Enhanced luminescence of a Ba2GdSbO6:Mn4+ red phosphor via cation doping for warm white light-emitting diodes

Abstract

With admirable luminescence performance and a cheap price, non-rare-earth-based oxide red phosphors are a potential competitor of rare-earth-doped phosphors for warm white LEDs (WLEDs). Herein, a novel double-perovskite Ba₂GdSbO₆:Mn⁴⁺ phosphor, demonstrating strong red emission ascribed to a spin-forbidden Mn⁴⁺:²E_g → ⁴A_2g transition in the region of 620–750 nm, has been synthesized via a solid-state reaction route. The microstructure and luminescence properties are investigated in detail. The concentration quenching mechanism and thermal stability based on thermal quenching characteristics are also discussed. Importantly, Li⁺, Mg²⁺, Zn²⁺, Si⁴⁺, Ti⁴⁺ and Ge⁴⁺ dopants are discovered to be beneficial for enhancing Mn⁴⁺ luminescence, and the related mechanisms are comprehensively described. In addition, by combining red-emitting Ba₂GdSb_0.994O₆:0.003Mn⁴⁺,0.003Mg²⁺ with the commercial blue-emitting BaMgAl₁₀O₁₇:Eu²⁺ and green-emitting Ba₃La₆(SiO₄)₆:Eu²⁺ phosphors in various ratios, a series of WLED devices with a tunable correlated color temperature (CCT) evolving from 6256 to 3486 K and a color rendering index (CRI) increasing from 72.1 to 88.3 are achieved.