Exciton Management in Organic Solar Cells - Speaker Dr. Mark Thompson
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. Thompson will discuss his 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, he hase 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.
Speaker: Dr. Mark E. Thompson, Department of Chemistry, University of Southern California
Dr. Thompson 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 two years as a postdoctoral fellow in the Inorganic Chemistry laboratory at Oxford University. 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. 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.