High-Performance Electron Transport Layer via Ultrasonic Spray Deposition for Commercialized Perovskite Solar Cells

Among deposition methods, ultrasonic spray-coating has particularly strong potential for large-scale production due to its low cost and capability to produce thin films with large-scale areas for industrial applications. In this work, SnO2 electron transport layers (ETLs) were successfully prepared via ultrasonic spray-coating at a low temperature. A series of spraying parameters were optimized to adjust the drying process. Finally, compact pinhole-free ETLs with high transmittance and preeminent electron migration efficiency were obtained. The small-area perovskite solar cells (PSCs) (0.29 cm2) were fabricated based on the aforesaid SnO2 ETLs exhibiting a distinguished power conversion efficiency (PCE) of 18.72%. More than 85% of the original PCE was retained after the cells were stored in a drying tower (room temperature (RT), 30% relative humidity (RH)) for 1000 h without encapsulation, which reflects the remarkable stability of the devices. Moreover, minimodules (4 cm × 4 cm) were also fabricated successfully with a PCE of 10.57%.