Perovskite solar cell with SnO 2 mesoporous thin films as electron transport layer: facile fabrication, investigation of the effects of growth parameters

Mesoporous SnO 2 thin films were prepared via a facile sol gel-based method. The effects of two different solvents (ethanol and 1-butanol), different drying conditions (relative humidity (RH) of 34 and 80%), and calcination temperatures ( T C = 300, 400, and 500 °C) on the structural and surface properties of the layers were investigated. The SnO 2 thin films prepared with butanol exhibited lower thickness, lower surface area, and higher surface macro-roughness. The polarity, viscosity, and steric hindrance of solvents were compared and their effects on the final layer properties were discussed. The results of characterization analyses revealed that thicker and puffier SnO 2 thin films with a higher surface area were obtained under higher humidity. Higher T C resulted in higher surface macro-roughness, while the highest surface area of 88.2 m 2 /g was obtained for mild T C = 400 °C. Perovskite solar cells (PSCs) were fabricated with different mesoporous SnO 2 thin films and an electron transport layer (ETL). The highest power conversion efficiency of 13.09% was obtained for the PSCs containing SnO 2 thin film prepared with ethanol as solvent, dried under RH = 80%, and calcined at T C = 400 °C. The factors describing the best performance were explored and discussed.