Modulating anti-thermal and concentration quenching for enhanced dysprosium emission

Abstract

Phosphors may exhibit a reduction in luminosity due to the thermal-quenching (TQ) effect at higher temperatures, which has led to considerable research on the thermal stability of light output. However, color consistency, which defines the temperature tolerance of the CIE diagram for emitting light, has rarely been considered. In this study, Tm³⁺- and Dy³⁺-doped Sr₃LaAl₃B₄O₁₅ (SLAB) phosphors are reported as promising white light-emitting materials, exhibiting enhanced photoluminescence and excellent thermal stability. Comprehensive characterization was performed using X-ray diffraction, Rietveld refinement, TEM, SEM, ESR, and diffuse reflectance spectroscopy. Energy transfer (ET) modulation between Tm³⁺ and Dy³⁺ was observed, contributing to effective anti-TQ behavior and intrinsic suppression of concentration quenching. Despite the typical tendency of Ln³⁺ ions toward concentration quenching, the strong emission from the Tm³⁺–Dy³⁺ system confirms the viability of high Tm³⁺ doping. ET efficiencies of 70.2% (conventional) and 78.28% (this work) were achieved via electric dipole interactions. A high anti-TQ performance (105.8% at 400 K) and a low chromaticity shift (ΔEs = 10.31 × 10⁻³) indicate superior thermal stability, comparable to that of commercial phosphors like CASN:Eu²⁺ and BMAO:Eu²⁺. White LEDs using SLAB:0.015Tm³⁺,0.05Dy³⁺ phosphors, alone or blended with SLAB:0.1Eu³⁺, emit warm-white light (CCT ∼3032–3467 K) with high color rendering (R_a ≥ 86.4), confirming their promise for use in solid-state lighting.