Impedance spectroscopy of a poly(p-phenylenevinylene)-based light-emitting diode device

A poly-p-phenylenevinylene (PPV)-based light-emitting diode (LED) device was studied by means of comprehensive ac impedance measurements. Separate regions of frequency-dependent responses, the bulk and depleted (interface) regions, with distinct electrical properties, were identified and characterized. The ac J–E characteristics revealed the space-charge limited conduction mechanism, which was specifically assigned to the depleted region. Besides, a direct estimate of the trap density in the bulk region was obtained from the applied voltage dependence of the charge concentration.