Emission increase in persistent inorganic phosphor improving absorption property by surface chemical modification

Abstract

Since an inorganic phosphorescent material showing bright and long-lasting afterglow can preserve light for a long time, they have been widely applied in commercial products. In particular, the discovery of SrAl2O4: Eu2+codoped with Dy3+ions gave a great impact in relatively high luminance and extremely long lifetime, however, no new material exceeding this has been discovered. Here, we report a method of enhancing emission intensity by surface chemical modification of the inorganic phosphor. The silane coupling method was adopted and that can widely apply to inorganic phosphor with metal oxide. When bonding silane coupling agents having functional group of vinyl or amino to inorganic phosphor of SrAl2O4: Eu2+, Dy3+, increase in emission intensity about 20% or 10% is achieved under the same excitation conditions. This enhancement is attributed to increase in carrier trapping amount inside the phosphor due to the improvement of UV absorption efficiency.