Co-reporter:Xueping Zong, Wenhua Qiao, Yu Chen, Zhe Sun, Mao Liang, Song Xue
Tetrahedron 2017 Volume 73, Issue 24(Issue 24) pp:
Publication Date(Web):15 June 2017
DOI:10.1016/j.tet.2017.05.020
•Two binaphthol based hole-transporting materials were prepared.•Benzyl and hexyl were introduced as edge chain onto the binaphthol core.•Perovskite solar cells work well with the two materials at low-doping level.A novel hole-transporting material (Q221) is synthesized by introducing benzyl groups onto the 1,1′-bi-2-naphthol central core as edge chains and bis(4-methoxyphenyl)amine-substituted 9H-carbazole as donor groups. A reference molecule (Q222) is prepared with hexyl edge chains. The introduction of edge chains influences their molecular orbital energy levels. Q221-based CH3NH3PbI3 perovskite solar cells with carbon counter electrode exhibit the highest power conversion efficiency of 10.37% at a low doping level of Li-TFSI/TBP (15 mM/100 mM), and that of Q222-based cells is 8.87%. Q221-based cells doping with Li-TFSI/TBP of 15 mM/100 mM shows much better photovoltaic parameters compared to those doping with Li-TFSI/TBP of 30 mM/200 mM, when aged in ambient air of 30% RH without encapsulation. The new binaphthol based hole-transporting materials shows a great potential in fabricating effective perovskite solar cells.Download high-res image (240KB)Download full-size image
Co-reporter:Qi Zhang, Hongyan Wang, Yixin Dong, Quanping Wu, Song Xue
International Journal of Hydrogen Energy 2017 Volume 42, Issue 25(Volume 42, Issue 25) pp:
Publication Date(Web):22 June 2017
DOI:10.1016/j.ijhydene.2017.05.088
•Sn-doped hematite photoanodes via mid-situ and ex-situ doping methods were prepared.•The morphology of Sn-doped Fe2O3 films was varied with Sn precursors in the mid-situ doping process.•200% photocurrent density enhancement was obtained for sample Fe2O3/SnCl2–H2O soaked in SnCl2 solution.•The photocurrent can be further improved by surface modification of the Sn-doped hematite with SnCl4 through ex-situ process.•The IPCE value of 16.1% was obtained at 400 nm for sample Fe2O3/SnCl2/SnCl4-300 at 1.23 VRHE.In this study, we report the facile fabrication of Sn-doped hematite film via mid-situ and ex-situ doping methods for efficient photoelectrochemical (PEC) performances. The morphology of Sn-doped Fe2O3 films was varied with Sn precursor in the mid-situ doping process. The addition of SnCl2 rendered a smooth-surfaced and well-distributed nanorod morphology, but SnCl4 gave a deformed nanorod structure covered with layered coalescence of SnO2 particles. The former demonstrated much higher photoelectrochemical performances as photoanodes than the latter. The photocurrent can be further improved by surface modification with SnCl4 through spin-coating method. The effects of Sn precursors on the morphology, surface characteristics and the PEC properties of the photoanodes are investigated.
Co-reporter:Wenhua Qiao;Yu Chen;Fusheng Li;Xueping Zong;Zhe Sun;Mao Liang
RSC Advances (2011-Present) 2017 vol. 7(Issue 1) pp:482-492
Publication Date(Web):2016/12/20
DOI:10.1039/C6RA25606F
New star-shaped and efficient hole-transporting materials based on a 1,1′-bi-2-naphthol central core for perovskite solar cells are developed via facile synthesis. The 1,1′-bi-2-naphthol is first applied into the field of perovskite solar cells. The 2,7-carbazole-bis(4-methoxy-phenyl)-amine and 3,6-carbazole-bis(4-methoxy-phenyl)-amine are used as end groups. A reference compound based on a 3,3′-biphenyl core is prepared as well. The new materials have suitable highest occupied molecular orbital levels to match well with the valence band of CH3NH3PbI3, and they all exhibit a glass transition temperature higher than 160 °C. A device fabricated by hole-transporting materials based on 1,1′-bi-2-naphthol and 2,7-carbazole-bis(4-methoxy-phenyl)-amine in conjunction with a carbon counter electrode achieves the highest power conversion efficiency of 8.38% under the illumination of 100 mW cm−2, which is comparable to that fabricated by commercial spiro-OMeTAD (8.73%). Dark current, IPCE and IMVS measurements are also discussed. The introduction of 2,7-carbazole-bis(4-methoxy-phenyl)-amine onto the 1,1′-bi-2-naphthol central core tends to enhance Jsc of a device, and 3,6-carbazole-bis(4-methoxy-phenyl)-amine improves Voc. This work provides a new series of hole-transporting materials to fabricate economic and efficient perovskite solar cells.
Co-reporter:Wenhua Qiao;Yu Chen;Fusheng Li;Xueping Zong;Zhe Sun;Mao Liang
RSC Advances (2011-Present) 2017 vol. 7(Issue 1) pp:482-492
Publication Date(Web):2016/12/20
DOI:10.1039/C6RA25606F
New star-shaped and efficient hole-transporting materials based on a 1,1′-bi-2-naphthol central core for perovskite solar cells are developed via facile synthesis. The 1,1′-bi-2-naphthol is first applied into the field of perovskite solar cells. The 2,7-carbazole-bis(4-methoxy-phenyl)-amine and 3,6-carbazole-bis(4-methoxy-phenyl)-amine are used as end groups. A reference compound based on a 3,3′-biphenyl core is prepared as well. The new materials have suitable highest occupied molecular orbital levels to match well with the valence band of CH3NH3PbI3, and they all exhibit a glass transition temperature higher than 160 °C. A device fabricated by hole-transporting materials based on 1,1′-bi-2-naphthol and 2,7-carbazole-bis(4-methoxy-phenyl)-amine in conjunction with a carbon counter electrode achieves the highest power conversion efficiency of 8.38% under the illumination of 100 mW cm−2, which is comparable to that fabricated by commercial spiro-OMeTAD (8.73%). Dark current, IPCE and IMVS measurements are also discussed. The introduction of 2,7-carbazole-bis(4-methoxy-phenyl)-amine onto the 1,1′-bi-2-naphthol central core tends to enhance Jsc of a device, and 3,6-carbazole-bis(4-methoxy-phenyl)-amine improves Voc. This work provides a new series of hole-transporting materials to fabricate economic and efficient perovskite solar cells.
Co-reporter:Jingwen Jia;Yu Chen;Liangsheng Duan;Zhe Sun;Mao Liang
RSC Advances (2011-Present) 2017 vol. 7(Issue 72) pp:45807-45817
Publication Date(Web):2017/09/22
DOI:10.1039/C7RA08965A
Three D–π–A sensitizers incorporating dithieno[3,2-b:2′,3′-d]pyrrole (DTP)-based π-linkers were synthesized for fabricating efficient dye-sensitized solar cells (DSSCs). The DTP-based π-spacers were attached by 10-phenyl-10H-phenothiazine (JW1), 5,5,10,10,15,15-hexapropyl-10,15-dihydro-5H-diindeno[1,2-a:1′,2′-c]fluorene (JW2) and 4-hexyloxyphenyl (JW3). The bulky groups and alkyl chains are introduced to suppress dye aggregation as well as reduce electron recombination. An additional double bond spacer was introduced between the arylamine donor and DTP-based π-spacer in the studied dyes. Based on the theoretical calculation results, all of the dye molecules display good electron transport. The photovoltaic performances of device based on JW1, JW2 and JW3 were measured by J–V characterizations in Co-phen based electrolyte, achieving power conversion efficiencies of 7.09%, 7.87% and 6.50%, respectively. The incident photon-to-current conversion efficiency (IPCE) follows the order JW2 > JW1 > JW3, which is accordance with their photovoltaic performances. IMVS results indicate that the three dyes incorporating the modified DTP-based π-spacers have an influence on the CB shift of TiO2 and the inhibition of charge recombination. Therefore, the DTP-based π-spacer is a promising building block for developing new dyes to build highly efficient DSSCs.
Co-reporter:Kai Miao;Mao Liang;Zhihui Wang;Chunyao Zhang;Zhe Sun
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 3) pp:1927-1936
Publication Date(Web):2017/01/18
DOI:10.1039/C6CP07335B
Thiophene derivatives, including thieno[3,2-b][1]benzothiophene (TBT), benzo[b]thiophene (BT), 2-phenylthieno[3,2-b]thiophene (PTT) and 2-phenylthiophene (PT), have been introduced as donors for the construction of triarylamine organic dyes (M52, M53, M56, M57 and M52A). The absorption, electrochemical and photovoltaic properties as well as the stabilities of these dyes are systematically investigated and compared with the reference dye (M55), whose donor is composed of the hexyloxybenzene (HOB) unit. It is found that introducing the TBT, BT, PTT or PT donors positively shifted the HOMO and LUMO levels of the organic dyes, providing a larger driving force for regeneration and reducing the energy loss for electron injection. In addition, we found that M52, which contains the TBT unit, exhibited better photovoltaic performance and photostability as compared to the reference dye. In contrast, M53 displayed the lowest efficiency and stability of these dyes, indicating that the BT unit is not a good building block for donors. Interestingly, upon the incorporation of the mixed donor (TBT–HOB), M52A achieved a desirable driving force for regeneration without a loss in light absorption, thus resulting in a further improved photovoltaic performance with respect to that of M52. This work demonstrates that introducing donors based on thiophene derivatives is a good strategy for tuning the energy levels and thereby enhancing the efficiency of the resulting devices.
