Luminescence properties of GAGG: 0.06Ce3+, xMn2+, xSi4+ phosphors and their application in white LEDs

Abstract

We synthesized a series of Ce³⁺ and Mn²⁺ co-doped Gd₃Al₄GaO₁₂(GAGG): 0.06Ce³⁺, xMn²⁺, xSi⁴⁺ (x = 0, 0.05, 0.1, 0.15, 0.2, 0.3) garnet phosphor samples using a high-temperature solid-state reaction method, where Si⁴⁺ ions were co-doped to serve as charge compensators. The emission spectrum of Mn²⁺ in these phosphors exhibits two bands around 595 nm and 702 nm, likely due to Mn²⁺ ions occupying the dodecahedral and octahedral coordination sites within the GAGG matrix. Increasing the concentration (x) of Mn²⁺ in the GAGG: 0.06Ce³⁺, xMn²⁺, xSi⁴⁺ phosphors effectively enhances the Ce³⁺ → Mn²⁺ energy transfer efficiency, intensifies the orange and red emissions of Mn²⁺, and tunes the emission spectra of the phosphors. The GAGG: 0.06Ce³⁺, xMn²⁺, xSi⁴⁺ (x = 0, 0.2, 0.3) phosphor samples were encapsulated with blue LED chips (λ = 450 nm) to fabricate white LEDs. As x increases from 0 to 0.3, the correlated color temperature (CCT) of the white LEDs decreases from 4014 K to 3447 K, while the color rendering index (CRI) increases from 74.8 to 84.5. These results demonstrate that the introduction of Mn²⁺ into GAGG: 0.06Ce³⁺ phosphor can effectively enhance its orange and red emission components through Ce³⁺ → Mn²⁺ energy transfer, thereby improving the chromaticity performance of white LEDs.