Complex resistivity of polymer light-emitting diodes

Complex resistivity measurements in dark and under vacuum were carried out to study the electrical behavior of luminescent polymer diodes (LEDs) having ITO or gold as hole injector electrodes, aluminium as the cathode, and poly[(2-methoxy-5-hexyloxy)-p-phenylenevinylene] - MH-PPV as the luminescent layer. The results obtained were analysed by a model based on resistor-capacitor circuits, which made possible to distinguish between bulk from interface effects, and the contribution of each phenomenon to the electrical current. It was also shown that bulk properties already exist in a film of 0.4 μm thick, and from the theoretical fittings it was obtained the dielectric constant and resistivity of MH-PPV.