Odd-even effects in charge transport across n-alkanethiolate-based SAMs.
This paper compares rates of charge transport across self-assembled monolayers (SAMs) of n-alkanethiolates having odd and even numbers of carbon atoms (nodd and neven) using junctions with the structure M(TS)/SAM//Ga2O3/EGaIn (M = Au or Ag). Measurements of current density, J(V), across SAMs of n-alkanethiolates on Au(TS) and Ag(TS) demonstrated a statistically significant odd-even effect on Au(TS), but not on Ag(TS), that could be detected using this technique. Statistical analysis showed the values of tunneling current density across SAMs of n-alkanethiolates on Au(TS) with nodd and neven belonging to two separate sets, and while there is a significant difference between the values of injection current density, J0, for these two series (log|J0Au,even| = 4.0 ± 0.3 and log|J0Au,odd| = 4.5 ± 0.3), the values of tunneling decay constant, β, for nodd and neven alkyl chains are indistinguishable (βAu,even = 0.73 ± 0.02 Å(-1), and βAu,odd= 0.74 ± 0.02 Å(-1)). A comparison of electrical characteristics across junctions of n-alkanethiolate SAMs on gold and silver electrodes yields indistinguishable values of β and J0 and indicates that a change that substantially alters the tilt angle of the alkyl chain (and, therefore, the thickness of the SAM) has no influence on the injection current density across SAMs of n-alkanethiolates.
Department of Chemistry and Chemical Biology, Harvard University , 12 Oxford Street, Cambridge, Massachusetts 02138, United States.
Mostafa
M
Baghbanzadeh
Felice C
FC
Simeone
Carleen M
CM
Bowers
Kung-Ching
KC
Liao
Martin
M
Thuo
Mahdi
M
Baghbanzadeh
Michael S
MS
Miller
Tricia Breen
TB
Carmichael
George M
GM
Whitesides
D000473:Alkanes / Q000138:chemical synthesis / Q000737:chemistry*; D004579:Electron Transport; D006046:Gold / Q000737:chemistry; D012834:Silver / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis / Q000737:chemistry*
D000473:Alkanes; D013438:Sulfhydryl Compounds; D012834:Silver; D006046:Gold