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Seminar 2/10/2016 - Michael S. Arnold, University of Wisconsin-Madison: Breakthroughs in the Materials Science of Carbon Nanotubes and ....

Feb 10, 2016  ·  12:00 p.m. 1:00 p.m.  ·  Bowen Hall Auditorium

Title: Breakthroughs in the Materials Science of Carbon Nanotubes and Graphene Nanoribbons and their Application in Transistors and Photovoltaics

Abstract: Carbon nanotubes and graphene nanoribbons are among the best charge transport materials ever discovered. The transformative potential of these materials in electronics and optoelectronics has already been demonstrated, on a single nanostructure level. However, implementing them in scaled, macroscopic devices involving many nanostructures has been much more difficult. My work addresses challenges – in controlling the growth, processing, ordering, and heterogeneity of carbon nanomaterials and in understanding phenomena beyond the scale of single nanostructures – that must be overcome to exploit carbon nanomaterials in (opto)electronics technology.

In this talk, I will present on two recent breakthroughs from my lab: (1) We have perfected the purification of semiconducting carbon nanotubes from heterogeneous mixtures of semiconducting and metallic nanotubes and pioneered a scalable approach for assembling them into aligned arrays. These advances have allowed us to create the highest performance carbon nanotube field effect transistors (FETs) ever demonstrated in terms of on-state conductance, rivaling or exceeding the conductance of Si and III-V FETs for the first time. (2) We have discovered a new CVD-based synthesis for high aspect-ratio, self-orienting, semiconducting graphene nanoribbons that are < 10 nm in width but 100’s of nanometers in length, with smooth armchair edges. The nanoribbons are grown from the bottom-up by exploiting a giant anisotropy in crystal growth rate on a Ge(001) catalyst substrate. This advance overcomes the shortcomings of top-down lithographically defined nanoribbons, which are limited by their rough and disordered edges, and provides a promising route for integrating semiconducting graphene directly onto a conventional semiconductor wafer platform.

Bio: Michael S. Arnold is currently an Associate Professor of Materials Science and Engineering at the University of Wisconsin-Madison. There, he has directed the Advanced Materials for Energy and Electronics Group since 2008. Prof. Arnold graduated summa cum laude from the University of Illinois at Urbana-Champaign with a Bachelor of Science degree in Electrical Engineering in 2001. He earned his Doctor of Philosophy degree in 2006 from Northwestern University in Materials Science and Engineering under Professors Mark Hersam and Sam Stupp. Prof. Arnold conducted post-doctoral research at the University of Michigan at Ann Arbor from 2006-2008 with Professor Stephen Forrest. Arnold has been a recipient of the National Science Foundation CAREER award (2014); the American Chemical Society Arthur K. Doolittle Award in Polymeric Materials Science and Engineering (2012); the Presidential Early Career Award for Scientists and Engineers (PECASE) – nominated by the U.S. Department of Defense, Army Research Office (2011); the U.S. Department of Energy (DOE) Early Career Research Award (2011); and a 3M Non-Tenured Faculty Award (2011, 2012, 2013).

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.

Seminar 2/17/2016 - Shelby Nelson, Eastman Kodak: Thin-film Electronics by Spatial ALD: Achieving High Performance with Low Process Complexity

Feb 17, 2016  ·  12:00 p.m. 1:00 p.m.  ·  Bowen Hall Auditorium

Abstract: Patterning thin-film transistors for “printed electronics” applications can be challenging both for resolution and for alignment accuracy. This is particularly true for high-performance devices with submicron channel lengths, and for diverse and deformable substrates. Printing organic-based devices requires additional consideration of issues such as printing dynamics and orthogonality of solvents.  In this talk, I will describe alternative approaches to scalable thin-film electronics based on spatial atomic layer deposition (SALD) of metal oxides. Using the relatively high deposition speed of SALD, the conformality of the deposited layers, and the surface-sensitivity of the technique, we have explored both print-compatible high-performance vertical transistors, and patterned-by-printing circuitry. A reliable ZnO mobility above 10 cm2/Vs, on-off ratio above 107, and uniform threshold voltage values across the substrate give these approaches promise for large-area applications.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.

