A General Large-Scale Fabrication of Tin Oxide with Interfacial Engineering via Trichloropropylsilane for Hysteresis-Free MAPbI3 Perovskite Solar Cells Exceeding 20% PCE

Abstract We demonstrate a facile chemical bath deposition (CBD) of SnO2 films as excellent ETLs using a low temperature method (70 °C). The vacuum drying treatment and trichloropropylsilane (C3H7Cl3Si, Cl-Si) are employed for surface modification on SnO2 films due to the hygroscopicity of most metal oxides. The results reveal that the water molecules adsorbed on the CBD-SnO2 films can be desorbed by vacuum drying, and the hydrolysis products of Cl-Si can bond to SnO2 films through hydroxyl groups. Thus, the hydrophobicity of CBD-SnO2 is enhanced by employing the Cl-Si treatment, which is beneficial to improve the crystallinity of MAPbI3. The Cl-Si modified SnO2 films exhibit efficient electron extraction and hole blocking ability due to the higher electronic conduction band energy level than the pristine SnO2. Consequently, the MAPbI3 PSCs based on the hydrophobic Cl-Si/SnO2 exhibit a high PCE of 20.12% with low hysteresis, retaining 80% of the initial PCE after 500 h without any encapsulation at ambient condition. The 5 × 5 cm2 PSC modules prepared with this strategy achieve 15.24% efficiency (14.44% at forward scanning) with an aperture area of 10 cm2.