Unraveling the Defect-Related Luminescence in a Eu²⁺-Doped Chlorosilicate Phosphor

Defects play non-negligible roles in many luminescent processes, where the significant and remarkable influence in the phosphor performance in various ways is observed. A full and clear perception of defects would be beneficial for the further development of the luminescence mechanism and design of phosphors. In this study, the defect-related luminescence in a chlorosilicate phosphor Ca₂SiO₃Cl₂: Eu²⁺ was deeply studied. Except for the green emission originating from the d-f transition of the Eu²⁺ ion, a blue emission band with unique sensitivity to temperature and excitation energy was confirmed to be induced by the defects. The defects related to anion vacancies in the material acted as electron traps and luminescence centers simultaneously, which were well-identified by luminescence spectra and theory calculation analysis. This study uncovered the peculiar behavior and action mechanism of defects in the luminescence process and demonstrates a new path to understanding the origin of the luminescence center.