Facet Dependent Photoluminescence Blinking from Perovskite Nanocrystals

Abstract

Photoluminescence (PL) blinking of nanoparticles, while detrimental to their imaging applications, may benefit next‐generation displays if the blinking is precisely controlled by reversible electron/hole injections from an external source. Considerable efforts are made to create well‐characterized charged excitons within nanoparticles through electrochemical charging, which has led to enhanced control over PL‐blinking in numerous instances. Manipulating the photocharging/discharging rates in nanoparticles by surface engineering can represent a straightforward method for regulating their blinking behaviors, an area largely unexplored for perovskite nanocrystals (PNCs). This work shows facet engineering leading to different morphologies of PNCs characterized by distinct blinking patterns. For instance, examining the PL intensity trajectories of single PNCs, representing the instantaneous photon count rate over time, reveals that the OFF‐state population significantly increases as the number of facets increases from six to twenty‐six. This study suggests that extra‐faceted PNCs, owing to their polar facets and expanded surface area, render them more susceptible to photocharging, which results in larger OFF‐state populations. Furthermore, the fluorescence correlation spectroscopy (FCS) study unveils that the augmented propensity for photocharging in extra‐faceted PNCs can also originate from their greater tendency to form complexes with neighboring molecules.