Experimental modeling and evaluation of the afterglow phosphors using multiple single exponential equations

On the basis of multiple first-order kinetics exponential equations, the decay curves of afterglow materials have been successfully fitted by many researchers. The decay times in an equation were provided to evaluate afterglow behaviors for material properties. In this study, we searched associated equations and found useful cues from constants in the equations indicating photoluminescence behaviors affected by the experimental conditions as well as the physical properties of a sample. As the boundary conditions are set for an equation, the relationships among the equation׳s parameters correspond to physical behaviors, such as the initial and long-term intensity and the refraction point. Different thick-film patches were created for various experimental tests, and experimental data was collected from other resources. The results demonstrate that there is a high correlation among the physical parameter αi and the illuminate intensity, patch thickness, and phosphor density. We report that the τi in the decay curve equation represents the slope change of the curve profile and affects only the declining rate of the curve and not its position, i.e., light intensity. That is, τi may not be the dominant factor in the equation for evaluating the afterglow behavior of a phosphor material.