Beyond Single-Molecule Conductance: Understanding and Controlling Charge Transport by External Stimuli and Supramolecular Interactions

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This project is jointly funded by the Electronic and Photonic Materials Program (EPM) in the Division of Materials Research (DMR) and by the Chemical Structure, Dynamics and Mechanisms Programs A and B (CSDM-A and CSDM-B) in the Division of Chemistry (CHE).Nontechnical Description: The drive to miniaturize electronics has not only motivated the search for new organic and inorganic (macro)molecular materials, but has also spurred the development of tools required for studying circuits with single molecules as active elements. Most past research on creating molecular-scale electronic devices has focused on the impact of molecular structure on the device properties. This project goes beyond such studies by developing methods to exploit the environment around molecular devices in order to control and modulate electronic characteristics. The project contributes to the realization of functional molecular devices as well as expansion of an arsenal of experimental methods to study and control charge transport at the single-molecule level. An integral part of the activities include the introduction of interdisciplinary science bridging physics, chemistry and engineering to middle-school, high-school, and undergraduate students, in order to instill a desire to pursue careers in science. Both PIs' laboratories are bridged thus K-12 school students can experience, first-hand, life in interdisciplinary research environment at Columbia University.Technical Description: There is a strong need to understand and use the environment around molecular junctions to control charge transfer characteristics and enable creating functional molecular-scale analogs of circuit elements. Most past research efforts on transport at the molecular level have focused on correlating conductance to molecular structure, while the impact of the immediate environment around the junction has largely been ignored. This project aims to use the molecular environment as an external stimulus to control and alter the electronic characteristics of single-molecule devices, exploiting electrostatic, electrochemical and supramolecular interactions. The goals of this project are two-fold: (1) to understand the effects of the environment on the conduction properties of molecular junctions; and (2) to design and measure materials that respond to the environment in a controlled manner. This interdisciplinary research project goes beyond studying the fundamental components in molecular junctions - contacts, molecules, and electrodes - to establish an understanding of the interface between the junctions and the environment. It uses the scanning tunneling microscope based break-junction technique to study solvent/encapsulant effects, redox responsive systems, and supramolecular interactions in a large number of single-molecule devices.