Formulation of PC71BM isomers in P3HT-based polymer solar cells

Abstract Formulation engineering, featuring with different ingredients combined, is a useful strategy for making efficient electronic acceptors because it can achieve effects that cannot be obtained from its components when these are used singly. Herein, we show a contour plot with different formulations of isomeric phenyl-C 71 -butyric acid methyl ester (PC 71 BM) as electron acceptors in poly(3-hexylthiophene) (P3HT):PC 71 BM polymer solar cells (PSCs). Upon altering fullerene formulation the PCEs change in the range of 0.87–4.01%. The optimized formulation consisting of ~ 80% α-PC 71 BM, ~ 10% β 1 -PC 71 BM, and ~ 10% β 2 -PC 71 BM exhibits the best PCE of 4.01%, which mainly benefits from the optimum morphology of P3HT-fullerene heterojunction film. The present work demonstrates a successful strategy by controlling morphology of PC 71 BM isomers to improve the PCE of P3HT-based PSCs, and consolidates the photovoltaic performance of polymer solar cells heavily dependent on the formulation of fullerene-based electron acceptors.