Abstract: Zero-dimensional all-inorganic Cs₃Cu₂I₅ perovskite emerges as a highly promising X-ray imaging material due to its lead-free nature, high luminescence efficiency, and unique photophysical properties originating from self-trapped excitons (STE). However, achieving the efficient, controllable synthesis and performance optimization of its nanocrystalline form remains a significant challenge. This study developed a facile one-pot synthesis strategy, aiming to fabricate Cs₃Cu₂I₅ perovskite nanocrystals with high crystallinity, high luminescence efficiency, and excellent stability by synergistically optimizing the Cs/Cu molar ratio and the concentration of the oleic acid (OA)/oleylamine (OAm) dual-ligand system. The potential of these nanocrystals as scintillators for X-ray imaging was subsequently evaluated. The Cs/Cu molar ratio of 0.67 : 1 facilitates the formation of pure-phase Cs₃Cu₂I₅ nanocrystals. A ligand concentration of 650 mmol/L promotes the effective passivation of surface defects by OA and OAm, thereby suppressing non-radiative recombination. The synthesized Cs₃Cu₂I₅ nanocrystals exhibit outstanding optical properties, including a photoluminescence quantum yield (PLQY) as high as 83%. Remarkably, they retain over 90% of initial photoluminescence intensity after 35 d of storage under ambient conditions, demonstrating superior environmental stability. The composite film constructed from Cs₃Cu₂I₅ nanocrystals and polydimethylsiloxane (PDMS) shows promising scintillation performance, with a light yield of 14019 ph/MeV, a detection limit as low as 1.3 μGyₐᵢᵣ/s. Furthermore, a spatial resolution of 12 lp/mm is achieved, enabling the acquisition of clear X-ray imaging photographs. This work provides a valuable reference for the efficient preparation and performance regulation of high-performance, lead-free perovskite nanocrystals scintillators for next-generation X-ray imaging devices.

Key words: perovskite nanocrystals, scintillator, Cs₃Cu₂I₅, luminescence intensity, stability