Improving microstructure and stability of FAMAPbI3 perovskite using bilayer TiO2/SnO2 electron transport layer

Abstract

An efficient electron transport layer (ETL) is important to transport electrons while blocking holes and to reduce the electrical shunting between transparent electrode/perovskite interface to enhance the performance and stability of perovskite solar cells (PSCs). TiO2 is widely utilized as ETL. However, it has a lower carrier mobility and tends to catalyse the degradation of the perovskite absorber layer. Alternatively, SnO2 also has a suitable wide band gap and exhibits better carrier mobility. In this work, we have compared the performance and stability of the perovskite absorber layer deposited on different TiO2, SnO2 and TiO2/SnO2 ETL. The bilayer ETL shows greater mobility facilitating effective charge extraction and achieving greater power conversion efficiency (∼13 %) in PSCs. Our results show that improved wettability and microstructure of bilayer TiO2/SnO2 ETL resulted in a compact and large-grained FAMAPbI3 film, which increased the performance and stability of the perovskite layer in ambient conditions (28–35 °C, RH 70 %). © 2025