhang, Chunyu Zhao, Anders Hagfeldt and Tingli Ma
Chemical Communications 2013 vol. 49(Issue 69) pp:7626-7628
Publication Date(Web):24 Jun 2013
DOI:10.1039/C3CC44518F
For the first time, nonstoichiometric WO2.72 was used as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). Oxygen-vacancy-rich WO2.72 nanorod bundles with notable catalytic activity for triiodide and thiolate reduction were prepared in this study. The photovoltaic parameters of dye-sensitized solar cells (DSSCs) with WO2.72 nanorod bundles as CEs are superior compared with those of the WO3-based cells, and nearly the same as those of the precious metal Pt-based cells. In a non-corrosive organic redox couple, the performance of WO2.72 CEs is better than that of Pt and WO3 CEs in DSSCs.
Co-reporter:Mingxing Wu, Xiao Lin, Wei Guo, Yudi Wang, Lingling Chu, Tingli Ma and Kezhong Wu
Chemical Communications 2013 vol. 49(Issue 11) pp:1058-1060
Publication Date(Web):29 Oct 2012
DOI:10.1039/C2CC37360B
The dye-sensitized solar cells (DSCs) using SnO2 and Nb2O5 counter electrodes (CEs) prepared in N2 atmosphere yielded power conversion efficiencies (PCE) of 6.09% and 4.65%, much higher than the PCE values (1.84%, 0.97%) of the DSCs using the same SnO2 and Nb2O5 CEs prepared in air.
Co-reporter:Liang Wang, Hong Zhang, Chaolei Wang, and Tingli Ma
ACS Sustainable Chemistry & Engineering 2013 Volume 1(Issue 2) pp:205
Publication Date(Web):December 18, 2012
DOI:10.1021/sc300153b
The highly soluble polyvinyl acetate (PVAc) was synthesized by simple solution polymerization, which was used to prepare the gel-state dye-sensitized solar cells (DSCs) for the first time. The values for open-circuit photovoltage (Voc), short-circuit photocurrent density (Jsc), and fill factor (FF) of gel electrolyte-based DSCs were 0.712 V, 16.78 mA cm–2, and 68%, respectively, yielding an overall photovoltaic conversion efficiency (PCE) of 8.18%, which is comparable to a liquid electrolyte-based one with a value of 8.27%. The results of the electrochemical impedance spectra (EIS) revealed that the large charge transfer resistances at the TiO2/dye/electrolyte interface and the large diffusion resistances of the redox couple in the electrolyte are responsible for similar PCEs of gel and liquid electrolytes. The long-term stability test revealed that the PCE of the gel electrolyte-based DSC did not decay after 1000 h under AM1.5 simulated solar illumination at 60 °C and 40–50% humidity, which is superior to a liquid electrolyte-based DSC. This new method overcomes the degradation of DSCs arising from volatilization and leakage of the liquid electrolyte and promotes the industrialization process of DSC.Keywords: Dye-sensitized solar cell; Gel-state electrolyte; High solubility; Highly stable; Polyvinyl acetate
Co-reporter:Yudi Wang, Chunyu Zhao, Mingxing Wu, Wei Liu, Tingli Ma
Electrochimica Acta 2013 Volume 105() pp:671-676
Publication Date(Web):30 August 2013
DOI:10.1016/j.electacta.2013.04.154
Binary composite of Pt decorated transition metal compounds (WO2, TiC, and VN) were introduced into dye-sensitized solar cells and excellent performance were obtained, almost 20% better than unitary materials. Ternary composite of Pt/WO2/TiO2 was also prepared to further improve the photovoltaic performance.Preparing binary and ternary composites as counter electrodes is an effective path to improve performance and reduce cost for dye-sensitized solar cells.
Co-reporter:Chaolei Wang, Liang Wang, Yantao Shi, Hong Zhang, Tingli Ma
Electrochimica Acta 2013 Volume 91() pp:302-306
Publication Date(Web):28 February 2013
DOI:10.1016/j.electacta.2012.12.096
Novel polymer gel electrolytes (PGEs) with high ionic conductivity based on polyvinyl (acetate-co-methyl methacrylate) [P(VA-co-MMA)] were prepared by soaking porous copolymers in an organic electrolyte solution [acetonitrile (ACN) or 3-Methoxypropionitrile (MPN)] that contained an I3−/I− as redox couple. Quasi-solid-state dye-sensitized solar cells (QS-DSSCs) were fabricated with the PGEs, and the best PGE was selected and optimized. Using the best PGE and under 100 mW cm−2 light illumination (AM1.5), the QS-DSSC achieved a high photovoltaic conversion efficiency of 9.10%, nearly the same as that for the DSSC based on the original liquid electrolyte. Introduction of TiO2 nanoparticles into the PGEs further enhanced PGEs ionic conductivity and the conversion efficiency to 9.40%. Subsequent results revealed that our QS-DSSC had a better stability because it could maintain 96.7% of its initial efficiency after long-time (1000 h) exposure to simulative sunlight. Besides, for the first time, large-area QS-DSSCs were fabricated by screen printing of PGE, other than the traditional vacuum injection that was infeasible for the viscous gel electrolyte. Finally, our 5 cm × 7 cm QS-DSSC sub-module exhibited a conversion efficiency higher than 4%.
Co-reporter:Zhenhua Ci, Xiaoqiang Yu, Ming Bao, Chaolei Wang, Tingli Ma
Dyes and Pigments 2013 Volume 96(Issue 3) pp:619-625
Publication Date(Web):March 2013
DOI:10.1016/j.dyepig.2012.11.004
New metal-free organic sensitizers containing a benzo[d]thiazole or phenyl unit as the π-conjugated system, a triphenylamine as an electron donor, and a cyanoacrylic acid moiety as an electron acceptor were synthesized and used for dye-sensitized solar cells. Photophysical and electrochemical properties of these dyes were investigated, and their performances as sensitizers in solar cells were measured. The introduction of a benzo[d]thiazole unit into the molecular structure resulted in a high incident photon-to-current conversion efficiency (more than 70%) from 340 nm to 600 nm. One solar cell containing a benzo[d]thiazole unit, produced a η of 5.85% (JSC = 10.63 mA cm−2, VOC = 0.72 V, and ff = 0.77) under 100 mW cm−2 simulated AM 1.5 G solar irradiation.Graphical abstractHighlights► Three organic dyes with different π-conjugated bridges were applied in dye-sensitized solar cells. ► The benzo[d]thiazole unit was introduced into D–π–A organic sensitizer to inhibit aggregation. ► The device based on sensitizer DBT1 achieved an efficiency of 5.85% was measured for a solar cell device.
Co-reporter:Chunlei Wang, Fanning Meng, Mingxing Wu, Xiao Lin, Tonghua Wang, Jieshan Qiu and Tingli Ma
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 34) pp:14182-14187
Publication Date(Web):27 Jun 2013
DOI:10.1039/C3CP52525B
A novel bio-inspired Pt- and FTO-free integrated pure carbon counter electrode (CE) for dye-sensitized solar cells (DSSCs) has been designed and fabricated using a porous carbon sheet as a conducting substrate and ordered mesoporous carbon (OMC) as the catalytic layer. A rigid, crustose lichen-like, integrated carbon–carbon composite architecture with a catalytic layer rooted in a porous conducting substrate was formed by a process of polymer precursor spin coating, infiltration and pyrolysis. The integrated pure carbon CE shows very low series resistance (Rs), owing to the high conductivity of the carbon sheet (sheet resistance of 488 mΩ □−1) and low charge-transfer resistance (Rct), due to the large specific surface area of the OMC layer that is accessible to the redox couple. The values of Rs and Rct are much lower than those of a platinized fluorine-doped thin oxide glass (Pt/FTO) electrode. Cells with this CE show high solar-to-electricity conversion efficiencies (8.11%), comparable to that of Pt/FTO based devices (8.16%).
