The commercial implementation of lead halide perovskite in optoelectronic applications, particularly in X-ray imaging and radiation detection, has been significantly hindered by their toxicity, instability, and strong self-absorption [1,2]. In this study, we explore lead-free copper iodide perovskite as environmentally friendly, earth-abundant, and cost-effective alternative materials for scintillator-based radiation detection. Among all the phases of cesium copper iodide compound, CsCu₂I₃ (1-D structure) and Cs₃Cu₂I₅ (0-D structure) are the two stable phases that exhibit broadband yellow and blue emission, respectively [3]. These materials possess promising optoelectronic properties, including high stability and bright emission, which are essential for scintillator. Their large Stokes shift enables low reabsorption losses, which is critical for achieving high scintillation efficiency [2,4].

In this study, we present a comparative study of CsCu₂I₃ and Cs₃Cu₂I₅ nanocrystals (NCs) synthesized via a mechanochemical ball milling method. These NCs are expected to enhance the scintillation performance properties compared to those observed in previous studies. This approach offers a simple, cost-effective, and scalable method that is suitable for large-scale production. Previous studies have reported that the light yield of CsCu₂I₃ and Cs₃Cu₂I₅ NCs synthesised via mechanochemical using mortar is 12.54 ph/keV and 16.5 ph/keV, respectively, with decay time of 125 ns and 841 ns [1]. Furthermore, CsCu₂I₃ nanocrystals (NCs) embedded in polymer resin using the same fabrication approach exhibit a light yield of 9.4 ph/keV at 180 K and approximately 2 ph/keV at room temperature [2]. However, this reduced light yield is primarily attributed to Fresnel losses introduced by the polymer matrix [2]. In comparison, CsCu₂I₃ single crystals synthesized via the antisolvent vapor crystallization method show significantly better performance, delivering a light yield of 26.5 ph/keV, an average decay time of 93 ns, and an energy resolution of 8.5%, indicating that single crystals still provide superior light yield, albeit with slower response times. Interestingly, depositing NCs on the surface of these single crystals leads to lower light yield but faster decay times, including a notable sub-nanosecond component [5]. Further optimization of the scintillation properties of such hybrid NC–crystal systems will be explored in future work.

From the NC perspectives, these results highlight the strong potential of copper iodide perovskite NCs for use in scintillator-based radiation detection systems and provide a benchmark for evaluating the performance of the mechanochemically method with further optimization.