Graphene-Organic Hybrids as Opto-Electronically Active Nanosystems
Jürgen P. Rabe
Department of Physics & IRIS Adlershof, Humboldt-Universität zu Berlin
Newtonstr. 15, 12489 Berlin, Germany
Hybrid systems based on graphenes and organic molecules, including nanographenes, provide a most versatile platform for both understanding and applying opto-electronically active nanosystems.
Graphenes, on the one hand, can be used, e.g., as transparent top electrodes for conjugated polymers, where they serve on the same time as protective barriers against oxygen and water, thereby preventing the lifetime limiting photooxidation of the polymer . Moreover, they may be deposited onto transparent substrates such as bare mica , on which also single layers are readily detectable in optical microscopy . Deposited onto single macromolecules such as DNA on mica, graphenes allow further to protect the molecules also mechanically against shear forces, e.g. during scanning force microscopy in contact mode , thereby offering new prospects for analytical scanning probe microscopy and optical techniques . Deposited on bare mica graphenes provide also a novel semihydrophilic slit pore of self-adjustable size, which can be used to study molecular liquids in confined geometries . We used Scanning Probe Microscopy, Electrostatic Force Microscopy, and Raman Spectroscopy to investigate both the structure and the electronic properties of graphene conforming to molecular water layers on the mica surface.
Nanographenes, on the other hand, i.e. extended molecularly defined polycyclic aromatic hydrocarbons, suitably derivatized at their molecular peripheries, provide robust and highly versatile active components for single-molecule electronics, which have been put to work in an STM configuration at the interface between organic solutions and graphite . Similarly they can be applied onto single and double layer graphenes on insulating substrates such as oxidized silicon, and also fully transparent substrates such as mica, which offers new prospects for single molecule spectroscopy and molecular opto-electronics.
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