Design, Solution Synthesis and Luminescence Properties of Rare-Earth Doped Afterglow Phosphor for Glow-in-the Dark Applications

Long afterglow (LA) phosphors are a particular type of luminescent materials that store up the photon energy and demonstrate photoluminescence emission even after the source of excitation has been ceased off. The majority of the researchers now agree that the stored energy gets captured at the various trapping levels associated with intrinsic or intentional defects and later released thermally. As the source of excitation is eliminated, trapped charge carriers may acquire sufficient thermal energy from ambient surroundings resulting into recombination of the charge carriers. Since detrapping of charge carriers is associated with the thermal energy, these are also known as thermo luminescent materials. The entire phenomena of afterglow luminescence include the excitation of charged carriers, charge carrier migration, and trapping at defect centers; the thermal release of the trapped charge carriers; and finally the recombination of the charge carriers resulting in delayed afterglow luminescence.