Co-reporter:Gaoyang Ge, Panpan Dai, Ziyi Lu, Mao Liang, Huanhuan Dong, Zhe Sun, Song Xue
Dyes and Pigments 2016 Volume 128() pp:8-18
Publication Date(Web):May 2016
DOI:10.1016/j.dyepig.2016.01.007
•Three new dithieno[3,2-b:2′,3′-d]pyrrole (DTP) units were synthesized.•The effects of substituent on DTP are apparent.•The truxene-substituted DTP is a promising candidate for photovoltaic cells.Three new dithieno[3,2-b:2′,3′-d]pyrrole units (DTPA1–3) based on the truxene core have been designed and synthesized for a potential application in photovoltaic cells. One of these units (DTPA1) has been employed to construct a new organic dye (M47), exhibiting a higher solar-to-electrical energy conversion efficiency when compared to reference dyes (M48 and M49) under the same conditions. Absorption spectra, electrochemical cyclic voltammetry, theoretical calculations, current voltage curves and controlled intensity modulated photovoltage spectroscopy have been investigated. M47 sensitized solar cells employing a cobalt electrolyte afford a short circuit photocurrent of 12.1 mA cm−2, an open circuit voltage of 758 mV, and a fill factor of 0.56, corresponding to an overall power conversion efficiency of 5.1% under standard AM 1.5 sunlight. These results suggest that the truxene-substituted dithieno[3,2-b:2′,3′-d]pyrrole derivatives are promising candidates for photovoltaic cells.
Co-reporter:Jiang Wang, Yu Chen, Mao Liang, Gaoyang Ge, Renjie Zhou, Zhe Sun, Song Xue
Dyes and Pigments 2016 Volume 125() pp:399-406
Publication Date(Web):February 2016
DOI:10.1016/j.dyepig.2015.11.004
•A novel truxene-based hole-transporting material was synthesized by a facile route.•The truxene-based material exhibits high thermal stability and excellent solubility.•This new material can be used for perovskite solar cells with carbon cathode.Developing effective hole-transporting material is critical to achieve high efficiency CH3NH3PbI3 perovskite solar cells. A new thermal-stable truxene-based material, 2,7,12-tri(N,N-di(4-methoxyphenyl)amino)-5,5′,10,10′,15,15′-hexapropyltr-uxene, has been synthesized by a facile route. A reference compound, 1,3,5-tris(di-p-anisylamino)benzene, was prepared as well. Their optical, electronic properties, thermal stability and photovoltaic performances were investigated. This new truxene-based material exhibits a high decomposition temperature (432 °C), a high glass transition temperature (134 °C), and a suitable highest occupied molecular orbital level well-matched with the valence band of CH3NH3PbI3. The device based on this new material in conjunction with a carbon counter electrode achieves a power conversion efficiency of 3.18% under the illumination of 100 mW cm−2, which is better than that of the reference compound (0.93%). These results indicate truxene core is a promising building block for hole-transporting material.
Co-reporter:Min Wang, Hongyan Wang, Quanping Wu, Chuangli Zhang, Song Xue
International Journal of Hydrogen Energy 2016 Volume 41(Issue 15) pp:6211-6219
Publication Date(Web):27 April 2016
DOI:10.1016/j.ijhydene.2016.01.168
•Three phosphate mediated hematite thin films were prepared by aging FeOOH nanorods in phosphate solutions (Na3PO4, Na2HPO4 and NaH2PO4).•The film morphology and surface characteristic is found to be strongly affected by the aging conditions.•Slightly acidic phosphate aging solution (Na2HPO4) led to the formation of well dispersed hematite nanorods with highly crystalline structure.•The as-synthesized film exhibited 2.1 times higher photocurrent density than that of bare α-Fe2O3.Solar hydrogen production via photoelectrochemical water splitting using hematite thin films is a promising approach for the chemical storage of solar energy. Nanorod structured hematite photoanodes provide a direct path for electron collection and hole transport, which have been attracting growing interest. In this study, efficient hematite thin films were synthesized though dissolution and recrystallization of FeOOH nanorods in phosphate solutions. It is found that the morphology and surface characteristic, and PEC photoelectrochemical properties of the hematite films are strongly affected by the aging conditions. The phosphate (NaH2PO4) mediated hematite film exhibits 2.1 times higher photocurrent density than that of bare α-Fe2O3. The influences of phosphate solutions including Na3PO4, Na2HPO4 and NaH2PO4, pH values, and aging time on the morphology regulation, isoelectric point, and PEC photoelectrochemical properties of the hematite films are investigated.
Co-reporter:Huanhuan Dong, Mao Liang, Chunyao Zhang, Yungen Wu, Zhe Sun, and Song Xue
The Journal of Physical Chemistry C 2016 Volume 120(Issue 40) pp:22822-22830
Publication Date(Web):September 23, 2016
DOI:10.1021/acs.jpcc.6b06604
Fused-ring thiophene compounds emerged as an important type of building blocks for organic dyes toward the dye-sensitized solar cells (DSSCs) because of their good charge transfer and light-harvesting properties. Nevertheless, some fused-ring thiophenes have a lack of desired alkyl chains or side alkyl chains, which may induce a severe charge recombination in devices. In this work, the hex-1-en-1-ylbenzene (HEYB) unit was introduced in two new fused-ring thiophene organic dyes (M60 and M59), resulting in a modest dihedral angle (∼36°) between the donor and spacer in dyes. The effect of the HEYB unit on optical, electrochemical, and photovoltaic properties has been investigated by comparing with their congeners (M42 and M58) without the HEYB unit. It is found that introduction of the HEYB unit in arylamine donor enhanced the driving force for dye regeneration and beneficial for suppressing dye aggregation as well as reducing the charge recombination. Device performance characteristics demonstrate that introduction of the HEYB unit in the arylamine donor is a feasible strategy toward enhancing the performance of fused-ring thiophene organic dyes. Benefiting from this strategy, a dye-sensitized solar cell employing the M60 photosensitizer and a cobalt electrolyte exhibits a good power conversion efficiency of 9.75% measured under the 100 mW cm–2, simulated AM1.5 sunlight.
Co-reporter:Ziyi Lu, Mao Liang, Panpan Dai, Kai Miao, Chunyao Zhang, Zhe Sun, and Song Xue
The Journal of Physical Chemistry C 2016 Volume 120(Issue 45) pp:25657-25667
Publication Date(Web):October 25, 2016
DOI:10.1021/acs.jpcc.6b07356
Borondipyrromethene (BODIPY) dyes are one of the most interesting organic dyes because of their unique characteristic in capturing near-infrared (NIR) solar radiation. However, the highest reported conversion efficiency of BODIPY dyes is still far behind that of other organic dyes. Herein, we demonstrated an efficient strategy for enhancing the photovoltaic performance of BODIPY dyes, i.e., introducing a long linker between the light harvesting antenna and acceptor. Interestingly, the linker length has opposite effects on the BODIPY (M62, M63, M66, and LB1) and triphenylamine (M64 and M65) dyes. This work suggests that the incorporated long linker in BODIPY dyes shows several favorable characteristics: (i) improving the light harvesting capability of BODIPY dyes in longer wavelength without a big change of the HOMO levels; (ii) efficiently increasing the photocurrent and photovoltage, leading to dramatically improved performance; (iii) significantly reducing the charge recombination between electrons in TiO2 and electrolyte acceptor species and oxidized dye molecules at the interface. As a result, M63 with a binary linker display a 4.79 times higher conversion efficiency compared to that of M62 with a single linker. This finding could contribute to molecular engineering in the design of highly efficient BODIPY dyes.
Co-reporter:Yudan Wang
The Journal of Physical Chemistry C 2016 Volume 120(Issue 26) pp:13891-13900
Publication Date(Web):June 13, 2016
DOI:10.1021/acs.jpcc.6b01712
Kinetics of the recombination at TiO2/dye/electrolyte interfaces is vital to establish reliable strategy for reducing energy loss in dye sensitized solar cell (DSCs). The semilogarithmic plots of open circuit voltage–light intensity indicate that the DSCs exhibit different recombination behaviors in high and low voltage regions. Even so, the average orders of recombination reaction in the two regions are both found to be expressed as the summation of the apparent charge transfer coefficient and the averaged density distribution parameter. This statement is based upon the fact that the “steady-state” electron lifetimes in cobalt complex based DSCs are well interpreted by using the Butler–Volmer model. Combining the results of electron lifetime, the order of recombination reaction, and density distribution, we addressed that the dominant pathway of recombination in cobalt complex based DSCs is via the trapping states rather than the conduction band. In addition, the variation of the Fermi level in TiO2 film could affect the adsorbing configurations of 4-tert-butylpyridine molecules and Li+/H+ cations at TiO2 surfaces and hence engenders the nonexponential distribution of electron density at higher Fermi level.
