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.