Size-dependent multiexciton dynamics governs scintillation from perovskite quantum dots

TL;DR

This study combines theoretical and experimental approaches to understand how the size of perovskite quantum dots influences their scintillation properties, revealing key mechanisms that optimize their performance for radiation detection.

Contribution

It provides the first validated model predicting size-dependent scintillation yield and kinetics in perovskite nanocrystals, guiding future nanoscintillator design.

Findings

Larger nanocrystals exhibit higher scintillation efficiency due to increased stopping power.

Size-dependent exciton dynamics significantly influence light emission under ionizing radiation.

The model accurately predicts scintillation behavior without free parameters.

Abstract

The recent emergence of quantum confined nanomaterials in the field of radiation detection, in particular lead halide perovskite nanocrystals, offers potentially revolutionary scalability and performance advantages over conventional materials. This development raises fundamental questions about the mechanism of scintillation itself at the nanoscale and the role of particle size, arguably the most defining parameter of quantum dots. Understanding this is crucial for the design and optimisation of future nanotechnology scintillators. In this work, we address these open questions by theoretically and experimentally studying the size-dependent scintillation of CsPbBr3 nanocrystals using a combination of Monte Carlo simulations, spectroscopic, and radiometric techniques. The results reveal and unravel a complex parametric space where the fine balance between the simultaneous effects of size-dependent energy deposition, (multi-)exciton population, and light emission under ionizing excitation, typical of confined particles, combine to maximize the scintillation efficiency and time performance of larger nanocrystals due to greater stopping power and reduced Auger decay. The remarkable agreement between theory and experiment produces a fully validated descriptive model that unprecedentedly predicts the scintillation yield and kinetics of nanocrystals without free parameters, providing the first fundamental guide for the rational design of nanoscale scintillators.