Investigating the properties of molecular wires on gold and diamond

Abstract

The self assembly and electron transport properties of various molecular films on different substrates were investigated in this thesis. In Chapter 3, we proved that the two-step strategy of coupling transition metal complexes to pyridine-terminated oligo(phenylene)ethynylene self-assembled monolayer formed well-ordered molecular assemblies using various surface characterization techniques. Electrical measurements revealed enhanced conductivity, rectification and negative differential resistance in the transition metal-OPP molecular films. In Chapter 4, theoretical simulations of the molecular wires based on the first-principles density functional theory and non-equilibrium Greenb s function revealed electrical properties consistent with the experimental results. In Chapter 5, we demonstrated strong rectification in assemblies of molecular dyads comprising a bithiophene segment as the photo-active electron donor and either a C60 or dicyano moiety as the electron acceptor in sandwich device structures. Diamond-based solar cells incorporating 2T-C60 molecular dyads were then studied using impedance spectroscopy under different lighting conditions and various applied dc potentials.