Luminescence properties of multicolor-tunable emitting LiYGeO4: Tb3+, Eu3+ phosphors with excellent thermal stability for WLEDs

Abstract

In order to investigate the impact of rare earth (Tb3+/Eu3+) ion doping on the luminescent properties of LiYGeO4, a series of LiYGeO4: 30%Tb3+, yEu3+ (0.0% ≤ y ≤ 1.0%) phosphors were successfully prepared using the solid-state reacthion in this work. The analysis revealed that Tb3+/Eu3+ ions were successfully doped into the LiYGeO4 lattice, confirmed by of X-ray diffractometer (XRD) patterns, Rietveld refinement, and element distribution results. The LiYGeO4: 30%Tb3+, yEu3+ samples exhibit efficient excitation by both ultraviolet (378 nm) and blue light (482 nm). Furthermore, the luminescence intensity, quantum yield, and thermal stability under 378 nm excitation were found to be greater than those under 482 nm excitation. Increasing the concentration of Eu3+ ion doping resulted in an energy transfer from the green region to the yellow region and finally to the orange red region, as evidenced by the Commission Internationale de L′Eclairage (CIE) coordinates of LiYGeO4: 30%Tb3+, yEu3+ phosphors. The white light emitting diodes (WLEDs) prepared utilizing LiYGeO4: 30%Tb3+, 0.75%Eu3+ phosphor shows a high color rendering index (Ra) of ∼93.2, a low correlated color temperature (CCT) of 5134 K, emitting bright natural light. This study helps to understand the mechanism of energy transfer, improves the luminescent material system of LiYGeO4, and provides new ideas and options for designing a high-performing lighting sources.