PMSE 256 |
| Organic semiconductors have garnered tremendous interest as new materials for applications in light emitting diodes (OLED), photovoltaics (OPV) and thin film transistors (TFT). While development of OLEDs and TFTs has expanded rapidly, research in OPVs is further behind owing to the more difficult operation mechanism, low charge carrier mobilities and inefficient absorption of organic materials in the bulk of the solar spectrum. Self organization by crystallization leading to close intermolecular interactions, possibly in the g-g stacking regime, is a promising approach to improve carrier mobility. Star-shaped phenylenevinylene-based oligomers as previously reported by our group have shown strong intermolecular interactions, two-dimensional charge delocalization and potential for OLED and OPV applications.1Thiophene-based g-conjugated oligomers2 and polymers3 are a subject of considerable interest as they form some of the most environmentally and thermally stable materials and exhibit interesting optoelectronic properties. Planarization and assembly of the backbone in the form of g stacks leading to promising electronic and photonic properties and synthetic versatility of thiophenes make them very attractive materials for solar cells. OPVs based on polythiophene are the best organic solar cells reported so far.4 Based on the promising properties of thiophene materials and the earlier encouraging work on star-shaped oligomers we have developed a new class of thiophene-based star molecules in our effort to investigate the structure-property relationships and application of these materials in OPVs. In these materials we have been able to systematically engineer the HOMO-LUMO energy levels, alter the photophysical properties and red-shift the absorption to efficiently harness the solar energy. The two-dimensional structural architecture may help arrange these molecules into liquid crystal phases enabling g-g stacking, and help improve carrier mobilities. Basic synthetic strategy adopted and recent results obtained with these materials and their applications in OPVs will be described. |
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Joint PMSE/POLY Poster Session
6:00 PM-8:00 PM, Tuesday, 12 September 2006 Moscone Center -- Hall D, Poster
Division of Polymeric Materials: Science & Engineering |