Co-reporter:Ziyi Lu, Panpan Dai, Chunbo Wang, Mao Liang, Xueping Zong, Zhe Sun, Song Xue
Tetrahedron 2016 Volume 72(Issue 23) pp:3204-3212
Publication Date(Web):9 June 2016
DOI:10.1016/j.tet.2016.04.044
A new series of triarylamine-free organic dyes based on dithieno[3,2-b:2′,3′-d]pyrrole has been synthesized for dye-sensitized solar cells (DSSCs). The photophysical properties and DSSC performances of these dyes have been characterized. The effects of substituent in dithieno[3,2-b:2′,3′-d]pyrrole on the performance of the dyes have been investigated by their absorption spectra, electrochemical and photovoltaic properties. In comparison with the hexyl, the incorporation of 4-hexyloxyphenyl in dithieno[3,2-b:2′,3′-d]pyrrole has resulted in an improved light harvesting capacity, stability and thus photocurrent as well as efficiency of cells. X69 sensitized DSSCs affords a short circuit photocurrent of 12.1 mA cm−2, an open circuit voltage of 520 mV, and a fill factor of 0.67, corresponding to an overall conversion efficiency of 4.21% under standard AM 1.5 sunlight.
Co-reporter:Zhihui Wang, Mao Liang, Yulin Tan, Liyan Ouyang, Zhe Sun and Song Xue
Journal of Materials Chemistry A 2015 vol. 3(Issue 9) pp:4865-4874
Publication Date(Web):15 Jan 2015
DOI:10.1039/C4TA06705C
We report two new triarylamine-cyanoacrylic acid based push–pull dyes, X76 and X77, featuring the π-conjugated linkers of dihexyl- and dihexyloxybenzene-substituted dithieno[2,3-d:2′,3′-d′]thieno[3,2-b:3′,2′-b′]dipyrrole (DTDP), respectively. The absorption, electrochemical, and photovoltaic properties for all sensitizers have been systematically investigated. Both dyes containing a DTDP moiety showed good light harvesting ability as compared to that of the reference dye incorporating the hexyl-substituted dithieno[3,2-b:2′,3′-d]pyrrole (DTP) linker. Moreover, the substituents of DTDP moiety significantly influenced the electrochemical and photovoltaic properties of the dyes. The incident photon-to-current efficiency (IPCE) of the X77-based device is higher at longer wavelengths, and extends to nearly 800 nm. A dye-sensitized solar cell employing the X77 photosensitizer and the Co-bpy electrolyte exhibits a power conversion efficiency of 6.6% measured under the 100 mW cm−2 simulated AM1.5 sunlight.
Co-reporter:Xueping Zong, Zhe Sun, Hui Wang, Jiang Wang, Mao Liang and Song Xue
Chemical Communications 2015 vol. 51(Issue 74) pp:14076-14079
Publication Date(Web):03 Aug 2015
DOI:10.1039/C5CC04607F
Organolead iodide perovskite showing tubular morphology was fabricated on mesoporous TiO2 film via a one-step spin-coating procedure. These perovskite tubes with the external diameter of 1 μm were found to facilitate the charge separation at perovskite/hole-transport material (HTM) interfaces. This engenders a tubular perovskite device showing a higher fill factor over the device with planar perovskite, and improves power conversion efficiency accordingly.
Co-reporter:Kan Liu, Hongyan Wang, Quanping Wu, Jun Zhao, Zhe Sun, Song Xue
Journal of Power Sources 2015 Volume 283() pp:381-388
Publication Date(Web):1 June 2015
DOI:10.1016/j.jpowsour.2015.02.144
•Nanocube structured α-Fe2O3 thin film was synthesized from a hydrothermal process.•Different synthetic routes for phospahte modified-hematite thin films were compared.•Two types of phosphate complex were formed on the surface of hematite films.•The amount and nature of the phosphate complex were discussed.A thin film of α-Fe2O3 on FTO substrate has been synthesized from hydrothermal process in an aqueous solution of FeCl3 and Na2HPO4. A nanocube structure of α-Fe2O3 is observed within the formed hematite films and coated with phosphate ions on the surface. For comparison, another phosphate modified hematite film has been prepared by soaking the bare hematite film in Na2HPO4 solution. A negative electrostatic field can be built up on the surface of both phosphate modified hematite which will promote charge separation and extraction of photoexcited holes to the electrode surface. It is found that different types of phosphate complex exist in the hematite films, which has been determined by the isoelectric point (IEP) of the hematite films, and consequently influences the formation and strength of the electrostatic field. The effects of phosphate ions on the morphology, surface characteristics and the photoelectrochemical properties of the hematite thin films are investigated and the mechanism is proposed.
Co-reporter:Qi Xia, Mao Liang, Yulin Tan, Weixue Gao, Liyan Ouyang, Gaoyang Ge, Zhe Sun, Song Xue
Organic Electronics 2015 Volume 17() pp:285-294
Publication Date(Web):February 2015
DOI:10.1016/j.orgel.2014.12.026
•Two new triarylamine dyes were synthesized for cobalt solar cells.•The introduction of triphenylamine donor leads to an enhanced photocurrent.•Cobalt cells based on M40 show a high efficiency of 8.83%.Triphenylamine (TPA) and their derivatives are well-known electron-rich compounds that are widely used in various optical and electronic fields. Here, two new organic dyes (M40 and M41) featuring TPA or dihexyloxy-substituted triphenylamine (DHO–TPA) electron donor have been designed and synthesized. M40 sensitized DSCs employing the Co(II/III)tris(1,10-phenanthroline)-based redox electrolyte affords a short circuit photocurrent of 14.32 mA cm−2, an open circuit voltage of 907 mV, and a fill factor of 0.68, corresponding to an overall conversion efficiency of 8.83% under standard AM 1.5 sunlight. This efficiency is much higher than those of the M41 sensitized DSCs, being 7.81% under the same conditions. Absorption spectra, electrochemical measurements, theoretical calculations, and photovoltaic measurements are used to compare the light absorptions, energy-levels, and charge transfer dynamics that contribute to the photovoltaic behavior.
Co-reporter:Yake Zhang, Zhe Sun, Hui Wang, Yudan Wang, Mao Liang and Song Xue
RSC Advances 2015 vol. 5(Issue 14) pp:10430-10439
Publication Date(Web):06 Jan 2015
DOI:10.1039/C4RA13224F
We prepared nitrogen doped graphene (NG) by reacting pristine graphene oxide (GO) with urea hydrothermally and elucidated its usage as a Pt-free cathode material in the DSCs based on cobalt complex redox shuttles. In the process of hydrothermal reaction, the graphene oxide sheets are kept in a flocculating state. This experimental protocol prevents the graphene sheets from gelation and yields a maximum nitrogen content of 7.6 at%. The resultant NG sediments can be readily deposited onto conductive glass sheet for fabricating a porous cathode. The content ratio of the doped nitrogen atoms to the residual oxygen atoms is demonstrated as a determinant factor affecting the electrocatalytic activities of the as-prepared NG sheets. Annealing treatment to the NG cathodes gives rise to a remarkable increase of exchange current density. Moreover, the XPS results indicate that the electrochemically active pyridinic-N groups formed in the early stage of hydrothermal reaction are unstable to annealing. However, their thermal stability can be improved by extending the time of the hydrothermal reaction. By optimizing the composition of the embedded nitrogen species and oxygen containing groups, the DSCs with the NG cathode yield a maximal device efficiency of 8.2%.
Co-reporter:Yulin Tan, Mao Liang, Ziyi Lu, Yequan Zheng, Xinli Tong, Zhe Sun, and Song Xue
Organic Letters 2014 Volume 16(Issue 15) pp:3978-3981
Publication Date(Web):July 24, 2014
DOI:10.1021/ol5018036
A series of D−π–A organic dyes, X72–75, containing novel triarylamine electron donors have been synthesized for dye-sensitized solar cells (DSCs). The superiority of the asymmetric design of the triphenylamine electron donor over the symmetrical triphenylamine when applied in organic dyes for cobalt cells has been observed. Using X72 with the cobalt(II/III) redox shuttle resulted in an overall power conversion efficiency (PCE) of 9.18%, outperforming the state-of-the-art dye C218 under the same conditions.
