A novel red phosphor Ba3La2W2O12:Eu3+ with intense 5D0-7F4 transition and excellent thermal stability for white LEDs.

Abstract

Red-emitting phosphors with high thermal stability are of great significance for improving the performance of phosphor-converted white light-emitting diodes (pc-WLEDs). A series of Ba3La2W2O12:xEu3+ (BLWO:xEu3+, 0 ≤ x ≤ 0.12, Δx = 0.02) red phosphors excitable by UV-near UV and blue light were successfully synthesized via high-temperature solid-state reaction. The crystal structure, micromorphology, and optical properties of the BLWO:Eu3+ phosphor were systematically investigated. The emission spectrum of the BLWO:Eu3+ phosphor is dominated by the red emission at 616 nm originating from the electric dipole 5D0 → 7F2 transition of Eu3+. Notably, the 5D0 → 7F4 emission at 702 nm exhibits remarkable intensity, reaching approximately 70% of the strongest 5D0 → 7F2 emission (616 nm). The optimal Eu3+ doping concentration in the BLWO:Eu3+ phosphor was determined to be 0.06, with the concentration quenching mechanism governed by electric quadrupole-quadrupole (q-q) interactions. The BLWO:0.06Eu3+ phosphor demonstrates excellent quantum efficiencies with an internal quantum efficiency (IQE) of 62.91% and an external quantum efficiency (EQE) of 35.23%, along with outstanding thermal stability. Benefiting from these superior properties, the phosphor was successfully employed in WLED fabrication. The resulting device exhibits warm white light with CIE 1931 chromaticity coordinates of (0.3453, 0.3518) and a high color rendering index (Ra) of 80.3.