Design of Long Persistent White Phosphorescence in a Composite Phosphor Via Energy Transfer Mechanism

A high quality composite phosphor powder of warm to cool white emission and long afterglow phosphorescence was reported by the process of energy transfer in a composite phosphor. The composite phosphor particles include at least two types of phosphor particles viz. a blue white persistent component and yellow fluorescent component. The blue white extremely long persistent component transfers its afterglow to the yellow fluorescent component in the composite phosphor followed by the color mixing process to generate the white afterglow. The composite phosphor is designed in such a way that the excitation spectrum of the fluorescent component was overlapped as much with the afterglow emission of the persistent component. The composite phosphor emission spectrum can be well tuned from warm to cool white depending on the proportions of the composite phosphors and energy transfer extent. Phosphor includes powders, ceramics and resin composites.