Co-reporter:Zhihui Wang, He Wang, Mao Liang, Yulin Tan, Fangyi Cheng, Zhe Sun, and Song Xue
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 8) pp:5768
Publication Date(Web):March 25, 2014
DOI:10.1021/am500575s
Indoline photosensitizers exhibit impressive short-circuit photocurrent but generally low molar extinction coefficient and rapid charge recombination, which limits their application in thin-film dye-sensitizerd solar cells (DSCs). Here, we incorporate a new dithieno[3,2-b:2′,3′-d]pyrrole (DTP) segment (i.e., dihexyloxy-triphenylamine (DHO-TPA) substituted DTP) as the conjugated π-linker to construct a series of high molar absorption coefficient indoline dyes (XW69, XW70, and XW71) for DSCs employing a cobalt(II/III) redox electrolyte. Interestingly, this DTP linker is demonstrated as an efficient building block, not only slowing down the kinetics of charge recombination of titania electrons with tris(1,10-phenanthroline)cobalt(III) ions but also making a great contribution to the light absorption properties in comparison with the dihexylaniline substituted DTP. With respect to the dihexyloxy-triphenylamine dye (XW68), these new indoline dyes exhibit stronger light-harvesting and thus better power conversion efficiency of DSCs made from thin titania films. Benefitting from the bulky rigidity of the donor and π-conjugation unit, the XW70 dye displays a promising conversion efficiency as high as 8.78%, with a short-circuit current density (JSC) of 13.3 mA cm–2, open-circuit voltage (VOC) of 943 mV, and fill factor (FF) of 0.70 under AM 1.5 illumination (100 mW cm–2). Furthermore, the effect of light irradiation on these dyes adsorbed on nanocrystalline TiO2 films was investigated, proving the photostability of these indoline chromophores. Our work has valued the feasibility of judicious design of indoline chromophores to obtain organic photosensitizers for high-efficiency iodine-free DSCs made from thin titania films.Keywords: dithienopyrrole; dye-sensitized solar cell; indoline dyes; photostability; truxene;
Co-reporter:Yue Zhang, Yufeng Zhang, Zhihui Wang, Mao Liang, Dongdong Jia, Quanping Wu, Song Xue
Journal of Power Sources 2014 Volume 253() pp:167-176
Publication Date(Web):1 May 2014
DOI:10.1016/j.jpowsour.2013.12.032
•Propyl chains are better than hexyl chains in current generation in iodine cell.•Hexyl chains are superior in suppression of charge recombination in cobalt cell.•Electron lifetime of the cobalt cell is strongly dependent upon the alkyl chains.•Effects of TBP on the performance of cells are also correlated to alkyl chains.•An efficiency of 7.86% was achieved for the M24 sensitized cobalt cell.To develop high-efficiency organic dyes for dye-sensitized solar cells (DSCs), a comprehensive understanding on the structure–property relationship of metal-free organic photosensitizers is warranted. To address this issue, two organic dyes (M14 and M24) featuring, respectively, propyl chains and hexyl chains have been engineered. Interestingly, it is found that the length of alkyl chains has different effects on the performance DSCs with different electrolyte (e.g., iodine electrolyte and cobalt electrolyte). Herein, we scrutinize the effects of the length of alkyl chains in terms of light-harvesting, interfacial kinetic parameters, as well as their joint contribution to the photovoltaic performance. Furthermore, the dependence of conduction band shift and electron lifetime on the concentration of 4-tert-butylpyridine (TBP) in electrolyte is also investigated.
Co-reporter:Lina Wang, Mao Liang, Yue Zhang, Fangyi Cheng, Xuda Wang, Zhe Sun, Song Xue
Dyes and Pigments 2014 Volume 101() pp:270-279
Publication Date(Web):February 2014
DOI:10.1016/j.dyepig.2013.10.016
•Two new D–A–π–A indoline dyes were synthesized for dye-sensitized solar cells.•Employing D–A–π–A indoline dye for cobalt cell is feasible.•Structure–property relationship of dyes in different electrolyte was reported.D–A–π–A indoline dyes have exhibited an especially excellent performance and are regarded as one of the most promising classes of arylamine organic sensitizers. Two new D–A–π–A indoline dyes (XS45 and XS46) with different additional donor as well as a reference D–π–A indoline dye (XS47) have been synthesized to investigate the influence of donor and bridge structure in indoline dyes on the photovoltaic properties of dye-sensitized solar cells employing iodine/cobalt electrolyte. The incorporation of bulky dipropylfluorene unit in the donor part significantly increases the light harvesting ability and notably retards the charge recombination at the titania/electrolyte interface. On the other hand, the introduction of benzothiadiazole (BTD) in spacer not only evokes a large responsive range of wavelengths into NIR region, but also decreases the molar absorption coefficients of indoline dyes. DSCs incorporating Co(II/III)tris(1,10-phenanthroline)-based redox electrolyte/iodine electrolyte and three synthesized organic dyes as photosensitizers are described. The results confirm that using D–A–π–A indoline dyes as sensitizers for cobalt cells is feasible.
Co-reporter:Chuangli Zhang, Quanping Wu, Xuebin Ke, Juan Wang, Xin Jin, Song Xue
International Journal of Hydrogen Energy 2014 Volume 39(Issue 27) pp:14604-14612
Publication Date(Web):12 September 2014
DOI:10.1016/j.ijhydene.2014.07.120
•Ultrathin hematite films on TiO2/FTO were synthesized in control thickness by two-phase hydrolysis.•TiO2 underlayer alleviated dead layer and enhanced hematite light harvesting.•Photoelectrochemical performance was dramatically enhanced by TiO2 underlayer.•A photocurrent of 0.683 mA cm−2 and IPCE of 19.8% were obtained at +1.5 V vs. RHE.Ultrathin hematite (α-Fe2O3) film deposited on a TiO2 underlayer as a photoanode for photoelectrochemical water splitting was described. The TiO2 underlayer was coated on conductive fluorine-doped tin oxide (FTO) glass by spin coating. The hematite films were formed layer-by-layer by repeating the separated two-phase hydrolysis-solvothermal reaction of iron(III) acetylacetonate and aqueous ammonia. A photocurrent density of 0.683 mA cm−2 at +1.5 V vs. RHE (reversible hydrogen electrode) was obtained under visible light (>420 nm, 100 mW cm−2) illumination. The TiO2 underlayer plays an important role in the formation of hematite film, acting as an intermediary to alleviate the dead layer effect and as a support of large surface areas to coat greater amounts of Fe2O3. The as-prepared photoanodes are notably stable and highly efficient for photoelectrochemical water splitting under visible light. This study provides a facile synthesis process for the controlled production of highly active ultrathin hematite film and a simple route for photocurrent enhancement using several photoanodes in tandem.
Co-reporter:Chunbo Wang, Mao Liang, Jingjing Huang, Fangyi Cheng, He Wang, Yajun Guo, Song Xue
Tetrahedron 2014 70(36) pp: 6203-6210
Publication Date(Web):
DOI:10.1016/j.tet.2014.01.052
Co-reporter:Hui Wang ; Zhe Sun ; Yake Zhang ; Yue Zhang ; Mao Liang ; Dongdong Jia
The Journal of Physical Chemistry C 2014 Volume 118(Issue 1) pp:60-70
Publication Date(Web):December 10, 2013
DOI:10.1021/jp407769s
A simplified reaction–diffusion model is proposed to show the origins of inefficient charge transport in dye-sensitized solar cells (DSCs) based on bulky complex redox shuttles. In this model, diffusion length of the oxidized species in electrolyte solution is defined and assumed to depend on the average density of the conduction band electrons. The resulting quasi-linear equations enable the density profiles of electrons and redox shuttles to be calculated directly. When the charge transport of a DSC is under diffusion limitation, diffusion overpotential is shown to serve as an additional potential, which maintains a high level of electron density in TiO2 film, even at short circuit. The photocurrent output is therefore considerably limited because of the accelerated recombination reaction. Moreover, short circuit current density is confined by the diffusion limited current density under inefficient charge transport, and close to the photocurrent density at high diffusivity of redox shuttles. For the DSC with slow redox shuttles, a critical thickness of TiO2 film is observed. This is the maximum thickness allowing the charge transport to be free from diffusion limitation. The optimized film thickness yielding the maximum power conversion efficiency is shown to be slightly less than the critical thickness, which implies the potential usage of the critical thickness in designing the state-of-art DSC.
Co-reporter:Zhihui Wang;Dr. Mao Liang;He Wang; Peng Wang;Dr. Fangyi Cheng;Dr. Zhe Sun; Xue Song
ChemSusChem 2014 Volume 7( Issue 3) pp:795-803
Publication Date(Web):
DOI:10.1002/cssc.201301155
Abstract
The judicious design of electron donors is one of the viable tactics to improve the efficiency of organic dyes for dye-sensitized solar cells (DSCs) employing outer-sphere redox couples. Herein, a hexahexyltruxene-substituted 4-(hexyloxy)-N-phenylaniline (HT-HPA) segment is constructed and employed as the electron donor in two organic push–pull dyes (M28 and M29) with high molar absorption coefficient values. Relative to its congener (C241) possessing the dihexyloxy-substituted triphenylamine electron donor, M29 exhibits red-shifted absorption as well as enhanced maximum molar absorption coefficient values. A thorough comparison with M29 and C241 demonstrates that the HT-HPA segment adequately insulates the TiO2 surface from the electrolyte, which prevents back-recombination and prolongs electron lifetime in the semiconductor. The diminishment of charge recombination not only enables attainment of strikingly high photovoltages (approaching 1 V), but also overcompensates the disadvantageous impact of lower dye-load amounts. As a result, the dye transformation from C241 to M29 brings forth an efficiency improvement from 7.3 % to 8.5 % at the 100 mW cm−2 simulated AM1.5 conditions. Our work should shed light on the future design of more powerful push–pull organic photosensitizers for iodine-free DSCs.