Co-reporter:Sining Yun, Liang Wang, Chunyu Zhao, Yanxiang Wang and Tingli Ma
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 12) pp:4286-4290
Publication Date(Web):01 Feb 2013
DOI:10.1039/C3CP44048F
A Pt/SiC nanocomposite with ∼10 wt% Pt loading was used as a counter electrode (CE) in dye-sensitized solar cells (DSCs), it shows a high power conversion efficiency (PCE) of 7.07% (a DSC with a SiC CE has a PCE of 3.29%), reaching 98.5% of the level obtained using a Pt CE (7.18%). This work provides substantial support for developing low-cost Pt-loaded composite CEs for DSCs. Pt/SiC use is expected to reduce the dependence on the Pt in DSCs, while it can also be expected to be used in many chemical and electrochemical processes required to control the amount of Pt and prevent Pt nanoparticle aggregation.
Co-reporter:Liang Wang, Hong Zhang, Rile Ge, Chaolei Wang, Wei Guo, Yantao Shi, Yanan Gao and Tingli Ma
RSC Advances 2013 vol. 3(Issue 31) pp:12975-12980
Publication Date(Web):07 May 2013
DOI:10.1039/C3RA41180J
A series of bis(oxalate)borate ionic liquids (ILBOBs) were developed for the first time as the necessary components of the electrolyte system for dye-sensitized solar cells (DSCs). It was found that the photovoltaic performances of DSCs were significantly improved by 26% to 45% with these ILBOBs in the organic solvent electrolytes. Systematic investigations were carried out to reveal the effects of the chain lengths of the quaternary ammonium BOB as well as the cations of the ILBOBs on the performances of the DSCs. Among them, the highest power conversion efficiency (PCE) was achieved by the DSC based on the electrolyte containing 1-ethyl-3-methylimidazolium bis(oxalate)borate (EmimBOB). Specifically, the addition of EmimBOB increased the short circuit current densities (Jsc) from 11.87 mA cm−2 to 15.99 mA cm−2, and the open-circuit voltage (Voc) from 0.721 V to 0.742 V, accompanied by a final 45% improvement of the overall PCE from 6.01% to 8.73% under AM 1.5, 100 mW cm−2 illumination. As an ionic liquid, EmimBOB was also used to develop a solvent-free electrolyte system. Compared with the one containing pure 1-methyl-3-propylimidazolium iodide (PMII), the hybrid solvent-free electrolyte system based on the EmimBOB/PMII combination notably increased the PCE of the DSCs from 3.48% to 5.38%. Finally, using solvent-free electrolytes, the long-term stability of the DSC devices were remarkably improved.
Co-reporter:Yahong Xie, Chunyang Zhang, Fan Yue, Yun Zhang, Yantao Shi and Tingli Ma
RSC Advances 2013 vol. 3(Issue 45) pp:23264-23268
Publication Date(Web):19 Sep 2013
DOI:10.1039/C3RA43731K
Various novel hierarchical Cu2ZnSnS4 nanostructures were successfully prepared by a solvothermal approach. Their structures and morphologies were characterized using XRD and SEM, and the photovoltaic and catalytic performance based on those prepared hierarchical Cu2ZnSnS4 nanostructures as counter electrode (CE) materials in dye-sensitized solar cells (DSSCs) was investigated. Results indicated that the photovoltaic and catalytic performance of DSSCs depend on the microstructures and morphologies of the electrodes, and the sample with monodisperse nanoparticle structure as CE yielded an overall light conversion efficiency of 6.98% with a fill factor of 66.0%, a short circuit current of 14.26 mA cm−2 and an open circuit voltage of 0.74 V, which were comparable with those of Pt (η = 6.91%) under the same device configuration.
Co-reporter:Yu-Rong Gao, Ling-Ling Chu, Wei Guo, Ting-Li Ma
Chinese Chemical Letters 2013 Volume 24(Issue 2) pp:149-152
Publication Date(Web):February 2013
DOI:10.1016/j.cclet.2013.01.010
A novel benzodithiophene-containing organic dye BDT was synthesized and characterized as a sensitizer for a nanocrystalline TiO2-based dye-sensitized solar cell. The BDT dye shows two major electronic absorptions. The absorption of the BDT dye covers a broad visible range from 300 nm to 550 nm. The benzodithiophene unit was used as a π bridge with several advantages: (1) It facilitates the electron transfer from the donor to the acceptor; (2) A facile structural modification on the 4,8-positions in the benzodithiophene unit can be achieved; (3) Fusing benzene with two flanking thiophene units improves the thermal stability. Under simulated AM1.5G solar light (100 mW/cm2) illumination, the DSC based on BDT gives a power conversion efficiency of 1.78%.A novel benzodithiophene-containing organic dye BDT was synthesized and characterized as a sensitizer for a nanocrystalline TiO2-based dye-sensitized solar cell. Under simulated AM1.5G solar light (100 mW/cm2) illumination, the DSC based on BDT gives a power conversion efficiency of 1.78%.
Co-reporter:Dr. Sining Yun;Mingxing Wu;Yudi Wang;Jing Shi;Xiao Lin; Anders Hagfeldt; Tingli Ma
ChemSusChem 2013 Volume 6( Issue 3) pp:411-416
Publication Date(Web):
DOI:10.1002/cssc.201200845
Co-reporter:Mingxing Wu ; Xiao Lin ; Yudi Wang ; Liang Wang ; Wei Guo ; Daidi Qi ; Xiaojun Peng ; Anders Hagfeldt ; Michael Grätzel ;Tingli Ma
Journal of the American Chemical Society 2012 Volume 134(Issue 7) pp:3419-3428
Publication Date(Web):January 23, 2012
DOI:10.1021/ja209657v
Three classes (carbides, nitrides and oxides) of nanoscaled early-transition-metal catalysts have been proposed to replace the expensive Pt catalyst as counter electrodes (CEs) in dye-sensitized solar cells (DSCs). Of these catalysts, Cr3C2, CrN, VC(N), VN, TiC, TiC(N), TiN, and V2O3 all showed excellent catalytic activity for the reduction of I3– to I– in the electrolyte. Further, VC embedded in mesoporous carbon (VC–MC) was prepared through in situ synthesis. The I3–/I– DSC based on the VC–MC CE reached a high power conversion efficiency (PCE) of 7.63%, comparable to the photovoltaic performance of the DSC using a Pt CE (7.50%). In addition, the carbide catalysts demonstrated catalytic activity higher than that of Pt for the regeneration of a new organic redox couple of T2/T–. The T2/T– DSCs using TiC and VC–MC CEs showed PCEs of 4.96 and 5.15%, much higher than that of the DSC using a Pt CE (3.66%). This work expands the list of potential CE catalysts, which can help reduce the cost of DSCs and thereby encourage their fundamental research and commercial application.
Co-reporter:Yudi Wang, Mingxing Wu, Xiao Lin, Zhicong Shi, Anders Hagfeldt and Tingli Ma
Journal of Materials Chemistry A 2012 vol. 22(Issue 9) pp:4009-4014
Publication Date(Web):25 Jan 2012
DOI:10.1039/C2JM15182K
Three nanomaterials, namely, titanium carbide (TiC), tungsten oxide (WO2), and vanadium nitride (VN), are introduced into dye-sensitized solar cells (DSCs) as counter electrode (CE) catalysts to replace the expensive Pt CE. Three kinds of substrates of bare glass (BG), Ti foil, and polyimide (PI) film are applied as F-doped tin oxide (FTO)-free substrates for rigid and flexible DSCs; thus realizing FTO-free and Pt-free CEs simultaneously in the DSC system. A carbon layer is used as an electron collector to replace the expensive FTO conductive layer in the insulative BG and PI film. Cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization curves are performed to compare the catalytic activities of these CEs for the reduction of triiodide to iodide. The results demonstrate that the DSCs that use TiC, WO2, and VN as CEs on Ti foil have better photovoltaic performance than those that use CEs on traditional FTO glass. Moreover, the TiC, WO2, and VN on the BG substrates show excellent catalytic activities that can match the performance of the CEs on FTO glasses.
