Polymer solar cells (PSCs) with inverted structure can greatly improve photovoltaic stability. Th... more Polymer solar cells (PSCs) with inverted structure can greatly improve photovoltaic stability. This paper reports a novel method to lower the work function of indium tin oxide (ITO) through the modification with a thin layer of zwitterions which have both positive and negative charges in the same molecule. Zwitterions have a strong dipole moment due to the presence of the two types of charges and are immobile under electric field. Zwitterions with both conjugated and saturated structure were investigated. A zwitterion thin layer is formed on ITO by spin coating a methanol solution of the zwitterion. The zwitterion-modified ITO sheets can be used as the cathode for the electron collection of inverted PSCs. The inverted poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PC(61)BM) PSCs can exhibit photovoltaic efficiency as high as 3.98% under simulated AM1.5G illumination (100 mW cm(-2)), which is comparable to that of PSCs with normal architecture. The effective ...
Small molecules with dithieno[3,2-b;2&amp... more Small molecules with dithieno[3,2-b;2',3'-d]thiophene as central building block and octyl cyanoacetate and octyl cyanoacetamide as different terminal building blocks have been designed and synthesized. The amide containing small molecule can form intermolecular hydrogen bonding between N-H...O = C of the amide group. The photovoltaic properties and active layer morphologies of the two molecules in bulk heterojunction solar cells are compared to study the influence of hydrogen bonding on the active layer morphology. New methanofullerene compound containing amide group has also been synthesized and compared with conventional fullerene electron acceptors.
ABSTRACT Three new conjugated polymers based on 5-decylthiazol-2-yl substituted benzodithiophene ... more ABSTRACT Three new conjugated polymers based on 5-decylthiazol-2-yl substituted benzodithiophene have been synthesized by Stille cross-coupling polymerization. 1,3-Dibromo-5-octylthieno[3,4-c]pyrrole-4,6-dione (M1), 2,5-diethylhexyl-3,6-bis(5-bromothiophen-2-yl)pyrrolo[3,4-c]-pyrrole-1,4-dione (M2) and 4,6-dibromo-thieno[3,4-b]thiophene-2-dodecyl carboxylate (M3) were used as acceptor building blocks for the synthesis of conjugated donor-acceptor polymers. The thermal, optical, electrochemical, and photovoltaic properties of the synthesized polymers were studied.
Solution-processed organic photovoltaic cells (OPVs) hold great promise to enable roll-to-roll pr... more Solution-processed organic photovoltaic cells (OPVs) hold great promise to enable roll-to-roll printing of environmentally friendly, mechanically flexible and cost-effective photovoltaic devices. Nevertheless, many high-performing systems show best power conversion efficiencies (PCEs) with a thin active layer (thickness is ~100 nm) that is difficult to translate to roll-to-roll processing with high reproducibility. Here we report a new molecular donor, benzodithiophene terthiophene rhodanine (BTR), which exhibits good processability, nematic liquid crystalline behaviour and excellent optoelectronic properties. A maximum PCE of 9.3% is achieved under AM 1.5G solar irradiation, with fill factor reaching 77%, rarely achieved in solution-processed OPVs. Particularly promising is the fact that BTR-based devices with active layer thicknesses up to 400 nm can still afford high fill factor of ~70% and high PCE of ~8%. Together, the results suggest, with better device architectures for longe...
This letter reports dye-sensitized solar cells with a thin film of multiwall carbon nanotube/cond... more This letter reports dye-sensitized solar cells with a thin film of multiwall carbon nanotube/conducting poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) composite as the counterelectrode. The composite thin film was prepared by spin coating the aqueous solution of the composite. The devices exhibited high performance with the energy conversion efficiency of 6.5%, short-circuit current of 15.5 mA cm-2, open-circuit voltage of 0.66 V, and fill factor
Polymer solar cells (PSCs) with inverted structure can greatly improve photovoltaic stability. Th... more Polymer solar cells (PSCs) with inverted structure can greatly improve photovoltaic stability. This paper reports a novel method to lower the work function of indium tin oxide (ITO) through the modification with a thin layer of zwitterions which have both positive and negative charges in the same molecule. Zwitterions have a strong dipole moment due to the presence of the two types of charges and are immobile under electric field. Zwitterions with both conjugated and saturated structure were investigated. A zwitterion thin layer is formed on ITO by spin coating a methanol solution of the zwitterion. The zwitterion-modified ITO sheets can be used as the cathode for the electron collection of inverted PSCs. The inverted poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PC(61)BM) PSCs can exhibit photovoltaic efficiency as high as 3.98% under simulated AM1.5G illumination (100 mW cm(-2)), which is comparable to that of PSCs with normal architecture. The effective ...
Small molecules with dithieno[3,2-b;2&amp... more Small molecules with dithieno[3,2-b;2',3'-d]thiophene as central building block and octyl cyanoacetate and octyl cyanoacetamide as different terminal building blocks have been designed and synthesized. The amide containing small molecule can form intermolecular hydrogen bonding between N-H...O = C of the amide group. The photovoltaic properties and active layer morphologies of the two molecules in bulk heterojunction solar cells are compared to study the influence of hydrogen bonding on the active layer morphology. New methanofullerene compound containing amide group has also been synthesized and compared with conventional fullerene electron acceptors.
ABSTRACT Three new conjugated polymers based on 5-decylthiazol-2-yl substituted benzodithiophene ... more ABSTRACT Three new conjugated polymers based on 5-decylthiazol-2-yl substituted benzodithiophene have been synthesized by Stille cross-coupling polymerization. 1,3-Dibromo-5-octylthieno[3,4-c]pyrrole-4,6-dione (M1), 2,5-diethylhexyl-3,6-bis(5-bromothiophen-2-yl)pyrrolo[3,4-c]-pyrrole-1,4-dione (M2) and 4,6-dibromo-thieno[3,4-b]thiophene-2-dodecyl carboxylate (M3) were used as acceptor building blocks for the synthesis of conjugated donor-acceptor polymers. The thermal, optical, electrochemical, and photovoltaic properties of the synthesized polymers were studied.
Solution-processed organic photovoltaic cells (OPVs) hold great promise to enable roll-to-roll pr... more Solution-processed organic photovoltaic cells (OPVs) hold great promise to enable roll-to-roll printing of environmentally friendly, mechanically flexible and cost-effective photovoltaic devices. Nevertheless, many high-performing systems show best power conversion efficiencies (PCEs) with a thin active layer (thickness is ~100 nm) that is difficult to translate to roll-to-roll processing with high reproducibility. Here we report a new molecular donor, benzodithiophene terthiophene rhodanine (BTR), which exhibits good processability, nematic liquid crystalline behaviour and excellent optoelectronic properties. A maximum PCE of 9.3% is achieved under AM 1.5G solar irradiation, with fill factor reaching 77%, rarely achieved in solution-processed OPVs. Particularly promising is the fact that BTR-based devices with active layer thicknesses up to 400 nm can still afford high fill factor of ~70% and high PCE of ~8%. Together, the results suggest, with better device architectures for longe...
This letter reports dye-sensitized solar cells with a thin film of multiwall carbon nanotube/cond... more This letter reports dye-sensitized solar cells with a thin film of multiwall carbon nanotube/conducting poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) composite as the counterelectrode. The composite thin film was prepared by spin coating the aqueous solution of the composite. The devices exhibited high performance with the energy conversion efficiency of 6.5%, short-circuit current of 15.5 mA cm-2, open-circuit voltage of 0.66 V, and fill factor
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Papers by Kuan Sun