Co-reporter:Guo Li, Mao Liang, Hui Wang, Zhe Sun, Lina Wang, Zhihui Wang, and Song Xue
Chemistry of Materials 2013 Volume 25(Issue 9) pp:1713
Publication Date(Web):April 7, 2013
DOI:10.1021/cm400196w
Indoline dyes exhibit impressive short-circuit photocurrent (JSC) but show generally low open-circuit voltage (VOC) in dye-sensitized solar cells (DSCs). To retard charge recombination in DSCs, four indoline dyes (XS41, XS42, XS43, and XS44) featuring, respectively, dipropylfluorene, hexyloxybenzene, tert-butylbenzene, and hexapropyltruxene electron donors, have been engineered. The incorporation of bulky rigid groups (i.e., dipropylfluorene and hexapropyltruxene unit) can notably retard the charge recombination at the titania/electrolyte interface. Moreover, we have developed two organic dyes (TC1 and TC2) as alternative coadsorbents to chenodeoxycholic acid (CDCA). Interestingly, it is found that regardless of the dye selection coadsorption with TC2 shows an improved VOC as well as JSC in comparison with its TC1 analogues. Dependence of photovoltage on the structure of TC1/TC2 was also investigated. The results suggest that the change in VOC is likely correlated with the molecular matching between the dyes and the coadsorbents. Combining the two contributions, high VOC in indoline-based DSCs can be realized. The results of XS41, upon coadsorption with TC2, produce a JSC of 16.1 mA cm–2, a VOC of 770 mV, and a fill factor of 0.66, corresponding to a power conversion efficiency of 8.18% under simulated AM1.5G solar light (100 mW cm–2). These findings pave a new way to achieve further efficiency enhancement of indoline dyes.Keywords: charge recombination; coadsorbent; indoline dyes; molecular matching; open-circuit photovoltage;
Co-reporter:Zhihui Wang, Mao Liang, Yujie Hao, Yue Zhang, Lina Wang, Zhe Sun and Song Xue
Journal of Materials Chemistry A 2013 vol. 1(Issue 38) pp:11809-11819
Publication Date(Web):01 Aug 2013
DOI:10.1039/C3TA12746J
Dithieno[3,2-b:2′,3′-d]pyrrole (DTP) compounds with strong electron-donating ability are promising spacers for photosensitizers. A series of new arylamine organic dyes bearing N-heterocycle-substituted DTP spacers has been designed and synthesized for iodine-free dye-sensitized solar cells (DSCs). The absorption, electrochemical, and photovoltaic properties for all the sensitizers have been systematically investigated. It was found that the incorporation of a dihexylaniline or hexylcarbazole unit, instead of a benzene unit, can notably retard the charge recombination at the titania–electrolyte interface, thus improving the cell photocurrent and photovoltage. Furthermore, we found a significant efficiency enhancement upon prolonging the adsorption time during the dye uptake from solution. When the dye adsorption was performed for 36 hours, the photovoltaic performance parameters measured under standard reporting conditions improved, in comparison to cells stained for 12 hours. The effects of adsorption time, correlated dye load amounts and electron lifetime were also scrutinized in terms of light-harvesting, interfacial kinetic parameters, as well as their joint contribution to the photovoltaic performance. Profiting from the favorable influence that the 36 hours dye uptake exerts on photovoltaic performance, we have realized a highly efficient iodine-free DSC displaying a power conversion efficiency of 8.20% measured at 100 mW cm−2 simulated AM1.5 conditions.
Co-reporter:Yongbo Shi, Mao Liang, Lina Wang, Hongyu Han, Lingshan You, Zhe Sun, and Song Xue
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 1) pp:144
Publication Date(Web):December 12, 2012
DOI:10.1021/am302318z
Two ruthenium complexes featuring bulky ancillary ligands, XS48 and XS49, were synthesized and studied as dyes in dye-sensitized solar cells (DSCs). Both dyes exhibit higher solar-to-electrical energy conversion efficiency when compared to a commonly used N3 sensitizer under the same conditions. To examine the influence of the bulky ancillary ligands and alleviate the electron recombination in cells, we have developed a dual functioned truxene-based coadsorbent (MXD1) as an alternative candidate to chenodeoxycholic acid (CDCA). This coadsorbent not only effectively shields the back electron transfer from the TiO2 to I3– ions but also enhances the light harvesting ability in the short wavelength regions. The photovoltaic performance of XS48-sensitized DSC was independent of the coadsorbents, while XS49 with large bulky ancillary ligand presented better performance when coadsorbent was employed. Interestingly, the simultaneous adsorption-to-sequential adsorption of XS48/49 and MXD1 has caused a notably improved photovoltage, which can be primarily ascribed to the enhanced dye adsorption and retardation of charge recombination. These results not only provide a new vision on how ancillary ligands affect the performance of ruthenium complexes but also open up a new way to achieve further efficiency enhancement of ruthenium complexes.Keywords: ancillary ligand; charge recombination; coadsorbent; extinction coefficients; ruthenium complexes; sequential adsorption;
Co-reporter:Zhihui Wang, Mao Liang, Lina Wang, Yujie Hao, Chunbo Wang, Zhe Sun and Song Xue
Chemical Communications 2013 vol. 49(Issue 51) pp:5748-5750
Publication Date(Web):09 May 2013
DOI:10.1039/C3CC42121J
Three dithieno[3,2-b:2′,3′-d]pyrrole (DTP) units with different hexyloxyphenyl (HOP) substituents have been developed for triphenylamine organic dyes (XS54–XS56). The introduction of the 4-HOP-DTP unit has resulted in a stronger light harvesting capacity, accounting for the observed photocurrent enhancement in the case of XS54, while the 2-HOP-DTP/2,4-HOP-DTP units induce a strikingly large photovoltage improvement in the cases of XS55 and XS56 due to their higher steric hindrance.
Co-reporter:Yujie Hao, Mao Liang, Zhihui Wang, Lina Wang, Yongyu Sun, Zhe Sun and Song Xue
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 37) pp:15441-15449
Publication Date(Web):10 Jul 2013
DOI:10.1039/C3CP52131A
The development of arylamine photosensitizers with high extinction coefficients, and suitable electronic structures and steric properties is necessary for improving the efficiency of dye-sensitized solar cells (DSCs) employing iodine-free redox shuttles. A new truxene-based organic sensitizer, M20, incorporating a 3,4-ethylenedioxythiophene (EDOT) moiety as an electron donor was synthesized and compared to its reference sensitizer, M4. M20 sensitized DSCs employing the Co(II/III) tris(1,10-phenanthroline)-based redox electrolyte exhibit a short circuit photocurrent of 11.8 mA cm−2, an open circuit voltage of 903 mV, and a fill factor of 0.69, corresponding to an overall conversion efficiency of 7.35% under standard AM 1.5 sunlight, which is higher than that of 6.86% for equivalent M4 sensitized DSCs. The effects of 4-tert-butylpyridine (TBP) as an additive on the photovoltaic performance of truxene-dye-sensitized nanocrystallineTiO2 solar cells were also investigated.
Co-reporter:Zhe Sun, Ren-Kai Zhang, Huan-Huan Xie, Hui Wang, Mao Liang, and Song Xue
The Journal of Physical Chemistry C 2013 Volume 117(Issue 9) pp:4364-4373
Publication Date(Web):February 12, 2013
DOI:10.1021/jp311146h
Three adsorbents, that is, 4-N,N-dimethylaminopyridine (DMAP), tetrabutylammonium isonicotinate (TBAIN), and methyl isonicotinate (MIN), were employed for blocking charge recombination in the dye-sensitized solar cells (DSCs) with poly(ethylene oxide)/poly(ethylene glycol) blend electrolyte. Photovoltage–light intensity measurements showed the adsorbents not only decrease the recombination rate but also prompt the nonideality of recombination. The energy level of the TiO2 band edge (Ec) is elevated by the adsorbents, which also result in the increase in the characteristic temperature (T0), reflecting a deeper distribution of the electrons at the surface states. An electron transfer model on the basis of the Marcus theory was applied to calculate the rate of nonideal recombination as well as the ideality factor. The results indicate that the increases in Ec and T0 both foster the nonideal recombination. The decreased recombination is further attributed to the upward shift of the TiO2 band edge, which reduces the densities of the electrons in the conduction band and at the surface states. Another reason for that is the increase in T0, which results in the drop of the averaged possibility of electron transfer via the surface states. The enhancement of open-circuit voltage follows the sequence of DMAP > TBAIN > MIN, which is correlated to the negative charge of pyridine-N of the adsorbents in terms of the quantum calculations. By measuring IPCE and impedance spectra, the adsorbents are shown to improve the electron collection but impede the electron injection from the excited dye. As a result, the short-circuit current of the adsorbent-doped DSCs is enhanced with the sequence of TBAIN > DMAP > MIN.
Co-reporter:Yujie Hao, Mao Liang, Zhihui Wang, Fangyi Cheng, Chunbo Wang, Zhe Sun, Song Xue
Tetrahedron 2013 69(49) pp: 10573-10580
Publication Date(Web):
DOI:10.1016/j.tet.2013.10.041
Co-reporter:Guo Tian, Xinli Tong, Yi Cheng, Song Xue
Carbohydrate Research 2013 370() pp: 33-37
Publication Date(Web):5 April 2013
DOI:10.1016/j.carres.2013.01.012
An efficient and tin-catalyzed production of 5-hydroxymethyl furfural (5-HMF) from carbohydrates is reported. The efficient conversion of glucose has been investigated using the combination of SnCl4 and different quaternary ammonium salts. It was found that tetrabutyl ammonium bromide (TBAB) was able to efficiently promote conversion of glucose to 5-HMF in the presence of SnCl4. For instance, a 69.1% yield of 5-HMF was obtained with SnCl4–tetrabutyl ammonium bromide (SnCl4–TBAB) system in DMSO for 2 h at 100 °C in air. The effects of catalyst amount, reaction time, and reaction temperature were investigated in detail. Furthermore, the SnCl4–TBAB was also employed to the conversion of fructose, sucrose, inulin, starch, and cellulose. The competitive results were obtained under mild conditions.Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Efficient production of 5-hydroxymethylfurfural from carbohydrates is achieved. ► A 69.1% yield of 5-hydroxymethylfurfural is obtained from glucose. ► The effects of reaction time, temperature, and catalyst amount are investigated. ► Conversion of sucrose, inulin, and starch is studied with SnCl4–TBAB system.
