Mixed 2D-cation passivation towards improved durability of perovskite solar cells and dynamics of 2D-perovskites under light irradiation and at high temperature†

Abstract

A low-dimensional perovskite layer is important as a passivation layer for the 3D perovskite photo-absorber to increase the photovoltaic performance and stability. Here, we provide an effective passivation technique that enhances the durability of perovskite solar cells and investigate the impact of the 2D perovskite on the photovoltaic properties under light irradiation as well as high-temperature conditions. Our proposed mixed 2D cation (n-butylammonium iodide (BAI) and n-octylammonium iodide (OAI)) passivation can control the opto-electronic properties of the 2D perovskites and improve the durability of perovskite solar cells. Furthermore, our main finding is that the migration of the 2D perovskite into the 3D perovskite layer, during light and high-temperature stability tests, causes the reduction of the photovoltaic properties of the perovskite solar cells. This information suggests how to design the 2D perovskite layer leading to stable perovskite solar cells from the viewpoint of cation migration, which can be the novel design strategy for the 2D/3D perovskite system.