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This paper investigates the optoelectronic properties of CsPbBr3, a lead-based perovskite, and Cs2AgBiBr6, a lead-free double perovskite, in composite thick films synthesized using mechanochemical and hot press methods, with poly(butyl methacrylate) as the matrix. Comprehensive characterization was conducted, including X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV–visible spectroscopy (UV–Vis), and photoluminescence (PL). Results indicate that the polymer matrix does not significantly impact the crystalline structure of the perovskites but has a direct impact on the grain size and surface area, enhancing the interfacial charge transfer of the composites. Optical characterization indicates minimal changes in bandgap energies across all different phases, with CsPbBr3 exhibiting higher photocurrent than Cs2AgBiBr6. This is attributed to the CsPbBr3 superior charge carrier mobility. Both composites showed photoconductive behavior, with Cs2AgBiBr6 also demonstrating higher-energy (X-ray) photon detection. These findings highlight the potential of both materials for advanced photodetector applications, with Cs2AgBiBr6 offering an environmentally Pb-free alternative. 

Abstract A combination of novel techniques such as a solvent‐free thin‐film deposition, perovskite patterning, and¹⁰B back‐fill technique enables the high neutron detection efficiency in a perovskite‐based microstructured thermal neutron detector. High‐efficiency cesium lead bromide (CsPbBr₃) perovskite‐based microstructured detectors are demonstrated here. Trenches up to 10 µm deep are etched into the CsPbBr₃thin films using a novel dry etching process involving a combination of HBr and Ar plasma. The microstructured diodes are then backfilled with isotopically enriched boron as neutron conversion material via a sedimentation process to preserve the perovskite integrity. The fabricated microstructured CsPbBr₃thermal neutron detectors show an efficiency of 4.3%. This represents >1.2x efficiency improvement over planar silicon (3.5%) and >2x efficiency improvement over planar CsPbBr₃(2.1%) detectors, respectively. More importantly, gamma‐ray discrimination of 10⁷is measured in CsPbBr₃‐based microstructured neutron detectors.