Self-Assembly of Photoluminescent Copper(I)−Dithiol Multilayer Thin Films and Bulk Materials

Brust, Mathias; Blass, P. M.; Bard, Allen J.

doi:10.1021/la970493u

Cited by 133 publications

(185 citation statements)

References 31 publications

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“…Previous studies showed that BDMT is adsorbed on a Au surface with a benzene ring perpendicular to the surface. 35,[45][46][47][48][49] In this orientation, one thiol group binds to the Au surface and the other is free on the surface. This free thiol group on the surface may lead to the formation of a multilayer as indicated by previous studies.…”

Section: Resultsmentioning

confidence: 99%

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Electrochemical Metal Deposition on Top of an Organic Monolayer

Uosaki

2006

J. Phys. Chem. B

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Electrochemical deposition of metals (platinum or gold) only on top of an organothiolate, 1,4-benzenedimethanethiol (BDMT) or hexanedithiol (HDT), self-assembled monolayer (SAM) on a Au(111) substrate was achieved by electrochemical reduction of PtCl 4 2-or AuCl 4 -ion, which was preadsorbed on one free thiol end group of the dithiol SAM formed on a Au surface, in a metal-ion-free sulfuric acid solution at potentials more negative than the reduction potential of the metal ion. Angle-resolved X-ray photoelectron spectroscopy (AR-XPS) measurement after the reduction of preadsorbed PtCl 4 2-ion on BDMT/Au(111) electrode showed the presence of Pt not underneath but on top of the BDMT SAM. After a negative potential scan of the Pt/BDMT/Au(111) electrode to -1.30 V in 0.1 M KOH solution, a typical cyclic voltammogram of a clean Au(111) electrode was obtained, showing that the BDMT SAM with a Pt layer was reductively desorbed. These results proved that a Pt-BDMT SAM-Au substrate sandwich structure without a short circuit between the two metals was successfully constructed by this technique. Furthermore, a decanethiol (DT) monolayer was constructed on a Au layer, which was formed by the reduction of preadsorbed AuCl 4 -ion on HDT/Au(111) electrode. The formation of DT/Au/HDT/Au(111) structure was confirmed as two cathodic peaks corresponding to reductive desorption of DT from Au on top of the HDT/Au(111) at -0.97 V and that of Au/ HDT from Au(111) at -1.12 V were observed when potential was scanned negatively to -1.35 V.

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Section: Resultsmentioning

confidence: 99%

“…Then the metal ions in the solution bind to the free SH end group of the SAM surface. [35][36][37] Finally, the electrode is transferred to a metal-ion-free solution, and the adsorbed metal ions are electrochemically reduced to form a metal layer on top of the SAM.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Metal Deposition on Top of an Organic Monolayer

Uosaki

2006

J. Phys. Chem. B

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“…Adsorption of HS-C x H 2x -SH (Cx-dithiol) from ethanol onto a gold surface results in a monolayer with one thiol bonded to gold, the so-called standing-up phase (28,(35)(36)(37)(38)(39). X-ray photoelectron spectroscopy (XPS) is a versatile surface technique that discriminates between chemisorbed S-Au (S2p: 161.9 Ϯ 0.1 eV) versus unbound S-C (S2p: 163.5 Ϯ 0.1 eV), and is used to validate the orientation of the monolayers.…”

Section: Methodsmentioning

confidence: 99%

Electron tunneling through alkanedithiol self-assembled monolayers in large-area molecular junctions

