High performance inverted structure perovskite solar cells based on a PCBM: Polystyrene blend electron transport layer

Hybrid organic/inorganic perovskite solar cells are among the most competitive emerging photovoltaic technologies. Here, we report on NiO-based inverted structure perovskite solar cells with a high power conversion efficiency of 10.68%, which is achieved by adding a small percentage (1.5 wt%) of high molecular weight polystyrene (PS) into the PCBM electron transport layer (ETL). The addition of PS facilitates the formation of a highly smooth and uniform PCBM ETL that is more effective in preventing undesirable electron-hole recombination between the perovskite layer and the top electrode. As a result, the V_OC of the PCBM:PS-based cells is increased from 0.97 V to 1.07 V, which leads to significantly enhanced power conversion efficiencies of the solar cells. Our study provides a simple and low-cost approach to improving the ETL film quality and the performance of inverted perovskite solar cells.