Mixed-Cation Perovskite Scintillators for X-Ray Detection
Creators: name: O'Neill, Joseph Gerard
Publisher: name: University of Surrey
Year: 2023

description: Scintillation detectors play a crucial role in various scientific and medical applications and are being explored for applications as beamline monitors of synchrotrons. Traditional X-ray detectors predominantly rely on either high-resolution inorganic scintillating materials such as NaI or fast-response organic materials such as stilbene. Scintillator development focuses on finding materials which balance X-ray conversion efficiency, time response, production cost and toxicity. This thesis covers the work performed exploring mixed-cation perovskite scintillators as promising alternatives for X-ray detection. <br>
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description: CsPbX 3 and Cs-based mixed-cation perovskites were chosen as the materials to investigate. The effect of varying the perovskites’ cation and halide composition, size, and synthesis route on their scintillation performance was explored. A comprehensive study of their structural and optical properties using techniques including X-ray diffraction, photoluminescence and radioluminescence spectroscopy, and time-resolved scintillation measurements. Of particular interest was the impact that quantum confinement effects had on the scintillators as the crystals’ radii approached their Bohr exciton radius.<br>
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description: Following these initial characterisations, prototype nanocomposite scintillators incorporating the CsPbX 3 perovskites were produced, and the light output and time response was characterised for a range of mass loadings and nanocrystal sizes. The effect of loading these nanocrystals into a transparent material is discussed in terms of optical transmission and light yield as a function of the halide composition of the perovskite. The results obtained from two commercial vendors of perovskite nanocrystals were compared, and the optimisation carried out to improve the consistency of the particle size and its effect on the light output and X-ray sensitivity is discussed.<br>
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description: Building on this work, the Cs-based mixed cation perovskites were further investigated. Single crystals were grown via a hydrothermal reaction, milled into a powder and pressed into pellets, while nanocrystals were directly synthesised via mechanosynthesis. The optimisation of the two synthesis methods and the standard sample fabrication processes are discussed, alongside modelling the complex double perovskite structure. The structural and scintillation properties of the different forms of perovskite are compared, with the nanocomposite disks proving to have the highest X-ray sensitivity relative to active mass loading. <br>
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description: The findings of this research contribute to the development of efficient and cost-effective X-ray detection materials for beamline monitors and beyond. The unique properties of mixed-cation perovskites, such as high light yield, tunable bandgap, and ease of synthesis, make them promising candidates for future X-ray detection applications. The insights gained from this work provide a foundation for further optimisation and exploration of mixed-cation perovskite scintillators, opening new avenues for advanced X-ray imaging and detection technologies.<br>