Dresden 2006 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 23: POSTER Functional Organic Thin Films

CPP 23.14: Poster

Thursday, March 30, 2006, 17:00–19:00, P2

Charge carrier transport in P3HT diodes and transistors — •Silviu Grecu, Andreas Opitz, and Wolfgang Brütting — Experimental Physics IV, University of Augsburg, 86135 Augsburg, Germany

It has been demonstrated recently that the hopping mobility in semiconducting polymers depends on the charge carrier concentration. Owing to differences in the densities of injected carriers of several orders of magnitude between organic field-effect transistors (FETs) and diodes, significant differences in the charge carrier mobilities of these devices have been observed.

We have investigated the temperature dependence of the mobility for three different kinds of organic devices: hole-only diodes, metal-insulator-semiconductor (MIS) diodes and FETs fabricated from regioregular poly(3-hexylthiophene) (rr-P3HT). Surface treatment of the substrate and different solvents for the polymer are used to change the degree of ordering of the polymer and study its influence on charge carrier transport. The charge carrier mobilities as extracted from space-charge limited currents of diodes, from relaxation frequencies in MIS diodes and from the transfer characteristics of FETs show different magnitude and temperature dependence. Applying an analytical model [1] for the hopping mobility in amorphous films a distinction between the effects of charge carrier density on the one hand and of structural anisotropy on the other hand is possible.

[1] W.F. Pasveer et al., Phys. Rev. Lett. 94 (2005) 206601.