Temperature engineering for sensitively electrostatic spray-coated CsPbBr₃ direct X-ray detector with low detection limit

Direct X-ray detectors can directly register the energies of X-ray interactions, enabling charge-integrating systems with higher sensitivity and superior spatial and/or energy resolution compared with traditional indirect, scintillator-based X-ray detectors. However, technical challenges in depositing thick films have limited the fabrication of perovskite semiconductors for direct X-ray detection. Here, we report a temperature-engineering strategy for electrostatic-spray (E-spray) coating of CsPbBr₃ to realize direct X-ray detectors. High-quality ∼40-µm-thick CsPbBr₃ films with enhanced surface uniformity and crystallinity are achieved by controlling the substrate temperature during deposition and annealing. The underlying principle-improving thick-film quality via substrate-temperature control-is clarified. The X-ray sensitivity of the CsPbBr₃ detector is as high as 7486.5 µC Gy_air⁻¹ cm⁻², and the detection limit is 0.165 µGy s⁻¹. This work provides practical insights into crystallization-control strategies and paves the way for future advancements in CsPbBr₃-based X-ray detector technologies.