Luminescence properties of novel dual-emission (UV/red) long afterglow phosphor LiYGeO4: Eu3+

Here, a new LiYGeO4: Eu3+ phosphor exhibiting long red persistent luminescence (PerL) is developed herein. Experimental results show that LiYGeO4: Eu3+ with a low doping concentration of Eu3+ emits high-intensity red PerL, which lasts for more than 21 h. The red PerL of the preirradiated LiYGeO4: Eu3+ phosphor can be repeatedly excited to increase its intensity via short-term stimulation using low-energy near-infrared (NIR) light. Furthermore, LiYGeO4: Eu3+ exhibits strong intrinsic emission, enhancing the f-f emission of Eu3+. The PerL emission, photoluminescence (PL) emission, and thermoluminescence (TL) spectra are identical, suggesting the emission originating from the host and Eu3+ center. TL measurements were conducted to intensively study the trap characteristics of LiYGeO4: Eu3+ using the Booth-Bohun and T-m-T-stop methods. Results reveal the underlying mechanism of the PerL and the importance of Eu3+ as the introduced traps in LiYGeO4: Eu3+. LiYGeO4: Eu3+ with a high doping concentration of Eu3+ exhibits excellent PL properties and thermal stability, with its quantum efficiency surpassing those of commercial phosphors such as Y2O3: Eu3+, suggesting its potential application in solid-state lighting. Thus, the doping of LiYGeO4: Eu3+ with low and high concentrations of Eu3+ can be helpful in fabricating materials exhibiting different luminescence properties.