Design, Synthesis Of Novel Molecular Devices And Investigation On Their Molecular Conductance

The pursuit of molecular electronics has created an increasing interest in the electrical measurement of single molecule in past decades. Understanding charge transport properties in metal/molecule/metal junctions is an important step towards using individual molecules as building blocks for electronic devices.This thesis aims to understand charge transport mechanism in molecular devices. We design series of OPV type molecular wires, metal coordination compound, and investigated the electron transport properties in these molecular wires by using both theory and STM break junction (STM-BJ) method. The main results of the thesis are listed as following:1. We have designed and synthesized six OPV molecules containing different terminal groups. The molecular conductance of these OPV molecules has been studied by using STM-BJ method. The terminal anchor groups play crucial roles to the formation of molecular junctions. Six different groups, including-SMe (TOPV), pyridyl (POPV),-NH2(AOPV), thiophene (ThiOPV), and-CN (CNOPV) groups have been studied for their effects on the molecular conductance. It is revealed that the molecular conductance is in the following sequence:POPV> TOPV> AOPV> ThiOPV> CNOPV> NOPV. We have also demonstrated that the conductance of POPV molecular wire can be strongly affected by the acidity of the solution.2. We have synthesized the metal complexes containing1,10-phenantroline ligand, and measured their molecular conductance by STM-BJ method. When the anchor groups are amine or nitrate moieties, the metal complex may form stable junctions. The molecular conductance exhibits strong dependence on the metal ion in the complex.3. Theoretical investigation has been conducted to study the molecular conductance of multiple terminal devices. The calculation indicates that more terminals benefit charge transportation. Meanwhile, asymmetrical molecule shows ratification effects. This result may help to design novel multi-terminal molecular devices.