Structure and Electronic Transport of Highly Conductive Langmuir-Blodgett Films of Tridecylmethylammonium-Au(dmit)2

Abstract

Electronic transport measurements are reported for Langmuir-Blodgett (LB) films of tridecylmethylammonium-Au(dmit)₂ for 300-4 K. The conductivity after electrochemical oxidation is 30-50 S/cm at room temperature, increases with decreasing temperature, and begins decrease at about 200 K. The conductivity at lower temperatures is explained by two-dimensional variable range hopping (2D VRH). The thermoelectric power (S) is positive and well fitted by a linear combination of the temperature dependence of 2D VRH (S _v\proptT ^1/3) and that of metal (S _m\proptT). These results can be explained by a model in which highly conductive metallic regions are separated by thin weakly conductive regions. The UV/visible absorption spectra and the X-ray diffraction patterns indicate that a large structural change occurs accompanied by electrochemical oxidation.