Unraveling the Origin of the Long Fluorescence Decay Component of Cesium Lead Halide Perovskite Nanocrystals

• DOI: 10.1021/acsnano.0c04401
• Publication Date: 2020-11-11T14:55:11Z
• Authors: Michael A. Becker; Caterina Bernasconi; Maryna I. Bodnarchuk; Gabriele Rainò; Maksym V. Kovalenko; David J. Norris; Rainer F. Mahrt; Thilo Stöferle
• Keywords: Trion; Biexciton

A common signature of nearly all nanoscale emitters is fluorescence intermittency, which a rapid switching between "on"-states exhibiting high photon emission rate and "off"-states with much lower rate. One consequence intermittency occurring on time scales longer than the exciton decay so-called delayed emission, manifested by long radiative component. Besides their dominant fast decay, fully inorganic cesium lead halide perovskite quantum dots exhibit component at cryogenic temperatures that often attributed to dark exciton. Here, we show its origin investigating temporal variations in intensity concomitant times found single CsPbBr3 dots. We attribute different levels trace high-intensity state an Auger-reduced low-intensity trion occurs when excitation sufficiently strong. Surprisingly, observe exponent this power-law-dependent correlated intensity, cannot be explained existing charge carrier trapping models. Our analysis reveals mainly governed present both state. The absence fine structure trions clarifies vanishing role for findings are essential development complete photophysical model captures observed features colloidal nanocrystals.