A Review on Luminescence properties in Eu Doped Phosphate Phosphors

In 1996, Matsuzawa et al. reported on the enormously long-lasting afterglow of SrAl2O4: Eu 2+ co-doped with Dy ions, which was more than 10-times brighter than the previously widely used ZnS: Cu. Since then, research for stable and efficient phosphors has constantly gained attractiveness. However, even today almost 15 years after the invention of SrAl2O4: Eu 2+ the number of luminescent materials is still comparatively low. Furthermore, the mechanism behind this phenomenon is still uncertain. Although most of the authors agree on the general features, such as the existence of long-lasting trap levels, many details are still shrouded in unknown. In this review, we present an outline of the important phosphate based phosphors of known luminescent materials based on Eu doping and how they were prepared, and we take a closer look at the mechanisms and applications that have been suggested to explain bright afterglow in various compounds.