Prof. Rachel Segalman
Dept of Chemical Engineering
In the last decade, the use of self-assembling block copolymers to nanopattern substrates and template synthesis has made incredible gains as a primary step towards the fabrication of nanodevices. Many studies have demonstrated a sophisticated level of control over the self-assembling, coil-type polymer systems to produce long range order. The knowledge now exists to begin to pattern polymers with a much higher degree of complexity and inherent functionality. It is apparent, for instance, that the mesostructure of conductive polymers impacts their luminescence and photovoltaic efficiency. For instance, block copolymers made from electron donating and electron accepting blocks are interesting for applications in photovoltaics where self assembly on the size scale of an exciton diffusion length (~10nm) is advantageous. Continuous, nanometer-scale interpenetrating phases of electron donor and acceptor components would permit exciton dissociation to occur throughout the active layer and allow all separated charges to be easily transported to the proper electrode. In this talk, I will discuss the materials concepts necessary for the production of efficient organic optoelectronic-device structures, the synthesis of donor-acceptor block copolymers, and the aggregation and device performance of these materials. The potential of semiconducting block copolymers lies in the promise of a self-assembled active layer which is optimized to promote exciton dissociation and can be made into large area, mechanically flexible, inexpensive devices.
Bio: Dr. Segalman is an Assistant Professor of Chemical Engineering at UC Berkeley and Faculty Scientist of LBNL. She graduated from the University of Texas at Austin with a B.S. in Chemical Engineering. While pursuing a Ph.D. with Ed Kramer at UC Santa Barbara, she developed a graphoepitaxial strategy for aligning arrays of block copolymer spheres over distances previously unobserved. Further quantitative microscopic analysis of this nanometer scale patterning then led to fundamental discoveries as to the nature of ordering and melting on in two dimensions. Dr. Segalman then did a year of postdoctoral research in Strasbourg, France studying the synthesis of conducting block copolymers. Her current research is focused on understanding the connection between morphology and properties in conducting polymers. More detail on the Segalman group at Berkeley can be found at: http://cheme.berkeley.edu/people/faculty/segalman/segalman.html