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Thermoelectrics: Direct Solar Thermal Energy Conversion

Terry M. Tritt^a1, Harald Böttner^a2 and Lidong Chen^a3

^a1 Clemson University, USA

^a2 Fraunhofer Institut für Physikalische Meβtechnik, Germany

^a3 China Academy of Sciences, China

The field of thermoelectricity began in the early 1800s with the discovery of the thermoelectric effect by Thomas Seebeck. Seebeck found that, when the junctions of two dissimilar materials are held at different temperatures (ΔT), a voltage (V) is generated that is proportional to ΔT. The proportionality constant is the Seebeck coeffcient or thermopower: α = −δV/ΔT. When the circuit is closed, this couple allows for direct conversion of thermal energy (heat) to electrical energy. The conversion effciency, η_TE, is related to a quantity called the fgure of merit, ZT, that is determined by three main material parameters: the thermopower α, the electrical resistivity ρ, and the thermal conductivity κ.

Terry M. Tritt can be reached at CU Complex Materials Laboratory, 118 Kinard Laboratory, Clemson University, Clemson, SC 29634–0978, USA; tel. 864–656–5319, and e-mail ttritt@clemson.edu.

Tritt is a professor of physics at Clemson University. The focus of the program is on electrical and thermal transport in new and novel materials, with current interests in materials for thermoelectric refrigeration and power generation applications. Tritt is considered an international expert in the feld of thermoelectric materials research. His primary research expertise lies in electrical and thermal transport properties and phenomena (especially in measurement and characterization techniques) in new and novel materials. In addition, Tritt has recently become involved in the synthesis and characterization of thermoelectric nanomaterials. He has extensive expertise in measurement science and has built an internationally known laboratory for the measurement and characterization of thermoelectric materials parameters, particularly thermal conductivity. Tritt has served as lead organizer of three Materials Research Society symposia on thermoelec-trics materials (MRS Volumes 478, 545 and 626). Tritt will serve as an MRS Meeting Chair for the Spring 2009 Meeting. He has been a member of the executive board of the International Thermoelectrics Society (ITS) since 1999, and served as chairman and host of the 24th ITC-2005 at Clemson in June of 2005. Tritt has written more than 150 journal publications and regularly gives invited presentations at national and international meetings. He also was recently an author and lead editor of a MRS Bulletin theme (March 2006) on thermoelectric materials and devices. Tritt edited a three-volume set on “Recent Trends in Thermoelectric Materials Research” (Academic Press-2000) and has recently edited a book by Kluwer Press on thermal conductivity.

Harald Böttner can be reached at Fraunhofer Institute for Physical Measurement Techniques, Heidenhofstraβe 8, D-79110 Freiburg, Germany; tel. +49–761–8857–121, and e-mail harald.boettner@ipm.fraunhofer.de.

Böttner is head of the Department Thermoelectric Systems at the Fraunhofer Institute for Physical Measurement Techniques in Freiburg, Germany. He graduated in chemistry from the University of Münster (UM), Germany, and also received his PhD degree from UM in 1977. In 1978, Böttner joined the Fraunhofer ISC, Würzburg. He moved to his current position in 1980. Böttner developed IV-VI infrared semiconductor lasers through 1995. From 1995 to 2003, he worked with semiconductor gas sensors. He started working with activities in thermoelectrics in 1989. Böttner's research activities are focused on thin flm and nanoscale thermoelectrics, as well as microelectronics-related device technology. He has authored or co-authored approximately 20 patents and more than 100 papers in journals, proceedings, reviews, and chapters in handbooks. Böttner also is a board member of the International Thermoelectric Society.

Lidong Chen can be reached at Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Rd., Shanghai 200050, China; tel. +86–21–5241–4804, and e-mail cld@mail.sic.ac.cn.

Chen is a professor and deputy director of the Shanghai Institute of Ceramics at the Chinese Academy of Sciences. He graduated with a degree in chemistry engineering at Hunan University, China, in 1981, and received his PhD degree in materials science from Tohoku University, Japan, in 1990. Chen worked primarily on advanced ceramics until 1996. Afterward, he started activities in thermoelectrics. Chen's current research activities are focused on the exploration of new thermoelectric compounds and nano-composite materials and on developing thermoelectric device technology.