Field effect mobility in thin films of poly(3-alkylthiophene)

Abstract

We report studies of the transport properties of thin films of the neutral polymer poly(3-alkylthiophene). Our measurements were done using a field effect transistor structure, which allows measurements of the mobility of the charge carrier in the film, as well as the conductance. We have also studied the temperature dependence of these parameters. The field effect mobility in the channel was found to be typically 10 −5 cm 2/Vs. (with a surface conductance of 10 −8 1 μ and a density of charge carriers of 10 11 cm −2 at room temperature). The field effect mobility in the channel was found to decrease with temperature, partly reversibly and partly non-reversible. The decrease of mobility with temperature may possibly be related to the formation of conjuction defects on the polymer, leading to loss of planarity and decreasing conjugation lengths.