Center on Materials & Devices for Information Technology Research An NSF Science & Technology Center July 20 th, 2006 Investigating Carbon Nanotube Films for Potential Electrode Applications Patrick Duggan, MDITR REU student

Center on Materials & Devices for Information Technology Research An NSF Science & Technology Center July 20 th, 2006 Outline Motivation for creating electrodes from CNT Creating thin films of CNT –Procedure –Problems Modes for improvement –Production –Augmentation of Sampling Results and Recommendations OLED Device

Center on Materials & Devices for Information Technology Research An NSF Science & Technology Center July 20 th, 2006 Problems with Entrenched Technology Brittle material tensile failure (crack) strain ITO (Indium-tin oxide)2.5% ITO (evaporated on PET)1.2% ~ 2.0% depends on thickness thin film ITO (Indium Tin Oxide) currently used for electrodes –Highly conductive –Highly transparent in visible spectrum ITO is brittle making it inflexible Mechanical limitations of brittle materials –tensile/compressive stresses in the barrier layers –shear stress between layers –adhesion strength between thin film layers (Crawford, G., Cairns, D., (Nov. 2005). Flexible Substrate )

Center on Materials & Devices for Information Technology Research An NSF Science & Technology Center July 20 th, 2006 Why create thin films of CNT? CNT remain conductive under stress –Same amount of contact points Creation of Flexible Electronics –Flexible OLEDs and OPVs GOAL: CNT films w/comparable –Conductivity –Transmittance

Center on Materials & Devices for Information Technology Research An NSF Science & Technology Center July 20 th, 2006 Creating thin films of CNT The SolutionVacuum Filtration Membrane RemovalAttaching Substrate CNT Deposition Final Product

Center on Materials & Devices for Information Technology Research An NSF Science & Technology Center July 20 th, 2006 Problems in creating the CNT films Creases CracksAir Bubbles Radial Defects Tears Conglomerates

Center on Materials & Devices for Information Technology Research An NSF Science & Technology Center July 20 th, 2006 Improving the Procedure Dilution –Where does dilution happen? –Improvement from DI water –Results Dispersion Solution –DMF (dimethyl formamide) –Nitromethane –Results

Center on Materials & Devices for Information Technology Research An NSF Science & Technology Center July 20 th, 2006 Augmentation of Sampling Heat –Evaporate remnants of chemicals –Results Silver –3-5 nm layer –Solder CNT network –Results Additional attempts –PEDOT:PSS –Light, high efficiency

Center on Materials & Devices for Information Technology Research An NSF Science & Technology Center July 20 th, 2006 Comparison to ITO

Center on Materials & Devices for Information Technology Research An NSF Science & Technology Center July 20 th, 2006 Recommendations Significant progress made from Nitromethane –Test other solvents Alignment of CNT network, Composite films, Multiple baths More research will create a comparable electrode to ITO Potential use in Top Emitting OLEDs Potential use in infrared regime

Center on Materials & Devices for Information Technology Research An NSF Science & Technology Center July 20 th, 2006 Acknowledgements Dr. Samuel Graham, faculty advisor Roderick Jackson, student advisor Nam Su Kim, mentor Entire research group William Potscavage and Kippelen Group Olanda Bryant and Dr. Keith Oden, program directors