Orange-emitting Dy³⁺/Sm³⁺ co-doped phosphate glasses with enhanced quantum yield and excitation-independent luminescence

Orange-emitting phosphors with high color purity, stable quantum efficiency, and excitation versatility are essential for next-generation solid-state lighting and radiation-responsive photonic systems. Herein, we present a mechanism-driven study of Dy 3+ /Sm 3+ co-doped potassium–alumino–phosphate glass with composition 15K 2 O.20Al 2 O 3 .(64-X)P 2 O 5 .1Dy 2 O 3 .XSm 2 O 3 (X= 0-2.0 mol%) was synthesized via the melt quenching technique. Systematic Sm 3+ incorporation induces structural densification, reflected in increased density and refractive index, which enhances local field strength and modulates interionic distances governing energy-transfer dynamics. Spectroscopic analysis reveals efficient non-radiative Dy 3+ →Sm 3+ energy transfer, enabling controlled spectral tuning from Dy 3+ -dominated green–yellow emission to intense Sm 3+ -centered orange emission at 598 nm. Time-resolved photoluminescence confirms progressive shortening of Dy 3+ lifetimes, yielding a maximum energy-transfer efficiency of 33.3%, while Sm 3+ decay remains nearly unaffected, indicating efficient sensitization. Notably, the glasses exhibit excitation-independent luminescence, with photoluminescence and X-ray–excited luminescence displaying nearly identical spectral profiles, highlighting their multifunctional optical response. A maximum absolute photoluminescence quantum yield of 15.38% is achieved at low Sm 3+ concentrations, demonstrating competitive radiative efficiency within a chemically robust phosphate network. Colorimetric analysis reveals tunable emission from green–yellow to warm orange, with correlated color temperatures in the range of 2000–3000 K. A maximum external photoluminescence quantum yield of 15.38% is achieved at low Sm 3+ concentrations.