The role of atmospheric conditions in the nonradiative recombination in individual CH3NH3PbI3 perovskite crystals

Abstract

Organic–inorganic metal halide perovskites have been emerging as potential candidates for lightweight photovoltaic applications in space. However, fundamental physics concerning the effect of atmosphere on the radiative and nonradiative recombination in perovskites remains far from well understood. Here, we investigate the creation and annihilation of nonradiative recombination centers in individual CH₃NH₃PbI₃ perovskite crystals by controlling the atmospheric conditions. We find that the photoluminescence (PL) of individual perovskite crystals can be quenched upon exposure from air to vacuum, while the subsequent PL enhancement in air shows a pressure dependence. Further analysis attributes the PL decline in vacuum to the activation of nonradiative trap sites, which is likely due to the lattice distortion caused by the variation of local strain on perovskites. With a gradual increase of the air pressure, the light-assisted chemisorption of oxygen on perovskite will passivate these nonradiative trap sites while simultaneously restoring the lattice imperfection, leading to PL enhancement. The present findings suggest that placing the perovskite in an environment with moderate oxygen content can protect the material from photophysical losses that can be pronounced under inert conditions.