Diketopyrrolopyrrole-based Conjugated Polymers as Additives to Optimize Morphology for Polymer Solar Cells

• Published in: Chinese journal of polymer science Vol. 34; no. 4; pp. 491 - 504
• Main Authors: Liao, Xun-fan, Wang, Jing, Chen, Shuang-ying, Chen, Lie, Chen, Yi-wang
• Format: Journal Article
• Language: English
• Published: Beijing Chinese Chemical Society and Institute of Chemistry, CAS 01.04.2016
• Subjects: 3-己基噻吩; Additives; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Copolymers; Devices; Industrial Chemistry/Chemical Engineering; Light absorption; Morphology; Photovoltaic cells; Polymer Sciences; Polymerization; Solar cells; 共轭聚合物; 可见光吸收; 吡咯基; 太阳能电池; 形态; 无规共聚物; 添加剂; Additive; Ternary random copolymers; Morphology; Polymer solar cells
• ISSN: 0256-7679; 1439-6203
• DOI: 10.1007/s10118-016-1761-0

Novel random copolymers for optimizing the morphology of the active layer for high performance organic photovoltaic devices have been demonstrated. Three ternary random copolymers PTBDTDPPSiCN（3/7）, PTBDTDPPSiCN（5/5）, PTBDTDPPSiCN（7/3） were prepared by polymerization of electron-donating thienyl-substituted benzodithiophene （TBDT） with 2,5-bis[8-（1,1,3,3,5,5,5-heptamethyltrisiloxane-3-yl）octly]-pyrrolo[3,4-c]pyrrole-1,4-dione （DPPSi） and 2,5-dio[5-（5-cyano-5,5-dimethyl-pentyl）]-3,6-dithiophen-2-yl-pyrrolo[3,4-c]pyrrole-1,4-dione （DPPCN） of different ratios. The DPPCN block can well-tune the light absorption and molecular packing, while the DPPSi block is in favor of enhancing the charge mobility. And the formation of organic Si--O--Si networks is beneficial to stabilize the morphology of the active layer. These new copolymers have narrow bandgaps and broaden visible light absorption from 500 nm to 1000 nm. Careful balance of the contents of the trimethoxysilyl group and the cyano group can well-tune the surface energy and morphology of the copolymers. Incorporation of these novel copolymers as additives into the blend of poly（3-hexylthiophene） （P3HT） and [6,6]-phenyl-C60-butyric acid methyl ester （PC61BM） is found to effectively broaden the light absorption, improve the compatibility and morphology of the active layer. As a result, some devices with certain ratios of these copolymers as additives achieve the enhanced efficiency compared with the device based on pristine P3HT：PC61BM.