Cs₃Cu₂I₅ Nanocrystals with Near-Unity Photoluminescence Quantum Yield for Stable and High-Spatial-Resolution X-ray Imaging

With almost negligible self-absorption and high photoluminescencequantum yield (PLQY), zero-electronic-dimensional Cs3Cu2I5 emerges as an excellent scintillator. Ball-millingis a desired method to prepare Cs3Cu2I5 scintillators at a large scale; however, the defects generated duringball-milling and large particle size hinder its scintillation properties.Theoretical analysis suggests that utilizing a molecule with a smallsurface energy and a passivation group during ball-milling could bea two-birds-with-one-stone strategy, which can simultaneously improvethe PLQY of particles by defect passivation and decrease the particlesize by minimizing the surface energy of particles and inhibitingparticle rewelding. Accordingly, we successfully prepared Cs3Cu2I5 nanoparticles with a near-unity PLQYand smaller size using a passivator (nonaethylene glycol monododecylether, C12E9)-assisted ball-milling method.The interaction of C12E9 with Cs3Cu2I5 has been verified and could enhance theluminescence performance of Cs3Cu2I5. Further, the Cs3Cu2I5 nanoparticlecoating delivered a spatial resolution of 17.5 lp mm(-1)@MTF = 0.2 in X-ray imaging and excellent stability under prolongedX-ray irradiation with total dose of 10.9 Gy(air), equalto the dose of 108,000 medical chest X-ray inspections. These resultssuggest that this in situ passivator-assisted ball-milling methodis effective for large-scale production of high-quality Cs3Cu2I5 nanoparticles with excellent scintillationperformance.