Event
MSE Seminar Series: Luz Martinez-Miranda
Friday, September 14, 2012
1:00 p.m.-2:00 p.m.
Room 2108 Chemical and Nuclear Engineering Bldg.
JoAnne Kagle
301 405 5240
jkagle@umd.edu
Liquid Crystals and Their Contribution to the Field of Photovoltaics
Luz Martinez-Miranda
Associate Professor
Department of Materials Science & Engineering
University of Maryland College Park
Organic photovoltaic cells are studied because of their ease of fabrication and relatively low price. In 2003, the results of a heterojunction consisting of a liquid crystal and a polymer liquid crystal were published. Heterojunctions studied until then consisted principally of an electron donor polymer and an electron acceptor polymer. Liquid crystals exhibit molecular orientation in their ordered phases (the smectic and the nematic). Alignment of the liquid crystal such that the delocalized electrons are parallel to the substrate provides a path for electrons, and holes, to move between and to reach the electrodes. Nanoparticles incorporated in a liquid crystal tend to align in rows in the liquid crystal. Together they form a heterojunction whose properties can be varied according to the nanoparticle size and shape, and the type of liquid crystal used. Nanowires combined with liquid crystals have the same effect while providing more support to the structure. A polymeric liquid crystal has the same effect in offering more support to the nanoparticles. The enhanced ordering of the liquid crystals can contribute to the increase in the efficiency of solar cells made up of organic materials.