Co-reporter:Yudi Wang, Chunyu Zhao, Da Qin, Mingxing Wu, Wei Liu and Tingli Ma
Journal of Materials Chemistry A 2012 vol. 22(Issue 41) pp:22155-22159
Publication Date(Web):20 Aug 2012
DOI:10.1039/C2JM35348B
A transparent flexible Pt counter electrode (CE) was prepared on indium tin oxide–polyethylene naphthalate film using a simple dip coating method for dye-sensitized solar cells (DSCs), and a high catalytic activity was achieved. The DSC using this transparent flexible CE gave a power conversion efficiency (PCE) of 6.95% with front illumination, and a PCE of 5.18% with rear illumination.
Co-reporter:Wei Guo, Yihua Shen, Mingxing Wu and Tingli Ma
Chemical Communications 2012 vol. 48(Issue 49) pp:6133-6135
Publication Date(Web):23 Apr 2012
DOI:10.1039/C2CC31903A
All-solid-state inorganic–organic heterojunction solar cells (HSCs) were designed and fabricated using earth-abundant element, non-toxic, low-cost SnS-sensitized mesoporous spherical TiO2 films under ambient conditions using a solution-processable, simple, and convenient fabrication technique. SnS-HSCs show a promising photovoltaic performance, with an efficiency of 2.8% and a significantly high VOC of 0.85 V.
Co-reporter:Liang Wang, Eric Wei-Guang Diau, Mingxing Wu, Hsueh-Pei Lu and Tingli Ma
Chemical Communications 2012 vol. 48(Issue 20) pp:2600-2602
Publication Date(Web):11 Jan 2012
DOI:10.1039/C2CC17389A
We developed several low-cost catalysts with high catalytic activity, which were used as counter electrodes in dye-sensitized solar cells (DSCs). They showed higher efficiencies than that of Pt. The efficiencies were improved by 18–42% for the DSCs composed of active carbon, niobium dioxide, ordered mesoporous carbon and commercial titanium carbide.
Co-reporter:Sining Yun, Liang Wang, Wei Guo, Tingli Ma
Electrochemistry Communications 2012 Volume 24() pp:69-73
Publication Date(Web):October 2012
DOI:10.1016/j.elecom.2012.08.008
The Pt-like electrocatalytic activity of counter electrodes (CEs) prepared from tantalum oxides for dye-sensitized solar cells (DSCs) is demonstrated. The low ratio of oxygen to metal atom of the oxide favors the electrocatalytic activity of these CE materials for I3− reduction in DSCs. TaO, used as a CE in DSCs, shows superior electrocatalytic activity and a high power conversion efficiency of 6.48%, up to 90.5% of the level obtained using Pt as a CE (7.16%). This work develops the use of novel tantalum oxide CE materials for low cost and high efficiency DSCs.Tantalum oxide as a CE in DSCs shows a superior electrocatalytic activity and a higher power conversion efficiency of 6.48%, reaching 90.5% of the level obtained using Pt as a CE (7.16%).Highlights► Tantalum oxide and tantalum pentoxide were synthesized using a simple and facile chemical route. ► Tantalum oxide and tantalum pentoxide as catalysts were firstly tested for use in the DSC system. ► Tantalum oxide as a CE in DSCs shows a highly Pt-like electrocatalytic activity. ► TaO-DSC shows a higher PCE (6.48%), reaching 90.5% of the level obtained using Pt as a CE (7.16%). ► Tantalum oxide has great potential for substitution of Pt in DSCs while providing comparable performance.
Co-reporter:Yudi Wang;Mingxing Wu;Xiao Lin;Anders Hagfeldt;Tingli Ma
European Journal of Inorganic Chemistry 2012 Volume 2012( Issue 22) pp:3557-3561
Publication Date(Web):
DOI:10.1002/ejic.201200329
Abstract
Titanium carbide (TiC) has been used as a counter electrode (CE) catalyst in place of Pt for triiodide reduction in dye-sensitized solar cells (DSCs). Its catalytic activity can be comparable to that of Pt. The effect of the thickness of the TiC layer on the performance of the DSCs was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and Tafel polarization measurements. We found that as the film thickness increased, the fill factor and short-circuit current density increased, which led to improved power-conversion efficiency. When the TiC film was thicker than 20 μm, however, no significant continuous improvement in the catalytic activity was observed. A high power-conversion efficiency of 6.46 % was obtained for the DSC by using a TiC CE at the optimized film thickness, a value similar to that obtained with a Pt CE.
Co-reporter:Dr. Wei Guo;Yihua Shen;Dr. Mingxing Wu;Dr. Liang Wang;Linlin Wang ; Tingli Ma
Chemistry - A European Journal 2012 Volume 18( Issue 25) pp:7862-7868
Publication Date(Web):
DOI:10.1002/chem.201103904
Abstract
Low-cost quantum-dot sensitized solar cells (QDSSCs) were fabricated by using the earth-abundant element SnS quantum dot, novel TiC counter electrodes, and the organic disulfide/thiolate (T2/T−) redox couple, and reached an efficiency of 1.03 %. QDSSCs based on I−/I3−, T2/T−, and S2−/Sx2− redox couples were assembled to study the role of the redox couples in the regeneration of sensitizers. Charge-extraction results reveal the reasons for the difference in JSC in three QDSSCs based on I−/I3−, T2/T−, and S2−/Sx2− redox couples. The catalytic selectivity of TiC and Pt towards T2/T− and I−/I3− redox couples was investigated using Tafel polarization and electrochemical impedance analysis. These results indicated that Pt and TiC show a similar catalytic selectivity for I−/I3−. However, TiC possesses better catalytic activity for T2/T− than for I−/I3−. These results indicate the great potential of transition metal carbide materials and organic redox couples used in QDSSCs.
Co-reporter:Mingxing Wu;Yudi Wang;Xiao Lin; Anders Hagfeldt; Tingli Ma
ChemCatChem 2012 Volume 4( Issue 9) pp:1255-1258
Publication Date(Web):
DOI:10.1002/cctc.201200061
Co-reporter:Dr. Mingxing Wu; Tingli Ma
ChemSusChem 2012 Volume 5( Issue 8) pp:1343-1357
Publication Date(Web):
DOI:10.1002/cssc.201100676
Co-reporter:Yurong Gao, Lingling Chu, Mingxing Wu, Linlin Wang, Wei Guo, Tingli Ma
Journal of Photochemistry and Photobiology A: Chemistry 2012 Volume 245() pp:66-71
Publication Date(Web):1 October 2012
DOI:10.1016/j.jphotochem.2012.07.005
We fabricated low-cost carbon and carbides counter electrodes (CEs) with excellent adhesion by adding an industrial conductive carbon paste (CC) as a binder for dye-sensitized solar cells (DSSCs). We compared the electrochemical catalytic activity of CC and carbon dye (Cd)/CC in the reduction of triiodide to iodide using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). CC and Cd/CC electrodes both exhibit electrochemical catalytic activity for triiodide reduction. After investigating the influence of CC on the performance of DSSCs, we also chose several transition metal carbides, including molybdenum carbide (MoC), tungsten carbide (WC), ordered mesoporous carbon (OMC), MoC embedded in OMC (MoC-OMC), and WC embedded in OMC (WC-OMC) as catalytic materials of CEs. DSSCs based on the carbon and carbides CEs reached efficiencies of 4.50–6.81%. The results indicate that CC is a superior binder for Pt-free catalysts in DSSCs.Graphical abstract. The adhesion of Pt-free counter electrodes was improved by low-cost conductive carbon paste (CC) as a binder. Dye-sensitized solar cell (DSSC) based on carbon dye counter electrode obtained an energy conversion efficiency of 6.81%, reaching 93.0% that of sputtered Pt CE. The influences of CC on the performance of DSSC system were investigated in detail. CC is a superior binder for low-cost CEs for DSSCs.Highlights► The adhesion of Pt-free counter electrodes was improved by low-cost conductive carbon paste (CC) as a binder. ► Dye-sensitized solar cell (DSSC) based on carbon dye counter electrode obtained an energy conversion efficiency of 6.81%, reaching 93.0% that of sputtered Pt CE. ► The influences of CC on the performance of DSSC system were investigated in detail. ► CC is a superior binder for low-cost CEs for DSSCs.
