| fourth General Session |
Novel Properties Of Polymers & Nanocomposites |
Conversion of Electrons into Photons and Photons into Electrons through Nanoscience
Zakya H. Kafafi
Naval Research Laboratory, Washington D.C. 20375, USA
A review will be given on progress made in developing organic light-emitting diodes (OLEDs) and organic photovoltaics (OPVs) using molecularly engineered materials and nanostructured interfaces.
References
1. S. H. Lee, B-B Jang, and Z. H. Kafafi, “Highly Fluorescent Solid-State Asymmetric Spirosilabifluorene Derivatives” J. Am. Chem. Soc. 127, 9071 (2005).
2. A. J. Mäkinen, J. P. Long, N. J. Watkins, and Z. H. Kafafi, “Sexithiophene Adlayer Growth on Vicinal Gold Surfaces” J. Phys. Chem. B 109, 5456 (2005).
3. L. C. Palilis, J. S. Melinger, M. A. Wolak, and Z. H. Kafafi, “Excitation Energy Transfer in Pentacene Doped Tris(8-Hydroxyquinolinato) Aluminum” J. Phys. Chem. B 109, 5790 (2005).
4. Gary Kushto, Woohong Kim, and Zakya H. Kafafi, “Flexible Organic Photovoltaics using Conducting Polymer Electrodes” Appl. Phys. Lett. 86, 093502 (2005).
5. C. Risko, G. P. Kushto, Z. H. Kafafi, and J. L. Brédas, “Electronic Properties of Silole-Based Organic Semiconductors” J. Chem. Phys. 121, 9031 (2004); ibid,122, 099901(2005).
6. W. H. Kim, L. C. Palilis, M. Uchida, and Z. H. Kafafi, “Efficient Silole-Based Organic Light-Emitting Devices Using High Conductivity Polymer Anodes” Chem. of Mater. Special Issue on Organic Electronics (Invited), 16, 4681 (2004).
7. H. Kim, G. P. Kushto, C. B. Arnold, Z. H. Kafafi, and A. Piqué, “Laser Processing of Nanocrystalline TiO2 Films for Dye-Sensitized Solar Cells” Appl. Phys. Lett. 85, 464 (2004).
8. P. A. Lane and Z. H. Kafafi, “Solid-State Organic Photovoltaics: A Review of Molecular and Polymeric Devices” in “Organic Photovoltaics: Mechanisms, Materials, and Devices” Sam Sun and Serdar Sariciftci, Editors, CRC Press, Taylor & Francis Group (Publisher). 49-106 (2005).
9. Zakya H. Kafafi, “Organic Electroluminescence” Editor, CRC Press, Taylor & Francis Group, Boca Raton, Florida (2005)
Nanomaterials for 3D Microfabrication, Sensing and Imaging
Joseph W. Perry
Georgia Institute of Technology
Atlanta, GA30332-0245, USA
joe.perry@chemistry.gatech.edu
I will describe the design of conjugated organic chromophores with large two-photon cross sections and the use of these chromophores in highly efficient nanomaterials for two-photon 3D microfabrication, [1,2] sensing [3] and imaging [4,5] applications. Two-photon excitation of materials with focused laser beams allows for free-form patterning of materials in three dimensions with nanoscale (<200 nm) resolution. We have been developing efficient photoactive materials for two-photon 3D patterning of polymers via positive and negative patterning processes. We have also developed a class of photoactive nanocomposites based on Ag, Au, and Cu metal nanoparticles that allow for direct patterning of continuous metal features using lasers or electron beams. An overview of our efforts to develop two-photon 3D microfabrication will be presented and the potential for the manufacturing of a wide range of 3D microstructures for photonic, biomedical, microfluidic, and micromechanical applications will be highlighted. Progress in the development and application of two-photon probes for sensing and cellular imaging applications, the assembly of two photon dyes on metal nanoparticles to make ultrabright nanobeacons, and the strong enhancement of two-photon excited fluorescence by coupling of chromophores to clusters of metal nanoparticles will also be discussed.
References
1. "Two-Photon Polymerization Initiators for Three-Dimensional Optical Data Storage and Microfabrication" B. H. Cumpston, S. Ananthavel, S. Barlow, D. L. Dyer, J. E. Ehrlich, L. L. Erskine, A. A. Heikal, S. M. Kuebler, I.-Y. Lee, D. McCord-Maughon, J. Qin, H. Röckel, M. Rumi, X.-L. Wu, S. R. Marder, and J. W. Perry, Nature 398, 51-54 (1999).
2. “An Efficient Two-Photon-Generated Photoacid Applied to Positive-Tone 3D Microfabrication" W. Zhou, S. M. Kuebler, K. Braun, T. Yu, J. K. Cammack, C. Ober, J. W. Perry, and S. R. Marder, Science 296, 1106-1109 (2002).
3. “Metal-Ion Sensing Fluorophores with Large Two-Photon Absorption Cross Sections: Aza-Crown Ether Substituted Donor-Acceptor-Donor Distyrylbenzenes” S. J. K. Pond, O. Tsutsumi, M. Rumi, O. Kwon, E. Zojer, J.-L. Brédas, S. R. Marder, and J. W. Perry, J. Am. Chem. Soc. 126, 9291-9306 (2004).
4. “Ultrabright Supramolecular Beacons Based on the Self-Assembly of Two-Photon Chromophores on Metal Nanoparticles" F. Stellacci, C. A. Bauer, T. Meyer-Friedrichsen, W. Wenseleers, S. R. Marder, and J. W. Perry, J. Am. Chem. Soc. 125, 328-329 (2003).
5. “Real-Time Differentiation of G-Protein Coupled Receptor Agonist and Antagonist by Two Photon Fluorescence Laser Microscopy” M. Cai, M. Stankova, S. J. K. Pond, J. W. Perry, H. I. Yamamura, D. Trivedi, and V. J. Hruby, J. Am. Chem. Soc. 126, 7160-7161 (2004).
Novel Organic Materials For Electronic Applications
Bilal R. Kaafarani
American University of Beirut
Beirut, Lebanon
Identification of organic semiconducting materials with high charge-carrier mobility, especially electron transport, is crucial for a wide range of organic electronic applications such as light-emitting diodes, solar cells, and field-effect transistors. Discotic liquid-crystal mesophases are quasi-two-dimensional arrangements, which are often constituted of molecules with a rigid central aromatic core and extended flexible chains. These molecules usually pack in the form of well-defined columns that can form one-dimensional paths for charge transport along the stacked conjugated cores due to intermolecular p-p orbital overlap within the stacks. We report the synthesis and properties of novel discotic materials that are formed of 6,7,15,16-tetrakis(alkylthio)quinoxalino[2',3':9,10]phenanthro[4,5-abc]phenazine TQPP-[SR]4. Finally, we will discuss their optical and transport properties.
