Chemical optimization of benzo-dithiophene and benzo-[2,1,3]thiadiazole copolymers for the high performance, green-solvent-processed polymer solar cells

• Published in: Solar energy Vol. 173; pp. 1043 - 1050
• Main Authors: Chen, YunXiang, You, Guofeng, Lin, Xinyu, Yuan, Xiyue, Zou, Ding, Wang, Wen, Yang, Renqing, Zhen, Hongyu, Ling, Qidan
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 01.10.2018; Pergamon Press Inc
• Subjects: Copolymers; Diphenyl ether; Non-halogen solvent; Optimization; Organic chemistry; Photovoltaic cells; Polymer solar cells; Polymeric donor; Polymers; Solar cells; Solar energy; Solvents; Spacer; Trimethylbenzene; Non-halogen solvent; Spacer; Polymer solar cells; Polymeric donor
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2018.08.036

With an alky thiophene and a bare thiophene as spacer, PBTTF-H exhibits high photovoltaic properties in the non-halogenated processed devices. [Display omitted] •Three new BDF-FBT based polymers with different spacer were investigated.•With an alky thiophone and a bare thiophone as the spacer, PBTTF-H performs best.•A hexyl side chain leads a PCE gap of 5% between PBTTF-C6 and PBTTF-H based cells. In this work, we demonstrate the chemical optimization of benzo[1,2-b:4,5-b′]dithiophene (BDT)-5,6-difluorobenzo-[2,1,3]thiadiazole (FBT) D-A alternating copolymer for obtaining the efficient polymeric donors for the environment-friendly solution processed polymer solar cells (PSCs). Three polymers PBTF, PBTTF-C6 and PBTTF-H, in which one or two alky thiophene units are inserted into the backbone of BDT-FBT alternating copolymer, present much different performances either in the PSCs processed from halogenated solvent and additive or in the PSCs processed from non-halogenated solvent and additive. With an alky thiophene and a bare thiophene as the spacer, PBTTF-H performs best among the three. Especially when the devices processed from 1,2,4-trimethylbenzene and diphenyl ether, in which the highest PCE of 6.80% is achieved with a VOC of 0.77 V, a JSC of 13.67 mA cm−2 and a FF of 64.2%. We think these results will cast light on developing new polymeric donors of the green-solvent-processed PSCs.