Modeling Energy Transfer Processes in Gd2O2S:Yb3+Er3+

Abstract

In literature, several models have been developed to describe energy transfer processes between luminescent ions. These models however sometimes fail to accurately describe real systems because they make certain assumptions e.g. random distributions of luminescent ions or fast migration, which are not always true. In this work, a model was developed that includes all the microscopic properties of the luminescent crystal and can accurately describe the behavior of its luminescent ions. The luminescent phosphor investigated in this thesis is the Yb3+/Er3+ couple embedded in a Gd2O2S host, which is well known for its upconverting ability. Experimental photoluminescence decay data of high quality samples were fitted to the model to obtain parameters for the different processes taking place in the crystal. The following parameters were obtained: γYb = 3.45 ms-1, γEr = 0.51 ms-1, energy transfer strength = 3.71 ms-1nm6, and energy back transfer strength = 3.64 ms-1nm6. These parameters were used in Monte Carlo simulations to accurately model the behavior of the luminescent ions in the crystal for different concentrations.