CsPbBr₃ and Cs₂AgBiBr₆ Composite Thick Films with Potential Photodetector Applications

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.