Enhancing the Efficiency\nand Stability of Perovskite\nSolar Cells Via Hybrid Electron Transport Layer Strategy

Tin oxide (SnO<sub>2</sub>) is extensively employed as\nthe electron\ntransport layer (ETL) for perovskite solar cells, but the presence\nof unsaturated Sn dangling bonds and oxygen vacancy defects at surface\nhinders effective carrier transport. Herein, we present an effective\nstrategy for constructing a hybrid ETL by doping ZnF<sub>2</sub> into\nthe SnO<sub>2</sub>, effectively addressing the oxygen vacancy defects\nat both the bulk and interface of SnO<sub>2</sub>, thus markedly minimizing\nnonradiative recombination losses. Additionally, the process-induced\nstrong bonding between F and Sn atoms facilitates the establishment\nof electron transfer pathways, leading to an increased electron cloud\ndensity within SnO<sub>2</sub> and enhanced electron transfer capability,\nthus further suppressing charge accumulation at the interface. The\nhybrid ETL strategy can be adaptable to perovskites with various cations.\nThe MAPbI<sub>3</sub> and Cs<sub>0.1</sub>FA<sub>0.9</sub>PbI<sub>3</sub> perovskite solar cells achieved remarkable PCEs of 21.31%\nand 24.91%, respectively. Moreover, the hybrid ETL design significantly\nenhances device stability. After 600 h of ambient storage, the unencapsulated\noptimized devices retained approximately 90% of their initial efficiency.