Kavli Affiliate: Paul Alivisatos
| First 5 Authors: Abdullah S. Abbas, Daniel Chabeda, Daniel Weinberg, David T. Limmer, Eran Rabani
| Summary:
Lead-halide perovskite nanocrystals have recently emerged as desirable
optical materials for applications such as coherent quantum light emitters and
solid-state laser cooling due to their short radiative lifetime and near-unity
photoluminescence quantum yield. Here, we investigate the effect of CsPbBr3
nanocrystal size on the radiative lifetime under ambient conditions.
High-quality nanocrystals, with monoexponential time-resolved photoluminescence
decay behaviors, unveil a non-monotonic trend in radiative lifetime. This
non-monotonicity appears to reflect a behavior common among II-VI (CdSe) and
perovskites semiconducting nanocrystals. We find that large nanocrystals in the
weak quantum confinement regime exhibit long radiative lifetimes due to a
thermally accessible population of dim states. Small nanocrystals within the
strong quantum confinement regime, surprisingly, also show long radiative
lifetimes, due however to a substantial reduction in oscillator strength.
Nanocrystals in the intermediate quantum confinement regime displays the
shortest radiative lifetime, as their oscillator strength is enhanced relative
to particles in the strong confinement regime, but do not have sufficient
low-lying dim states like the large particles to counteract this affect. These
findings shed light on the impact of nanocrystal size on radiative lifetime and
pave the way for tailored optical materials in various optical applications.
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