Functional‐Group‐Induced Single Quantum Well Dion–Jacobson 2D Perovskite for Efficient and Stable Inverted Perovskite Solar Cells

Abstract In two‐dimensional/three‐dimensional (2D/3D) perovskite heterostructure, randomly distributed multiple quantum wells (QW) 2D perovskites are frequently generated, which are detrimental to carrier transport and structural stability. Here, the high quality 2D/3D perovskite heterostructure is constructed by fabricating functional‐group‐induced single QW Dion–Jacobson (DJ) 2D perovskites. The utilization of ─OCH₃ in the precursor solution facilitates the formation of colloidal particles with uniform size, resulting in the production of a pure 2D DJ perovskite with an n value of 3. This strategy facilitates the improvement of 3D structural stability and expedites carrier transport. The resultant devices accomplish a power conversion efficiency of 25.26% (certified 25.04%) and 23.56% at a larger area (1 cm²) with negligible hysteresis. The devices maintain >96% and >89% of their initial efficiency after continuous maximum power point tracking under simulated AM1.5 illumination for 1300 h and under damp‐heat conditions (85 °C and 85% RH) for 1010 h, respectively.