Timing performance of lead halide perovskite nanoscintillators embedded in a polystyrene matrix

Abstract

Nanomaterials like CsPbBr₃, benefiting from quantum confinement effects to feature ultra-fast decay time and tunable emission, are paving the way for the next generation of fast timing detectors. However, an ongoing challenge is to exploit their favorable properties in a full detector, given their size and instability. Embedding halide perovskite nanocrystals in solid matrices like organic polymers can provide the required stability and, in the case of high nanoparticle filling factors with little aggregation, results in a flexible scintillator, featuring sub-ns decay times. In this work, we present the production, characterization, and – for the first time – time resolution measurements of CsPbBr₃ nanocrystals embedded in polystyrene, using two different surface ligands (OA + OAm and DDAB) and three different filling factors of up to 10%. The samples were characterized by spectroscopic methods, namely photo- and radio-luminescence as well as transmittance, while scintillation decay kinetics was measured in a time correlated single photon counting setup upon X-ray excitation. The characterization results suggest that, for both ligands, a 10% filling factor with little to no aggregation can be obtained. In addition, the time resolution of these materials was measured using a novel setup coupled to analog silicon photomultipliers and low energy pulsed X-ray excitation. When comparing with the state of the art inorganic (LYSO:Ce) crystal, more than twofold time resolution improvement was obtained, despite the lower light transport and small energy deposition. These first promising results represent the starting point for the optimization of CsPbBr₃ nanocrystals embedded in polymer matrices and their application in fast timing detectors for TOF-CT, TOF-PET and high energy physics.