High‐Efficiency Cyan–Green‐Emitting Y₃Sc₂Ga₃O₁₂:Ce Phosphor for Microcrystals and Ultrathin Phosphor‐Glass Composite for Light‐Emitting Diode

Abstract Developing efficient cyan‐green phosphors and ultrathin phosphor‐glass composites (PGCs) with remarkable chemical and thermal stability is important for fabricating full‐visible‐spectrum white light‐emitting diodes (LEDs). In this study, a garnet‐structured cyan‐green phosphor, known as Y₃Sc₂Ga₃O₁₂:Ce (YSGG:Ce), is synthesized, exhibiting an intense excitation peak at 420 nm and broad‐emission band centered at 507 nm. Theoretical analysis indicates that a phonon with a characteristic energy of 90 meV is predominantly involved in the luminescence process. However, the phosphor powder exhibits a notable thermal quenching phenomenon for temperatures higher than 220 K. Ultrathin PGCs with the thickness of 37 µm are manufactured to achieve good thermal stability. Three types of composites are subsequently integrated onto 412 nm blue chips to prepare LED devices. The resulting device has a low correlated color temperature of 2925 K and impressive color‐rendering index of 93.5, and its precise chromaticity coordinates aligned with the black‐body locus. Therefore, this study highlights the promising applications of high‐efficiency PGCs in high‐quality LEDs.