ZrSnO₄: A solution-processed robust electron transport layer of efficient planar-heterojunction perovskite solar cells

A robust electron transport layer (ETL) is an essential component in planar-heterojunction perovskite solar cells (PSCs). Herein, a sol-gel-driven ZrSnO₄ thin film is synthesized and its optoelectronic properties are systematically investigated. The optimized processing conditions for sol-gel synthesis produce a ZrSnO₄ thin film that exhibits high optical transmittance in the UV-Vis-NIR range, a suitable conduction band maximum, and good electrical conductivity, revealing its potential for application in the ETL of planar-heterojunction PSCs. Consequently, the ZrSnO₄ ETL-based devices deliver promising power conversion efficiency (PCE) up to 19.05% from CH₃NH₃PbI₃-based planar-heterojunction devices. Furthermore, the optimal ZrSnO₄ ETL also contributes to decent long-term stability of the non-encapsulated device for 360 h in an ambient atmosphere (T~25^◦C, RH~55%,), suggesting great potential of the sol-gel-driven ZrSnO₄ thin film for a robust solution-processed ETL material in high-performance PSCs.