Synthesis and photoluminescence properties of red-emitting Y6WO12:Eu3+ phosphors

Abstract

For a system of white-light-emitting diodes (WLEDs) fabricated using near-ultraviolet (UV) LED chips coated with RGB tri-color phosphors, the most important issue is enhancing the efficiency of the red phosphor. Y6WO12:Eu3+ phosphor is a potential material that can emit red color under near-UV excitation. This work investigated the luminescence properties of Y6WO12:Eu3+ under UV light excitation. The photoluminescence (PL) emission intensity of EuxY6–xWO12 (x = 0.1–1.0) phosphor from the 5D0→7F2 transition increased with Eu3+ content until x = 0.9. For x > 0.9, the PL emission intensity decreased due to concentration quenching. The decay time of EuxY6–xWO12 (x = 0.1–1.0) phosphor for the 5D0→7F2 transition was about 0.6–0.7 ms and did not decrease obviously, which means that there was no nonradiative energy transfer in the phosphor. The asymmetry ratio (5D0 → 7F2/5D0 → 7F1) of EuxY6–xWO12 (x = 0.1–1.0) was about 2, which caused the PL emission intensity of EuxY6–xWO12 (x = 0.1–1.0) phosphor from the 5D0→7F2 transition to be higher than that from the 5D0→7F1 transition. The chromaticity coordinates of the EuxY6–xWO12 (x = 0.1–1.0) phosphor were close to the chromaticity coordinates of the standard red color. The EuxY6–xWO12 (x = 0.9) phosphor showed the highest quantum efficiency.