Cation defects succeed in triggering super stability of narrow-band blue-emitting phosphors Ca₃Sc₂Si₃O₁₂: Bi³⁺ for backlighting display application

High-performance white light-emitting diodes (WLEDs) used for backlighting display applications require innovative and thermally stable narrow-band emission phosphors, particularly non-rare-earth Bi³⁺-activated phosphors. In this study, we demonstrate a defect-engineering strategy to create novel anti-thermal quenching phosphors Ca₃Sc₂Si₃O₁₂: xBi³⁺ (CSSO: xBi³⁺). Through structure refinement of CSSO: 0.06Bi³⁺ phosphor, we found that Bi occupies both Ca and Sc sites in the CSSO lattice. Direct visualization of atomic-resolution TEM and thermoluminescence spectra confirmed the formation of point defects due to the non-equivalent substitution of Ca²⁺ for Bi³⁺. Fluorescent-decay analysis revealed that two luminescence sites contribute to the blue-emitting of CSSO:Bi³⁺ phosphors. CSSO: 0.06Bi³⁺ phosphor exhibits outstanding thermal stability, with an integrated emission intensity of 103.6% at 423 K compared to that at 298 K. However, the addition of Li or Na as charge compensators reduced cationic defects, leading to a decrease in thermal stability. We believe that V_Ca ^″ defects are primarily responsible for the anti-thermal quenching behavior of CSSO: xBi³⁺ phosphors. An optimized CSSO: 0.06Bi³⁺ phosphor-based WLED displays a high color rendering index (CRI) of 90 and a wide color gamut (90% National Television System Committee (NTSC) standard), indicating its potential for use in industrial applications as a backlighting display.