Co-reporter:Xueping Zong, Mao Liang, Tao Chen, Jiangnan Jia, Lina Wang, Zhe Sun and Song Xue
Chemical Communications 2012 vol. 48(Issue 53) pp:6645-6647
Publication Date(Web):14 May 2012
DOI:10.1039/C2CC32926C
Two new truxene-based organic sensitizers (M15 and M16) featuring high extinction coefficients were synthesized for dye-sensitized solar cells employing cobalt electrolyte. The M16-sensitized device displays a 7.6% efficiency at an irradiation of AM1.5 full sunlight.
Co-reporter:Quan-Ping Wu, Ying-Jun Xu, Xiao-Bing Cheng, Mao Liang, Zhe Sun, Song Xue
Solar Energy 2012 Volume 86(Issue 2) pp:764-770
Publication Date(Web):February 2012
DOI:10.1016/j.solener.2011.12.005
Three organic dyes XS24–26 containing N,N-dimethylaniline and butoxybenzene have been designed, synthesized and applied in the dye-sensitized solar cells (DSSCs). The influence of secondary electron-donating groups on the performance of DSSCs is discussed. The dimethylaniline is beneficial to extend absorption spectrum, whereas butoxybenzene is useful to suppress electron recombination. XS26 containing butoxybenzene and thiophene unit gives the highest power efficiency η of 5.67%, with a JSC of 12.36 mA cm−2, VOC of 680 mV, and ff of 0.67.Highlight► Triarylamines containing N,N-dimethylaniline and butoxybenzene unit for DSSCs. ► The dimethylaniline unit extends absorption spectrum. ► The butoxybenzene is useful to suppress electron recombination. ► A power efficiency η of 5.67% was obtained in dye with butoxybenzene unit.
Co-reporter:Xiaobing Cheng, Siyuan Sun, Mao Liang, Yongbo Shi, Zhe Sun, Song Xue
Dyes and Pigments 2012 Volume 92(Issue 3) pp:1292-1299
Publication Date(Web):March 2012
DOI:10.1016/j.dyepig.2011.09.019
Three triarylamine organic dyes (XS28–30) containing a cyclopentadithiophene unit as the conjugated bridge have been designed and synthesized for a potential application in dye-sensitized solar cells (DSSCs). Their absorption spectra, electrochemical and photovoltaic properties have been investigated. The incorporation of ethyl-substituted cyclopentadithiophene is highly beneficial to light-harvesting and preventing close π–π aggregation, thus favorably generating high efficiency. For a typical device, a solar energy conversion efficiency (η) of 5.8% based on XS29 was achieved under simulated AM 1.5 solar irradiation (100 mW cm−2) with a short-circuit photocurrent density (JSC) of 14.4 mA cm−2, an open-circuit voltage (VOC) of 601 mV, and a fill factor (ff) of 0.68. These results suggest that the functionalized cyclopentadithiophene unit is a promising candidate for DSSCs.Highlights► Three organic dyes were designed and synthesized for dye-sensitized solar cells. ► Cyclopentadithiophene moieties acted as the conjugated bridge. ► High photocurrent were achieved based on the three dyes without any conadsorbent.
Co-reporter:Ren-Kai Zhang, Zhe Sun, Huan-Huan Xie, Xiang Wu, Mao Liang, Song Xue
Solar Energy 2012 Volume 86(Issue 9) pp:2346-2353
Publication Date(Web):September 2012
DOI:10.1016/j.solener.2012.05.005
Poly(N-propyl-vinylimidazolium iodide-co-poly(ethylene glycol) methyl ether methacrylate) with a comb-like configuration was synthesized. The copolymer and its blend with poly(ethylene oxide) (PEO) were used to prepare the polymer electrolytes for solid dye-sensitized solar cells. The amorphous characteristics and the ion-crosslinking effects of the copolymer and its blend electrolyte were analyzed by WAXS, DSC and FT-IR. The copolymer and PEO in the blend electrolyte were shown to play the roles of decreasing the crystallinity and breaking the ion-crosslinking, respectively. The blend electrolytes thus presented the highest ionic conductivity among the prepared electrolytes. The as-prepared DSSCs yielded the energy conversion efficiency of 3.46% at 100 mW cm−2. The impedance results indicated the improved photovoltaic performance of the blend electrolyte was originated from the increased ionic diffusion coefficient and the prevented downward movement of the conduction band edge of TiO2.Highlights► A comb-like copolymer with PEGMA and imidazolium iodide moieties was synthesized. ► Copolymer/poly(ethylene oxide) blend electrolytes yields the highest conductivity. ► Blending makes polymer electrolyte to be amorphous and reduces ion-crosslinking. ► An efficiency of 3.46% for the blend electrolyte based DSSC was obtained.
Co-reporter:Huanhuan Xie, Zhe Sun, Hui Wang, Mao Liang, Song Xue
Synthetic Metals 2012 Volume 162(Issue 24) pp:2383-2389
Publication Date(Web):31 December 2012
DOI:10.1016/j.synthmet.2012.11.022
Oligo(ethylene glycol) terminated by pyridine derivatives was designed and synthesized for improving the performance of the dye-sensitized solar cells (DSCs) with poly(ethylene oxide) based electrolyte. Effects of the plasticizer on retarding the recombination reaction in DSCs were characterized by current density–voltage characteristics. Combined with the results on electron density measurements, photovoltage–intensity characteristics correlate the retarded electron recombination with the upward movement of the conduction band edge and the reduced order of recombination reaction. The increased electron lifetimes of the DSCs with plasticizer modified electrolyte were confirmed by a small perturbation voltage decay technique. Additionally, WAXS measurements show that the presence of the plasticizer decreases the crystallinity of PEO electrolyte, which facilitates the mass transport of the redox species as impedance spectra indicated. By introducing guanidinium thiocyanate into the plasticizer modified PEO electrolyte, the performance of the DSCs is further improved, which yields the highest efficiency of 3.5%.Highlights► Oligo(ethylene glycol) terminated by pyridine derivatives was synthesized as plasticizer. ► PEO electrolyte for dye sensitized solar cell (DSC) was modified with the plasticizer. ► The plasticizer in DSC retards recombination reaction and leveling up the band edge. ► Addition of GuSCN into the modified electrolyte yields the highest efficiency of 3.5%.
Co-reporter:Xueping Zong, Mao Liang, Changrong Fan, Kai Tang, Guo Li, Zhe Sun, and Song Xue
The Journal of Physical Chemistry C 2012 Volume 116(Issue 20) pp:11241-11250
Publication Date(Web):May 10, 2012
DOI:10.1021/jp301406x
Developing photosensitizers with high extinction coefficients, proper electronic structures, and steric properties is warranted for the dye-sensitized solar cells (DSCs) employing one-electron outer-sphere redox shuttles. DSCs incorporating Co(II/III)tris(1,10-phenanthroline)-based redox electrolyte and three synthesized organic dyes as photosensitizers (M14, M18, and M19) are described. The hexapropyltruxene group on the dyes retards the rate of interfacial back electron transfer from the conduction band of the nanocrystalline titanium dioxide film to the [Co(III)(phenanthroline)3]3+ ions, which enables attainment of high photovoltages approaching 0.9 V. The measurement of photocurrent transients shows that the mass transport limitation of the cobalt redox shuttle has been largely removed by using thin TiO2 films. DSCs sensitized with M14 in combination with the cobalt redox shuttle yield a DSC with an overall power conversion efficiency (PCE) of 7.2% under 100 mW cm–2 AM1.5 G illumination. The influences of the dye structure on the performance of DSCs were also investigated.
Co-reporter:Xiaobing Cheng, Mao Liang, Siyuan Sun, Yongbo Shi, Zijian Ma, Zhe Sun, Song Xue
Tetrahedron 2012 68(27–28) pp: 5375-5385
Publication Date(Web):
DOI:10.1016/j.tet.2012.04.113
Co-reporter:Xiaoli Hao, Mao Liang, Xiaobing Cheng, Xiaoqing Pian, Zhe Sun, and Song Xue
Organic Letters 2011 Volume 13(Issue 20) pp:5424-5427
Publication Date(Web):September 29, 2011
DOI:10.1021/ol201858b
A new class of organic sensitizers incorporating a benzo[1,2-b:4,5-b′]dithiophene (BDT) unit as conjugated spacer has been synthesized and successfully used for dye-sensitized solar cells (DSSCs). The length of the π-conjugated spacers has a strong impact on electro-optical properties of these dyes, leading to the conversion efficiencies ranging from 4.17 to 5.68% under AM 1.5 G irradiation. This result indicates that the BDT unit is a promising candidate in organic sensitizers.
Co-reporter:Zhe Sun, Ren-Kai Zhang, Huan-Huan Xie, Mao Liang, Rui-Hong Du, Song Xue
Electrochimica Acta 2011 Volume 56(Issue 22) pp:7555-7562
Publication Date(Web):1 September 2011
DOI:10.1016/j.electacta.2011.06.089
4-N,N-Dimethylaminopyridine (DMAP) was introduced into poly(ethyleneoxide)/oligo(ethylene glycol) (PEO/PEG) electrolytes for dye-sensitized solar cells (DSCs). The improved photovoltaic performance of DMAP-doped DSCs was attributed to the integrated effects of the upward displacement of the TiO2 band edge and the decrease in the electron recombination rate. Remarkably, the presence of DMAP suppresses electron recombination via two combined pathways involving the dissociation of triiodide to iodide by a complexation reaction and a modification of the surface state distribution in the band gap of TiO2. With the addition of DMAP, the open-circuit voltage enhances dramatically. The short-circuit photocurrent density has a small increase at low DMAP concentration and drops afterwards. The power conversion efficiency is 4.07%, which corresponds to a 63% increase over that of the DSC without DMAP.
