Perovskite solar cell with SnO2 mesoporous thin films as electron transport layer: facile fabrication, investigation of the effects of growth parameters

Abstract

Mesoporous SnO2 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 (TC  =  300, 400, and 500 °C) on the structural and surface properties of the layers were investigated. The SnO2 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 SnO2 thin films with a higher surface area were obtained under higher humidity. Higher TC resulted in higher surface macro-roughness, while the highest surface area of 88.2 m2/g was obtained for mild TC  =  400 °C. Perovskite solar cells (PSCs) were fabricated with different mesoporous SnO2 thin films and an electron transport layer (ETL). The highest power conversion efficiency of 13.09% was obtained for the PSCs containing SnO2 thin film prepared with ethanol as solvent, dried under RH = 80%, and calcined at TC  =  400 °C. The factors describing the best performance were explored and discussed.