Nonstoichiometry Promoted Solventless Recrystallization of a Thick and Compact CsPbBr Film for Real-Time Dynamic X-Ray Imaging.

Inorganic CsPbBr 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 CsPbBr 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 PbBr within the CsPbBr film, which induces melting point depression and promotes recrystallization of CsPbBr at a temperature much lower than its melting point concomitant with the escape of PbBr. Consequently, thick and compact films of CsPbBr 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 × 10 µC Gy cm and a low detection limit of 136 nGy s, along with exceptional operational stability. Notably, the CsPbBr-based flat-panel detector achieves a high resolution of 0.65 lp pix and the first demonstration of real-time dynamic X-ray imaging for perovskite-based devices.