The charge mobility in polymer LEDs-the low frequency impedance method

The negative contribution to the capacitance found in low frequency dielectric spectroscopy provides an elegant way to measure the hole and electron mobilities in polymer devices. We present a closer look into this method. By analyzing the results of hole only and double carrier PPV devices, we argue that the reference capacitance to choose is not the zero-field capacitance but rather the one which corresponds to the fully depleted state. © 2003 Elsevier Science B.V. All rights reserved.