Co-reporter:Quan-Ping Wu, Lu Zhang, Mao Liang, Zhe Sun, Song Xue
Solar Energy 2011 Volume 85(Issue 1) pp:1-6
Publication Date(Web):January 2011
DOI:10.1016/j.solener.2010.11.011
Three organic dyes with D-π-D-π-A structure based on triarylamine, dimethylarylamine, and rhodanine-3-acetic acid moieties are designed and synthesized. Incorporating thiophene moieties into the system affords sensitizers with high molar extinction coefficients. These dyes were applied into nanocrystalline TiO2 dye-sensitized solar cells through standard operations. For a typical device the maximal monochromatic incident photon-to-current conversion efficiency (IPCE) can reach 73%, with a short-circuit photocurrent density (Jsc) of 7.3 mA/cm2, an open-circuit voltage (Voc) of 636 mV, and a fill factor (ff) of 0.61, corresponding to an overall conversion efficiency (η) of 2.86%.
Co-reporter:Mao Liang, Xue-Ping Zong, Hong-Yu Han, Chao Chen, Zhe Sun, Song Xue
Materials Letters 2011 Volume 65(Issue 9) pp:1331-1333
Publication Date(Web):15 May 2011
DOI:10.1016/j.matlet.2011.02.002
A new functionalized-triarylamine dye (MXD10) has been designed, synthesized, and characterized. Two CH3(CH2)4CH=CH– units were introduced into triphenylamine for improvement of light harvesting, suppression of dye aggregation and retardation of charge recombination. Photophysical, electrochemical and photovoltaic measurements are in accord with the molecular design. Device based on MXD10 gave a maximum power conversion efficiency of 6.47% under simulated AM 1.5 irradiation (100 mW cm−2) with JSC = 15 mA/cm2, VOC = 635 mV, and ff = 0.68.
Co-reporter:Kai Tang;Mao Liang;Yongkang Liu;Zhe Sun
Chinese Journal of Chemistry 2011 Volume 29( Issue 1) pp:89-96
Publication Date(Web):
DOI:10.1002/cjoc.201190066
Abstract
Three organic dyes XS17–19 based on N,N-dimethylaryl amine and rhodamine-3-acetic acid moieties are designed and synthesized. These dyes were applied into nanocrystalline TiO2 dye-sensitized solar cells through standard operations, showing strong absorption bands at around 320–650 nm, and exhibiting broad IPCE responses. Cell based on XS17 gave a Jsc of 3.7 mA/cm2, an open circuit voltage of 550 mV, and a fill factor of 0.68, corresponding to an overall conversion efficiency of 1.4%. The low overall conversion efficiency is due to the modest IPCE and Voc values, which mainly stem from the acceptor of rhodanine-3-acetic acid.
Co-reporter:Zhihui Wang, Meiyi Li, Wenqin Zhang, Jiangnan Jia, Fei Wang, Song Xue
Tetrahedron Letters 2011 Volume 52(Issue 45) pp:5968-5971
Publication Date(Web):9 November 2011
DOI:10.1016/j.tetlet.2011.08.134
A highly efficient and selective rearrangement reaction of bromohydrins to aldehydes mediated by CF3CO2ZnEt was described. The secondary and tertiary aldehydes were prepared under mild conditions in good to excellent yields (85–99%). The scope and limitations of this rearrangement process were also investigated.
Co-reporter:Ying-Jun Xu, Mao Liang, Xiu-Jie Liu, Hong-Yu Han, Zhe Sun, Song Xue
Synthetic Metals 2011 Volume 161(5–6) pp:496-503
Publication Date(Web):March 2011
DOI:10.1016/j.synthmet.2010.12.033
Three triarylamine organic dyes (XS19–21) containing N,N-dimethylaniline and butoxybenzene units as secondary electron-donating groups are synthesized and characterized. When these dyes were applied into nanocrystalline TiO2 dye-sensitized solar cells through standard operations, high open-circuit voltage (more than 730 mV) were obtained. The effects of the secondary electron-donating groups as well as the π spacers on the photovoltaic performance of the DSSCs were examined. For a typical device, 5.79% of solar energy conversion efficiency (η) based on XS21 was achieved with a short-circuit photocurrent density (JSC) of 10.0 mA cm−2, an open-circuit voltage (VOC) of 782 mV, and a fill factor (ff) of 0.74.
Co-reporter:Hongyu Han, Mao Liang, Kai Tang, Xiaobing Cheng, Xueping Zong, Zhe Sun, Song Xue
Journal of Photochemistry and Photobiology A: Chemistry 2011 Volume 225(Issue 1) pp:8-16
Publication Date(Web):1 December 2011
DOI:10.1016/j.jphotochem.2011.09.019
Molecular design and understanding the structure–property relationship of π-conjugated spacer play pivotal roles in realization of considerable enhancement performance of dye-sensitized solar cells (DSSCs). Three triphenylmaine dyes, namely MX11-13, have been designed and synthesized, which incorporate 2,2,6,6-tetramethylbenzo[1,2-d;4,5-d′]bis[1,3]dioxole (TMBD), phenyl and 1,4-dipropoxybenzene (DPB) as π-conjugated spacer, respectively. The effects of alkoxy substituent upon the photophysical, electro-chemical characteristics and performance of dye-sensitized solar cells are investigated. For a typical device, the MX13-based cell affords an overall power conversion efficiency (η) of 7.02%, with short-circuit photocurrent density (JSC), open-circuit voltage (VOC) and fill factor (ff) of 15.5 mA cm−2, 697 mV and 0.65, respectively.Graphical abstractHighlights► Triarylamine organic dyes featuring alkoxy substituent phenylene spacer. ► Introduction of alkoxy groups into the spacer is beneficial to light-harvesting. ► The highest conversion efficiency of 7.02% was obtained based on the three dyes.
Co-reporter:Meng Lu, Mao Liang, Hong-Yu Han, Zhe Sun, and Song Xue
The Journal of Physical Chemistry C 2011 Volume 115(Issue 1) pp:274-281
Publication Date(Web):December 13, 2010
DOI:10.1021/jp107439d
We report here on the synthesis and photophysical/electrochemical properties of three functional triarylamine organic dyes (MXD5−7) as well as their application in dye-sensitized nanocrystalline TiO2 solar cells (DSSCs). For the designed dyes, the nonplanar structures of bis-hexapropyltruxeneamino take the role of electron donor. The introduction of bis-hexapropyltruxeneamino units brought about superior performance over the simple triphenylamine dye, in terms of light-capturing abilities and suppressing dye aggregation. Among three dyes, the DSSCs based on the dye MXD7 showed the best photovoltaic performance: a short-circuit photocurrent density (JSC) of 11.8 mA cm−2, an open-circuit photovoltage (VOC) of 772 mV, and a fill factor (ff) of 0.68, corresponding to an overall conversion efficiency of 6.18% under 100 mW cm−2 irradiation. These dyes exhibited high VOC values, possible origin for which was investigated regarding the TiO2 surface blocking, conduction band movement, and electrolyte-dye interaction.
Co-reporter:Ling-Guo Meng, Hui-Fang Liu, Jian-Long Wei, Sun-Na Gong, Song Xue
Tetrahedron Letters 2010 Volume 51(Issue 13) pp:1748-1750
Publication Date(Web):31 March 2010
DOI:10.1016/j.tetlet.2010.01.093
A facile synthesis of 2-alkyl-substituted chromanones from ortho-acylphenols and terminal alkynoates is described. The method contains two consecutive processes in one-pot reaction through a DABCO-catalyzed condensation reaction and a KOBut-mediated intramolecular cycloaddition to afford the desired products.
Co-reporter:Lu Zhang, Yongkang Liu, Zhongyuan Wang, Mao Liang, Zhe Sun, Song Xue
Tetrahedron 2010 66(18) pp: 3318-3325
Publication Date(Web):
DOI:10.1016/j.tet.2010.02.095
Co-reporter:Ling-Guo Meng, Bin Hu, Quan-Ping Wu, Mao Liang and Song Xue
Chemical Communications 2009 (Issue 40) pp:6089-6091
Publication Date(Web):26 Aug 2009
DOI:10.1039/B909279J
PPh3-catalyzed α-addition reactions of 1-(o-hydroxyaryl)-1,3-diketones to terminal alkynoates involving carbon–carbon bond cleavage to give multifunctional vinylesters are described.
Co-reporter:Jun-Li GAO;Yong-Kang LIU
Chinese Journal of Chemistry 2008 Volume 26( Issue 9) pp:1689-1692
Publication Date(Web):
DOI:10.1002/cjoc.200890305
Abstract
A self-condensation reaction of α,β-acetylenic ketones via organozinc species CF3CO2ZnEt to afford the β-branched Morita-Bayllis-Hillman adducts has been developed. This reaction system provides functionalized trisubstituted olefins in good yields. Organozinc species CF3CO2ZnCH2I, an efficient cyclopropanation reagent, can also react with aromatic acetylenic ketones to provide 2,5-dihydrofurans in moderate yields.
