One-dimensional hybrid nanostructure arrays from pi-conjugated organic small molecules and inorganic semiconductors for use in excitonic devices

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The major themes of this research program are the growth, characterization and device applications of organized 'hybrid' one-dimensional (1-D) nanostructures composed of both organic and inorganic semiconductors. 1-D semiconductor architectures such as nanotubes (NTs) and nanowires (NWs) exhibit unique nanoscale phenomena (not normally observed in the bulk) which originate in orientation anisotropy and size confinement effects. They have also been demonstrated to achieve enhancement of bulk properties. Due to these characteristics, they can be used to design unconventional material and device configurations and hold the promise of overcoming difficult obstacles in the fields of photovoltaics and photonics. One such obstacle in the area of photonics is the small value of the third order non-linear susceptibility (chi3) in most conventional materials, which is currently impeding progress in the areas of real-time holography and all-optical switching. Another obstacle is in the area of low cost excitonic solar cells where achievement of higher energy conversion efficiencies is impeded by the exciton diffusion bottleneck. Hybrid organized nanostructures have the potential to dramatically improve the performance of excitonic devices and overcome the obstacles mentioned above. Therefore, we propose to exploit the unique properties and architecture of 1-D hybrid nanostructures to obtain superior performance in excitonic devices. A distinguishing feature of our approach is that we aim to create not nanocomposites, but oriented and aligned 1-D hybrid NT/NW arrays. We also note that there are hundreds of reports each on carbon nanotubes, gold nanowires, titanium dioxide nanotubes, silicon nanowires, etc. In contrast, pi-conjugated organic nanotube and nanorod arrays have received little attention and constitute a frontier area of research. A key component of our research program is the comprehensive study of crystalline nanotube and nanorod arrays made from small-molecule pi-conjugated systems. Another component is the advancement of excitonics, the science and technology of manipulating electrostatically bound excited states in pi-conjugated organic semiconductors and nanostructured inorganic semiconductors.