Electrical and Optical Properties of Alq(3)-Based Organic Light-Emitting Diodes Driven by DC and AC Voltages

Abstract

Electrical and optical properties of Alq(3)-based organic light-emitting diodes were investigated by driving the device with DC and AC voltages to investigate dynamic behavior of the device. In the operation of the device with (DC+AC) voltage, luminance of the device depended on the DC bias, and less affected by small AC signal. A phase difference between the applied voltage and current was observed because of the appearance of capacitive effect as the frequency increases. And a distribution of space charge was confirmed by the impedance measurement. As the frequency increases, accumulation of holes reduces, which results in a decrease of space-charge region.