Numerical simulation of charge transfer and light emission in SrS:Ce thin-film electroluminescent devices

When an AC voltage is applied to a thin-film electroluminescent device with an SrS:Ce phosphor layer, the current flowing through the phosphor layer and the emitted light can be complex functions of time. In order to explain the observed current and light waveforms, a numerical model has been constructed for the electrical and optical behavior of such a device. This model is based on the tunneling of electrons from the phosphor-insulator interface, multiplication of the electron current and creation of positive space charge in the high field region, recombination of electrons with the positive charges in the low-field region, and a back-flow of electrons from the anodic interface when the field there changes sign. The rather simple model is able to simulate a number of features observed in current and light characteristics quite well. It could serve as a reference for the interpretation of new experimental results.