Akkerman

Naber

Jongbloed

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

179

222

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The electrical transport through self-assembled monolayers of alkanedithiols was studied in large-area molecular junctions and described by the Simmons model [Simmons JG (1963) J Appl Phys 34:1793-1803 and 2581-2590] for tunneling through a practical barrier, i.e., a rectangular barrier with the image potential included. The strength of the image potential depends on the value of the dielectric constant. A value of 2.1 was determined from impedance measurements. The large and well defined areas of these molecular junctions allow for a simultaneous study of the capacitance and the tunneling current under operational conditions. Electrical transport for octanedithiol through tetradecanedithiol self-assembled monolayers up to 1 V can simultaneously be described by a single effective mass and a barrier height. There is no need for additional fit constants. The barrier heights are in the order of 4 -5 eV and vary systematically with the length of the molecules. Irrespective of the length of the molecules, an effective mass of 0.28 was determined, which is in excellent agreement with theoretical predictions. and consist of a saturated carbon backbone with one (or two) thiol end groups. Experimentally, the tunneling current through a monolayer of alkane(di)thiols was shown to be temperatureindependent and to decrease exponentially with increasing molecular length (4, 5). The transport has been interpreted in terms of the classical tunneling model through a thin insulating film as provided by Simmons (24,25). In this model the tunneling current depends on the mean value of the barrier height, allowing for a simplification of the problem of an arbitrarily shaped potential barrier to that of a rectangular barrier. This model has been applied to junctions based on SAMs (4, 26), but an extra fit parameter ␣ is needed to obtain a fit to the measured data. However, as already explained by Simmons (24, 25), for a practical tunnel junction the image potential has to be taken into account. This effect has been neglected in the literature so far.The system studied in this article is a tunnel junction with an alkanedithiol SAM as the insulating film, a bottom gold electrode, and a highly conducting polymer as a top contact. The polymeric top contact allows for the fabrication of devices with a yield of almost unity for areas up to 100 m in diameter (5). The highly conducting polymer used is PEDOT:PSS, a waterbased suspension of poly(3,4-ethylenedioxythiophene) stabilized with poly(4-styrenesulfonic acid). The polymer acts as a cushion for the thermally evaporated metal atoms to land on and prevents the metal atoms from penetration into the molecular layer. Consequently, the formation of electrical shorts is prevented (27). Simmons ModelThe tunneling current density J through a rectangular potential barrier with height 0 is given by (4, 24, 26):wherewhere ⌬s is the barrier width at the Fermi level of the electrodes, here equal to the total length s of the tunneling path between the electrodes, m e is the bare electron mass, V is th...

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“…Dithiol SAMs have been utilized to make nanodevices, for measurements of electricity transport, and for multilayer formation. [4][5][6][7][14][15][16][17]22,23,25,[30][31][32][33][34][35][36][37][38][39][40] So far, most studies have focused on their use either as a linker for metal nanoparticles to study charge transfer or as a spacer for multilayer formation. Compared to the well-studied monothiolate SAMs, not many reports have focused on the growth and structure of dithiol SAMs, and disagreements exist among the literature reported concerning the preparation of dithiol SAMs, the resulting structures, and the quality of dithiol SAMs.…”

Section: Introductionmentioning

confidence: 99%

“…42 On the other hand, Bard et al used HSC 6 SH as a linker to construct a copper(I)-dithiol multilayer thin film, which was evidenced by ellipsometric, X-ray photoelectron and fluorescence spectroscopic, and electrochemical techniques. 30 HSC 6 SH was also used for the preparation of CdS nanoparticle-dithiol multilayer by one of us 33,34 and Alivisatos. 43 a Au nanoparticle on a Au surface was reported recently.…”

Section: Introductionmentioning

confidence: 99%

1,6-Hexanedithiol Self-Assembled Monolayers on Au(111) Investigated by Electrochemical, Spectroscopic, and Molecular Mechanics Methods

Qu¹,

Kim²,

Lee³

et al. 2009

J. Phys. Chem. C

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1,6-Hexanedithiol (HSC 6 SH) self-assembled monolayers (SAMs) on Au(111) were formed in a 1 mM ethanolic solution and were investigated by voltammetry in 0.1 M aqueous KOH solution. HSC 6 SH SAMs on Au(111) were further probed by X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), sum frequency generation spectroscopy (SFG), and molecular mechanics calculation (MMC). An identical investigation was performed with the self-assembly of hexanethiol (C 6 SH) on Au(111) for comparison. Linear sweep voltammograms showed that a full monolayer of thiolate (7.6 ((0.2) × 10 -10 mol -2) chemisorbed on Au(111) with both HSC 6 SH and C 6 SH, while the peak potential of the electroreduction of the former assembly was more negative than that of the latter. XPS revealed that two different forms of sulfur existed at HSC 6 SH SAMs on Au(111), i.e. a thiolate and a thiol. The STM image could not be resolved with HSC 6 SH SAMs, while it was atomically well-defined with the C 6 SH case. SFG results showed that alkyl chains within the HSC 6 SH SAMs were in an all-trans conformation. Thus the experimental results concluded that densely packed and higly oriented HSC 6 SH SAMs could be successfully formed on Au(111) with the incubation conditions in the practical solution. MMC presented that HSC 6 SH SAMs were more stable than C 6 SH ones because of the additional end-end interaction among the thiol groups faced up to the air, albeit both SAMs were tilted by 28°from the surface normal.

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Self-Assembly of Photoluminescent Copper(I)−Dithiol Multilayer Thin Films and Bulk Materials

Cited by 133 publications

References 31 publications

Electrochemical Metal Deposition on Top of an Organic Monolayer

Electrochemical Metal Deposition on Top of an Organic Monolayer

Electron tunneling through alkanedithiol self-assembled monolayers in large-area molecular junctions

1,6-Hexanedithiol Self-Assembled Monolayers on Au(111) Investigated by Electrochemical, Spectroscopic, and Molecular Mechanics Methods

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