Design of novel thiazolothiazole-based conjugated polymer for efficient fullerene and non-fullerene organic solar cells

Abstract

We report the synthesis of novel low bandgap conjugated polymer P1 comprising thiazolothiazole, benzothiadiazole and thiophene units and investigation its photovoltaic properties in organic solar cells with [70]PCBM ([6,6]-phenyl-C71-butyric acid methyl ester) and high-performing non-fullerene IT-4F acceptor (9-bis(2-methylene-((3-(1,1-dicyanomethylene)-6,7-difluoro)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2’,3’-d’]-s-indaceno [1,2-b:5,6-b’]dithiophene). Polymer P1 showed promising results in both fullerene and non-fullerene organic solar cells. In particular, P1/IT-4F blends demonstrated enhanced charge carrier mobilities and suppressed trap-assisted recombination, which resulted in impressive short-circuit current densities and decent power conversion efficiency of 8.8 % in solar cells. The fullerene-based devices delivered efficiency of 8.2 % with remarkably high open-circuit voltages. The obtained results feature conjugated polymers based on thiazolothiazole as promising absorber materials for organic solar cells.