Novel Eu3+-activated Ca3Ga2Ge4O14 red-emitting phosphors with high quantum efficiency for plant growth lighting and white LEDs

Abstract

In recent years, rare-earth-based phosphors for near-ultraviolet (NUV)-triggered white light emitting diodes (w-LEDs) have become a research hotspot. However, it is still not possible to obtain phosphors with high quantum yield, excellent color purity and multiple applications. Hence, a series of novel Eu³⁺-activated Ca₃Ga₂Ge₄O₁₄ (CGG) red-emitting phosphors with high quantum efficiency, excellent color purity and good thermal stability were prepared by a high-temperature solid-phase method. All the CGG:Eu³⁺ phosphors emitted dazzling red emission with excitation at 394 nm. The optimal Eu³⁺ doping concentration of compounds was 12% with an excellent color purity of 97.89%, and the concentration quenching mechanism was investigated as dipole–dipole interactions. Meanwhile, the synthetic samples exhibited good thermal stability with the activation energy of 0.26 eV. Remarkably, the internal quantum yield of the prepared phosphors reaches 94.26%. Furthermore, the emission spectra of the prepared red-LEDs overlap considerably with the absorption spectra of P_R and P_FR required for plant growth. The w-LED device emits warm white light with a high color rendering index of 91.64 and an appropriate correlated color temperature of 4808 K. These excellent luminescence properties indicate that the prepared CGG:Eu³⁺ phosphors exhibit extensive potential for applications in plant growth lighting and white LEDs.