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

Abstract

Enhancing the light emission of organic–inorganic hybrid perovskites is significant for various optoelectronic applications. For that purpose, phosphine oxide-based compounds have been widely employed to suppress non-radiative recombination, ascribed to their strong ability to passivate defective sites. Herein, we report that besides passivating defects, phosphine oxide derivatives can induce surface reconstruction of perovskite films, forming well-defined nanocrystals during the spin-coating process. This in situ nanocrystallization is achieved based on the strong interaction between –PO groups and perovskites, which leads to partial dissolution of perovskite grains followed by 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 a brightness over three times higher than that of the control devices (from 890 to 2961 cd m⁻²). This work reveals a previously unrecognized function of phosphine oxide derivatives in addition to defect passivation, providing an effective in situ nanocrystallization strategy to boost the light emission of perovskite films.