We investigated temperature dependence of the electrical conductance of single oligothiophene molecular wires with the length of 2.2 nm (5-mer), 5.6 nm (14-mer) and 6.7 nm (17-mer) by using the scanning tunneling microscopy break junction method. Results show that the dominant charge carrier transport for 5-mer molecule is tunneling while for 17-mer molecule is hopping. The carrier transport mechanism of 14-mer are tunneling transport (T ≤ 350 K) and hopping transport (T &gt
350 K) indicating that hopping and tunnelling transport are competitive process in the molecular junction. © 2011 Materials Research Society.