Science at the Edge
Engineering Seminar
May
17th,
2013
11:30
a.m.
1400
Biomedical and
Physical Sciences Building
Refreshments
served
at 11:15 a.m.
Mark
E. Thompson
Department
of
Chemistry
University
of
Southern California
Abstract
The
exciton is a critical part of each of the processes leading to
photocurrents in
Organic PhotoVoltaics (OPVs), and being able to control the
location, lifetime
and energy of the exciton is essential to achieving high
efficiency. We have
investigated methods for tuning
exciton energies and controlling their migration paths, both
intramolecularly
and within a thin film. I
will discuss
our most recent work with both organic dyes, such as
squaraines and dipyrrins
as well as porphyrinic materials for OPVs.
This involves a careful materials design study that
leads to both low
energy absorption (into the nearIR) and the efficient use of
multiple absorbers
to efficiently harvest photons through the entire visible
spectrum. To that end
we have used transient
absorption spectroscopy and measured the rates of singlet and
triplet energy
transfers between organic dyes (BODIPY and tetracenes). Both intra- and
inter-molecular energy
transfers take place on the picoseconds time scale. Thus, the systems are
fully equilibrated into
the lowest energy triplet state(s) before nonradiative decay. Using this approach we
can efficiently
harvest energy across the visible and into the NIR. I will
also discuss our
latest results with new singlet fission materials for
efficient light
harvesting in OPVs. Our control of singlet and triplet
excitons has been
important in exploring the use of singlet fission to enhance
the efficiencies
of OPVs.
Bio
Dr. Mark E. Thompson is
Professor of Chemistry and Materials Science at the University
of Southern
California. He
received his B.S. degree in Chemistry in 1980 (U.C. Berkeley)
and his Ph.D. in
chemistry in 1985 (California Institute of Technology). He spent 2 years as a
postdoctoral fellow in
the Inorganic Chemistry laboratory at Oxford University. Prof. Thompson took a
position in the
chemistry department at Princeton University in 1987, as an
assistant
professor. In 1995 he
moved his research
team to the University of Southern California, where he is
currently a
Professor of Chemistry. He
has won a
number of awards, including the MRS Medal in 2006, given by
the Materials
Research Society, and the Jan Rachman Prize for Outstanding
Achievement in Flat
Panel Displays, also in 2006, given by the Society for
Information Display. In
2011 he was named the 12 of the top 100 most
influential chemists in the world by Thomson-Rueters. In 2012 he was received
the Alexander von
Humboldt Research Award. He
currently has over 250 papers in print and over 125 US
patents. His research
interests involve the optical
and optoelectronic properties of molecular materials and
devices, particularly
organic LEDs and solar cells, as well as nanoscale materials,
catalysis and
biosensors.
For further
information
please contact Prof. Christina Chan, Department of Chemical
Engineering and
Materials Science at [log in to unmask]
Persons with disabilities have the right
to request and
receive reasonable accommodation. Please call the Department of
Chemical
Engineering and Materials Science at 355-5135 at least one day
prior to the
seminar; requests received after this date will be met when
possible.