Thermoelectricity in Molecular Junctions

doi:10.1126/science.1137149

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1137149v1

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Published Online February 15, 2007
Science DOI: 10.1126/science.1137149

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Submitted on November 3, 2006
Accepted on January 29, 2007

Thermoelectricity in Molecular Junctions

Pramod Reddy ¹, Sung-Yeon Jang ², Rachel Segalman ³^*, Arun Majumdar ⁴^*

¹ Applied Science and Technology Program, University of California Berkeley, CA 94720, USA.
² Department of Chemical Engineering, University of California, Berkeley, CA 94720, USA; Materials Science Division, Lawrence Berkeley Laboratory, Berkeley, CA 94720, USA; Present address: Optoelectronic Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea.
³ Applied Science and Technology Program, University of California Berkeley, CA 94720, USA; Department of Chemical Engineering, University of California, Berkeley, CA 94720, USA; Materials Science Division, Lawrence Berkeley Laboratory, Berkeley, CA 94720, USA.
⁴ Applied Science and Technology Program, University of California Berkeley, CA 94720, USA; Materials Science Division, Lawrence Berkeley Laboratory, Berkeley, CA 94720, USA; Departments of Mechanical Engineering and Materials Science and Engineering, University of California, Berkeley, CA 94720, USA.

^* To whom correspondence should be addressed.
Rachel Segalman , E-mail: segalman{at}berkeley.edu
Arun Majumdar , E-mail: majumdar{at}me.berkeley.edu

By trapping molecules between two gold electrodes with a temperaturedifference across them, the junction Seebeck coefficient of1,4-benzenedithiol (BDT), 4,4'-dibenzenedithiol (DBDT) and 4,4''-tribenzenedithiol(TBDT) in contact with gold was measured at room temperatureto be (+8.7 ± 2.1) microvolts per Kelvin (µV/K), (+12.9± 2.2) µV/K, and (+14.2 ± 3.2) µV/K, respectively.The positive sign unambiguously indicates p-type (hole) conductionin these heterojunctions, while the Au Fermi level positionfor Au-BDT-Au junctions was identified to be 1.2 eV above thehighest occupied molecular orbital (HOMO) level of BDT. Theability to study thermoelectricity in molecular junctions providesthe opportunity to address these fundamental unanswered questionsabout their electronic structure while also offering an opportunityto begin exploring molecular thermoelectric energy conversion.

THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:

Nuclear Coupling and Polarization in Molecular Transport Junctions: Beyond Tunneling to Function.: M. Galperin, M. A. Ratner, A. Nitzan, and A. Troisi (2008)
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