A highly efficient Na-doped Cs₃Cu₂I₅ scintillator for γ-ray detection and flexible X-ray imaging

As a novel lead-free perovskite derivative material, zero-dimensional Cs₃Cu₂I₅ crystals exhibit remarkable optical properties and hold great application prospects in the field of radiation detection. To further enhance the scintillation performance and detection efficiency, we fabricated high-quality, centimeter-level Cs₃Cu₂I₅:Na⁺ single crystals using a low-cost anti-solvent method. Na⁺ doping in the Cs₃Cu₂I₅ lattice optimizes the photoluminescence quantum yield (PLQY) to 95%, which can be attributed to enhanced exciton-phonon coupling and boosted self-trapped exciton fraction. Compared to the intrinsic crystal, the energy resolution and light yield of Cs₃Cu₂I₅:5%Na⁺ under ¹³⁷Cs γ-rays are improved by 22% and 10.5%, respectively. Under X-ray excitation, Cs₃Cu₂I₅:5%Na⁺ crystals exhibit stronger RL intensity, faster response speed, lower afterglow and lower detection limit. Based on excellent X-ray detection capability, a breakthrough spatial resolution of 25.6 LP per mm@MTF = 0.2 is achieved for the Cs₃Cu₂I₅:5%Na⁺@PMMA flexible film. Cs₃Cu₂I₅:Na⁺ crystals boast superior optical performance, exceptional detection capabilities, cost-effectiveness and eco-friendliness, rendering them a highly competitive candidate for high-resolution γ-ray detection and flexible X-ray imaging.