Regulating luminescence thermal quenching based on the synergistic effect of energy transfer and energy gap modulation

Abstract

Thermal quenching is the core challenge that hinders the application of luminescent materials. Herein, a synergistic mechanism involving energy transfer and energy gap modulation is proposed based on the local crystal field regulation around sensitizers. The substitution of coordination cation V⁵⁺/P⁵⁺ weakens the crystal field strength of the sensitizer Bi³⁺, and the weakening of crystal field splitting causes an increase in the ³P₁ energy level, thus increasing its energy gap. Compared with the YVO₄:Bi³⁺,Eu³⁺ phosphor, the thermal stability of the YV_0.25P_0.75O₄:Bi³⁺,Eu³⁺ phosphor is significantly improved, and the relative emission intensity of Eu³⁺ continuously increases with heating and reaches 1.24 times the original intensity at 523 K and does not show a decreasing trend in the studied temperature range. The anti-thermal quenching performance is mainly attributed to the increasing thermal quenching activation energy (ΔE) of the sensitizer by energy gap modulation, which enhances the energy transfer to compensate thermal quenching. Based on the thermal quenching characteristics of the materials, an optical thermometer is designed. The maximum relative sensitivity (S_r) and absolute sensitivity (S_a) are as high as 1.74% K⁻¹ and 0.59 K⁻¹, respectively, and the minimum temperature resolution reaches 0.288 K. The synergistic effect between energy gap modulation of the sensitizer and energy transfer enables the regulation of thermal quenching. Thus, this study provides a new strategy for exploiting high-performance luminescent materials.