Finite perovskite hierarchical structures via ligand confinement leading to efficient inverted perovskite solar cells

Multi-dimensional lead halide perovskite solar cells (PSCs) exhibit great promise as a next generation photovoltaic technology. Herein, we develop a unique approach via interfacial ligand confinement for constructing finite 2D/3D hierarchical perovskite structures to obtain efficient and stable inverted PSCs and modules. It is found that the introduction of a diamine masking reagent atop the 3D perovskite layer can regulate cation exchange via hydrogen bonding resulting in the formation of a finite and dense 2D layer, which is beneficial not only to accomplish top-contact passivation but also to enhance electron extraction at the electron selective contact. As a result, inverted PSCs and modules with finite 2D/3D perovskite layers achieve remarkable power conversion efficiencies (PCEs) of 24.7% and 21.6% (certified PCE of 21.2%), respectively, representing one of the best-performing inverted mini-modules reported so far. Furthermore, encapsulated PSCs are found to retain over 90% of their original PCE after 1000 hours of illumination. Overall, this work presents an effective approach for further advancing perovskite photovoltaics.