Zn (II)-doped cesium copper halide nanocrystals with high quantum yield and colloidal stability for high-resolution X-ray imaging

Abstract

Scintillators are essential for high-energy radiation detection in a variety of potential applications. However, due to complex fabrication processes and nanocrystal homogeneity, conventional scintillators are challenging to meet the need for cost-effective, environmentally friendly, and flexible X-ray detection. Here, monodisperse nanocrystals (NCs) with small grain size and colloidal stability are obtained by adjusting the doping concentration of Zn2+ ions and controlling the morphology uniformity of Cs3Cu2I5 NCs. The photoluminescence quantum yield (PLQY) for the optimal doping concentration is as high as 92.8%, which is a 28.5% improvement compared to nondoped NCs. Density functional theory calculations reveal that the Zn2+ dopant inclines to occupy Cu sites and the I-rich condition suppresses the formation of I vacancy, enriching the excited electron density at the band-edge to enhance the self-trapped exciton emission. Moreover, high luminescence performance and flexible X-ray scintillator films are prepared using Zn2+-doped Cs3Cu2I5 NCs, with a spatial resolution of up to 15.7 lp mm–1. This work provides an effective strategy for the development of environmentally friendly, low-cost, and efficient blue-emitting 0D all-inorganic metal halides, as well as shows their great potential for high-performance flexible lead-free and low-toxicity X-ray detector applications.