Blinking Beats Bleaching: The Control of Superoxide Generation by Photo‐ionized Perovskite Nanocrystals

Abstract

Moisture‐ or oxidation‐induced degradation is a major challenge in the advancement of perovskites‐based technology. The oxidation is caused by electron transfer from a photo‐excited perovskite nanocrystal to oxygen and the formation of superoxide that disintegrates the perovskite structure. In air, the emission intensity of a methylammonium lead iodide (MAPbI3) perovskite nanocrystal continuously decreases, whereas a nanocrystal in argon or a polymer shows exceptionally stable emission intensity. Surprisingly, in air, the emission intensity of a nanocrystal with long‐lived OFF states completely recovers after the OFF state. This property, along with the rate of non‐radiative relaxation that exceeds the rate of electron transfer suggest that the perovskite nanocrystals produce and react with superoxide in the excited neutral state, but not in the ionized state. In other words, the ultrafast non‐radiative relaxation in the ionized state hinders electron transfer to oxygen and prevents oxidation of perovskites.

Synthesis, optoelectronic properties and applications of halide perovskites

“…13a). 40 Such a decrease is attributed to self-sensitized generation of superoxide and the subsequent oxidative disintegration of MAPbI3 nanocrystals (Fig. 13b).…”

“…Single-molecule micro-spectroscopy, which is widely used in the field of cadmium and lead chalcogenide QDs is helpful for obtaining insight into the properties of perovskites at the single particle level. Single particle studies reveal PL characteristics of perovskites thin films, 37 microcrystals, 38 nanocrystals [38][39][40] and QDs. 41,42 Blinking is characterized by a sequence of stochastic bright (ON) and dark (OFF) events (Fig.…”

A Biomimetic Self‐Shield Interface for Flexible Perovskite Solar Cells with Negligible Lead Leakage

“…More rational strategies need to be applied into FPSCs, on the one hand to improve their operational stability under complex environmental conditions, and on the other hand to reduce the irreversible lead leakage for damaging ecological water, soil and biological health. [ 23–25 ]…”

Blinking Mechanisms and Intrinsic Quantum‐Confined Stark Effect in Single Methylammonium Lead Bromide Perovskite Quantum Dots

“…[3][4][5][6][7][8][9][10][11][12] Despite these advantages, PL blinking occurs in perovskite QDs, compromising the performance of PL-based applications. [13][14][15] PL blinking refers to the intensity intermittency between bright (on) and dim/dark (off) states with time. [16][17][18] Non-radiative Auger recombination and surface trap-induced non-radiative recombination are the two models for explaining this phenomenon.…”