Orientation Engineering via 2D Seeding for Stable 24.83% Efficiency Perovskite Solar Cells

Abstract Organic‐inorganic hybrid perovskite solar cells (PSCs) have been extensively researched as a promising photovoltaic technology, wherein the orientation of the perovskite film plays a crucial role in the power conversion efficiency (PCE) and stability. Here, a seed‐mediated method is developed to in situ grow a layer of 2D perovskite seed for epitaxial growth of 3D perovskite atop it to construct a high‐quality 2D/3D heterojunction. It is found that the epitaxial 3D perovskite film exhibits a preferred [112] direction, which is different from traditional perovskites with a preferred [001] orientation. The oriented perovskite film consists of large‐sized grains with low defect density, long charge‐carrier lifetime, and good stability, resulting in efficient PSCs with a champion efficiency of 24.83%. In addition, the devices exhibit high stability under ambient, thermal, and continuous light‐soaking conditions. This work provides an effective strategy for achieving high‐quality perovskite films with tunable orientation to simultaneously boost the efficiency and stability of PSCs.