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Self‐Assembled‐Monolayer Formation of Long Alkanedithiols in Molecular Junctions
Author(s) -
Akkerman Hylke B.,
Kronemeijer Auke J.,
van Hal Paul A.,
de Leeuw Dago M.,
Blom Paul W. M.,
de Boer Bert
Publication year - 2008
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.200700623
Subject(s) - monolayer , molecule , dithiol , phase (matter) , materials science , x ray photoelectron spectroscopy , self assembled monolayer , chemical physics , crystallography , chemistry , analytical chemistry (journal) , nanotechnology , chemical engineering , organic chemistry , engineering
The orientation of alkanedithiol molecules in self‐assembled monolayers (SAMs) is of vital importance for their transport properties in molecular junctions. It is demonstrated that a too‐low concentration of long alkanedithiols in ethanol leads to the formation of looped molecules, resulting in a 50‐fold increase of the current through the SAM. X‐ray photoelectron spectroscopy measurements show that high‐concentration dithiol solutions result in a preferential standing‐up phase. To obtain an almost full standing‐up phase of 1,14‐tetradecanedithiol (C14) a 30 m M concentration in ethanol is required, whereas a 0.3 m M concentration leads to a highly looped monolayer. The conduction through the full standing‐up phase of C14 and C16 is in accordance with the exponential dependence on molecule length as obtained from shorter alkanedithiols.