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.