Thermoelectricity in molecular junctions

Science

Volumn 315, Issue 5818, 2007, Pages 1568-1571

  Reddy, Pramod ^a   Jang, Sung Yeon ^b,c,e   Segalman, Rachel A ^a,b,c   Majumdar, Arun ^a,c,d  

^a UNIVERSITY OF CALIFORNIA   (United States)

^b University of California   (United States)

^c LAWRENCE BERKELEY NATIONAL LABORATORY   (United States)

^d UNIVERSITY OF CALIFORNIA   (United States)

^e Korea Institute of Science and Technology   (South Korea)

Author keywords

[No Author keywords available]

Indexed keywords

1,4 BENZENEDITHIOL; 4,4' DIBENZENEDITHIOL; 4,4'' TRIBENZENEDITHIOL; GOLD; THIOL DERIVATIVE; UNCLASSIFIED DRUG;

CONDUCTIVITY; ELECTRODE; GOLD; TEMPERATURE GRADIENT;

ANALYTICAL ERROR; ARTICLE; ELECTRIC CONDUCTIVITY; ELECTRIC POTENTIAL; ELECTRICITY; ELECTRODE; ELECTRONICS; ENERGY; ENERGY CONVERSION; MOLECULE; PRIORITY JOURNAL; ROOM TEMPERATURE; TEMPERATURE DEPENDENCE; TEMPERATURE SENSITIVITY; THERMOELECTRICITY;

EID: 33947412649     PISSN: 00368075     EISSN: 10959203     Source Type: Journal    
DOI: 10.1126/science.1137149     Document Type: Article

References (32)

1. A. Aviram, M. A. Ratner, Chem. Phys. Lett. 29, 277 (1974).
2. W. U. Huynh, J. J. Dittmer, A. P. Alivisatos, Science 295, 2425 (2002).
3. G. Yu, J. Gao, J. C. Hummlen, F. Wudl, A. J. Heeger, Science 270, 1789 (1995).
4. M. A. Reed, C. Zhou, C. J. Muller, T. P. Burgin, J. M. Tour, Science 278, 252 (1997).
5. H. Park et al., Nature 407, 57 (2000).
6. B. Xu, N. J. J. Tao, Science 301, 1221 (2003).
7. P. Damle, A. W. Ghosh, S. Datta, Chem. Phys. 281, 171 (2002).
8. M. Paulsson, S. Datta, Phys. Rev. B 67, 241403 (2003).
9. F. Zahid, A. W. Ghosh, M. Paulsson, E. Polizzi, S. Datta, Phys. Rev. B 70, 245317 (2004).
10. Consider a molecule strongly bound to one electrode and very weakly bound to the other. An example of this is scanning tunneling spectroscopy; the tip is weakly interacting with the molecule, which is strongly bound to a substrate. Under bias, such a configuration produces asymmetric I-V curves because the chemical potential of the tip crosses the HOMO and LUMO levels of the molecule, whereas that of the substrate is pinned to the molecular levels. Hence, by applying a tip bias, one can determine the chemical potential position with respect to the HOMO and LUMO levels. However, to make realistic molecular devices, the molecule cannot be weakly bound to one electrode, given that otherwise the device would be mechanically unstable and electrically irreproducible because of uncertainties of the contact. But in the case of a molecule strongly bound to both the electrodes, the chemical potential of both of electrodes is pinned and hence, symmetric I-V curves are produced under bias (9). This symmetry in the I-V characteristics makes it impossible to determine whether transport is through HOMO or LUMO levels (9).
11. X. Y. Xiao, B. Q. Xu, N. J. Tao, Nano Lett. 4, 267 (2004).
12. M. Di Ventra, S. T. Pantelides, N. D. Lang, Phys. Rev. Lett. 84, 979 (2000).
13. E. G. Emberly, G. Kirczenow, Phys. Rev. B 58, 10911 (1998).
14. J. G. Kushmerick et al., Phys. Rev. Lett. 89, 086802 (2002).
15. J. Taylor, M. Brandbyge, K. Stokbro, Phys. Rev. Lett. 89, 138301 (2002).
16. W. Liang, M. P. Shores, M. Bockrath, J. R. Long, H. Park, Nature 417, 725 (2002).
17. J. Park et al., Nature 417, 722 (2002).
18. H. K. Lyeo et al., Science 303, 816 (2004).
19. C. C. Williams, H. K. Wickramasinghe, Nature 344, 317 (1990).
20. J. C. Poler, R. M. Zimmerman, E. C. Cox, Langmuir 11, 2689 (1995).
21. One might suspect that the heat flow from the substrate to the tip would cause the tip temperature to increase. However, tip-substrate heat transport is mostly due to conduction through air (thermal conductance through the molecules trapped in between the tip and the substrate or through a liquid meniscus, if present, is very small in comparison) (22). Because the tip-sample thermal resistance is sufficiently larger than that between the Au tip and the thermal reservoir, the Au tip will be at the reservoir temperature. Our group has previously shown this to be true (22). Further analysis that supports the idea that the tip is at ambient temperature is provided in (23). Hence, the temperature difference applied across the substrate and the reservoir is the same as that across the tip-substrate junction.
22. L. Shi, A. Majumdar, J. Heat. Trans. 124, 329 (2002).
23. Materials and methods are available as supporting material on Science Online.
24. S. Y. Jang, P. Reddy, A. Majumdar, R. A. Segalman, Nano Lett 6, 2362 (2006).
25. B. de Boer et al., Langmuir 19, 4272 (2003).
26. F. J. Blatt, Thermoelectric Power of Metals (Plenum Press, New York, 1976), pp. xv, 264.
27. M. Buttiker, Y. Imry, R. Landauer, S. Pinhas, Phys. Rev. B 31, 6207 (1985).
28. F with respect to HOMO and LUMO levels of a monolayer.
29. G. D. Mahan, J. O. Sofo, Proc. Natl. Acad. Sci. U.S.A. 93, 7436 (1996).
30. T. E. Humphrey, H. Linke, Phys. Rev. Lett. 94, 096601 (2005).
31. R. Y. Wang, R. A. Segalman, A. Majumdar, Appl. Phys. Lett. 89, 173113 (2006).
32. We acknowledge support from NSF under grant no. EEC-0425914, the NSF-Nanoscale Science and Engineering Center (NSEC) Center of Integrated Nanomechanical Systems, the Berkeley-Industrial Technology Research Institute (ITRI, Taiwan) Research Center, and the Department of Energy Basic Energy Sciences (DOE-BES) Thermoelectrics Program and DOE-BES Plastic Electronics Program at the Lawrence Berkeley National Laboratory.