Adjustment of Bi3+ Luminescence and Thermal Quenching Properties by B'-Site Ion Substitution Strategy in Double Perovskite CaLaMgSb/TaO6:Bi3+ Phosphor

Abstract

Thermal quenching has always been one of the most difficult issues in creating high-quality phosphor conversion light-emitting diodes (pc-LED), and a family of strategies are urgently needed to improve the luminescence performance of phosphors at high temperatures. In this contribution, a novel B'-site substitution CaLaMgSb_xTa_1-xO₆:Bi³⁺ phosphor was constructed using an ion substitution strategy in the matrix with a green activator Bi³⁺ and a novel double perovskite material. When Sb⁵⁺ replaces Ta⁵⁺, a surprising increase in luminescence intensity occurs and the thermal quenching properties are greatly improved. The shift of the Raman characteristic peak to a smaller wavenumber and the reduction of the Bi-O bond length confirm that the crystal field environment around Bi³⁺ changes, which has a substantial effect on the crystal field splitting and nepheline effect of Bi³⁺ ions, affecting the crystal field splitting energy (D_q). This results in a corresponding increase of the band gap and the thermal quenching activation energy (ΔE) of the activator Bi³⁺. From the perspective of D_q, the intrinsic relationships among the activator ion band gap, bond length, and Raman characteristic peak changes were analyzed, and a mechanism for regulating luminescence thermal quenching properties was constructed, which provides an effective strategy for improving the promising new materials such as double perovskite.