Tunable photoluminescence and energy transfer of novel phosphor Sr9La2W4O24:Sm3+, Eu3+ for near-UV white LEDs

Novel Sr9La2W4O24:xSm3+ and Sr9La2W4O24:0.15Sm3+, yEu3+ orange-red phosphors with double perovskite tungsten structure are synthesized by high-temperature solid-phase reaction method. X-ray diffraction patterns indicate the prepared phosphors are pure phase with a tetragonal structure and the SEM image displays the long string structure with a diameter of one micron. Under the excitation of near-UV light, the Sm3+ and Eu3+ ions activated Sr9La2W4O24 phosphors exhibit their characteristic emissions in the orange-red region, and the emitting light color of the Sr9La2W4O24:0.15Sm3+, yEu3+ phosphors can be adjusted from orange to red by increasing the concentration of Eu3+ ions implying their potential applications as orange-red emitting phosphor for LED in solid-state lighting. The optimal doping concentration of Sm3+ ions in Sr9La2W4O24:xSm3+ phosphors is around 15 mol%. The energy transfer from Sm3+ to Eu3+ is discussed and the major mechanism for concentration quenching is the dipole–dipole (d–d) interaction.