Co-reporter:Mingxing Wu, Xiao Lin, Tonghua Wang, Jieshan Qiu and Tingli Ma
Energy & Environmental Science 2011 vol. 4(Issue 6) pp:2308-2315
Publication Date(Web):16 May 2011
DOI:10.1039/C1EE01059J
Nine kinds of carbon materials were introduced into dye-sensitized solar cells (DSCs) system as counter electrodes (CEs). We also compared the electrochemical catalytic activity of these carbon materials with Pt for the reduction of triiodide to iodide by measuring cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel-polarization curve. The nine kinds of carbon materials in this work included synthesized well-ordered mesoporous carbon (Com), activated carbon (Ca), carbon black (Cb), conductive carbon (Cc), carbon dye (Cd), carbon fiber (Cf), carbon nanotube (Cn), discarded toner of a printer (Cp) and fullerene (C60). All carbon materials showed electrochemical catalytic activity for triiodide reduction in the DSCs system. In particular, the synthesized Com showed excellent electrochemical catalytic activity which can be comparable to the performance of Pt. After optimizing the proportion of TiO2 added into the carbon paste and the spray time of the carbon paste, the DSCs based on these carbon CEs achieved energy conversion efficiencies of 2.8–7.5%. The results demonstrate that carbon material is a promising substitute for the expensive Pt CE for low-cost DSCs.
Co-reporter:Qingqing Miao;Liqiong Wu;Jingnan Cui;Mingdong Huang;Tingli Ma
Advanced Materials 2011 Volume 23( Issue 24) pp:2764-2768
Publication Date(Web):
DOI:10.1002/adma.201100820
Co-reporter:Mingxing Wu, Qingyu Zhang, Jinqiu Xiao, Chunyu Ma, Xiao Lin, Chunyu Miao, Youjing He, Yurong Gao, Anders Hagfeldt and Tingli Ma
Journal of Materials Chemistry A 2011 vol. 21(Issue 29) pp:10761-10766
Publication Date(Web):20 Jun 2011
DOI:10.1039/C1JM11422K
Two novel flexible counter electrodes (CEs) on Ti sheets using molybdenum and tungsten nitrides (Mo2N, W2N) as catalysts were synthesized and used in a dye-sensitized solar cell (DSC) system. High catalytic activity of the two nitride CEs for the reduction of triiodide were proved by cyclic voltammetry, electrochemical impedance spectroscopy and Tafel-polarization measurements. The DSCs based on Mo2N and W2N CEs achieved power conversion efficiencies of 6.38 and 5.81%, reaching 91 and 83% of the photovoltaic performance of the DSC using a Pt CE, respectively. This research paves a promising way to develop new CE catalysts and reduce the cost of DSCs.
Co-reporter:Xiao Lin, Mingxing Wu, Yudi Wang, Anders Hagfeldt and Tingli Ma
Chemical Communications 2011 vol. 47(Issue 41) pp:11489-11491
Publication Date(Web):26 Sep 2011
DOI:10.1039/C1CC14973C
Synthesized niobium oxides (Nb2O5 and NbO2) were applied for the first time as counter electrodes (CEs) in dye-sensitized solar cells (DSCs). The DSC using NbO2 CE showed a higher power conversion efficiency of 7.88%, compared with that of the DSC using Pt CE (7.65%).
Co-reporter:Mingxing Wu, Xiao Lin, Anders Hagfeldt and Tingli Ma
Chemical Communications 2011 vol. 47(Issue 15) pp:4535-4537
Publication Date(Web):08 Mar 2011
DOI:10.1039/C1CC10638D
Tungsten dioxide (WO2) nanorods were synthesized, which showed excellent catalytic activity for the reduction of triiodide to iodide. The dye-sensitized solar cell (DSC) using WO2 as a counter electrode (CE) reached a high energy conversion efficiency of 7.25%, which can match the performance of the DSC based on a Pt CE.
Co-reporter:Wei Guo, Yihua Shen, Gerrit Boschloo, Anders Hagfeldt, Tingli Ma
Electrochimica Acta 2011 Volume 56(Issue 12) pp:4611-4617
Publication Date(Web):30 April 2011
DOI:10.1016/j.electacta.2011.02.091
Three different types of nanocrystalline, N-doped TiO2 electrodes were synthesized using several nitrogen dopants through wet methods. The obtained nanocrystalline, N-doped TiO2 electrodes possessed different crystallite sizes, surface areas, and N-doping amounts. Characterizations were performed to reveal the nitrogen-doping processes for the wet methods using ammonia, urea, and triethylamine as the nitrogen dopants. Additionally, a high conversion efficiency of 8.32% was achieved by the dye-sensitized solar cells, based on the N-doped TiO2 electrodes. For instance, in comparison with the commercial P25 (5.76%) and pure anatase TiO2 electrodes (7.14%), significant improvements (44% and 17%, respectively) in the efficiencies were obtained. The findings also indicated that the ammonia nitrogen dopant was more efficient than other two nitrogen dopants. The electron transports, electron lifetimes, and charge recombination in the dye-sensitized N-doped TiO2 solar cells also differed from those in the pure TiO2-based dye-sensitized solar cells (DSCs). Specifically, an enhanced photocurrent of ca. 36% in N-doped DSCs resulted from the synergistic effects of the high dye uptake and the efficient electron transport. Moreover, the relationship between charge and voltage revealed that less charge was needed to get a high open-circuit voltage in the N-doping films.Highlights► Three different types of nanocrystalline N-doped TiO2 synthesized by several nitrogen dopants. ► N-doped DSCs achieves a high conversion efficiency of 8.32%. ► Ammonia acts as good nitrogen dopants. ► Enhanced photocurrent of ca. 36% in N-doped DSCs. ► Less charge are needed to get a high open-circuit voltage in N-doped films.
Co-reporter:Mingxing Wu, Yudi Wang, Xiao Lin, Naisen Yu, Liang Wang, Linlin Wang, Anders Hagfeldt and Tingli Ma
Physical Chemistry Chemical Physics 2011 vol. 13(Issue 43) pp:19298-19301
Publication Date(Web):10 Oct 2011
DOI:10.1039/C1CP22819F
Molybdenum sulfide (MoS2) and tungsten sulfide (WS2) are proposed as counter electrode (CE) catalysts in a I3−/I− and T2/T− based dye-sensitized solar cells (DSCs) system. The I3−/I− based DSCs using MoS2 and WS2 CEs achieved power conversion efficiencies of 7.59% and 7.73%, respectively.
Co-reporter:Wei Guo;Yihua Shen;Liqiong Wu;Yurong Gao ;Tingli Ma
European Journal of Inorganic Chemistry 2011 Volume 2011( Issue 11) pp:1776-1783
Publication Date(Web):
DOI:10.1002/ejic.201001241
Abstract
Multiwall carbon nanotube (MWCNT) fibrils were introduced into TiO2–xNx photoelectrodes to enhance charge collection efficiency as charge-transport pathways. For comparison, we also synthesized MWCNT/TiO2 nanocomposites to fabricate dye-sensitized solar cells (DSCs). The effect of MWCNTs on the photovoltaic performance of the DSCs was studied in detail. The performance of DSCs based on MWCNT/TiO2–xNx differs significantly from that of MWCNT/TiO2 photoelectrodes. A high energy conversion efficiency of 7.66 % was achieved in the dye-sensitized MWCNT/TiO2 nanocomposites solar cells. The results show that remarkable enhancement of ca. 33 % and ca. 40 % in the conversion efficiency (η) and short-circuit photocurrent density (Jsc), respectively, occurrs for the DSCs based on MWCNT/TiO2 than those made of pure TiO2 electrodes. The energy conversion efficiency of DSCs based on TiO2–xNx electrodes was 6.98 %, which is similar to that of MWCNT/TiO2–xNx DSCs (6.88 %–5.17 %). We also investigated the charge collection efficiency, electron transport, electron lifetime, and photocurrent transient behavior by electrochemical analysis. The introduced MWCNTs exhibit a smaller sheet resistance and electron transfer resistance, as well as a longer electron lifetime. A 20 % enhancement in the charge collection efficiency is achieved in the nanocomposite DSCs.
