We have investigated the performance of formamidinium lead bromide (FAPbBr${}_3$) perovskite X-ray detectors fabricated from polycrystalline material that is pressed into a pellet at high pressures. FAPbBr${}_3$ has been shown to exhibit a remarkable combination of electrical and physical properties, such that mechanically-formed polycrystalline pellets exhibit good charge transport properties suitable for use as X-ray detectors. We characterise the morphology and structure of FAPbBr${}_3$ pellets using photoluminescence (PL), electron microscopy (SEM) and X-ray diffraction (XRD), and demonstrate an improvement in the microstructure, density, and charge transport performance of the material as the pressure is increased from 12 MPa to 124 MPa. The use of annealing of the pellets after pressing also improves the stability and charge transport performance of the devices. Using a 40 kV X-ray beam, a maximum X-ray sensitivity of 169 µC Gy${}^{-1}$ cm${}^{-2}$ was measured, and the fast time response of the devices was demonstrated using a chopped X-ray beam.

This article details work performed on the synthesis and characterization of an inorganic mixed‐cation double halide perovskite, Cs₂Ag_.6Na_.4In_.85Bi_.15Cl₆ (CANIBIC). Single crystals have been created via a hydrothermal reaction, milled into a powder, and pressed into pellets, while nanocrystals have been directly synthesized via mechanosynthesis. A computational model is constructed to predict the X‐ray diffraction pattern of CANIBIC; this model aligns very well with the X‐ray diffraction pattern measured for CANIBIC crystal powder. This model can therefore be developed in the future as a tool to predict lattice parameters and crystal structures of other novel double‐halide perovskites. Photoluminescence spectra obtained from each format show broad emission centered at 630 nm, as is typical for self‐trapped exciton emission; self‐trapped exciton emission is also confirmed by investigating photoluminescence intensity as a function of laser power. Nanocomposites are produced via the loading of nanocrystals of CANIBIC into PMMA. Although nanocomposite disks consisting of a small proportion of CANIBIC nanocrystals in PMMA have a smaller mass attenuation coefficient than a pressed pellet of CANIBIC, these disks have comparatively bright radioluminescence due to their optical transparency. These nanocomposite disks are therefore a particularly useful format for the practical use of the CANIBIC scintillator.

The material family halide perovskites has been critical in recent room-temperature radiation detection semiconductor research. Cesium lead bromide (CsPbBr₃) is a halide perovskite that exhibits characteristics of a semiconductor that would be suitable for applications in various fields. In this paper, we report on the correlations between material purification and crystal material properties. Crystal boules of CsPbX₃ (where X = Cl, Br, I, or mixed) were grown with the Bridgman growth method. We describe in great detail the fabrication techniques used to prepare sample surfaces for contact deposition and sample testing. Current–voltage measurements, UV–Vis and photocurrent spectroscopy, as well as photoluminescence measurements, were carried out for material characterization. Bulk resistivity values of up to 3.0 × 10⁹ Ω∙cm and surface resistivity values of 1.3 × 10¹¹ Ω/□ indicate that the material can be used for low-noise semiconductor detector applications. Preliminary radiation detectors were fabricated, and using photocurrent measurements we have estimated a value of the mobility–lifetime product for holes (μτ)_h of 2.8 × 10⁻⁵ cm²/V. The results from the sample testing can shed light on ways to improve the crystal properties for future work, not only for CsPbX₃ but also other halide perovskites.