Detail:

Abstract:
　　Charge transport through and between molecules is central to many important processes in nature. In particular, studying the conductivity of single molecules can contribute to a better understanding of charge transport, and also help develop better molecular wires and other building blocks of molecular electronics, light harvesting devices, etc. We will discuss the results of different experiments designed to understand these processes at the single molecule level. We measure the conductivity of molecules using the Scanning Tunneling Microscope break-junction (STM-BJ) method that utilizes repeatedly formed circuits where one or a few molecules are trapped between two electrodes, at least one of which has nanoscale dimensions. The statistical analysis of thousands of measurements yields the conductance of single molecules.
　　One particular interest has been the role of the molecule-electrode contact in charge transport. In the simplest analysis this contact can present a substantial barrier to charge injection, which can have important consequences in devices such as dye sensitized semiconductor nanoparticle solar cells. We have demonstrated that carbodithioate termination of molecules can enhance conductivity by an order of magnitude.[1] We have also shown how the sensitivity of the electrical conductivity of single molecules to external perturbations can allow for switching and sensing,[2] as well as the use of single molecule conductance for the discovery of novel materials.[3]

REFERENCES:
　　1. Regulating a Benzodifuran Single Molecule Field Effect Transistor via Electrochemical Gating and Optimization of Molecule/Electrode Coupling, Zhihai Li, Hui Li, Songjie Chen, Toni Froehlich, Chenyi Yi, Christian Schönenberger, Michel Calame, Silvio Decurtins, Shi-Xia Liu, and Eric Borguet, Journal of the American Chemical Society 136　(25), 8867–8870 (2014)
　　2. Single-Molecule Sensing of Environmental pH-an STM Break Junction and NEGF-DFT Approach, Zhihai Li, Manuel Smeu, Sepideh A. Mamaghani, Yangjun Xing, Mark A. Ratner and Eric Borguet, Angewandte Chemie, 126 (4), 1116-1120 (2014)
　　3. Towards Graphyne Molecular Electronics, Zhihai Li, Manuel Smeu, Arnaud Rives, Valerie Maraval, Remi Chauvin, Mark A. Ratner, and Eric Borguet, Nature Communications 6:6321 (2015)