Improved Performance of Planar Perovskite Solar Cells Using an Amino-Terminated Multifunctional Fullerene Derivative as the Passivation Layer

Organic-inorganic metal halide perovskite solar cells (PSCs) have been revolutionizing the photovoltaic community in the past decade. However, the trap states in TiO2 as electron transport layer seriously affect the device photovoltaic performance and stability. Here, we design and synthesize a fullerene derivative C60NH2 featuring an amino-terminated group. We use C60NH2 as a passivation layer between TiO2 and perovskite in planar PSCs with standard configuration to improve the quality of the obtained perovskite film as well as electron transfer efficiency, resulting in an obvious increment of photovoltaic performance and stability of the devices. The champion power conversion efficiency of 18.34% is achieved under 100 mW cm-2 illumination utilizing C60NH2 as passivation layer with much less hysteresis. Planar PSCs demonstrate superior stability under natural sunlight and 40%-50% relative humidity after C60NH2 passivation. This work enriches choices of materials for interface engineering towards planar P...