Room temperature and non-halogenated solvent processed terpolymers for high-efficient polymer solar cells

Most of polymer solar cells (PSCs) are currently processed using halogenated solvents and require high temperature manufacturing. However, the realization of non-halogenated environmental-friendly solvents processing and room temperature treatment are the basis for future commercialization of batteries. In this work, two terpolymers PffBT4T-4T2FC-9/1 and PffBT4T-4T2FC-4/1 were synthesized by introducing a self-assembly third unit, bis(2-hexyldecyl)5,5 '''-dibromo-3 '',4 '-difluoro-[2,2':5',2 '':5 '',2 '''-quaterthiophene]-3,3 '''-dicarboxylate (4T2FC) into the poly [(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3 '''-di (2-octyldodecyl)-2,2'; 5 ',2; 5 '',2 '''-quaterthiophen-5,5 '''-diyl)] (PffBT4T-2OD) polymer matrix via random copolymerization. The obtained terpolymers have relatively weaker self-aggregation properties and enable the spin-coating process at room temperature compared with the pristine copolymer PffBT4T-2OD. More importantly, the ester group of the 4T2FC unit can improve the solubility of the conjugated polymers in halogen-free solvent. Ultimately, a superior power conversion efficiency (PCE) of 9.11% was obtained from the optoelectronic device based on PffBT4T4T2FC-9/1, which is one of the highest values of PSCs based on fullerene system treated with non halogenated solvents at room temperature. These results demonstrate that these new terpolymers with ester group are promising candidates for high performance environmental-friendly solvent processed solar cells.

Automated summary

By introducing ester group into new terpolymers, this study achieved a high power conversion efficiency under non-halogenated solvent treatment at room temperature. These polymers exhibit weaker self-aggregation properties and have the potential to be promising candidates for high performance environmental-friendly solvent processed solar cells.