The Evolution of Photoluminescence Properties of PEA₂SnI₄ Upon Oxygen Exposure: Insight into Concentration Effects

The time evolution of the photoluminescence properties in phenylethylammonium tin halide perovskite (PEA₂SnI₄) film as a function of oxygen concentration is reported. Photo-brightening and reversible photoluminescence quenching are observed in PEA₂SnI₄ film at ultralow oxygen concentration (< 1.5 vol%). In the case of 1.5 vol% < [O₂] < 21 vol%, the photoluminescence emission of PEA₂SnI₄ film can be partially recovered after resetting the samples to nitrogen box. As the oxygen concentration further increases with the range of 21 to 95 vol%, the photoluminescence emission of PEA₂SnI₄ film is significantly quenched and can only be slightly recovered after removing it to the nitrogen box. By correlating the material characterizations and theoretical analysis, the interactions between PEA₂SnI₄ and oxygen contain physisorption and chemical reactions are illustrated. Depending on the oxygen concentration, the chemical reactions between PEA₂SnI₄ and oxygen can be reversible and/or irreversible. The insights into oxygen concentration effects provide a guideline to optimize the stability of PEA₂SnI₄ for achieving high-performance optoelectronic devices.