Interconnected SnO2 Nanocrystals Electron Transport Layer for Highly Efficient Flexible Perovskite Solar Cells

This study reports on interconnected SnO2 electron transport layers (composed of presynthesized SnO2 nanocrystals interconnected by amorphous phase SnOx) processed at low temperature (120 °C) for highly efficient flexible perovskite solar cells. Herein, the amorphous phase SnOx serves as an effective binder to connect the SnO2 nanocrystals to obtain ultra‐smooth electron transport layers. Further characterization of the charge carrier kinetics at the perovskite/electron transport layer interface confirms that the interconnected SnO2 nanocrystals layer facilitates electron extraction and retards nonradiative charge carrier recombination. Consequently, a power conversion efficiency of 16.29% is achieved for flexible perovskite solar cells using the interconnected SnO2 electron transport layer on indium tin oxide/polyethylene terephthalate substrates.