Ternary copper halide (TCH) semiconductors are a fast-growing class of materials derived from metal-halide perovskites. Compared to their lead-based predecessors, TCH pseudo-perovskites consist of earth-abundant elements, are less toxic, and exhibit excellent stability under ambient conditions. Their altered elemental composition results in distinct photophysical changes, where self-trapped excitonic emission dominates the recombination pathway. As a consequence, these materials exhibit a large Stokes shift, high photoluminescence quantum yield, and negligible self-absorption, making them attractive for optoelectronic applications such as photodetectors, LEDs, X-ray detectors, and ionizing radiation detectors.

Within this material class, compositions range from purely inorganic systems (e.g., Cs₃Cu₂X₅, X = Br, I) to hybrid organic–inorganic compounds (e.g., (Gua)₃Cu₂I₅, where Gua = guanidinium cation). This compositional diversity, combined with tunable electronic structure, band gap, and spectral properties, gives rise to a continuously evolving material platform. Importantly, these variations also influence scintillation behaviour, offering a flexible framework for optimization. Therefore, understanding the relationship between composition, structure, and emission is essential for the development of high-performance TCH-based devices. For this reason, comparing these two subclasses within the material family can highlight fundamental differences and trade-offs in scintillation performance.

To translate these properties into practical applications, various synthesis strategies enable the realization of TCH materials in multiple forms, including single crystals, nanocrystals, and polycrystalline thin films. In this context, the development of scalable fabrication routes using low-toxicity solvent systems represents a key step toward the realization of stable and cost-effective optoelectronic devices.

In this presentation, a variety of TCH-based scintillator thin films will be showcased, prepared via a highly scalable synthesis approach. The focus will be on their structural properties, photoluminescent response, and scintillation performance. Our investigations include the determination of crystal structure, elemental composition, photoluminescence characteristics, quantum yields, and the radioluminescent light yield under alpha-particle irradiation. Finally, we highlight the potential of compositional tuning as a tool for optimization, as well as the fundamental differences between fully inorganic and hybrid materials.