Seminar: Rachel Segalman
Associate Professor of Chemical and Biomolecular Engineering
University of California, Berkeley
Molecular and Polymer Solution Processible Thermoelectrics
November 3, 2010 | 4:00pm | Elings Hall 1601
co-presented with the Center for Energy Efficient Materials
Thermoelectric materials for energy generation have several advantages over conventional power cycles including lack of moving parts, silent operation, miniaturizability, and CO2 free conversion of heat to electricity. Excellent thermoelectric efficiency requires a combination of high thermopower (S, V/K), high electrical conductivity (σ, S/cm), and low thermal conductivity (κ, W/mK). To date the best materials available have been inorganic compounds with relatively low earth abundance and highly complex, vacuum processing routes (and hence greater expense), such as Bi2Te3. Molecular materials and hybrid organic-inorganics bring the promise of inexpensive, solution processible, mechanically durable devices. While highly conductive polymers are now common place, they generally demonstrate low thermopower. Our work on molecular scale junctions that nanostructuring of organics allows them to act as thermionic filters between inorganic junctions which can lead to enhanced thermoelectric properties. We have taken inspiration from this fundamental understanding to design material systems in which we combine a high electrical conductivity, low thermal conductivity polymer with a nanoparticle that contributes high thermopower. Additionally, the work functions of the two materials are well-aligned which introduces the possibility of thermionic filtering at the interface and an additional boost to the power factor. The combination of these effects results in a new hybrid, solution processible material with a thermoelectric figure of merit within an order of magnitude of the Bi2Te3. In this talk, I will discuss both the use of thermoelectric measurements to gain insight to molecular junctions and how this insight translates to design principles for polymer and hybrid thermoelectrics.
B.S. University of Texas at Austin, (1998); Ph.D. University of California, Santa Barbara (2002); Hendrick C. Van Ness Lectureship, Rensselaer Polytechnic Institute (2009); Alfred P. Sloan Fellow (2009); Presidential Early Career Award in Science and Engineering (PECASE, 2008); Lawrence Berkeley National Lab, Materials Science Division's Young Scientist of the Year Award (2008); Mohr-Davidow Ventures Innovators Award (2007), Technology Review's Top 35 Innovators under 35 years old (TR35-2007), 3M Untenured Faculty Award (2006-2008), Hellman Family Young Faculty Award (2007); National Science Foundation CAREER Award (2005); Intel Young Faculty Award (2004); Chateaubriand Fellowship (2003); Corning Foundation Fellowship (2001); MRS Graduate Student Award Finalist (2001); National Science Foundation Fellowship (1998).