A phenomenological model for decay process of long-persistent phosphorescence

A sum of two or more exponential decay functions is empirically adopted nowadays to analyze the decay curve of long-persistent phosphor. However, the fitting parameters of this empirical model lack well-defined physical meanings, especially when the number of exponential decay function is greater than two. We propose a phenomenological model to describe the decay curve of long-persistent phosphor based on an analysis of the relationship between carrier concentration and light-emitting intensity. This model has a few fitting parameters with well-defined physical meanings as compared to the current empirical one. With this model, we quantitatively analyze the decay processes of typical long-persistent phosphors of SrAl2O4:Eu,Dy and obtain reasonable fitting results.