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Size Control Over Semiconducting Materials for Organic Electronics. Collen Leng 1 , Jeffrey M. Mativetsky 1 , John E. Anthony 2 , Yueh -Lin Loo 1 Chemical and Biological Engineering, Princeton University Chemistry, University of Kentucky. Why Organic Electronics?.
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Size Control Over Semiconducting Materials for Organic Electronics CollenLeng1, Jeffrey M. Mativetsky1, John E. Anthony2, Yueh-Lin Loo1 Chemical and Biological Engineering, Princeton University Chemistry, University of Kentucky
Why Organic Electronics? • Low cost solution processing • Mechanical flexibility • Lightweight http://images.sciencedaily.com/2008/02/080206154631-large.jpg http://ww1.prweb.com/prfiles/2009/10/04/167139/FlexibleOrganicElectronicsdisplay.jpg
Increasing Efficiencies of Organic Solar Cells • Increase charge transport • molecular packing and orientation • Increase surface area between donor and acceptor materials
Project Goal Make organic semiconducting nanowires • Size control of electron acceptors and donors • Increase interfacial surface area • Wire-like structures for efficient charge transport Method: templating using aluminum oxide membranes • Scanning electron micrographs of aluminum oxide membrane Top view of membrane Cross-section of membrane Cross-section (zoomed in) 300 μm 2 μm 2 μm
Set-up • Allow solution to penetrate membrane from I-tube • Cap off I-tube to sustain internal pressure and prevent the solution from completely flowing through membrane rubber stopper closed air solution Electron donor: ethyl-TES-ADT I-tube membrane Teflon gasket Viton O-rings
Nanowires Inside Porous Membrane Cross-sectional views 15 μm 15 μm 10 μm 2 μm
Extracting Nanowires NaOH: dissolve membrane, free nanowires Options for removing NaOH and alumina: 1.Vacuum filtration 2. Centrifuge Nanowire mixture Viton O-rings Air out Polycarbonate filter Fritted glass
Extracted Nanowires Bundles of ethyl-TES-ADT nanowires Close-up of ethyl-TES-ADT nanowires 1 μm 10 μm
Nanowires on Glass High-density nanowires on glass: Close-up of wires: 30 μm 100 μm
TEM & Electron Diffraction Occasional polycrystalline structures Bundle of ethyl-TES-ADT nanowires in a transmission electron microscope (TEM) Electron diffraction of nanowires to the left shows some polycrystallinity
PCBM and P3HT Nanowires? Nanowires of other materials can be made. [6,6]phenyl-C61-butyric acid methyl ester (PCBM) nanowires: - the most commonly used electron acceptor 3 μm
Future Plans • Structural studies: • Thinner nanowires (10 - 20 nm diameters) to better match exciton diffusion lengths • Crystallization to help electron transport • Structural characterization (Grazing Incidence X-ray Diffraction) • Photovoltaic studies: • Map photoexcited charge generation at donor-acceptor nanowire interfaces (Kelvin Probe Force Microscopy, Photoluminescence) • Nanowire-based solar cells
Acknowledgements • Professor Loo • Jeff Mativetsky • Gerry Poirier • Loo Lab • PEI/Siebel Energy Grand Challenge