Temperature-Induced Reversible Fluorescence Discoloration of Cs<sub>3</sub>Cu<sub>2</sub>Br<sub>5</sub> and Its Application in X-ray Imaging
Yuanhao Zhou, Zhicheng Wang, Guoxue Pan, Minghui Xu, Chujie Wang, Yiyang Chen, Xinxin Yang, Zhan Xu, Jing‐Tai Zhao, Qianli Li, Feng He
Abstract
As a promising new type of X-ray scintillator, lead-free metal halide materials have attracted extensive attention in recent years. Here, a blue emitter Cs 3 Cu 2 Br 5 is successfully synthesized by simply mixing CsBr aqueous solution and CuBr acid solution. Due to the self-trapped excitons emission, it has a large Stokes shift and negligible self-absorption. The light yield of Cs 3 Cu 2 Br 5 powder is calculated for the first time to be 22,000 ± 4000 photons/MeV. By using a new type of ultraviolet curable adhesive, the prepared Cs 3 Cu 2 Br 5 @UV films exhibit a high spatial resolution of 2.7 lp mm –1 in X-ray imaging, making it a promising candidate for high spatial X-ray imaging detectors. The prepared scintillator powder can change color at low temperatures (under 254 nm UV lamp), and photoluminescence emissions are 460 nm@300 K and 595 nm@240 K. The temperature-induced reversible fluorescence discoloration phenomenon of Cs 3 Cu 2 Br 5 is speculated to be due to the decrease of energy level degeneracy. Additionally, owing to the distinctive property of exhibiting noticeable color changes in response to temperature variations, Cs 3 Cu 2 Br 5 has the potential to become a thermochromic fluorescence material.