One-Dimensional Copper-Doped Rb₂AgI₃ with Efficient Sky-Blue Emission as a High-Performance X-ray Scintillator

Scintillators have garnered heightened attention for their diverse applications in medical imaging and security inspection. Nonetheless, commercial scintillators encounter challenges with costly rare-earth metals and toxic elements like thallium (Tl), driving the need for sustainable, cost-effective, and eco-friendly alternatives to meet contemporary X-ray detection demands. This study focuses on exploring the potential of Cu⁺-doped Rb₂AgI₃ as an effective metal halide (MH) scintillator. One-dimensional (1D) Rb₂AgI₃ and Cu⁺-doped Rb₂AgI₃ single crystals (SCs) were synthesized by using the conventional temperature-lowering crystallization method. When excited by UV light, Cu⁺-doped SCs emitted a broad sky-blue light at 490 nm with a high photoluminescence (PL) quantum yield (PLQY) of 76.48%. Remarkably, under X-ray excitation, these Cu⁺-doped SCs demonstrated an outstanding light yield of 36,293 photons MeV^-1, a relatively low detection threshold of 1.022 μGy_air s^-1, and a rapid scintillation decay time of 465 ns. The prepared translucent scintillation film has good uniformity and flexibility, with a high spatial resolution of 10.2 lp mm^-1. These results position Cu⁺-doped Rb₂AgI₃ as a leading candidate among promising X-ray scintillators, offering superior scintillation light yield, excellent stability, and nontoxicity.