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Originally published in Science Express on 15 February 2007
Science 16 March 2007:
Vol. 315. no. 5818, pp. 1568 - 1571
DOI: 10.1126/science.1137149
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Reports

Thermoelectricity in Molecular Junctions

Pramod Reddy,1* Sung-Yeon Jang,2,3*{dagger} Rachel A. Segalman,1,2,3{ddagger} Arun Majumdar1,3,4{ddagger}

By trapping molecules between two gold electrodes with a temperature difference across them, the junction Seebeck coefficients of 1,4-benzenedithiol (BDT), 4,4'-dibenzenedithiol, and 4,4''-tribenzenedithiol in contact with gold were measured at room temperature to be +8.7 ± 2.1 microvolts per kelvin (µV/K), +12.9 ± 2.2 µV/K, and +14.2 ± 3.2 µV/K, respectively (where the error is the full width half maximum of the statistical distributions). The positive sign unambiguously indicates p-type (hole) conduction in these heterojunctions, whereas the Au Fermi level position for Au-BDT-Au junctions was identified to be 1.2 eV above the highest occupied molecular orbital level of BDT. The ability to study thermoelectricity in molecular junctions provides the opportunity to address these fundamental unanswered questions about their electronic structure and to begin exploring molecular thermoelectric energy conversion.

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.
3 Materials Science Division, Lawrence Berkeley Laboratory, Berkeley, CA 94720, USA.
4 Departments of Mechanical Engineering and Materials Science and Engineering, University of California, Berkeley, CA 94720, USA.

* These authors contributed equally to this paper.

{dagger} Present address: Optoelectronic Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea.

{ddagger} To whom correspondence should be addressed. E-mail: majumdar{at}me.berkeley.edu (A.M.); segalman{at}berkeley.edu (R.A.S.)

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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)
Science 319, 1056-1060
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