Incorporation of two electron acceptors to improve the electron mobility and stability of perovskite solar cells

The excellent power conversion efficiency (PCE) and low-cost preparation processes of perovskite solar cells (PVSCs) have made them one of the promising photovoltaic candidates. However, the trap states and charge recombination produced a bad effect on the performance of PVSCs. In this work, a PCBM:ITIC mixture was incorporated onto the perovskite films as two electron acceptors via an anti-solvent approach with the formation of a mixture interlayer on the perovskite. Lewis acid/base defects were passivated by the PCBM:ITIC mixture, leading to a lower trap density, and charge mobility was enhanced due to the PCBM:ITIC mixture interlayer. As a consequence, the PCE of the PVSCs with PCBM:ITIC treatment was increased from 14.00% to 16.99%. In addition, the environmental stability of the PVSCs with PCBM:ITIC treatment improved with only 15% degradation after 40 days (60% relative humidity, room temperature).