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.