In situ nanocrystallization on the perovskite film surface for enhanced light emission

Abstract

Enhancing light emission of organic-inorganic hybrid perovskites is significant for various optoelectric applications. For that purpose, phosphine oxide-based compounds have been widely employed to suppress non-radiative recombination, ascribed to their strong passivation ability to defective sites. Herein, we report that besides passivating defects, phosphine oxide derivatives can induce the surface reconstruction of the perovskite film, forming well-defined nanocrystals during the spincoating process. This in situ nanocrystallization is achieved based on the strong interaction between -P=O groups and perovskites, which leads to partial dissolution of perovskite grains then rapid recrystallization to generate nanocrystalline structures. The nanocrystallized perovskite films exhibit considerably improved photoluminescence owing to the spatial carrier confinement effect, as well as increased electroluminescence performances. The resultant perovskite light-emitting diodes show pure red light with the brightness over three times higher than that of the control devices (from 890 to 2961 cd m -2 ). This work reveals an unaware function of phosphine oxide derivatives in addition to the defect passivation, providing an effective in situ nanocrystallization strategy to boost the light emission of the perovskite film.