Co-reporter:Qingqing Miao, Junxiong Gao, Zeqing Wang, Hang Yu, Yi Luo, Tingli Ma
Inorganica Chimica Acta 2011 Volume 376(Issue 1) pp:619-627
Publication Date(Web):1 October 2011
DOI:10.1016/j.ica.2011.07.046
Several nickel bis(dithiolene) complexes with strong and broad absorptions in the Near-IR (NIR) region (700–1100 nm) were synthesized by using green and simple synthetic routes. The physical and chemical properties of these dyes were systematically studied, including structure, optical spectroscopy and electrochemical behavior, etc. These NIR dyes were first applied to dye-sensitized solar cells (DSCs) and the photoelectrochemical performances were also investigated. The effects of different substituent groups on the properties of the dyes and photovoltaic performances of DSCs were discussed. Furthermore, we also applied the synthesized NIR dyes for constructing NIR absorbing filter. With their particular photoelectrochemical properties, the nickel bis(dithiolene) complexes exhibit promising prospects for future application.Graphical abstractSeveral nickel bis(dithiolene) complexes with strong and broad absorptions in the NIR region (700–1100 nm) were synthesized and systematically studied. They were first applied to DSCs and the photovoltaic performances of the devices were investigated. Furthermore, the application of NIR absorbing filter was also confirmed.Highlights► Nickel bis(dithiolene) NIR dyes were synthesized and systematically investigated. ► They were first applied to DSCs. ► Strong and broad absorptions in the NIR region with high ε were confirmed. ► The excellent reversibility was justified by CV/DPV. ► The application of NIR absorbing filter was also conducted.
Co-reporter:Qingqing Miao;Mingxing Wu;Wei Guo;Tingli Ma
Frontiers of Optoelectronics 2011 Volume 4( Issue 1) pp:103-107
Publication Date(Web):2011 March
DOI:10.1007/s12200-011-0201-6
Dye-sensitized solar cell (DSSC) is a new type of photoelectric device. To commercialize DSSC successfully, it is necessary to further improve the efficiency of energy conversion and reduce its cost. Nitrogen-doped (N-doped) TiO2 photoanode, the carbon counter electrode (CE), and a new type of hybrid photoanode were investigated in this study. The conversion efficiency of the DSSC reached by 10.10% as the DSSC was fabricated with the N-doped photoanode, and this efficiency is much higher than that of the undoped-DSSC with 8.90%; as the low-cost carbon was used as CE, the efficiency of the DSSC was 7.50%, it was as samilar as that of Pt CE (7.47%); the hybrid DSSC with multilayer photoanode by the film-transfer technique achieved a panchromatic response and a superposed short circuit current density (JSC) by using two complementary dyes.
Co-reporter:Wei Guo ; Yihua Shen ; Liqiong Wu ; Yurong Gao ;Tingli Ma
The Journal of Physical Chemistry C 2011 Volume 115(Issue 43) pp:21494-21499
Publication Date(Web):September 20, 2011
DOI:10.1021/jp2057496
We investigated the effect of varying amounts of N dopant on the performance of dye-sensitized solar cells (DSCs) based on the N-doped TiO2 electrodes. An interesting hierarchically macro-/mesoporous N-doped TiO2 structure with parallel macro-channels was formed by a simple template-free wet method. A series of N-doped TiO2 electrodes with varying N dopant amounts were fabricated for the DSCs. The N-doped DSCs achieve an overall conversion efficiency of 5.01–7.27%. The enhancement in the photocurrent density of N-doped DSCs was from 9% to 46% compared with undoped DSCs. The significantly enhanced photocurrent of the devices was found to be related to the N dopant amount and dye uptakes in N-doped TiO2 electrodes. The optimal N dopant amount for the N-doped TiO2 electrodes was 0.40%. Moreover, the charge transfer resistances demonstrated dependency on the N dopant amount. The electron lifetime of N-doped DSCs tended to decrease as the N dopant increased.
Co-reporter:Mingxing Wu ; Xiao Lin ; Liang Wang ; Wei Guo ; Yudi Wang ; Jinqiu Xiao ; Anders Hagfeldt ;Tingli Ma
The Journal of Physical Chemistry C 2011 Volume 115(Issue 45) pp:22598-22602
Publication Date(Web):September 26, 2011
DOI:10.1021/jp205886d
Tungsten dioxide imbedded in mesoporous carbon (WO2–MC) was obtained by in situ synthesis and then introduced into dye-sensitized solar cells (DSCs) as a counter electrode (CE) catalyst. Catalytic activity for redox couple regeneration was improved significantly through combining high electrical conductivity and catalytic activity into one material, WO2–MC, in which WO2 served as a catalyst and MC served as an electrical conductor. This has been proved by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The triiodide/iodide-based DSC using WO2–MC as CE showed a high power conversion efficiency (PCE) of 7.76%, which surpassed the performance of the DSC using traditional Pt CE (7.55%). In addition, the WO2–MC and WO2 nanorods exhibited higher catalytic activity than Pt for the regeneration of a new organic redox couple, di-5-(1-methyltetrazole) disulfide/5-mercapto-1-methyltetrazole N–tetramethylammonium salt (T2/T–). The PCE of the T2/T–-based DSCs using WO2–MC, WO2, and Pt were 5.22, 4.66, and 3.09%, respectively.
Co-reporter:Wei Guo, Liqiong Wu, Zhuo Chen, Gerrit Boschloo, Anders Hagfeldt, Tingli Ma
Journal of Photochemistry and Photobiology A: Chemistry 2011 Volume 219(2–3) pp:180-187
Publication Date(Web):15 April 2011
DOI:10.1016/j.jphotochem.2011.01.004
A series of nitrogen-doped and undoped TiO2 nanocrystals was prepared by several simple methods. Needle-like N-doped TiO2 nanocrystals and nanoparticles were obtained from commercial TiO2 powders. Several dye-sensitized solar cells (DSCs) were fabricated based on N-doped and undoped TiO2 electrodes. The N-doped DSCs achieved a high conversion efficiency of 10.1% and 4.8% using an organic electrolyte and an ionic liquid electrolyte, respectively. Systemic investigations were carried out on the properties of N-doped and undoped TiO2 powders, films, and DSCs. The electron transport time and electron lifetime were investigated by intensity-modulated photocurrent and photovoltage spectroscopy (IMPS/IMVS). Moreover, the electron injection of N-doped DSCs was studied by surface photovoltage spectroscopy (SPS). The synergetic effect of higher dye uptake, faster electron transport and higher photovoltage contributes to a higher conversion efficiency of N-doped DSCs. The stability test also demonstrated that the photodegradation of the DSCs was not accelerated and the DSC system was stabilized by the introduction of nitrogen into the TiO2 photoelectrode. These results indicate that the N-doped TiO2 nanocrystals prepared by our approach from commercial TiO2 are ideal semiconductor materials for DSCs.A highly efficient dye-sensitized solar cell (DSC) based on N-doped TiO2 electrode was fabricated, obtaining an energy conversion efficiency of 10.1%. The influences of the N-doped TiO2 on the DSC system were investigated in detail. The N-doped TiO2 nanocrystals simply prepared from commercially available TiO2 are ideal semiconductor materials for DSCs.
