Size‐Dependent Multiexciton Dynamics Governs Scintillation From Perovskite Quantum Dots

Abstract The recent emergence of quantum‐confined nanomaterials in the field of radiation detection, in particular lead halide perovskite nanocrystals, offers 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 optimization of future nanotechnology scintillators. In this work, these open questions are addressed by theoretically and experimentally studying the size‐dependent scintillation of CsPbBr 3 nanocrystals using a combination of Monte Carlo simulations, spectroscopic, and radiometric techniques. The results show that 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 agreement between theory and experiment produces a fully validated descriptive model that predicts the scintillation yield and kinetics of nanocrystals without free parameters, providing fundamental guidance for the rational design of nanoscale scintillators.