SCIENCE AT THE EDGE SEMINAR SERIES

Engineering Seminar

Friday, 13 January 2012 at 11:30am

Room 1400 Biomedical and Physical Sciences Bldg.

Refreshments at 11:15

Speaker: Michael S. Arnold
         Department of Material Science and Engineering,
         University of Wisconsin, Madison

Title:   Structure- and Property-Controlled Nanocarbon Materials for
         Electronics and Light-Harvesting

Abstract:

Semiconducting graphene-derived carbon nanomaterials such as carbon 
nanotubes and quantum-confined graphene nanostructures have exceptional 
properties that make them highly attractive for applications in 
semiconductor electronics and optoelectronics.  In this talk, I will 
detail two recent advances in carbon-based electronic materials that we 
have realized in my research group.  1) First, we have pioneered a new 
class of photovoltaic materials and devices based on structure-controlled 
and electronic-type controlled semiconducting carbon nanotubes in which we 
are employing the nanotubes as the primary optical absorber.  We have 
shown that we can efficiency harvest light using nanotubes and separate 
the photogenerated charges using all-carbon nanotube/C60 fullerene 
heterojunctions.  The carbon/carbon fullerene heterostructures are an 
evolution of polymer photovoltaic systems and exploit carbon nanotubes' 
strong near-infrared absorptivity, excellent charge transport 
characteristics, and chemical stability.  2) In the second part of the 
talk, I will introduce a new form of semiconducting graphene-based 
materials that we call nanoperforated graphene.  Nanoperforated graphene 
is created by perforating large-area graphene membranes with nearly 
close-packed hexagonal arrays of holes with sub-20 nm dimensionality.
I will detail how to scalably synthesize nanoperforated graphene using 
self-assembling lithographic approaches including block copolymer- and 
nanosphere-lithography and will show that it has semiconducting behavior 
with a band gap inversely proportional to its minimum feature size. 
I will also present on a new synthetic approach that we have pioneered for 
growing nanostructured graphene materials, from the bottom-up, that avoids 
edge-defect-inducing etching.  The combination of self-assembling 
lithography with bottom-up directed growth is expected to enable the 
scalable realization of high-performance, high-mobility semiconducting 
graphene materials for semiconductor electronics, plasmonic wave-guiding, 
and molecular sensing.