Strain-Released Cs₅Cu₃Cl₆I₂ Scintillators by Rb⁺ Doping for High-Resolution X-Ray Imaging

Scintillators with high light yield play a crucial role in medical diagnosis, security inspection, and nondestructive testing. Lead-free copper-based scintillators have recently gained attention for their remarkable luminescence efficiency, stability, and cost-effectiveness. However, their practical application in X-ray detectors is hindered by performance limitations and stability issues. In this study, we propose a strategy of metal ion doping to alleviate lattice strain in the Cs5Cu3Cl6I2 scintillator. The incorporation of Rb+ into the scintillator, termed Cs5Cu3Cl6I2:Rb, resulted in outstanding light yield (LY), ultrahigh photoluminescence quantum yield (PLQY), and excellent luminescent stability against heat, humidity, and continuous X-ray irradiation. Additionally, Cs5Cu3Cl6I2:Rb was in situ integrated with a complementary metal oxide semiconductor (CMOS) using blade coating after mixing with polydimethylsiloxane (PDMS). Consequently, the Cs5Cu3Cl6I2:Rb imaging device achieved a high spatial resolution over 10 line-pairs per millimeter, clearly revealing the internal details of objects. This outcome positions Cs5Cu3Cl6I2:Rb as a promising candidate for high-resolution X-ray imaging. The study underscores the significance of strain regulation in enhancing scintillation properties and introduces an effective doping strategy to realize superior scintillators for high-resolution X-ray imaging devices.