Engineering Large-Grain Metal Halide Perovskite Films via Chemical Vapor Deposition for High-Performance,...

Metal halide perovskites have emerged as promising semiconductors for high-performance photodetectors and X-ray sensors due to their high-Z composition, excellent charge transport, and intrinsic defect tolerance. However, scalable fabrication of thick, pinhole-free films with controlled crystallinity and long-term stability remains challenging, limiting their device performance. Here, we demonstrate the chemical vapor deposition of large-grain, phase-pure CsPbBr₃ films with thicknesses of ∼3 µm and grain sizes up to 35 µm, an order of magnitude larger than those obtained by conventional spin coating. By optimizing deposition parameters and substrate selection, we achieve smooth, uniform films with prolonged carrier decay times and enhanced charge transport, as evidenced by time-resolved photoluminescence and Drude-like behavior in terahertz photoconductivity measurements. Photodetectors based on these films exhibit ultralow dark currents (<1 pA cm^{- 2} at 0 V), high switching ratios (∼10⁴), responsivities up to 0.176 A W^{- 1}, and detectivities of 8.4 × 10^{1 2} Jones, while maintaining exceptional operational and ambient stability over one year. X-ray sensitivity measurements further confirm the potential of these devices for low-dose detection applications. This work establishes CVD as a reproducible, solvent-free route to high-quality halide perovskite films, providing a clear pathway to next-generation photodetectors and X-ray sensors with superior performance and long-term stability.