Electronic and transport properties of doped organic molecules for molecular wire applications

Electronic transport through a doped polythiophene (PT) fragments and metal porphyrin molecules, which can be used in molecular wire applications, has been investigated using the nonequilibrium Green's function formalism of quantum transport and the density functional theory (DFT) of electronic structures with local orbital basis sets. The conductance of a PT fragment is increased by Na doping. A Na-doped PT chain can be isolated using a nanotube of cross-linking α-cyclodextrin (CD) molecules. The results also show that the metal atoms enhance the conductivity of the porphyrin molecule. Moreover, the Au-molecule contact is a very important factor for realizing a molecular wire based on porphyrin molecules because the conductance strongly depends on the type of contact.