Enhancing the Efficiency and Stability of Perovskite Solar Cells Via Hybrid Electron Transport Layer Strategy

Tin oxide (SnO₂) is extensively employed as the electron transport layer (ETL) for perovskite solar cells, but the presence of unsaturated Sn dangling bonds and oxygen vacancy defects at surface hinders effective carrier transport. Herein, we present an effective strategy for constructing a hybrid ETL by doping ZnF₂ into the SnO₂, effectively addressing the oxygen vacancy defects at both the bulk and interface of SnO₂, thus markedly minimizing nonradiative recombination losses. Additionally, the process-induced strong bonding between F and Sn atoms facilitates the establishment of electron transfer pathways, leading to an increased electron cloud density within SnO₂ and enhanced electron transfer capability, thus further suppressing charge accumulation at the interface. The hybrid ETL strategy can be adaptable to perovskites with various cations. The MAPbI₃ and Cs_0.1FA_0.9PbI₃ perovskite solar cells achieved remarkable PCEs of 21.31% and 24.91%, respectively. Moreover, the hybrid ETL design significantly enhances device stability. After 600 h of ambient storage, the unencapsulated optimized devices retained approximately 90% of their initial efficiency.