Different factors affecting the performance of alternating-current thin-film electroluminescent (ACTFEL) devices are discussed. The Chen-Krupka model of electron transport was applied to examine the case of non-uniform distribution of the dopant concentration in the active layer. Based on the results, a ZnS doping profile is proposed which incorporates higher doping at the intel faces than in the bulk. Also, the asymmetry in the excitation efficiency of electrons near the two insulator-semiconductor interfaces (ISIs) of ACTFEL devices was studied and was ascribed to the difference in the interface quality arising from the choice of insulating material and to the selection of the annealing process, The role of the space charge stored near the ISI and the influence of drive conditions on the operational characteristics of the device are discussed.