https://scholars.lib.ntu.edu.tw/handle/123456789/370395
標題: | Comparison of thiophene- and selenophene-bridged donor-acceptor low band-gap copolymers used in bulk-heterojunction organic photovoltaics | 作者: | Chen, H.-Y. Yeh, S.-C. CHAO-TSEN CHEN |
公開日期: | 2012 | 卷: | 22 | 期: | 40 | 起(迄)頁: | 21549-21559 | 來源出版物: | Journal of Materials Chemistry | 摘要: | We report a detailed comparison of absorption spectroscopy, electrochemistry, DFT calculations, field-effect charge mobility, as well as organic photovoltaic characteristics between thiophene- and selenophene-bridged donor-acceptor low-band-gap copolymers. In these copolymers, a significant reduction of the band-gap energy was observed for selenophene-bridged copolymers by UV-visible absorption spectroscopy and cyclic voltammetry. Field-effect charge mobility studies reveal that the enhanced hole mobility of the selenophene-bridged copolymers hinges on the solubilising alkyl side chain of the copolymers. Both cyclic voltammetry experiments and theoretical calculations showed that the decreased band-gap energy is mainly due to the lowering of the LUMO energy level, and the raising of the HOMO energy level is just a secondary cause. These results are reflected in a significant increase of the short circuit current density (J SC) but a slight decrease of the open circuit voltage (V OC) of their bulk-heterojunction organic photovoltaics (BHJ OPVs), of which the electron donor materials are a selenophene-bridged donor-acceptor copolymer: poly{9-dodecyl-9H-carbazole-alt-5, 6-bis(dodecyloxy)-4,7-di(selenophen-2-yl) benzo[c][1,2,5]-thiadiazole} (pCzSe) or poly{4,8-bis(2-ethylhexyloxy)benzo[1,2-b;4,5-b′]dithiophene-alt-5,6- bis(dodecyloxy)-4,7-di(selenophen-2-yl)benzo[c][1,2,5]-thiadiazole} (pBDTSe), or a thiophene-bridged donor-acceptor copolymer: poly{9-dodecyl-9H-carbazole-alt- 5,6-bis(dodecyloxy)-4,7-di(thiophen-2-yl)benzo[c][1,2,5]-thiadiazole} (pCzS) or poly{4,8-bis(2-ethylhexyloxy)benzo[1,2-b;4,5-b′]dithiophene-alt-5, 6-bis(dodecyloxy)-4,7-di(thiophen-2-yl)benzo[c][1,2,5]-thiadiazole} (pBDTS); the electron acceptor material is [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Judging from our device data, the potential Se-Se interactions of the selenophene-bridged donor-acceptor copolymers, which is presumably beneficial for the fill factor (FF) of BHJ OPVs, is rather susceptible to the device fabrication conditions. © 2012 The Royal Society of Chemistry. |
URI: | http://www.scopus.com/inward/record.url?eid=2-s2.0-84866999315&partnerID=MN8TOARS http://scholars.lib.ntu.edu.tw/handle/123456789/370395 |
DOI: | 10.1039/c2jm33735e | SDG/關鍵字: | Alkyl side chains; Band gap energy; Bulk heterojunction; Charge mobilities; Device data; Device fabrications; DFT calculation; Donor-acceptor copolymers; Donor-acceptors; Electron acceptor materials; Electron donors; Field-effect; Fill factor; HOMO energy levels; Low band-gap copolymers; LUMO energy levels; Methyl esters; Organic photovoltaics; Theoretical calculations; Thiadiazoles; UV-visible absorption spectroscopy; Cyclic voltammetry; Density functional theory; Energy gap; Heterojunctions; Open circuit voltage; Organic compounds; Polycyclic aromatic hydrocarbons; Thiophene; Copolymers |
顯示於: | 化學系 |
在 IR 系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。