A METHOD FOR EVALUATING THE FREQUENCY-CHARACTERISTICS OF AC THIN-FILMELECTROLUMINESCENT DEVICES

Although there are some obvious variances in both electrical and optic al characteristics describing the frequency dependence in ACTFEL devic es, a method for the quantitative analysis of frequency characteristic s is still lacking. This paper presents a method for including the fre quency dependence. We assume that there is a phase shift between the a pplied voltage and the equivalent current emitted from the phosphor-in sulator interface. Combining the continuity equations and the tunnel c urrent formula, we have obtained the voltage in the phosphor layer, th e phase shift between the applied voltage and the tunnel current, the average current and the total amount of space charge in the phosphor l ayer at varying applied voltages and at different frequencies. Some ph ysical parameters of the phosphor layer can be obtained by fitting the theoretical model proposed to the experimental results in the range o f 500 Hz to 2000 Hz. The results are satisfactory.