Er3+ activated BaLaGaO4 multifunctional green phosphors for optical thermometers and WLEDs

Er³⁺-doped BaLaGaO₄ green phosphors was synthesized through a high-temperature solid-state reaction technique. The phase structure and morphology test results of the phosphor indicate that the BaLaGaO₄ material was successfully synthesized and Er³⁺ ions were successfully doped into the main lattice. This doping does change the basic structure of the crystal. BaLaGaO₄:Er³⁺ phosphor exhibits bright green emission centered at 545 nm when excited by 381 nm ultraviolet light or 980 nm near-infrared light. The optimal doping concentration is found to be x = 0.04. To quantify the temperature sensitivity of the phosphor, the fluorescence intensity ratio method was used. Within the temperature range of 298–473 K, the maximum relative sensitivities are 1.35%/K (298 K, 381 nm) and 1.45%/K (298 K, 980 nm), respectively. The maximum absolute sensitivities are 0.67%/K (473 K, 381 nm) and 0.69%/K (473 K, 980 nm), respectively. Finally, white light-emitting diodes (WLEDs) with a high colour index of Ra = 82 and a relatively low correlated colour temperature of CCT = 5064 K are obtained by integrating the synthesized BaLaGaO₄:0.04Er³⁺ green phosphor into warm WLEDs devices. These results suggest that Er³⁺-activated BaLaGaO₄ multifunctional phosphors hold considerable promise in the areas of optical temperature sensing and WLEDs phosphor conversion.