Progress in Solution Growth of Cuboid CsPbBr ₃ Single Crystals with Low Defect Densities and High-Sensitivity X-ray Detection

CsPbBr3 single crystals were used for room-temperature radiation detection. By incorporating tetramethylammonium bromide as a growth additive, we obtained large cm-sized, cuboid-shaped crystals with high yield and improved morphological control. This method offers a scalable and reproducible alternative to melt-based growth techniques. Comprehensive optical studies revealed sharp near-band-edge photoluminescence (PL) with distinct excitonic features, indicating low disorder and favorable radiative recombination dynamics. Power- and temperature-dependent PL measurements confirmed the presence of free and bound excitons, while time-resolved PL (TR-PL) showed biexponential decay behavior consistent with excitonic emission and defect-assisted recombination. The extracted average PL lifetimes ranged from ∼600 to over 1000 ns, depending on temperature and excitation conditions. Electron-phonon coupling effects were evident and indicative of polaron formation, impacting carrier transport. Thermally stimulated current (TSC) spectroscopy identified a distribution of deep and shallow traps, primarily associated with lead interstitials and halide or cation vacancies. Samples grown under optimized conditions exhibited reduced trap densities, demonstrating that defect concentrations can be effectively minimized through appropriate growth strategies. X-ray testing revealed that the best-performing solution-grown CsPbBr3 crystals achieve high saturation sensitivity (∼7250 μC Gy–1 cm–2) with a low dark current and reasonable bias requirements. Although μτ values remain lower than those of Bridgman-grown analogs, the detection performance is sufficient for practical applications. This work shows a direct connection between crystal growth conditions, defect landscape, excitonic behavior, and detector performance.