Dr. Frank Trixler, Department of Earth and Environmental Sciences, Ludwig-Maximilians-University Munich (LMU)

Project:
OSWD is a new approach which enables to grow supramolecular mono- and multilayers of insoluble organic semiconductors on substrate surfaces under ambient conditions. Several experimental evidences gained via solubility analysis, Scanning Tunneling Microscopy (STM) and nanomanipulation gave insight into the huge potential of OSWD for the controlled generation of self-assembled organic semiconductor layers with induced complexity. Approaches such as nanoscale guided self-assembly, desired and stable reconfigurations, self-repairing of damaged nanostructures as well as information storage into monolayers have been realized and published.

Besides the experimental evidences, an important support for OSWD was derived from Computational Chemistry: A comparison of Force Field Calculations regarding molecular interaction energies between organic semiconductor molecules and inorganic substrate surfaces, using the DREIDING Force Field within the software package CERIUS2, revealed a gain in binding energy for adsorbed molecules for those organic semiconductors which were successfully made to adsorb via the OSWD preparation technique.

Some aspects of OSWD which can be analyzed via Computational Chemistry are still unkonwn. For example, the role of binding agents as well as the influence of water layers covering each surface under ambient conditions is not clear so far. The possibility of nanoparticle surface energy reduction via amphiphilic molecules should also be proved via Molecular Modelling. Understanding all these factors is important to increase the controllability of guided non-covalent self-assembly and to achieve extremely local OSWD resticted to a selected area less than 100 nm in diameter. This local control will be crucial for combining OSWD with current Graphene research of our group for applications in nanoelectronics, photonics and sensors. Thus, more detailed Molecular Modelling studies are required.

Required Skills:
Molecular Modelling will be performed with the program MATEIRLAS STUDIO (Accelrys, Inc.) on a powerful Windows 7 workstation. MATERIALS STUDIO is a widely used commercial program which allows exchange of experience with a large user community. For geometry optimizations and energy calculations, Molecular Mechanics simulations will be performed by using the MS Modeling tool FORCITE PLUS. For these calculations both the Force Fields DREIDING II and UFF will be used to allow a comparison of the results. Molecular dynamics calculations will be performed by using the programs CHARMM and X-PLOR.

More information about the group:
Dr. Trixler's website