Co-reporter:Huizhi Zhou, Liqiong Wu, Yurong Gao, Tingli Ma
Journal of Photochemistry and Photobiology A: Chemistry 2011 Volume 219(2–3) pp:188-194
Publication Date(Web):15 April 2011
DOI:10.1016/j.jphotochem.2011.02.008
Twenty natural dyes, extracted from natural materials such as flowers, leaves, fruits, traditional Chinese medicines, and beverages, were used as sensitizers to fabricate dye-sensitized solar cells (DSCs). The photoelectrochemical performance of the DSCs based on these dyes showed that the open circuit voltages (Voc) varied from 0.337 to 0.689 V, and the short circuit photocurrent densities (Jsc) ranged from 0.14 to 2.69 mA cm−2. Specifically, a high Voc of 0.686 V was obtained from the dye extracted from mangosteen pericarp sensitizer. The photo-to-electric conversion efficiency of the DSC sensitized by the ethanol extract of mangosteen pericarp without purification reached 1.17%. Moreover, various components of the ethanol extract were extracted using different organic solvents. The photoelectrochemical performance of these extracts demonstrated that rutin was the most effectual component of the sensitizer for DSC.Graphical abstractThe dye-sensitized solar cells were fabricated using 20 natural dyes as sensitizers, which were extracted from flowers, leaves, fruits, traditional Chinese medicines, and beverages. The photoelectrochemical performance of the DSCs based on the dyes was studied. The DSC sensitized by mangosteen pericarp dye with a relatively high photo-to-electric conversion efficiency was investigated in detail.Highlights► Twenty natural dyes were used as sensitizers for dye-sensitized solar cells. ► A high Voc of 0.686 V was obtained from the dye extracted from mangosteen pericarp sensitizer. ► The photo-to-electric conversion efficiency of the mangosteen pericarp-sensitized DSC reached 1.17%. ► Rutin was the most effectual component of the sensitizer for DSC.
Co-reporter:Dr. Mingxing Wu;M.Sc. Xiao Lin; Anders Hagfeldt; Tingli Ma
Angewandte Chemie 2011 Volume 123( Issue 15) pp:3582-3586
Publication Date(Web):
DOI:10.1002/ange.201006635
Co-reporter:Dr. Mingxing Wu;M.Sc. Xiao Lin; Anders Hagfeldt; Tingli Ma
Angewandte Chemie International Edition 2011 Volume 50( Issue 15) pp:3520-3524
Publication Date(Web):
DOI:10.1002/anie.201006635
Co-reporter:Li Yang, Liqiong Wu, Mingxing Wu, Gang Xin, Hong Lin, Tingli Ma
Electrochemistry Communications 2010 Volume 12(Issue 7) pp:1000-1003
Publication Date(Web):July 2010
DOI:10.1016/j.elecom.2010.05.026
All-transparent and all-flexible dye-sensitized solar cells (DSCs) were fabricated using a novel, facile, and low-lost friction-transfer technique, which involved assembling TiO2 films on flexible substrates via high-temperature sintering. This friction-transfer technique led to a 25% enhancement in conversion efficiency compared with the compression method. The efficiency of the optimized all-flexible DSC reached 5.7%, which is approximately 73% higher than that of the all-flexible DSC prepared by the low-temperature sintering method (3.3%).
Co-reporter:Liang Wang, Yantao Shi, Yanxiang Wang, Hong Zhang, Huawei Zhou, Ying Wei, Shengyang Tao and Tingli Ma
Chemical Communications 2014 - vol. 50(Issue 14) pp:NaN1703-1703
Publication Date(Web):2013/11/21
DOI:10.1039/C3CC47163B
A composite catalyst of rosin carbon/Fe3O4 with marvellous morphology was synthesized and applied as a counter electrode (CE) in dye-sensitized solar cells (DSCs), demonstrating notable electrocatalytic activity for the reduction of I3−. Based on this CE, a high power conversion efficiency of 8.11% was achieved, comparable to that of the traditional Pt CE.
Co-reporter:Xiaojia Zheng, Jiahao Guo, Yantao Shi, Fengqiang Xiong, Wen-Hua Zhang, Tingli Ma and Can Li
Chemical Communications 2013 - vol. 49(Issue 83) pp:NaN9647-9647
Publication Date(Web):2013/08/23
DOI:10.1039/C3CC45064C
Porous chalcogels CoMoS4 and NiMoS4 made by a facile solution reaction displayed good electrocatalytic activity in the redox reaction of the I−/I3− shuttle. Dye-sensitized solar cells with these ternary compounds as counter electrodes (CEs) showed photovoltaic performance similar to the devices made with noble metal platinum CE (7.46%).
Co-reporter:Jiahao Guo, Yantao Shi, Yuting Chu and Tingli Ma
Chemical Communications 2013 - vol. 49(Issue 86) pp:NaN10159-10159
Publication Date(Web):2013/08/22
DOI:10.1039/C3CC45698F
Two transition metal tellurides, CoTe and NiTe2, were synthesized and for the first time employed as the counter electrodes (CEs) with high catalytic activity for reduction of I3− in dye-sensitized solar cells (DSCs). Using CoTe and NiTe2-based CEs, photoelectric conversion efficiencies (PCEs) of 6.92% and 7.21% were achieved for DSCs, respectively, comparable to that of 7.04% achieved when using a Pt-based CE. The results indicated that, serving as a CE in DSCs, telluride could be a cost-effective and efficient alternative to the noble metal Pt.
Co-reporter:Hong Zhang, Yantao Shi, Feng Yan, Liang Wang, Kai Wang, Yujin Xing, Qingshun Dong and Tingli Ma
Chemical Communications 2014 - vol. 50(Issue 39) pp:NaN5022-5022
Publication Date(Web):2014/03/25
DOI:10.1039/C3CC49458F
The ionic liquid N-butyl-N′-(4-pyridylheptyl)imidazolium bis(trifluoromethane)sulfonimide (BuPyIm-TFSI) was used as a dual-functional additive to improve the electrical properties of the hole-transporting material (HTM) for perovskite solar cells. BuPyIm-TFSI improved the conductivity of HTM and reduced the dark current of the solar cell simultaneously, thereby greatly increasing the power conversion efficiency.
Co-reporter:Hong Zhang, Yantao Shi, Liang Wang, Chaolei Wang, Huawei Zhou, Wei Guo and Tingli Ma
Chemical Communications 2013 - vol. 49(Issue 79) pp:NaN9005-9005
Publication Date(Web):2013/08/01
DOI:10.1039/C3CC44520H
Pyridyl iodides were synthesized to serve as effective, economical, green and dual function additives for high efficiency and stable DSCs. Using commercial P25 as the photoanode, a high PCE of 7.81% was achieved with a pyridyl iodide-containing electrolyte. Meanwhile, DSCs based on our novel electrolytes demonstrated better stability.
Co-reporter:Huawei Zhou, Yantao Shi, Qingshun Dong, Yanxiang Wang, Chao Zhu, Liang Wang, Ning Wang, Ying Wei, Shengyang Tao and Tingli Ma
Journal of Materials Chemistry A 2014 - vol. 2(Issue 12) pp:NaN4354-4354
Publication Date(Web):2014/01/02
DOI:10.1039/C3TA14345G
Sufficient contact, high catalytic activity, free electron transport and ionic diffusion are desired for liquid–solid heterogeneous electrocatalysis. However, preparing catalysts that simultaneously possess all of these four advantages has proven challenging. Nanostructures originating from anisotropic growth always exhibit specific structural advantages and unique physical, chemical or catalytic properties. Herein, via a facile and template-free solvothermal approach, we synthesized W18O49 nanofibers (NFs) and nanofiber bundles (NFBs), as well as hierarchical spheres (HSs). As catalyst for the counter electrode (CE) of dye-sensitized solar cells (DSCs), W18O49 NFs demonstrated remarkable electrocatalytic activity because: (i) abundant oxygen vacancies offered sufficient active sites for reduction of I3− into I−; (ii) the one dimensional NFs were more beneficial to electron transport; (iii) the two phases, the liquid electrolyte and the solid NFs, could fully contact each other, and meanwhile ions could diffuse freely among the networks constructed by the interlaced NFs. Notably, DSCs using the NF-based semitransparent CE achieved high photoelectric conversion efficiencies (PCEs) up to 8.58%, superior to those based on NFBs or HSs, and comparable to that of 8.78% using Pt as the CE. Furthermore, it was proven that both the electrolytic activity and the PCE deteriorated drastically when the NFs were destroyed. Our work here will be of great interest for both fundamental research and practical applications of W18O49 nanomaterials in other fields.
Co-reporter:Liang Wang, Yantao Shi, Hong Zhang, Xiaogong Bai, Yanxiang Wang and Tingli Ma
Journal of Materials Chemistry A 2014 - vol. 2(Issue 37) pp:NaN15283-15283
Publication Date(Web):2014/07/25
DOI:10.1039/C4TA03727H
Fe3O4 with hierarchical structures was successfully synthesized and introduced into dye-sensitized solar cells as the counter electrode. A power conversion efficiency of 7.65% based on Fe3O4 was achieved, which is superior to that of pyrolytic Pt (6.88%) and close to that for sputtered Pt (7.87%).
