SFB 658:  Elementary Processes in Molecular Switches at Surfaces

• Subject Area: Physics ; Chemistry
• Term: from 2005 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 12489635

The increasing miniaturisation and integration in electronic devices and sensors opens the perspective to use molecules as building blocks for functional molecular nanostructures. For applications like molecular electronics it will be essential to control the switching between different molecular states, which in nature is often realised by photoinduced conformational changes. Controlled switching of molecular function requires the synthesis and design of appropriate molecular nanosystems and a basic understanding of structural and electronic properties including the interaction with the environment. In addition, there is a demand for active control by external stimuli like electromagnetic fields, forces and currents. The interaction of molecules with surfaces opens new perspectives: It allows to assemble molecules with defined orientations and to vary the lateral couplings in a systematic manner. The contact of molecules to solid state interfaces is also essential to connect the molecular system with the outside world, in particular for electric transport.
The Collaborative Research Centre investigates molecular switching processes driven by external excitations in well defined molecular systems at solid surfaces. We focus on reversible conformational changes of individual molecules and ensembles leading to measurable changes of functional (e.g. optical, electronic or magnetic) properties of the system. Our focus on elementary processes includes investigation of all individual steps, physical parameters and interactions, which induce and influence the process of molecular switching. Research in the Collaborative Research Centre is based on various complementary methods from synthesis of molecular systems, characterisation of structural and electronic properties by quantitative surfaces sciences techniques and theoretical modelling. The long-term goals are to develop novel functionalities, like cooperative switching processes, and criteria for applications in molecular functional devices.

• DFG Programme: Collaborative Research Centres

Completed projects

• A01 - Fundamental switching mechanisms of molecules on metal surfaces investigated with scanning tunneling microscopy (Project Head Franke, Katharina )
• A02 - Conformational changes of single molecules on semiconductor surfaces induced by inelastic electron tunneling processes (Project Head Fölsch, Stefan )
• A03 - Electron transport through single molecules and graphene (Project Head Rabe, Jürgen P. )
• A04 - Excitation and structural transformation of single adsorbed molecules induced by localized optical fields (Project Head Elsässer, Thomas )
• A05 - Complex switching units and molecular architectures, studied by scanning tunneling microscopy (Project Heads Grill, Leonhard ;  Wolf, Martin )
• A06 - Molecular switches on carbon surfaces (Project Heads Reich, Stephanie ;  Setaro, Ph.D., Antonio )
• B01 - Molecular switching processes at surfaces: Optical-induced charge transfer and molecular orientation (Project Head Tegeder, Petra )
• B02 - Charge transfer dynamics and switching efficiency in photochromic molecular ensembles at surfaces (Project Heads Gahl, Cornelius ;  Weinelt, Martin )
• B03 - Magnetism and lateral ordering phenomena of switchable molecules at surfaces (Project Head Kuch, Wolfgang )
• B04 - Optische und magnetooptische Untersuchung von molekularen Magneten und photoinduzierten Dipolen auf Oberflächen (Project Heads Fumagalli, Paul ;  Rüdt, Christoph Benedikt )
• B05 - Surface-adsorbed switchable ensembles of metal complexes (Project Head Grohmann, Andreas )
• B06 - Photoswitchable units for fundamental processes on surfaces (Project Head Rück-Braun, Karola )
• B07 - Functional imin- and diazo-switching units (Project Head Haag, Rainer )
• B08 - Switching architectures for controlling charge transport (Project Head Hecht, Stefan )
• B09 - Molecular switching in self-assembled monolayers at liquid-solid interfaces (Project Heads Campen, Ph.D., Richard Kramer ;  Wolf, Martin )
• B10 - Structure, excitonic coupling and cooperative dynamics of switches on surfaces: Real-time and in situ x-ray structure investigations (Project Head Kowarik, Stefan M. )
• C01 - Ab initio Theorie des Ladungstransports durch einzelne Moleküle (Project Heads Gross, Eberhard K. U. ;  Kurth, Stefan )
• C02 - Quantum theory for light- and electron-driven molecular switches at surfaces: structure and dynamics (Project Heads Klamroth, Tillmann ;  Saalfrank, Peter )
• C03 - Ab initio Untersuchungen zur Funktionalität molekularer Schalter auf Oberflächen (Project Heads Reuter, Karsten ;  Scheffler, Matthias )
• C04 - Conformational changes and magnetic switching in deposited molecular structures (Project Heads Brouwer, Piet W. ;  von Oppen, Felix )
• C05 - Theory of excitation transfer in functionalized carbon nanotubes (Project Heads Knorr, Andreas ;  Malic, Ermin )
• C06 - Excitations of molecular switches on surfaces: Insight from first-principles (Project Head Draxl, Claudia )
• MGK - Integrated Research Training Group (Project Heads Kuch, Wolfgang ;  Reich, Stephanie )
• V - Zentrale Aufgaben (Project Heads von Oppen, Felix ;  Weinelt, Martin )
• Z - Photoelectron spectroscopy for the chemical analysis of molecular switches at surfaces (Project Heads Kuch, Wolfgang ;  Rück-Braun, Karola ;  Weinelt, Martin )

• Applicant Institution: Freie Universität Berlin
• Participating University: Humboldt-Universität zu Berlin; Technische Universität Berlin; Universität Potsdam
• Participating Institution: Fritz-Haber-Institut der Max-Planck-Gesellschaft (FHI); Paul-Drude-Institut für Festkörperelektronik (PDI)
• Spokespersons: Professor Dr. Felix von Oppen, until 7/2015; Professor Dr. Martin Weinelt, since 7/2015