In situ Ligand‐Managed SnO₂ Electron Transport Layer for High‐Efficiency and Stable Perovskite Solar Cells

Abstract Tin oxide (SnO₂) with high conductivity and excellent photostability has been considered as one of the most promising materials for efficient electron transport layer (ETL) in perovskite solar cells (PSCs). Among them, SnO₂ nanoparticles (NPs) dispersions have been extensively utilized due to their facile film formation. However, the inherent defects and agglomeration issues of SnO₂ NPs, as well as the limited tunability and instability of the post‐treatment process for surface/interface engineering strategy, still hinder its further applications. Herein, a ligand‐management strategy implemented during the in situ synthesis of NPs that can effectively achieve uniform modification of NPs is proposed. During the synthesis of SnO₂ NPs, the grafting reaction between diethyl 2‐chloromalonate (DCMA) and the surface of SnO₂ NPs is completed. Compared with the post‐treatment process, this intrinsic DCMA‐passivated SnO₂ (DCMA‐SnO₂) effectively reduces the trap state density at the interface between perovskite and ETL while enhancing surface chemical stability. Consequently, PSCs based on DCMA‐SnO₂ achieve a champion PCE of 25.39% for small cells (active area of 0.0655 cm²) and 20.61% for solar modules (active area of 23.25 cm²), demonstrating excellent shelf‐life/light soaking stability (advanced level of ISOS stability protocols). This ligand‐management strategy exhibits significant application potential in preparing high‐efficiency large‐area PSCs.