Abstract

Perovskite solar cells (PSCs) are promising for photovoltaic applications, with the electron transport layer (ETL) playing a crucial role in performance. TiO2 is commonly used as an ETL due to its excellent electron mobility, stability, and cost-effectiveness, but defects in TiO2 films can lead to performance losses. Surface treatments like defect passivation and mixing TiO2 with other oxides improve efficiency. Barium titanate (BaTiO3) is introduced to enhance TiO2-based ETLs, facilitating electron mobility. The bilayer TiO2/BaTiO3 ETLs improve carrier transport, reduce recombination, and optimize the growth of perovskite films. TiO2/BaTiO3-based PSCs show an 82 % performance increase compared to TiO2-based devices (7.7 % vs 13.0 %), thanks to improved electron transport, recombination resistance, and optimized band gap. Future integration with advanced materials or technologies could further boost PSC performance and versatility. © 2025 Elsevier B.V.