Dazzling Ca2LuScAl2Si2O12:Ce3+ green-emitting garnet-type phosphors for blue-chip-pumped white light-emitting diodes: broad emission band, high quantum efficiency and excellent thermal stability

Abstract

Exploring efficient, energy-saving and environmentally friendly phosphors is important for developing solid-state white light-emitting diodes (w-LEDs). Herein, we report a novel highly efficient green-emitting Ce³⁺-activated Ca₂LuScAl₂Si₂O₁₂ (abbreviated as CLSAS:Ce³⁺) garnet phosphor with high quantum efficiency and good thermal stability. These garnet phosphor samples doped with different Ce³⁺ ion concentrations were synthesized using a high-temperature solid-state method. The crystal structure and Ce³⁺ concentration-dependent luminescence properties of the phosphors were systematically studied. The as-prepared CLSAS:Ce³⁺ garnet phosphors exhibit broadband absorption in the spectral range of 250–510 nm with a maximum excitation wavelength of around 452 nm, matching well with the emission wavelengths of commercial blue LED chips. Under an excitation of 452 nm, the optimal CLSAS:4%Ce³⁺ sample exhibited a broad green emission band (emission peak: 531 nm; bandwidth: 114 nm) with CIE color coordinates of (0.3293, 0.5453) and high luminescence efficiency (internal quantum efficiency: 87.3%; external quantum efficiency: 56.6%). The CLSAS:4%Ce³⁺ sample also showed good thermal stability in the temperature range of 303–443 K. Its emission intensity at 423 K reached 79% of the emission intensity at 303 K, and it exhibited outstanding color stability with a small color chromaticity shift (ΔE = 1.07 × 10⁻³) at 423 K. Importantly, the fabricated w-LED device exhibits excellent photoelectric properties (CCT = 4978 K; Ra = 92.4; LE = 69.59 lm W⁻¹). The obtained efficient CLSAS:Ce³⁺ green phosphors have the potential for application in high-quality w-LEDs.