Isothermal Near-Room-Temperature Growth of Mechanically Robust Cs3Cu2I5 Single Crystals for Gamma-Ray Detection and X-Ray Imaging

Cs 3 Cu 2 I 5 is a lead-free, zero-dimensional inorganic perovskite noted for its low toxicity, excellent stability, and outstanding optical properties, making it a promising scintillator. Large Cs 3 Cu 2 I 5 single crystals are attainable by solution- or melt cooling; however, thermal stress associated with temperature changes often degrades processing yield and crystal quality. Here, we report the growth of large Cs 3 Cu 2 I 5 single crystals (≈3 cm) using a settled temperature and controlled antisolvent diffusion method. The isothermal near-room-temperature growth condition eliminates thermal stress and improves mechanical robustness. The as-grown crystals are readily machined into wafers with high structural integrity, evidenced by a narrow rocking curve FWHM of 20.6″. Cs 3 Cu 2 I 5 single-crystal wafers used for γ-ray detection to multiple sources ( 1 3 7 Cs, 2 4 1 Am, 6 0 Co, and 2 2 Na) exhibit outstanding scintillation performance, including a high light yield of 67 500 ph/MeV and an energy resolution of 4.4% ( 1 3 7 Cs). Furthermore, Cs 3 Cu 2 I 5 crystal wafers were utilized as an x-ray imaging screen, achieving a spatial resolution of 19.3 lp/mm at an MTF of 0.2. The developed technique promotes Cs 3 Cu 2 I 5 crystals toward ready-for-use applications.