Effect of colloid aggregation characteristic on ZnO interface layer and photovoltaic performance of polymer solar cells

Abstract

Abstract ZnO as a classical n-type semiconductor oxide is widely used as the electron transport layer for high-efficiency polymer solar cells by using solution processing. To study the effect of ZnO colloid aggregation size on the morphology of ZnO interface layer and photovoltaic performance of polymer solar cells. The ZnO colloid aggregation size was adjusted by aging time, and the PTB7-Th:PC71BM solar cells with various ZnO interface layers were fabricated. The results showed that morphology, structure and property of ZnO interface layer were depended on the ZnO colloid particle size, and then determined the photoelectric performance of the PTB7-Th:PC71BM solar cell. The best performance of PTB7-Th:PC71BM solar cell with 10.21% was obtained when the ZnO precursor solution was set at 2 h aging. The ZnO interface layer with good morphology and appropriate energy level improved the mobility and lifetime of charge carrier. Moreover, it also attributed good interface contact between the ZnO layer and the PTB7-Th:PC71BM active layer, which enhanced the electron transfer and reduced the charge recombination at the interface.