The increasing miniaturization 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 realized 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 inter-action 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 SFB 658 "Elementary processes in molecular switches at surfaces" 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 SFB 658 is based on various complementary methods from synthesis of molecular systems, characterization 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.