Improving the fill factor of N2200-based all polymer solar cells by introducing EPPDI as a solid additive

Abstract

A cheap and commercially available small molecule (namely EPPDI) is introduced to the active layer of N2200-based all polymer solar cells as a solid additive. EPPDI at the optimal ratio can improve the D-A nano-scale morphology and reduce trap density of the active layer by filling morphological spaces. As a result, the photovoltaic performance of the resulting devices based on PF2:N2200 are increased from 6.28% to 7.03% with significantly enhanced fill factor. This work demonstrates a facile approach for improving the performance of all polymer solar cells. • A cheap and commercially available small molecular solid additive. • No influence on the original polymer thin film order. • Reduce the morphological traps in active layer. • Improve the fill factor and power conversion efficiency of all polymer solar cells.