Optimization of photovoltaic device based on poly(3-hexylthiophene):C60 bulk heterojunction composites prepared with halogen-free solvent

Abstract

The combination of halogen-free solvent and neat fullerene is expected to reduce the economical and environmental costs of polymer photovoltaic devices. Recently, it has been found that a naturally produced solvent, 1,2,4-trimethylbenzene, enables the preparation of bulk heterojunction composites with neat C60. However, the power conversion efficiency (PCE) of such devices reported so far was less than 1%. In this research, the annealing effects on and film thickness dependence of the performance of photovoltaic devices based on a composite consisting of equivalent weights of poly(3-hexylthiophene) and C60 have been studied to improve the device performance. The optimized device showed a PCE of 1.21%, suggesting that neat C60 is a promising candidate electron acceptor material for polymer bulk heterojunction composites for environmentally friendly and cost-effective photovoltaic devices.