Co-reporter:Huawei Zhou, Yantao Shi, Da Qin, Jiang An, Lingling Chu, Chaolei Wang, Yudi Wang, Wei Guo, Liang Wang and Tingli Ma
Journal of Materials Chemistry A 2013 - vol. 1(Issue 12) pp:NaN3937-3937
Publication Date(Web):2013/02/07
DOI:10.1039/C3TA00960B
Low-cost bendable photoanodes and counter electrodes (CEs), as well as gel electrolytes, are potentially desired for the mass production of completely flexible dye-sensitized solar cells (DSSCs). In this work, via printing at low temperature, we fabricated titanium carbide (TiC)-functionalized conductive-carbon (CC) on flexible polyimide (PI) films to replace traditional and expensive Pt/ITO/PEN CEs. Morphology characterization revealed this composite CE was highly porous and homogeneous. Electrochemical investigations demonstrated that this Pt-and-ITO free flexible CE exhibited a high electro-catalytic activity. Finally, the conversion efficiencies of the all flexible quasi-solid DSSCs using this low-cost TiC-CC/PI CE achieved 86% of that based on a Pt/CC/PI CE. Thus, the facile fabrication process of this novel CE, along with its notable performance, are quite promising for the future roll-to-roll production of completely flexible DSSCs.
Co-reporter:Jiahao Guo, Yantao Shi, Chao Zhu, Lin Wang, Ning Wang and Tingli Ma
Journal of Materials Chemistry A 2013 - vol. 1(Issue 38) pp:NaN11879-11879
Publication Date(Web):2013/08/01
DOI:10.1039/C3TA12349A
Developing Pt-free and highly efficient counter electrodes (CEs) is meaningful and necessary for the cost reduction of dye-sensitized solar cells (DSCs). In this work, via a facile and reductant-free solvothermal approach, we report the controllable synthesis of NbSe2 nanosheets (NSs), nanorods (NRs), as well as the composite NbSe2/C for use as CEs in high efficiency DSCs. The morphology and structure of the three samples were characterized by SEM, XRD and TEM. Meanwhile, by cyclic voltammetry measurements, electrochemical impedance spectroscopy and Tafel polarization, we found some key issues which explain the difference in their electrocatalytic activity in the reduction of triiodide (I3−). Compared with electrodes based on NbSe2 NRs, NbSe2 NS-based CEs demonstrated lower resistances in charge transfer and ionic diffusion. Subsequently, DSCs with NbSe2 NS-based CEs achieved a conversion efficiency of 7.34%. In addition, NbSe2/C composite-based CEs could further reduce the series resistance and finally a conversion efficiency of 7.80% was obtained, comparable to an efficiency of 7.90% for Pt-based CEs. The NbSe2 in our work provides a cost-effective CE alternative to the noble metal Pt in DSCs.
Co-reporter:Yudi Wang, Mingxing Wu, Xiao Lin, Zhicong Shi, Anders Hagfeldt and Tingli Ma
Journal of Materials Chemistry A 2012 - vol. 22(Issue 9) pp:NaN4014-4014
Publication Date(Web):2012/01/25
DOI:10.1039/C2JM15182K
Three nanomaterials, namely, titanium carbide (TiC), tungsten oxide (WO2), and vanadium nitride (VN), are introduced into dye-sensitized solar cells (DSCs) as counter electrode (CE) catalysts to replace the expensive Pt CE. Three kinds of substrates of bare glass (BG), Ti foil, and polyimide (PI) film are applied as F-doped tin oxide (FTO)-free substrates for rigid and flexible DSCs; thus realizing FTO-free and Pt-free CEs simultaneously in the DSC system. A carbon layer is used as an electron collector to replace the expensive FTO conductive layer in the insulative BG and PI film. Cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization curves are performed to compare the catalytic activities of these CEs for the reduction of triiodide to iodide. The results demonstrate that the DSCs that use TiC, WO2, and VN as CEs on Ti foil have better photovoltaic performance than those that use CEs on traditional FTO glass. Moreover, the TiC, WO2, and VN on the BG substrates show excellent catalytic activities that can match the performance of the CEs on FTO glasses.
Co-reporter:Yudi Wang, Chunyu Zhao, Da Qin, Mingxing Wu, Wei Liu and Tingli Ma
Journal of Materials Chemistry A 2012 - vol. 22(Issue 41) pp:NaN22159-22159
Publication Date(Web):2012/08/20
DOI:10.1039/C2JM35348B
A transparent flexible Pt counter electrode (CE) was prepared on indium tin oxide–polyethylene naphthalate film using a simple dip coating method for dye-sensitized solar cells (DSCs), and a high catalytic activity was achieved. The DSC using this transparent flexible CE gave a power conversion efficiency (PCE) of 6.95% with front illumination, and a PCE of 5.18% with rear illumination.
Co-reporter:Jiahao Guo, Suxia Liang, Yantao Shi, Ce Hao, Xuchun Wang and Tingli Ma
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 43) pp:NaN28992-28992
Publication Date(Web):2015/09/25
DOI:10.1039/C5CP04862A
Exploiting an alternative of the Pt-based counter-electrode materials for the triiodide reduction reaction has become a major interest in the fundamental research of dye-sensitized solar cells. Transition-metal selenides have recently been demonstrated as promising non-precious metal electrocatalysts for the triiodide reduction reaction. Herein, we prepared a series of transition-metal selenides via a free-reductant solvothermal method and used them as counter-electrodes in high efficiency dye-sensitized solar cells. The electrochemical results showed that these selenides had excellent catalytic activity for the reduction of the triiodine/iodine couple, and except for MoSe2, the conversion efficiencies of the corresponding dye-sensitized solar cells were comparable to the sputtered Pt counter-electrode. Theoretical investigation clearly revealed that the unsatisfactory performance of MoSe2 mainly originated from the processes of adsorption and charge-transfer. These findings can help to better understand the electrocatalytic processes and thus offer some useful guidelines to develop more efficient electrochemical catalysts.
Co-reporter:Mingxing Wu, Yudi Wang, Xiao Lin, Naisen Yu, Liang Wang, Linlin Wang, Anders Hagfeldt and Tingli Ma
Physical Chemistry Chemical Physics 2011 - vol. 13(Issue 43) pp:NaN19301-19301
Publication Date(Web):2011/10/10
DOI:10.1039/C1CP22819F
Molybdenum sulfide (MoS2) and tungsten sulfide (WS2) are proposed as counter electrode (CE) catalysts in a I3−/I− and T2/T− based dye-sensitized solar cells (DSCs) system. The I3−/I− based DSCs using MoS2 and WS2 CEs achieved power conversion efficiencies of 7.59% and 7.73%, respectively.
Co-reporter:Sining Yun, Liang Wang, Chunyu Zhao, Yanxiang Wang and Tingli Ma
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 12) pp:NaN4290-4290
Publication Date(Web):2013/02/01
DOI:10.1039/C3CP44048F
A Pt/SiC nanocomposite with ∼10 wt% Pt loading was used as a counter electrode (CE) in dye-sensitized solar cells (DSCs), it shows a high power conversion efficiency (PCE) of 7.07% (a DSC with a SiC CE has a PCE of 3.29%), reaching 98.5% of the level obtained using a Pt CE (7.18%). This work provides substantial support for developing low-cost Pt-loaded composite CEs for DSCs. Pt/SiC use is expected to reduce the dependence on the Pt in DSCs, while it can also be expected to be used in many chemical and electrochemical processes required to control the amount of Pt and prevent Pt nanoparticle aggregation.