Seminar 2/24/2016 - Vibha Kalra, Drexel University: Freestanding Nanofiber Electrodes for Supercapacitors and Batteries

Feb 24, 2016  ·  12:00 p.m. 1:00 p.m.  ·  Bowen Hall Auditorium

Abstract: Fabrication of novel three-dimensional material architectures is essential for development of energy storage devices that allow high rate operation with sufficient energy capacity. After a short description of our group's overall research, I will present our specific work on development of binder-free freestanding nanofiber-based electrodes using a simple electrospinning methodology for application in supercapacitors(EDLC/Pseudocapacitors) and lithium-sulfur batteries. I will also talk about our work on molecular dynamics (MD) simulations to understand the effect of elongational flow, a key characteristic of electrospinning, on assembly within phase separating polymer blends - a material system relevant to the fabrication of nanofiber electrodes.

We have developed porous carbon nanofibers (PCNF) that exhibit specific surface area of >1500 m2/g and multi-levels of pore sizes in the range of micro (< 2 nm), meso (< 50 nm) and macropores (> 50 nm). We studied these materials both as electrodes in electric double layer capacitors (EDLC) (with aqueous and ionic liquid electrolytes) as a platform for polyanilene (PANi) deposition to develop hybrid supercapacitors. The unique combination of pores at different length scales allows us to achieve a battery-like energy density of up to 80 Wh/kg, while retaining high power and cycle life in EDLCs. In-operando infrared spectroelectrochemistry was conducted to understand the transport of ions through the carbon electrode pores and its effect on performance in ionic liquid-based EDLCs. In the hybrid supercapacitor devices, we demonstrated that the PCNF mats retain their EDLC behavior post PANi coating providing excellent electrochemical performance that integrates electric double layer and pseudocapacitive energy storage. We have also investigated the use of nanofiber materials for battery devices - Li-S, Li-O2 and redox flow batteries. In particular, for Li-S battery devices, we have demonstrated a facile methodology to localize soluble polysulfides that results in a high initial discharge capacity and capacity retention during cycling.

Bio: Vibha Kalra is an assistant professor in the Department of Chemical and Biological Engineering at Drexel University. Prof. Kalra received her BS degree from Indian Institute of Technology, Delhi, India in 2004 and PhD from Cornell University in 2009, both in Chemical Engineering. Prior to joining Drexel in the Fall of 2010, she worked at Intel Corporation in the electronic packaging research division. Prof. Kalra is an associate editor of Chemical Engineering Science Journal (since Sept. 2013). She is a recipient of several awards including the NSF CAREER award (2012), ONR summer faculty fellowship award (2013), AICHE DVS Outstanding Faculty of the Year Award (2015) and Outstanding Research Award, College of Engineering, Drexel University (2015).

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.

Seminar 3/9/2016 - Joseph Berry, National Renewable Energy Lab (NREL)

Mar 9, 2016  ·  12:00 p.m. 1:00 p.m.  ·  Bowen Hall Auditorium

Title and abstract to follow.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.

Seminar 3/23/2016 - Matthew Panzer, Tufts University

Mar 23, 2016  ·  12:00 p.m. 1:00 p.m.  ·  Bowen Hall Auditorium

Title and abstract to follow.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.

Seminar 4/6/2016 - Ted Sargent, University of Toronto

Apr 6, 2016  ·  12:00 p.m. 1:00 p.m.  ·  Bowen Hall Auditorium

Title and abstract to follow.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.

Seminar 4/13/2016 - Joao P. Cabral, Imperial College

Apr 13, 2016  ·  12:00 p.m. 1:00 p.m.  ·  Bowen Hall Auditorium

Title and abstract to follow.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.

Seminar 4/20/2016 - Oki Gunawan, IBM T.J. Watson Research Center

Apr 20, 2016  ·  12:00 p.m. 1:00 p.m.  ·  Bowen Hall Auditorium

Title and abstract to follow.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.

Seminar 4/27/2016 - Sascha Hilgenfeldt, University of Illinois

Apr 27, 2016  ·  12:00 p.m. 1:00 p.m.  ·  Bowen Hall Auditorium

Title and abstract to follow.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.