Biology Department Seminar

Long, conjugated molecules can act as semiconducting "molecular wires." They appear to have enormous potential for development of inexpensive solar photovoltaics from organic material. They may mimic some function of energy capture in photosynthesis, but rely in part on different principles.. A field called Organic Photovoltaics (OPV) or "plastic solar," has created solar cells having efficiencies reaching 5%. We will argue that popular methods for making organic photovoltaic cells make little use of the potential of conjugated molecules to act as "wires," due in part to our limited understanding of what that potential is. Past difficulties with transport confines peoples' thinking. Limitations on transport, particularly for excitons, are almost seen as absolute, although no fundamental basis is known for such a belief. Our research aims learn whether long, conjugated molecules can be good "wires." Experiments described here seek to understand how fast charges and excitons move in conjugated molecules and whether there are limits to the distances they move without trapping. The experiments inject electrons or holes into long, conjugated molecules having charge or exciton traps at the ends using Brookhaven's Laser Electron Accelerator Facility (LEAF). Alternatively lasers photoexcite those molecules to create excited states. Possible roles of "wires" in biology will be noted.