Preparation and Nanometer-scale Characterization of p-conjugated Organic Thin Film Materials

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9901293 Hamers The nanometer-scale growth, structure, and morphology of extensively conjugated p-electron systems will be investigated. This research is focused on conjugated p-electron systems such as sexithiophene, polypyrrole, and other solid materials that are organic conductors of electricity and/or have novel optical properties as a consequence of their conjugated p systems. The proposed research focuses on strategies for preparing and for characterizing conjugated systems in which the properties are highly anisotropic due to the local orientations of the molecules on the surface. Several schemes for achieving molecular orientation will be investigated, including the use of oriented bonds at the surface and the use of vicinal surfaces with high step densities. A wide variety of structural, chemical, electrical, and optical probes will be utilized to link the molecular structure and bonding with the resulting electrical and optical properties. Scanning tunneling microscopy will be used to investigate the structural order and the orientation of the films, while near-field scanning optical microscopy (NSOM) will be used to probe the local optical response. Reflectance-difference anisotropy spectroscopy will be used as a non-contact method for evaluating the degree of molecular orientation. %%% The proposed research will benefit society in several ways. First, through training of future scientists. The proposed research is quite interdisciplinary in scope, bridging gaps between synthetic chemistry, physical/analytical chemistry, and physics. Students and postdocs trained under this grant will receive the kind of interdiscplinary training that is needed for successful scientific careers. Secondly, the proposed research itself would benefit society in new ways. It is generally recognized that the advances in microelectronics technology over the last 25 years that have lead to the "computer revolution" cannot continue indefinitely using conventional approaches; the use of molecules as fundamental building blocks represents a new paradigm for microelectronics that, if successful, might enable new types of devices orders of magnitude smaller than those existing today. Organic light emitting diodes, for example, can in principle have efficiencies much higher than existing light bulbs, with the promise of great savings in energy costs; successful fabrication of such structures requires a significant research effort into the electrical conductivity and optical properties of organic then films. This project is co-funded with the Chemistry Division and the Office of Multidisciplinary Affairs.