Deep‐Red (Sr,Ba)Lu2O4: Eu2+ Phosphor for Full‐Spectrum Lighting

• Published in: Physica status solidi. PSS-RRL. Rapid research letters 2024-08, Vol.18 (8), p.n/a
• Main Authors: Wang, Shaoxiong, You, Fengluan, Wang, Shaojun, Pang, Tao, Zeng, Lingwei, Lin, Shisheng, Zheng, Yuanhui, Fang, Yongzheng, Chen, Daqin
• Format: Article
• Language: English
• Subjects: Barium; Color temperature; crystal field; deep‐red phosphors; Density functional theory; Europium; Excitation spectra; Light emitting diodes; Lighting; luminescent materials; oxide phosphors; Phosphors; Spectral emittance; Strontium; Thermal stability; Thermoluminescence; White light
• ISSN: 1862-6254; 1862-6270
• DOI: 10.1002/pssr.202400061

Developing violet‐light‐excitable deep‐red (650–660 nm) Eu2+‐activated phosphor is essential for full‐spectrum lighting. However, the related phosphors with facile synthesis, excellent optical performance, and superior thermal stability are scarce. Herein, a new class of (Sr,Ba)Lu2O4: Eu2+ deep‐red phosphor (660 nm) excitable by violet light via Ba2+‐induced local structure engineering is reported. Impressively, tunable emission from 615 to 682 nm, accompanied by significant improvement of thermal stability (81%@423 K), is achieved by partially substituting Sr2+ by Ba2+ in SrLu2O4: Eu2+. Crystal field analysis, density functional theory calculations, and thermoluminescence spectra confirm that the strong distortion and enhanced covalency of [EuO6] octahedron are responsible for spectral tunability, and the formation of shallow trapping states is beneficial for electron compensation to inhibit thermal quenching in the Sr0.85Ba0.15Lu2O4: Eu2+ phosphor. Finally, a white light‐emitting diode prototype fabricated by coupling of the Sr0.85Ba0.15Lu2O4: Eu2+ deep‐red phosphor and commercial blue/green phosphors with violet chip can yield sunlight‐like white light with an ultra‐high color rendering index (Ra = 95.2, R9 = 97.0) and an appropriate correlated color temperature of 4121 K, verifying its significant application potential in full‐spectrum solid‐state lighting. A new class of (Sr,Ba)Lu2O4:Eu2+ phosphor emitting deep‐red light in response to violet light excitation is developed. Specifically, Sr0.85Ba0.15Lu2O4:Eu2+ yields 660 nm emission with high photoluminescent quantum yield of 58.7% and superior thermal stability of 81%@423K benefiting from Ba2+‐alloying‐induced local structure modification.