Europhys. Lett., 65 (3) , pp. 386-392 (2004)
DOI: 10.1209/epl/i2003-10102-7

Photocurrent in conjugated polymers

B. Horovitz and E. Pazy

Department of Physics and Ilze Katz center for nanotechnology Ben-Gurion University of the Negev - Beer-Sheva 84105, Israel
(Received 2 June 2003; accepted in final form 28 November 2003)

Abstract
Non-linear photocurrent carriers in conjugated polymers, such as polarons, bipolarons and solitons, are considered at low photon energies where a tunnelling process is necessary. We show that polarons dominate the photocurrent I due to a novel electric-field-assisted tunnelling route for which $\ln I\sim -E^{-2/3}$ . For near-degenerate polymers with an electric field E which exceeds the confinement parameter and frequencies near twice the soliton energy, soliton formation is favored. Photocurrent data can then be used to identify the remarkable soliton conduction.

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