A Chain Entanglement Gelled SnO₂ Electron Transport Layer for Enhanced Perovskite Solar Cell Performance and Effective Lead Capture

SnO₂ is a widely used electron transport layer (ETL) material in perovskite solar cells (PSCs), and its design and optimization are essential for achieving efficient and stable PSCs. In this study, the in situ formation of a chain entanglement gel polymer electrolyte is reported in an aqueous phase, integrated with SnO₂ as the ETL. Based on the self-polymerization of 3-[[2-(methacryloyloxy)ethyl]dimethylammonium]propane-1-sulfonic acid (DAES) in an aqueous environment, combining the catalytic effect of LiCl (as a Lewis acid) with the salting-out effect, and the introduction of polyvinylpyrrolidone (PVP) as the other polymer chain, a chain entanglement gelled SnO₂ (G-SnO₂) structure is successfully constructed with a wide range of functions. The PDEAS-PVP chain entanglement gel achieves passivation and Pb²⁺ capture through chemical chelation mechanisms is explored. The results demonstrated that the all-in-air prepared PSC based on G-SnO₂ exhibited an excellent power conversion efficiency (PCE) of 24.77% and retained 83.3% of their initial efficiency after 2100 h of air exposure. Additionally, the PDEAS-PVP exposes more C═O and S═O active sites, significantly enhanced the lead absorption capability of the PSCs.