Theoretical Selection of 2D Perovskite for Constructing Efficient Heterojunction Solar Cells

Two-dimensional (2D) metal halide perovskites can co-construct with the state-of-the-art three-dimensional (3D) perovskite analogs to form 2D/3D perovskite heterojunction architectures, which enables the photovoltaic devices to deliver higher energy conversion efficiency and near-commercial stability. However, the question remains as to whether any type of 2D perovskite, i.e., RP, DJ, or ACI perovskites, is workable with a 3D analog to outperform the pristine 3D perovskites. Here, we investigate the structural and electronic properties of distinct types of 2D/3D perovskite heterojunctions based on first-principles calculations. We selected a 3D FAPbI3 perovskite combined with representative 2D RP, DJ, and ACI perovskites to construct a series of 2D/3D perovskite heterojunctions and analyzed the carrier transport kinetics and charge recombination of each heterojunction. The results indicate that RP-PbI, DJ-FAI, and ACI-FAI heterojunctions exhibited favorable transport and separation of photogenerated carriers, but the RP-PbI and ACI-FAI heterojunctions appear to possess greater potential for photovoltaic applications than the DJ-FAI heterojunction due to relatively fewer recombination losses. Moreover, based on the direction of photogenerated carrier transport at the heterojunction, we predict that RP-PbI would be superior to DJ-FAI for conventional 2D/3D devices and that the ACI-FAI heterojunction is expected to well function in the inverted 2D/3D devices.