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Identification of vibrational signatures from short chains of interlinked molecule-nanoparticle junctions obtained by inelastic electron tunnelling spectroscopy
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap. (Electron Microscopy and Nanoengineering)
Vise andre og tillknytning
2013 (engelsk)Inngår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 5, nr 11, s. 4673-4677Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Short chains containing a series of metal- molecule-nanoparticle nanojunctions are a nano-materials system with the potential to give electrical signatures close to those from single molecule experiments while enabling to build portable devices on a chip. Inelastic electron tunnelling spectroscopy (IETS) measurements provide one of the most characteristic electrical signals of single and few molecules. In interlinked molecule-nanoparticle (NP) chains containing of typically 5-7 molecules in a chain, the spectrum is expected to be a superposition of the vibrational signature of individual molecules. We have established a stable and reproducible molecule-AuNP multi-junction by placing few 1,8-octanedithiol (ODT) molecules into a versatile and portable nanoparticle-nanoelectrode platform and measured for the first time vibrational molecular signatures complex and coupled few-molecule-NP junctions. From quantum transport calculations, we model the IETS spectra and identify vibrational modes as well as the number of molecules contributing to the electron transport in the measured spectra.

sted, utgiver, år, opplag, sider
2013. Vol. 5, nr 11, s. 4673-4677
HSV kategori
Forskningsprogram
Teknisk fysik med inriktning mot materialvetenskap
Identifikatorer
URN: urn:nbn:se:uu:diva-198704DOI: 10.1039/C3NR00505DISI: 000319008700011OAI: oai:DiVA.org:uu-198704DiVA, id: diva2:617493
Prosjekter
KoF U3MECTilgjengelig fra: 2013-04-23 Laget: 2013-04-23 Sist oppdatert: 2019-04-24bibliografisk kontrollert
Inngår i avhandling
1. Computational Studies of Electron Transport in Nanoscale Devices
Åpne denne publikasjonen i ny fane eller vindu >>Computational Studies of Electron Transport in Nanoscale Devices
2013 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

In this thesis, a combination of density functional theory (DFT) based calculations and nonequilibrium Green’s functions are employed to investigate electron transport in molecular switches, molecular cords and nanoscale devices.

  Molecular electronic devices have been proposed as an approach to complement today’s silicon based electronic devices. However, engineering of such miniature devices and design of functional molecular components still present significant challenges.

  First, the way to connect a molecule to conductive electrodes has to be controlled. We study, in a nanoelectrode-nanoparticle platform, how structural changes affect the measured conductance and how current fluctuations due to these structural changes can be decreased. We find that, for reproducible measurements, it is important to have the molecules chemically bonded to the surfaces of adjacent nanoparticles. Furthermore, we show by a combination of DFT and theoretical modeling that we can identify signals from single-molecules in inelastic electron spectroscopy measurements on these devices.

  Second, active elements based on molecules, some examples being switches, rectifiers or memory devices, have to be designed. We study molecular conductance switches that can be operated by light and/or temperature. By tuning the substituents on the molecules, we can optimize the shift of the most conducting molecular orbital and increase the effective coupling between the molecule and the electrodes when going from the OFF to the ON-state of the switches, giving high switching ratio (up to three orders of magnitude). We also study so called mechanoswitches that are activated by a mechanical force elongating the molecules, which means that these switches could operate as sensors.

  Furthermore, we have studied two different classes of compounds that may function either as rigid molecular spacers with a well-defined conductance or as molecular cords. In both cases, we find that it is of great importance to match the conjugation of the anchoring groups with the molecular backbone for high conductance.

  The last part of the thesis is devoted to another interesting semiconductor material, diamond. We have accurately calculated the band structure and effective masses for this material. Furthermore, these results have been used to calculate the Hall coefficient, the resistivity and the Seebeck coefficient.

sted, utgiver, år, opplag, sider
Uppsala: Acta Universitatis Upsaliensis, 2013. s. i-x, 89
Serie
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1090
Emneord
Density functional theory, Molecular electronics, Organosilicon chemistry, Diamond, Molecular switches, Nanoelectrode bridge platform, Molecular cords
HSV kategori
Forskningsprogram
Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik
Identifikatorer
urn:nbn:se:uu:diva-209261 (URN)978-91-554-8781-2 (ISBN)
Disputas
2013-11-29, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (engelsk)
Opponent
Veileder
Tilgjengelig fra: 2013-11-08 Laget: 2013-10-16 Sist oppdatert: 2014-01-23

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Forlagets fullteksthttp://dx.doi.org/10.1039/C3NR00505D

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