uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
New Class of Molecular Conductance Switches Based on the [1,3]-Silyl Migration from Silanes to Silenes
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
Show others and affiliations
2013 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 21, 10909-10918 p.Article in journal (Refereed) Published
Abstract [en]

Based on first principles density functional theory calculations we propose a new molecularphotoswitch which exploits a photochemical [1,3]-silyl(germyl) shift leading from a silane to asilene (a Si=C double bonded compound). The silanes investigated herein act as the OFF state,with tetrahedral saturated silicon atoms disrupting the conjugation through the molecules. Thesilenes, on the other hand, have conjugated paths spanning over the complete molecules, andthus act as the ON state. We calculate ON/OFF conductance ratios in the range of 10 - 50at a voltage of +1 V. In the low bias regime the ON/OFF ratio increases to a range of 200 -1150. The reverse reaction could be triggered thermally or photolytically, with the silenebeing slightly higher in relative energy than the silane. The calculated activation barriers forthe thermal back-rearrangement of the migrating group can be tuned, and are in the range 108 -171 kJ/mol for the switches examined herein. The first principles calculations together witha simple one-level model shows that the high ON/OFF ratio in the molecule assembled in asolid state device is due to changes in the energy position of the frontier molecular orbitalscompared to the Fermi energy of the electrodes, in combination with an increased effectivecoupling between the molecule and the electrodes for the ON state.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2013. Vol. 117, no 21, 10909-10918 p.
Keyword [en]
Molecular electronics, organosilicon chemistry, electronic structure, density functional theory
National Category
Physical Chemistry
URN: urn:nbn:se:uu:diva-198705DOI: 10.1021/jp400062yISI: 000319896700005OAI: oai:DiVA.org:uu-198705DiVA: diva2:617501
Available from: 2013-04-23 Created: 2013-04-23 Last updated: 2013-11-08Bibliographically approved
In thesis
1. Computational Studies of Electron Transport in Nanoscale Devices
Open this publication in new window or tab >>Computational Studies of Electron Transport in Nanoscale Devices
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
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.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. i-x, 89 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1090
Density functional theory, Molecular electronics, Organosilicon chemistry, Diamond, Molecular switches, Nanoelectrode bridge platform, Molecular cords
National Category
Condensed Matter Physics Physical Chemistry
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
urn:nbn:se:uu:diva-209261 (URN)978-91-554-8781-2 (ISBN)
Public defence
2013-11-29, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (English)
Available from: 2013-11-08 Created: 2013-10-16 Last updated: 2014-01-23

Open Access in DiVA

No full text

Other links

Publisher's full texthttp://dx.doi.org/10.1021/jp400062y

Search in DiVA

By author/editor
Löfås, HenrikOrthaber, AndreasGrigoriev, AntonOtt, SaschaAhuja, RajeevOttosson, Henrik
By organisation
Materials TheoryDepartment of Chemistry - ÅngströmDepartment of Chemistry - BMCDepartment of Biochemistry and Organic Chemistry
In the same journal
The Journal of Physical Chemistry C
Physical Chemistry

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 595 hits
ReferencesLink to record
Permanent link

Direct link