Room-temperature synthesized SnO electron transport layers for efficient perovskite solar cells.

Tin oxide (SnO) is widely used as electron transport layer (ETL) material in perovskite solar cells (PSCs). Numerous synthesis methods for SnO have been reported, but they all require a proper thermal treatment for the SnO ETLs. Herein we present a simple method to synthesize SnO nanoparticles (NPs) at room temperature. By using butyl acetate as a precipitator and a proper UV-Ozone treatment to remove Cl residuals, excellent SnO ETLs were obtained without any thermal annealing. The highest power conversion efficiency (PCE) of the prepared PSCs was 19.22% for reverse scan (RS) and 18.79% for forward scan (FS). Furthermore, flexible PSCs were fabricated with high PCEs of 15.27%/14.74% (RS/FS). The low energy consuming SnO ETLs therefore show great promise for the flexible PSCs' commercialization.