Co-reporter:Quan-Ping Wu, Ying-Jun Xu, Xiao-Bing Cheng, Mao Liang, Zhe Sun, Song Xue
Solar Energy (February 2012) Volume 86(Issue 2) pp:764-770
Publication Date(Web):1 February 2012
DOI:10.1016/j.solener.2011.12.005
Three organic dyes XS24–26 containing N,N-dimethylaniline and butoxybenzene have been designed, synthesized and applied in the dye-sensitized solar cells (DSSCs). The influence of secondary electron-donating groups on the performance of DSSCs is discussed. The dimethylaniline is beneficial to extend absorption spectrum, whereas butoxybenzene is useful to suppress electron recombination. XS26 containing butoxybenzene and thiophene unit gives the highest power efficiency η of 5.67%, with a JSC of 12.36 mA cm−2, VOC of 680 mV, and ff of 0.67.Highlight► Triarylamines containing N,N-dimethylaniline and butoxybenzene unit for DSSCs. ► The dimethylaniline unit extends absorption spectrum. ► The butoxybenzene is useful to suppress electron recombination. ► A power efficiency η of 5.67% was obtained in dye with butoxybenzene unit.
Co-reporter:Ling-Guo Meng, Bin Hu, Quan-Ping Wu, Mao Liang and Song Xue
Chemical Communications 2009(Issue 40) pp:NaN6091-6091
Publication Date(Web):2009/08/26
DOI:10.1039/B909279J
PPh3-catalyzed α-addition reactions of 1-(o-hydroxyaryl)-1,3-diketones to terminal alkynoates involving carbon–carbon bond cleavage to give multifunctional vinylesters are described.
Co-reporter:Zhihui Wang, Mao Liang, Yulin Tan, Liyan Ouyang, Zhe Sun and Song Xue
Journal of Materials Chemistry A 2015 - vol. 3(Issue 9) pp:NaN4874-4874
Publication Date(Web):2015/01/15
DOI:10.1039/C4TA06705C
We report two new triarylamine-cyanoacrylic acid based push–pull dyes, X76 and X77, featuring the π-conjugated linkers of dihexyl- and dihexyloxybenzene-substituted dithieno[2,3-d:2′,3′-d′]thieno[3,2-b:3′,2′-b′]dipyrrole (DTDP), respectively. The absorption, electrochemical, and photovoltaic properties for all sensitizers have been systematically investigated. Both dyes containing a DTDP moiety showed good light harvesting ability as compared to that of the reference dye incorporating the hexyl-substituted dithieno[3,2-b:2′,3′-d]pyrrole (DTP) linker. Moreover, the substituents of DTDP moiety significantly influenced the electrochemical and photovoltaic properties of the dyes. The incident photon-to-current efficiency (IPCE) of the X77-based device is higher at longer wavelengths, and extends to nearly 800 nm. A dye-sensitized solar cell employing the X77 photosensitizer and the Co-bpy electrolyte exhibits a power conversion efficiency of 6.6% measured under the 100 mW cm−2 simulated AM1.5 sunlight.
Co-reporter:Zhihui Wang, Mao Liang, Yujie Hao, Yue Zhang, Lina Wang, Zhe Sun and Song Xue
Journal of Materials Chemistry A 2013 - vol. 1(Issue 38) pp:NaN11819-11819
Publication Date(Web):2013/08/01
DOI:10.1039/C3TA12746J
Dithieno[3,2-b:2′,3′-d]pyrrole (DTP) compounds with strong electron-donating ability are promising spacers for photosensitizers. A series of new arylamine organic dyes bearing N-heterocycle-substituted DTP spacers has been designed and synthesized for iodine-free dye-sensitized solar cells (DSCs). The absorption, electrochemical, and photovoltaic properties for all the sensitizers have been systematically investigated. It was found that the incorporation of a dihexylaniline or hexylcarbazole unit, instead of a benzene unit, can notably retard the charge recombination at the titania–electrolyte interface, thus improving the cell photocurrent and photovoltage. Furthermore, we found a significant efficiency enhancement upon prolonging the adsorption time during the dye uptake from solution. When the dye adsorption was performed for 36 hours, the photovoltaic performance parameters measured under standard reporting conditions improved, in comparison to cells stained for 12 hours. The effects of adsorption time, correlated dye load amounts and electron lifetime were also scrutinized in terms of light-harvesting, interfacial kinetic parameters, as well as their joint contribution to the photovoltaic performance. Profiting from the favorable influence that the 36 hours dye uptake exerts on photovoltaic performance, we have realized a highly efficient iodine-free DSC displaying a power conversion efficiency of 8.20% measured at 100 mW cm−2 simulated AM1.5 conditions.
Co-reporter:Yujie Hao, Mao Liang, Zhihui Wang, Lina Wang, Yongyu Sun, Zhe Sun and Song Xue
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 37) pp:NaN15449-15449
Publication Date(Web):2013/07/10
DOI:10.1039/C3CP52131A
The development of arylamine photosensitizers with high extinction coefficients, and suitable electronic structures and steric properties is necessary for improving the efficiency of dye-sensitized solar cells (DSCs) employing iodine-free redox shuttles. A new truxene-based organic sensitizer, M20, incorporating a 3,4-ethylenedioxythiophene (EDOT) moiety as an electron donor was synthesized and compared to its reference sensitizer, M4. M20 sensitized DSCs employing the Co(II/III) tris(1,10-phenanthroline)-based redox electrolyte exhibit a short circuit photocurrent of 11.8 mA cm−2, an open circuit voltage of 903 mV, and a fill factor of 0.69, corresponding to an overall conversion efficiency of 7.35% under standard AM 1.5 sunlight, which is higher than that of 6.86% for equivalent M4 sensitized DSCs. The effects of 4-tert-butylpyridine (TBP) as an additive on the photovoltaic performance of truxene-dye-sensitized nanocrystallineTiO2 solar cells were also investigated.
Co-reporter:Zhihui Wang, Mao Liang, Lina Wang, Yujie Hao, Chunbo Wang, Zhe Sun and Song Xue
Chemical Communications 2013 - vol. 49(Issue 51) pp:NaN5750-5750
Publication Date(Web):2013/05/09
DOI:10.1039/C3CC42121J
Three dithieno[3,2-b:2′,3′-d]pyrrole (DTP) units with different hexyloxyphenyl (HOP) substituents have been developed for triphenylamine organic dyes (XS54–XS56). The introduction of the 4-HOP-DTP unit has resulted in a stronger light harvesting capacity, accounting for the observed photocurrent enhancement in the case of XS54, while the 2-HOP-DTP/2,4-HOP-DTP units induce a strikingly large photovoltage improvement in the cases of XS55 and XS56 due to their higher steric hindrance.
Co-reporter:Xueping Zong, Mao Liang, Tao Chen, Jiangnan Jia, Lina Wang, Zhe Sun and Song Xue
Chemical Communications 2012 - vol. 48(Issue 53) pp:NaN6647-6647
Publication Date(Web):2012/05/14
DOI:10.1039/C2CC32926C
Two new truxene-based organic sensitizers (M15 and M16) featuring high extinction coefficients were synthesized for dye-sensitized solar cells employing cobalt electrolyte. The M16-sensitized device displays a 7.6% efficiency at an irradiation of AM1.5 full sunlight.
Co-reporter:Xueping Zong, Zhe Sun, Hui Wang, Jiang Wang, Mao Liang and Song Xue
Chemical Communications 2015 - vol. 51(Issue 74) pp:NaN14079-14079
Publication Date(Web):2015/08/03
DOI:10.1039/C5CC04607F
Organolead iodide perovskite showing tubular morphology was fabricated on mesoporous TiO2 film via a one-step spin-coating procedure. These perovskite tubes with the external diameter of 1 μm were found to facilitate the charge separation at perovskite/hole-transport material (HTM) interfaces. This engenders a tubular perovskite device showing a higher fill factor over the device with planar perovskite, and improves power conversion efficiency accordingly.
Co-reporter:Kai Miao, Mao Liang, Zhihui Wang, Chunyao Zhang, Zhe Sun and Song Xue
Physical Chemistry Chemical Physics 2017 - vol. 19(Issue 3) pp:NaN1936-1936
Publication Date(Web):2016/12/07
DOI:10.1039/C6CP07335B
Thiophene derivatives, including thieno[3,2-b][1]benzothiophene (TBT), benzo[b]thiophene (BT), 2-phenylthieno[3,2-b]thiophene (PTT) and 2-phenylthiophene (PT), have been introduced as donors for the construction of triarylamine organic dyes (M52, M53, M56, M57 and M52A). The absorption, electrochemical and photovoltaic properties as well as the stabilities of these dyes are systematically investigated and compared with the reference dye (M55), whose donor is composed of the hexyloxybenzene (HOB) unit. It is found that introducing the TBT, BT, PTT or PT donors positively shifted the HOMO and LUMO levels of the organic dyes, providing a larger driving force for regeneration and reducing the energy loss for electron injection. In addition, we found that M52, which contains the TBT unit, exhibited better photovoltaic performance and photostability as compared to the reference dye. In contrast, M53 displayed the lowest efficiency and stability of these dyes, indicating that the BT unit is not a good building block for donors. Interestingly, upon the incorporation of the mixed donor (TBT–HOB), M52A achieved a desirable driving force for regeneration without a loss in light absorption, thus resulting in a further improved photovoltaic performance with respect to that of M52. This work demonstrates that introducing donors based on thiophene derivatives is a good strategy for tuning the energy levels and thereby enhancing the efficiency of the resulting devices.
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