Investigation of the luminescence properties and energy transfer mechanisms in GdTaO:Bi,Eu phosphors for their potential application in full-spectrum WLEDs

In recent years, there has been increasing effort devoted to the development of single-phase white phosphors due to drawbacks such as severe reabsorption and color deviation in traditional white light-emitting diodes (WLEDs). A new feasible strategy has emerged for achieving white light emission through the Bi 3+ -Eu 3+ energy transfer in suitable single-phase phosphors. Therefore, a series of Gd 3 TaO 7 : x Bi 3+ and Gd 3 TaO 7 :0.01Bi 3+ , y Eu 3+ phosphors were synthesized via a high-temperature solid-state method, and their properties were systematically characterized. In Gd 3 TaO 7 , Bi 3+ occupies two kinds of Gd 3+ site, resulting in two broad emission bands peaking at 427 nm and 500 nm respectively under ultraviolet (UV) excitation, which arise from 3 P 1 → 1 S 0 transitions. By adjusting the concentration of Eu 3+ in Gd 3 TaO 7 :0.01Bi 3+ , y Eu 3+ , effective energy transfer can occur between Bi 3+ and Eu 3+ , thus enabling the regulation of green-white-red luminescence under 332 nm excitation and blue-white-red luminescence under 365 nm UV light irradiation. Upon stimulation with a 365 nm UV chip, Gd 3 TaO 7 :0.01Bi 3+ ,0.02Eu 3+ emits white light with CIE coordinates of (0.3509, 0.3202), a color temperature of 4629 K, and an impressive color rendering index of 87.96. The above results indicate the potential of Gd 3 TaO 7 :0.01Bi 3+ , y Eu 3+ phosphor as a viable candidate for WLED applications. In Gd3TaO7:0.01Bi 3+ , y Eu 3+ , the tuning of light from blue and green to red under UV excitation was achieved by adjusting the concentration of Eu 3+ , and a single-phase white phosphor suitable for a 365 nm LED chip was successfully synthesized.