A novel efficient Sr3In2WO9: Sm3+, Eu3+ phosphor for white LED applications

A series of Sr3In2WO9: xSm3+ (x = 0.02, 0.03, 0.04, 0.05, and 0.06) and Sr3In2WO9: 0.04Sm3+, yEu3+ (y = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, and 0.35) phosphors were synthesized by solid-state reaction method. Then the microstructure and optical properties of samples were tested by the corresponding means. The results show that the optimal doping concentration of single-doped Sm3+ phosphor is × = 0.04 and the performance of Sm3+/Eu3+ co-doped phosphors has been improved. The Sm3+ /Eu3+ co-doped phosphors exhibit characteristic emission of Sm3+ and Eu3+ under the excitation of 407 nm. The direct energy transfer mechanism between Sm3+ and Eu3+ originates from the dipole-quadrupole interaction. When y = 0.20, the energy transfer efficiency reaches 62.69%. The quantum yield of Sr3In1.76Sm0.04Eu0.20WO9 is as high as 69.42%, which possesses excellent thermal stability, and the relative luminescence intensity reaches 73% at 423 K, while the thermal quenching activation energy ΔE is 0.280 eV. At the same time, after the Sm3+/Eu3+ co-doping, the chromaticity coordinates shifted from (0.5661, 0.4282) for mono-doped Sm3+ to (0.6176, 0.3787). The correlated color temperature of the packaged WLED is calculated to be 5591 K, and the color rendering index Ra is 96. These results show that Sr3In2WO9:Sm3+, Eu3+ could be one of the potential candidates for white light-emitting LEDs under n-UV excitation.