THE EFFECT OF ACTIVATOR-ACTIVATOR INTERACTIONS ON PHOSPHOR EFFICIENCY

摘要

The relatively poor efficiency of phosphor materials in cathodoluminescence with low accelerating voltages is a major concern in the design of field emission flat panel displays operated below 5 kV. Our research on phosphors indicates that mechanisms involving interactions of excited activators have a significant impact on phosphor efficiency. Previously, we showed that persistence in both photoluminescence (PL) and cathodoluminescence (CL) deviates significantly from the sequential relaxation model, which assumes that higher excited manifolds in an activator de-excite primarily by phonon-mediated sequential relaxation to lower energy manifolds in the same activator ion. In addition to sequential relaxation, there appears to be strong coupling between activators, which results in energy transfer interactions. Some of these interactions negatively impact phosphor efficiency by nonradiatively de-exciting activators. Increasing activator concentration enhances these interactions. The net effect is a significant degradation in phosphor efficiency at useful activator concentrations, which is exaggerated when low―energy electron beams are used to excite the emission.