Influence of capacitance effect on alternating-current organic light-emitting diodes

The capacitance effect on ITO/poly[2-methoxy-5-[(2′-ethylhexyl)oxy]-p-phenylenevinylene] (MEH-PPV)/Al is studied by impedance spectroscopy technology, and the electroluminescence (EL) mechanism of this device driven by a sinusoidal alternating-current (AC) bias is suggested. By calculating the RC time constant of the device, we find that it is in good agreement with the lag-time between the EL and applied AC bias. Also, the influence of operating frequency on the EL intensity of the device is presented and it is concluded that a low operating frequency is good for a high device performance.