Eu³⁺-Activated Alkali Rare-Earth Double-Tungstate Nanoparticles for Near-Ultraviolet-Light-Triggered Indoor Illumination

Phosphors for near-ultraviolet (NUV)-triggered white light-emitting diodes (LEDs) have become an attractive research topic in recent years. However, it is still difficult for phosphors to have simultaneous high luminous intensity, superior color purity, and excellent thermal stability. Hence, a series of Eu³⁺-activated alkali rare-earth double-tungstate nanoparticles with high luminescence intensity were prepared by a facile hydrothermal reaction method. The influence of rare-earth ions and alkali cations on the luminescence properties was investigated. Impressively, the prepared phosphors exhibit superior color purity and excellent thermal stability. Meanwhile, the emission intensity and color purity can be controlled by tuning the concentrations of Eu³⁺ ions. By employing the resultant nanoparticles, a fabricated LED device emitted bright warm white light with a high color rendering index (CRI) of 92.12 and a suitable correlated color temperature (CCT) of 4689 K. This work straightly confirms that the prepared phosphors are promising candidates as red-emitting components applied in NUV-triggered indoor illumination.