ANALYTICAL CIRCUIT MODEL FOR THIN-FILM ELECTROLUMINESCENT DEVICES

A simple equivalent circuit is developed for alternating current thin film electroluminescent devices, With sinusoidal excitation voltage an exact analytical solution is presented for calculating the device current, transferred charge and the internal voltage across the phosphor layer. The circuit is used for modeling EL devices with widely varying phosphor layer materials that include ZnS, CaS, SrS, CaF2, SrF2, ZnF2 and multilayer structures prepared with Atomic Layer Deposition, The equivalent circuit gives a straightforward way to characterize the electrical properties of these materials, The fluorides have inferior breakdown properties compared to sulfides although they are much more symmetric, The strong asymmetry of SrS is attributed to its nonuniform defect distribution.