Voltage-modulated millimeter-wave spectroscopy on a polymer diode: mesoscopic charge transport in conjugated polymers

We present a new technique to determine the carrier mobility mu in semiconducting, undoped, conjugated polymers in the millimeter-wave frequency range, 10-500 GHz. This method probes charge conduction on mesoscopic length scales, a regime inaccessible to other transport experiments. The experiment is based on the detection of millimeter-wave absorption of field-induced charge in polymer diodes, and is applied to poly( p-phenylene vinylene). We demonstrate that locally mu can be as high as 10(-4) m(2)/V s, and deduce the typical hopping parameters in the mesoscopic high- mu regions in the material.