Abstract:

Organic photovoltaics (OPVs) are promising for developing low cost solar energy conversion technologies. Because light absorption in OPVs initially generates strongly bound excitons, an electron donor/acceptor interface with suitable HOMO/LUMO energy level offsets is necessary for efficient charge photogeneration. Bulk heterojunction polymer solar cells, consisting of a blend of a donor polymer semiconductor and a fullerene acceptor molecule, now have power conversion efficiencies of up to 6-8% depending on the selection of materials and device optimization. Realization of high efficiency (>10-15%) polymer solar cells requires advances in the synthesis, processing, tuning of electronic structure, and properties of polymer semiconductors. Towards this end, our laboratory is exploring molecular and nanoscale engineering approaches to tailoring materials for high performance bulk heterojunction (BHJ) polymer solar cells. In this talk I will use several examples to illustrate our efforts in this area. These include new small band-gap donor polymers for constructing highly efficient polymer/fullerene and hybrid polymer/inorganic nanocrystal solar cells. Nanostructured assemblies of new block copolymers are found to have enhanced photovoltaic properties compared to the parent homopolymers while self-assembled polymer nanowires (5-30 nm width and 400-900 aspect ratios) are shown to be good building blocks for constructing efficient bulk heterojunction solar cells. To overcome the drawbacks of fullerenes new oligomer acceptor materials are also being developed for OPVs.

Bio:

Samson A. Jenekhe holds the Boeing-Martin Endowed Professor of Chemical Engineering and Professor of Chemistry at the University of Washington. He graduated from Michigan Technological University with a BS degree in 1977. His graduate studies were at the University of Minnesota where he received the MS (Chemical Engineering, 1980), MA (Philosophy, 1981) and Ph.D. (Chemical Engineering, 1985). Following appointments at Honeywell, Inc., Physical Sciences Center, Minneapolis, MN (1982-1987) he started his academic career at the University of Rochester, where held the positions of Assistant, Associate, and Full Professor of Chemical Engineering, Professor of Materials Science, and Professor of Chemistry during 1988-2000. He assumed his current positions at the University of Washington in August 2000. His broad research interests are in the chemistry, physics, and engineering of organic semiconductors, electronic and optoelectronic devices, materials and devices for solar energy technologies, self-assembly and soft nanotechnology, and polymer science. He has served on the Editorial Advisory Boards of Macromolecules (1994-1996), Chemistry of Materials (1997-2002), Chemical Engineering Journal (2007-), and Micro- and Nano-systems (2009-). He is a Fellow of the American Association for the Advancement of Science and a Fellow of the American Physical Society. His research accomplishments are summarized in over 260 journal articles, h-index = 62, three edited books, and 24 issued US patents. He is a highly cited author in materials science, in engineering, and in chemistry. Thomson Reuters' Science Watch recently (March 2011) named him among the top 40 on their list of “Top Materials Scientists of the Past Decade,” 2000-2010, based on their analysis of the citations and impacts of 0.5 million researchers in the world.