Tailoring of Electron-Collecting Oxide Nanoparticulate Layer for Flexible Perovskite Solar Cells

Low-temperature-processed perovskite solar cells (PSCs), especially those fabricated on flexible substrates, exhibit device performance that is worse than that of high-temperature-processed PSCs. One of the main reasons for the inferior performance of low-temperature-processed PSCs is the loss of photogenerated electrons in the electron collection layer (ECL) or related interfaces, i.e., indium tin oxide/ECL and ECL/perovskite. Here, we report that tailoring of the energy level and electron transporting ability in oxide ECLs using Zn2SnO4 nanoparticles and quantum dots notably minimizes the loss of photogenerated electrons in the low-temperature-fabricated flexible PSC. The proposed ECL with methylammonium lead halide [MAPb-(I0.9Br0.1)(3)] leads to fabrication of significantly improved flexible PSCs with steady-state power conversion efficiency of 16.0% under AM 1.5G illumination of 100 mW cm(-2) intensity. These results provide an effective method for fabricating high-performance, low-temperature solution-processed flexible PSCs.