Crystal Growth Behaviors of Cs 3 Cu 2 I 5 During Melt Growth Processes and Inch-Sized Scintillation Performance

The Cs3Cu2I5-based single crystals with efficient exciton localization emissions have recently emerged as promising scintillators due to nonhygroscopicity, self-absorption-free nature, and high scintillation yield. Nonetheless, their intrinsic physical properties of incongruent melting and low thermal conductivity hinder the growth of high-quality, inch-sized single crystals. In this work, the crystal growth behaviors of Cs3Cu2I5 during melt growth processes are comprehensively studied, and optimized Bridgman growth procedures are developed to obtain inch-sized single crystals. The compositional precipitation during growth is revealed, such as the formation of CsI inclusions caused by the peritectic reaction. The low thermal conductivity, large thermal expansion, and brittleness combine to form a low resistance to mechanical and thermal shock, which results in a tendency to crack during growth, cooling, and processing. By optimizing the Bridgman growth parameters, Tl-doped Cs3Cu2I5 single crystals with a size of 40 mm × 35 mm × 5 mm can be obtained. These crystals exhibit a high light yield of 90,000 ± 3,000 photons/MeV and a decent energy resolution of 4.0 ± 0.2% at 662 keV. This work establishes a pathway for the scalable growth of high-performance Cs3Cu2I5-based single crystals for various radiation detection applications.