A novel yellow-emitting CaGdSbWO8:Dy3+single-phase phosphor with high thermal stability and application in w-LEDs

Dy3+ doped tungstate CaGdSbWO8 (CGSW) phosphors have been synthesized following a conventional high-temperature solid-state reaction at 1300 degrees C. Their phase purity, surface morphology, optical characteristics, thermal stability, and the Commission International de L'Eclairage (CIE) chromaticity were systematically studied. The results show that the CGSW:Dy3+ can be excited over a broad range from 250 nm to 470 nm. Four monitored emission peaks at 487 (blue light), 575 (yellow light), 667, and 754 nm are attributed to the 4F9/ 2-6H15/2, 4F9/2 -6H13/2, 4F9/2 -6H11/2, and 4F9/2 -6H9/2 energy level transition of Dy3+ ions, respectively. The critical quenching concentration of Dy3+ in CGSW:Dy3+ phosphor was 5 mol%, and the concentration quenching mechanism is due to the dipole-dipole interaction. Most notably, the prepared phosphors demonstrate the excellent thermal stability with a high activation energy (0.250 eV). The emission intensity of the concentration optimized (5 mol%) phosphor remained 93.0% at the typical operating temperature (420 K) of light-emitting diode (LED). The fabricated w-LED achieved a high Ra (89), low correlated color temperature (CCT) of 5096 K, and the CIE coordinates of (0.341, 0.334), which fell in the white region and were very near the standard National Television System Committee (NTSC) white point (0.333, 0.333). The results indicated that the CGSW: Dy3+ phosphors could participate in fabricating the w-LEDs as the yellow component.

Automated summary

Dy3+ doped tungstate CaGdSbWO8 (CGSW) phosphors were synthesized using a high-temperature solid-state reaction and their properties were systematically studied. The phosphors demonstrated a wide excitation range and emitted various colors attributed to different energy level transitions of Dy3+ ions. The concentration quenching behavior and thermal stability of the phosphors were also investigated. The optimized phosphor showed high emission intensity at typical operating temperature of LEDs, and the fabricated white LED exhibited high color rendering index and near-standard white coordinates.