Physisorption of Oxygen in SnO2 Nanoparticles for Perovskite Solar Cells

Although SnO
₂
is widely used in perovskite solar cells (PSCs) as the electron transport layer, there is still a need for a detailed investigation regarding the impact of physisorption on the performance of PSCs. Here, we report the role of physisorption of oxygen species from the ambient atmosphere in the oxidation states and defective oxides at the surface of SnO
₂
nanoparticles for the performance of PSCs. The SnO
₂
nanoparticle's thin film shows a higher oxidation state (Sn–O) and lower charge trap sites at an annealing temperature of 100 °C, and the SnO
₂
film based PSCs yield an efficiency of 18.04%. The annealing process results in the gradual desorption of physically adsorbed oxygen species. Therefore, the annealing process of SnO
₂
nanoparticle thin films in atmosphere is the key factor to control the oxidation states and defective oxides at the surface of SnO
₂
nanoparticle thin films.