Fig. 2. Effect on the PL intensity of MAPbBr₃ single crystals of exposure to different gaseous environments.

(A) PL intensity as a function of time in vacuum and on exposure to dry N₂, dry CO₂, and dry Ar. (B) PL intensity as a function of time on exposure to air, dry O₂, and moist N₂. In each panel, the blue shaded area indicates vacuum. The crystal was excited with a 400-nm wavelength laser; the laser power was kept constant at 0.71 μJ/cm².