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Chemistry Seminar, March 5
Dr. Jill Millstone, Post Doctorate - Jean Frechet's Lab
will speak on
"Designing Semiconductors Polymers for
Friday, March 5, 2010, 4-5 p.m.
Dr. Millstone will be available to meet with students at 3:15 to 3:50 p.m. in the Deck Room 103.
Solar cells based on conjugated polymers and fullerenes represent the state-of-the-art in organic photovoltaics, and depend on the efficient generation, separation, and extraction of photogenerated charge. Typically processed as bulk heterojunctions, these device structures are efficient only when the formation of continuous, interpenetrating, nanoscale morphologies can be obtained through processing parameters such as thermal annealing or solvent evaporation rates. Therefore it is necessary to develop both an understanding and an approach to designing materials which self-assemble into these morphologies with well-defined interfacial properties. Here, we present a series of developments in polymer design and processing which allow one to control active layer morphology via polymer crystallinity, compatibilization, and stability. We first examine the influence of polymer design on the formation of crystalline domains in thin films via the development of donor-acceptor block copolymers and polymers of controlled crystallinity. We build on this work to construct devices from pre-formed nanocrystalline regions of both donor and acceptor materials in the form of nanoparticles. Finally, we present methods to freeze favorable active layer morphologies via crosslinked conjugated polymers, which have proven efficient in both improving processibility and maintaining high power conversion efficiencies over an extended operating period.