Oxygen vacancy‐induced cerium self‐reduction in cyan‐emitting phosphors for high‐quality white lighting and visible light communication applications

Abstract Self‐reducing phosphors have attracted significant attention due to their avoidance of hazardous gases (H 2 /CO/N 2 ), offering safer and more economical alternatives. This work reveals oxygen vacancy defect‐induced Ce 3+ self‐reduction behavior in garnet structure. The Ca 2 Gd 1− x Zr 2 Al 3 O 12 :Ce 3+ cyan phosphors were successfully synthesized via conventional high‐temperature solid‐state reaction in ambient atmosphere. Photoluminescence (PL) spectra revealed a strong emission centered at 490 nm, aligning well with the cyan component required in WLEDs. The relatively short fluorescence lifetime further implies the potential of CGZA:Ce 3+/4+ phosphors for high‐speed visible light communication (VLC). By combining electron paramagnetic resonance (EPR) spectroscopy with density functional theory (DFT) calculations, the self‐reduction behavior of Ce 4+ to Ce 3+ in the garnet structure was elucidated. The results suggest that oxygen vacancies play a critical role in facilitating the reduction process. DFT calculations revealed that Ce doping significantly lowers the formation energy of oxygen vacancies, thereby promoting self‐reduction. These findings provide valuable insights into the design of novel self‐reducing Ce 3+ ‐based phosphors for advanced lighting and optical communication applications.