Crosslinked ion diffusion inhibitors stabilize 3D/2D perovskite heterostructures for efficient and stable photovoltaics

Abstract Two-dimensional (2D) and quasi-2D modifications of 3D perovskite active layers have contributed to advances in the performance of perovskite solar cells (PSCs); however, the ionic diffusion between the surface 2D and bulk 3D perovskites leads to the degradation of the 2D/3D perovskite heterostructure and limits the long-term stability of PSCs. Here we incorporate a crosslinked ion diffusion inhibitor (CDI) on the top of a 3D perovskite layer, and then deposit a 2D perovskite layer via a vapor-assisted two-step process to form a 3D/CDI/2D perovskite heterostructure. Photoluminescence spectra and thickness-profiled elemental analysis indicate that it is by inhibiting ion diffusion between the 2D and 3D perovskites that the CDI stabilizes the heterostructures. Based on carbon electrodes, we report small-area devices with an efficiency of 21.17%, and mini-modules with an efficiency of 19.56%. After 4,390-hours operation under maximum power point tracking and one-sun illumination at elevated temperature, devices retain 90% of initial performance.