A Novel Substrate-Free Ultrathin Cyan-Emitting Phosphor-Glass Composite Based on Ce-Activated Ca2YAlGa2Si2O12 Microcrystal

The substrate-free ultrathin phosphor-glass composite (PGC) provides significant advantages for all-inorganic light-emitting diodes (LEDs), offering enhanced resistance to light radiation and chemical corrosion. However, achieving a PGC thickness below 100 µm remains challenging due to its brittle nature. Herein, this work presents a novel strategy to fabricate an ultrathin cyan PGC for all-inorganic LEDs, based on our home-synthesized Ce-activated Ca₂YAlGa₂Si₂O₁₂ phosphor (CYAGS:Ce). The phosphor emits bright cyan light centered at λ_em 497 nm with a FWHM of 93 nm and an internal quantum yield (IQY) greater than 60%. The luminescence mechanism, including concentration and thermal quenching, is investigated in detail. Using tape-casting and low-temperature co-firing, an ultrathin PGC with a thickness of 98 µm is achieved. Structural and luminescence properties are compared to highlight the glass matrix's influence. Furthermore, based on as-prepared ultrathin PGCs, a compact LEDs with a low correlated color temperature (CCT, 3384 K) and high color-rendering index (CRI, R_a = 85.7) is obtained by integrating both red and cyan PGCs with a commercial 420 nm blue chip. This work advances the understanding of CYAGS:Ce cyan phosphor and provides a versatile strategy for fabricating ultrathin PGCs, highlighting their potential applications in all-inorganic LED lighting.