Ultralow‐Temperature SnO2 Electron Transport Layers Fabricated by Intermediate‐Controlled Chemical Bath Deposition for Highly Efficient Perovskite Solar Cells

As electron transport layers (ETLs) in perovskite solar cells (PSCs), tin oxide (SnO2 ) possess high carrier mobilities with appropriate energy band alignment and high optical transmittance. Herein, SnO2 ETLs were fabricated by intermediate-controlled chemical bath deposition (IC-CBD) at ultralow temperature, where the chelating agent effectively altered the nucleation and growth process. Compared with conventional CBD, SnO2 ETLs fabricated by IC-CBD had lower defects, smooth surface, good crystallinity, and remarkable interfacial contact with perovskite, resulting in good quality of perovskite, high photovoltaic performance (23.17 %), and enhanced stability of devices.