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Center for Excitonics
Seminar Series Announcement
TUES, October 4, 2011
3:00 PM
RLE Haus Room: 36-428
Comparing the Primary Electron Transfer Process in Organic Photovoltaic
Heterojunctions with Photosynthetic Reaction Centers
Garry Rumbles National Renewable Energy Laboratory, University of Colorado
Abstract
This presentation will focus on some of the fundamental science associated
with the rapidly emerging field of organic photovoltaics (OPV). It will
include a discussion of how the OPV field is evolving, examine some of the
fundamental scientific issues that underpin the subject, and will discuss
how spectroscopy can help to understand these issues. The goal is to enable
both a better understanding of how these systems function and consequently
help to advance solar energy conversion efficiencies of future OPV devices.
So-called organic photovoltaic devices have seen certified power conversion
efficiencies increase from 2.5% in 2001 to ~9% in 2011. Close inspection of
the strategies employed to realize this impressive improvement in
performance reveal a common approach of synthesizing new donor polymers,
fullerene acceptors and, in some cases, new device architectures. It is
questionable as to whether this approach will result in a similar four-fold
level of improvement over the next ten years. And it is this question that
motivates the work that will be described. At the heart of all OPV
devices is the donor-acceptor interface, where photogenerated excitons are
dissociated into separated charge carriers. Using flash photolysis,
timeresolved microwave conductivity as a tool for detecting mobile carriers,
a number of recently-studied systems will be demonstrated. These may include
systems that contain new conjugated polymers, novel derivatives of
fullerenes, single-walled carbon nanotubes and colloidal quantum dots, to
name a few. These studies will serve to highlight a fundamental issue that
we have yet fully understand: how are these carriers created with such
efficiency and yield, and in a system that does not immediately suggest that
this is possible? The talk will therefore include a speculative discussion
about how we might better understand this process by looking at the function
of Nature's photosynthetic reaction centers.
Bio
Garry received his B.Sc (hons) in Chemistry with Electronics at the
University of Southampton, United Kingdom in 1980 and his Ph.D in Molecular
Photochemistry at the University of London, United Kingdom in 1984.
Currently, he is a NREL Fellow in the Chemical and Material Science Center
at the National Renewable Energy Laboratory in Golden, Colorado as well as
Professor Adjoint in the Department of Chemistry and Biochemistry at the
University of Colorado, Boulder, Colorado. His research interest is in next
generation solar photoconversion concepts based on conjugated molecules and
polymers combined and nanostructured species, with a focus on the
fundamental photophysics of exciton dynamics and charge generation and
recombination kinetics.
Light refreshments will be served.
The Center for Excitonics is an Energy Frontier Research Center funded by
the U.S. Department of Energy, Office of Science and Office of Basic Energy
Sciences
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