Retrapping probability of charge in traps: The parameter and its implication in luminescence

Abstract

The phenomenon of luminescence manifested by phosphors has many practical applications right from illumination, display to scintillators. However of late it has a totally new application in form of persistent luminescence wherein a phosphor emits enough photons to be visible for the whole night. These materials are known as Glow-in-the-Dark pigment. Invented in Japan, today it is a material that is used to illuminate the roads in some parts of the world. The heart of the phenomenon is the retrapping probability (An) of charge in traps, one of the intrinsic parameters that can be estimated by measuring the long period afterglow of phosphors. The parameter An and its sister parameter recombination probability (Am) and their ratio have tremendous potentialities in designing Glow-in-the-Dark phosphors. This communication will evaluate the ratio Am/An of some commercial phosphors to show the possible limit of optimization in development of these phosphors.