Co-reporter:Sining Yun, Huawei Zhou, Liang Wang, Hong Zhang and Tingli Ma
Journal of Materials Chemistry A 2013 - vol. 1(Issue 4) pp:NaN1348-1348
Publication Date(Web):2012/11/13
DOI:10.1039/C2TA00680D
Hafnium oxygen nitride binary/ternary nanocomposites were prepared by combining Hf7O8N4, HfO2, and amorphous carbon through a simple chemical synthesis. The obtained HfO2 (Hf-R0-U), HfO2–C (Hf-R5-B), and Hf7O8N4–HfO2–C (Hf-R12-T) were characterized by XRD, SEM, FESEM, and electrochemical measurements. Dye-sensitized solar cells (DSCs) with binary Hf-R5-B and ternary Hf-R12-T composites as counter electrode (CE) showed superior electrocatalytic activity for I3− reduction and high power conversion efficiencies (PCE) of 6.71% and 7.85%, respectively, matching the performance of DSCs with Pt CE (7.19%). The design strategy demonstrated is promising for fabricating highly efficient and low-cost composite CE catalysts for DSCs.
Co-reporter:Mingxing Wu, Xiao Lin, Yudi Wang and Tingli Ma
Journal of Materials Chemistry A 2015 - vol. 3(Issue 39) pp:NaN19656-19656
Publication Date(Web):2015/08/05
DOI:10.1039/C5TA03682H
Dye- or quantum dot-sensitized solar cells (DSCs or QDSCs) comprise a sensitizer, a semiconductor, an electrolyte containing redox couple, and a counter electrode (CE), which have inspired a new wave of research. The challenges in realizing the practical application of such photovoltaic devices are the enhancement of photovoltaic performance, stability, and the reduction of fabrication costs. The CE is an important component, and the exploration of low cost CE catalysts to match the redox couples has become a feasible route in the pursuit of high power conversion efficiency and low production cost of the devices. This article reviews the development of CE catalysts for the regeneration of each type of iodide-free redox couple, including inorganic, organic, and transition metal complex-based redox couples, among others.
Co-reporter:Xiao Lin, Mingxing Wu, Yudi Wang, Anders Hagfeldt and Tingli Ma
Chemical Communications 2011 - vol. 47(Issue 41) pp:NaN11491-11491
Publication Date(Web):2011/09/26
DOI:10.1039/C1CC14973C
Synthesized niobium oxides (Nb2O5 and NbO2) were applied for the first time as counter electrodes (CEs) in dye-sensitized solar cells (DSCs). The DSC using NbO2 CE showed a higher power conversion efficiency of 7.88%, compared with that of the DSC using Pt CE (7.65%).
Co-reporter:Mingxing Wu, Xiao Lin, Anders Hagfeldt and Tingli Ma
Chemical Communications 2011 - vol. 47(Issue 15) pp:NaN4537-4537
Publication Date(Web):2011/03/08
DOI:10.1039/C1CC10638D
Tungsten dioxide (WO2) nanorods were synthesized, which showed excellent catalytic activity for the reduction of triiodide to iodide. The dye-sensitized solar cell (DSC) using WO2 as a counter electrode (CE) reached a high energy conversion efficiency of 7.25%, which can match the performance of the DSC based on a Pt CE.
Co-reporter:Wei Guo, Yihua Shen, Mingxing Wu and Tingli Ma
Chemical Communications 2012 - vol. 48(Issue 49) pp:NaN6135-6135
Publication Date(Web):2012/04/23
DOI:10.1039/C2CC31903A
All-solid-state inorganic–organic heterojunction solar cells (HSCs) were designed and fabricated using earth-abundant element, non-toxic, low-cost SnS-sensitized mesoporous spherical TiO2 films under ambient conditions using a solution-processable, simple, and convenient fabrication technique. SnS-HSCs show a promising photovoltaic performance, with an efficiency of 2.8% and a significantly high VOC of 0.85 V.
Co-reporter:Huawei Zhou, Yantao Shi, Liang Wang, Hong Zhang, Chunyu Zhao, Anders Hagfeldt and Tingli Ma
Chemical Communications 2013 - vol. 49(Issue 69) pp:NaN7628-7628
Publication Date(Web):2013/06/24
DOI:10.1039/C3CC44518F
For the first time, nonstoichiometric WO2.72 was used as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). Oxygen-vacancy-rich WO2.72 nanorod bundles with notable catalytic activity for triiodide and thiolate reduction were prepared in this study. The photovoltaic parameters of dye-sensitized solar cells (DSSCs) with WO2.72 nanorod bundles as CEs are superior compared with those of the WO3-based cells, and nearly the same as those of the precious metal Pt-based cells. In a non-corrosive organic redox couple, the performance of WO2.72 CEs is better than that of Pt and WO3 CEs in DSSCs.
Co-reporter:Mingxing Wu, Xiao Lin, Wei Guo, Yudi Wang, Lingling Chu, Tingli Ma and Kezhong Wu
Chemical Communications 2013 - vol. 49(Issue 11) pp:NaN1060-1060
Publication Date(Web):2012/10/29
DOI:10.1039/C2CC37360B
The dye-sensitized solar cells (DSCs) using SnO2 and Nb2O5 counter electrodes (CEs) prepared in N2 atmosphere yielded power conversion efficiencies (PCE) of 6.09% and 4.65%, much higher than the PCE values (1.84%, 0.97%) of the DSCs using the same SnO2 and Nb2O5 CEs prepared in air.
Co-reporter:Chunlei Wang, Fanning Meng, Mingxing Wu, Xiao Lin, Tonghua Wang, Jieshan Qiu and Tingli Ma
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 34) pp:NaN14187-14187
Publication Date(Web):2013/06/27
DOI:10.1039/C3CP52525B
A novel bio-inspired Pt- and FTO-free integrated pure carbon counter electrode (CE) for dye-sensitized solar cells (DSSCs) has been designed and fabricated using a porous carbon sheet as a conducting substrate and ordered mesoporous carbon (OMC) as the catalytic layer. A rigid, crustose lichen-like, integrated carbon–carbon composite architecture with a catalytic layer rooted in a porous conducting substrate was formed by a process of polymer precursor spin coating, infiltration and pyrolysis. The integrated pure carbon CE shows very low series resistance (Rs), owing to the high conductivity of the carbon sheet (sheet resistance of 488 mΩ □−1) and low charge-transfer resistance (Rct), due to the large specific surface area of the OMC layer that is accessible to the redox couple. The values of Rs and Rct are much lower than those of a platinized fluorine-doped thin oxide glass (Pt/FTO) electrode. Cells with this CE show high solar-to-electricity conversion efficiencies (8.11%), comparable to that of Pt/FTO based devices (8.16%).
Co-reporter:Mingxing Wu, Qingyu Zhang, Jinqiu Xiao, Chunyu Ma, Xiao Lin, Chunyu Miao, Youjing He, Yurong Gao, Anders Hagfeldt and Tingli Ma
Journal of Materials Chemistry A 2011 - vol. 21(Issue 29) pp:NaN10766-10766
Publication Date(Web):2011/06/20
DOI:10.1039/C1JM11422K
Two novel flexible counter electrodes (CEs) on Ti sheets using molybdenum and tungsten nitrides (Mo2N, W2N) as catalysts were synthesized and used in a dye-sensitized solar cell (DSC) system. High catalytic activity of the two nitride CEs for the reduction of triiodide were proved by cyclic voltammetry, electrochemical impedance spectroscopy and Tafel-polarization measurements. The DSCs based on Mo2N and W2N CEs achieved power conversion efficiencies of 6.38 and 5.81%, reaching 91 and 83% of the photovoltaic performance of the DSC using a Pt CE, respectively. This research paves a promising way to develop new CE catalysts and reduce the cost of DSCs.
Co-reporter:Liang Wang, Eric Wei-Guang Diau, Mingxing Wu, Hsueh-Pei Lu and Tingli Ma
Chemical Communications 2012 - vol. 48(Issue 20) pp:NaN2602-2602
Publication Date(Web):2012/01/11
DOI:10.1039/C2CC17389A
We developed several low-cost catalysts with high catalytic activity, which were used as counter electrodes in dye-sensitized solar cells (DSCs). They showed higher efficiencies than that of Pt. The efficiencies were improved by 18–42% for the DSCs composed of active carbon, niobium dioxide, ordered mesoporous carbon and commercial titanium carbide.
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