High quantum efficiency and excellent thermal stability in Eu3+ -activated CaY2ZrGaAl3O12 phosphors for wLEDs

There is a high demand for phosphorescent white light-emitting diodes (wLEDs) that possess low correlated color temperature (CCT) and high color rendering index (CRI), as they are considered to be environmentally friendly sources of solid-state illumination. A novel, UV-excited red light emitting Eu3+-activated CaY2ZrGaAl3O12 phosphor was synthesized for the preparation of warm wLEDs with high CRI and low CCT were obtained. Eu3+-doped CaY2ZrGaAl3O12 phosphors were synthesized with varying concentrations of Eu3+ dopant. The luminescence of Eu3+ was thoroughly examined at its optimal concentration of 20 mol%. Surprisingly, CaY2ZrGaAl3O12: 20%Eu3+ exhibits a broad excitation band of 200–550 nm and some sharp excitation peaks, the highest peak is observed at 251 nm. A dazzling red light, ranging from 550 to 750 nm, is emitted by CaY2ZrGaAl3O12: 20%Eu3+ phosphor. The excitation of ultraviolet light at a wavelength of 251 nm was employed, with an impressive internal quantum efficiency of 90.7% and a remarkable thermal quenching resistance. The wLED was packaged with green phosphor (BaMgAl10O17: Eu2+), red phosphor (CaY2ZrGaAl3O12: Eu3+), blue phosphor ((Ba, Sr)2SiO4: Eu2+) and 395 nm NUV LED chip, which emitted a dazzling warm white light when driven at a current of 20 mA. It has excellent CIE color coordinates (0.3893,0.3736), a low correlation color temperature (CCT) of 3738K, and an excellent color rendering index (Ra = 82.1). The application of the prepared new CaY2ZrGaAl3O12: Eu3+ red phosphor in wLED will promote the development of highly efficient luminous materials for healthy solid-state lighting.