Effects of electrolyte gating on single-molecule electronic transport

• Applicants: Professor Dr. Horst Köppel; Professor Dr. Wolfgang Wenzel
• Subject Area: Theoretical Chemistry: Molecules, Materials, Surfaces ; Theoretical Chemistry: Electronic Structure, Dynamics, Simulation
• Term: from 2011 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 203760017

In spite of significant results, molecular electronics remains confronted with major difficulties, e. g., the efficient control of the single-molecule transport via a gate electrode. Recent transport experiments demonstrated important practical advantages of the electrolyte gating. Advances in this field require a theoretical understanding beyond the presently used phenomenological Newns-Anderson framework, wherein the redox unit is modeled as a point-like singly occupied energy level, and the solvent as a classical oscillator. In close cooperation with the experimental group of Professor Wandlowski (Bern), we will develop for the first time a microscopic theory of the adiabatic transport in electrolytes, which will be refined in a stepwise fashion to approach the level of vacuum electronics theory. In the first step, we will perform quantum-mechanical/molecular mechanics calculations to microscopically account both for the inner and the outer relaxation, and a multi-MO (molecular orbital) uncorrelated redox unit. Basically, this is the theoretical level of most studies in vacuum electronics. The redox’ electronic structure will be next refined within an ab initio approach, which eliminates the physical ambiguity of the DFT-”orbitals” and accurately accounts for electron correlations. Further, we will refine the description of the intra-redox relaxation, which is important for the electrolyte gating. The realization of this project will generate a novel theoretical context for the microscopical understanding of the molecular transport in electrolytes.

• DFG Programme: Research Grants