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Volumn 126, Issue 37, 2004, Pages 11648-11657

Stable room-temperature molecular negative differential resistance based on molecule-electrode interface chemistry

Author keywords

[No Author keywords available]

Indexed keywords

ELECTRIC CURRENTS; ELECTRODES; FERMI LEVEL; MOLECULAR VIBRATIONS; MOLECULES; REDUCTION; SOLVENTS; SURFACE CHEMISTRY; SYSTEM STABILITY;

EID: 4544373598     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja049584l     Document Type: Article
Times cited : (65)

References (79)
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    • Hipps, K. W. Science 2001, 294, 535-537.
    • (2001) Science , vol.294 , pp. 535-537
    • Hipps, K.W.1
  • 29
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    • Grotendort, J., Ed.; John von Neumann Institute for Computing: Julich
    • Dolg, M. In Modern Methods and Algorithms of Quantum Chemistry; Grotendort, J., Ed.; John von Neumann Institute for Computing: Julich, 2000; Vol. 1, pp 479-508.
    • (2000) Modern Methods and Algorithms of Quantum Chemistry , vol.1 , pp. 479-508
    • Dolg, M.1
  • 32
    • 4544235899 scopus 로고    scopus 로고
    • note
    • 3) on Au (cf. Bruening et al.41), as we could not make such measurements for the molecules on Hg. Of special relevance were the ellipsometric thickness and the tilt angle of the alkyl chains relative to the surface normal.
  • 33
    • 4544324448 scopus 로고    scopus 로고
    • note
    • The energies of the (free) molecules were calculated at the SAOP/TZZP level of theory and were found to be between 15 and 50 kJ/mol higher than those with the PM3 optimized geometry.
  • 46
    • 4544307051 scopus 로고    scopus 로고
    • note
    • If the whole system, after assembly, is immersed in D1 water or in hexane, (to check for possible influence of residual solvent, esp. on the effects of scan rate and on hysteresis by using a polar and an apolar solvent) essentially the same NDR behavior is observed as for the dry system.
  • 48
    • 4544284188 scopus 로고    scopus 로고
    • note
    • -5 M (cf Muskal et al.47). Monolayer rearrangement (and ordering) then occurs after initial adsorption. This can be outside the solvent (as for the dry NDR measurements) or in the solvent (as for the wet electrochemistry experiments). For the dry measurements, we preferred shorter adsorption times to minimize solvent exposure as this improved reproducibility. For the wet electrochemistry measurements this was not an issue.
  • 49
    • 4544340728 scopus 로고    scopus 로고
    • note
    • Coverages of 75-100% were found for the small disulfides, used in Bruening et al.,41 on Au and of 75% for a disulfide with one palmitoyl group.
  • 52
    • 4544314715 scopus 로고    scopus 로고
    • note
    • This proposed mechanism is based on the one for binding cystine to mercury in solution, given in Stankovich et al.51
  • 53
    • 4544250120 scopus 로고    scopus 로고
    • note
    • x layer.
  • 54
    • 4544265497 scopus 로고    scopus 로고
    • note
    • The PVR value is the ratio of the peak and the valley currents that occur at the beginning and the end of the range over which the system shows negative differential resistance.
  • 55
    • 4544290985 scopus 로고    scopus 로고
    • note
    • The time delay between each voltage scan was 2 min.
  • 56
    • 4544353061 scopus 로고    scopus 로고
    • note
    • 3.
  • 58
    • 4544318072 scopus 로고    scopus 로고
    • note
    • x layer). The simulations show that the tunneling current is 8 times lower for the wider barrier.
  • 59
    • 4544369375 scopus 로고    scopus 로고
    • note
    • We define a delay time as the interval time between sequences of voltage scans.
  • 65
    • 4544376348 scopus 로고    scopus 로고
    • note
    • x is about 0.5 V. After adsorption of the molecules the CPD decreases to < 0.2 V.6
  • 66
    • 4544350449 scopus 로고    scopus 로고
    • note
    • 3-terminated disulfide molecules. We assume that the reduction potential for the other molecules in the series is similar.
  • 67
    • 4544227305 scopus 로고    scopus 로고
    • note
    • x and 2.5 nm as the length of, the molecules.
  • 68
    • 4544318073 scopus 로고    scopus 로고
    • note
    • Since one side of the interface is a semiconductor, extra charge at the interface will normally lead to realignment of the semiconductor energy band positions, with respect to the metal Fermi level. This will change the band bending and the barrier height for electron transport from the metal toward the semiconductor. However, here the reduction reaction occurs at forward bias potentials that are much higher than the barrier height, which means that no depletion layer is left in the semiconductor. Therefore, we can assume that the observed NDR does not result from changes in the metal/semiconductor barrier heights.
  • 69
    • 4544244570 scopus 로고    scopus 로고
    • note
    • 2N.
  • 71
    • 4544372620 scopus 로고    scopus 로고
    • note
    • x length, 1.2 and 2.4 nm as the lengths of the short and the long molecules (without S), respectively. For the Hg-S bond we took 5.5 as the dielectric constant and 0.25 nm as the bond length.
  • 78
    • 4544265498 scopus 로고    scopus 로고
    • note
    • Because of the negative charges on the disulfide molecules after bond breaking and reduction, their HOMO-LUMO gap will decrease.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.