Chemistry Department Seminar: Contact Scanning Tunneling Microscopy and stretching of molecular wire



Dr Yannick J. Dappe
Service de Physique de l’Etat Condensé, CNRS, CEA Saclay, Université Paris-Saclay


Molecular junctions are perceived as the ultimate step toward the miniaturization of electronic components based on organic materials. In that respect, intensive experimental developments of Scanning Tunneling Microscopy (STM) have pushed the limits of the instrument much beyond the simple imaging of nanostructures. It has become now a necessary tool for the study of electronic structure of atomic and molecular nanostructures, in particular in contact mode, to fabricate molecular junctions. In this seminar, I will present two examples of STM experiments in contact mode, one about the formation of a molecular junction with a C60 molecule, and the second one concerning the manipulation of a molecular wire. Experimental data are supported by a theoretical model, based on Density Functional Theory (DFT) calculations and a Keldysh-Green formalism for electronic transport calculation. Beyond the modelling of the results, Physics of both systems will be analyzed to reveal the important parameters that can be exploited for applications in molecular electronics.

Dr Yannick Dappe received his Ph.D in physics in 2002 from the University of Strasbourg where he received the “Prix ADRERUS“. Then, he went for a post doc at the Autonomous University of Madrid in the group of F. Flores where he developed a model to treat vdW interactions within the DFT formalism. In 2008, he was hired as CNRS Researcher at the IPCMS in Strasbourg, before joining the CEA-SPEC in 2012. He is an expert in electronic structure and transport calculations in DFT, including vdW interactions, with applications in graphitic and two-dimensional (2D) materials, and molecular electronics and STM modelling.

Yannick collaborates closely with Dr Li Yang since Oct 2015. The strong partnership has the necessary interdisciplinary experience in 2D material fabrication, STM, single molecule electronics, electronic structure and electronic transport calculations, which directly led to high profiled publications and external research grants.