Nonstoichiometry Promoted Solventless Recrystallization of a Thick and Compact CsPbBr₃ Film for Real-Time Dynamic...

Inorganic CsPbBr₃ perovskite emerges as a promising material for the development of next-generation X-ray detectors. However, the formation of a high-quality thick film of CsPbBr₃ has been challenging due to the low solubility of its precursor and its high melting point. To address this limitation, a nonstoichiometry approach is taken that allows lower-temperature crystallization of the target perovskite under the solventless condition. This approach capitalizes on the presence of excess volatile PbBr₂ within the CsPbBr₃ film, which induces melting point depression and promotes recrystallization of CsPbBr₃ at a temperature much lower than its melting point concomitant with the escape of PbBr₂. Consequently, thick and compact films of CsPbBr₃ are formed with grains ten times larger than those in the pristine films. The resulting X-ray detector exhibits a remarkable sensitivity of 4.2 × 10⁴ µC Gy_air ^-1 cm^-2 and a low detection limit of 136 nGy_air s^-1, along with exceptional operational stability. Notably, the CsPbBr₃-based flat-panel detector achieves a high resolution of 0.65 lp pix^-1 and the first demonstration of real-time dynamic X-ray imaging for perovskite-based devices.