Ultra-stable CsPbBr₃ Perovskite Nanosheets for X-Ray Imaging Screen

Wet chemistry methods, including hot-injection and precipitation methods, have emerged as major synthetic routes for high-quality perovskite nanocrystals in backlit display and scintillation applications. However, low chemical yield hinders their upscale production for practical use. Meanwhile, the labile nature of halide-based perovskite poses a major challenge for long-term storage of perovskite nanocrystals. Herein, we report a green synthesis at room temperature for gram-scale production of CsPbBr₃ nanosheets with minimum use of solvent, saving over 95% of the solvent for the unity mass nanocrystal production. The perovskite colloid exhibits record stability upon long-term storage for up to 8 months, preserving a photoluminescence quantum yield of 63% in solid state. Importantly, the colloidal nanosheets show self-assembly behavior upon slow solidification, generating a crack-free thin film in a large area. The uniform film was then demonstrated as an efficient scintillation screen for X-ray imaging. Our findings bring a scalable tool for synthesis of high-quality perovskite nanocrystals, which may inspire the industrial optoelectronic application of large-area perovskite film.