In-situ vacuum oxidation of ALD-SnO2 layer enabling highly efficient and stable perovskite solar cells

Abstract

Recent advances in perovskite solar cells (PSCs) have highlighted the urgent need for scalable commercialization technologies. Atomic layer deposition (ALD)-based SnO₂ has emerged as a promising electron transport layer (ETL), offering excellent reproducibility and uniformity. However, intrinsic defects such as oxygen vacancies limit further photovoltaic improvement. To address the defect problems, we developed an In-Situ vacuum oxidation (IVO) process that fundamentally enhances the intrinsic material quality of SnO₂ by incorporating controlled oxidation during ALD growth under vacuum conditions. This approach prevents oxygen vacancy formation in situ, improving the structural integrity of the oxide layer without external contamination risks associated with atmospheric exposure. The IVO-treated ALD-SnO₂ ETL achieved a power conversion efficiency of 23.39%, the highest reported value for single-layer ALD-SnO₂ PSCs while retaining 87% of initial performance after 1500 h without encapsulation, demonstrating exceptional long-term stability. This strategy presents a viable pathway toward commercialization of high-performance PSCs.