Change search
ReferencesLink to record
Permanent link

Direct link
Formation and electronic transport properties of bimolecular junctions based on aromatic coupling
KTH, School of Biotechnology (BIO), Theoretical Chemistry.
KTH, School of Biotechnology (BIO), Theoretical Chemistry.
KTH, School of Biotechnology (BIO), Theoretical Chemistry.ORCID iD: 0000-0003-0007-0394
2010 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 22, no 32, 325102- p.Article in journal (Refereed) Published
Abstract [en]

A systematic first-principles study on conductance-voltage characteristics of bi-(quasi) oligo(phenylene ethynylene)-monothiol molecular junctions reported by Wu et al (2008 Nat. Nanotechnol. 3 569) is presented. The so-called ortho-and para-conformations of the bimolecular junction are considered. Our calculation indicates that the bimolecular junction prefers to take the ortho-conformation because of its lower energy. The simulation supports the experimental findings that aromatic coupling between two molecules is strong enough to induce the formation of molecular junctions. By comparing with experimental results, structure parameters for a probable bimolecular junction are determined. The underlying mechanism for formation of the bimolecular junction and its electron transport is discussed.

Place, publisher, year, edition, pages
2010. Vol. 22, no 32, 325102- p.
Keyword [en]
National Category
Condensed Matter Physics
URN: urn:nbn:se:kth:diva-29417DOI: 10.1088/0953-8984/22/32/325102ISI: 000280542900013ScopusID: 2-s2.0-77956927461OAI: diva2:397859
QC 20110216Available from: 2011-02-16 Created: 2011-02-02 Last updated: 2012-05-15Bibliographically approved
In thesis
1. Theoretical Modeling of Intra- and Inter-molecular Charge Transport
Open this publication in new window or tab >>Theoretical Modeling of Intra- and Inter-molecular Charge Transport
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on theoretical study of charge transportproperties in molecular systems. The understanding of the transportprocess and mechanism in molecular systems is essential forthe design of new functional molecular materials and molecularelectronic devices. The molecular junctions and organic molecularcrystals have been used as the model systems to highlight the usefulnessof theoretical modelling. A molecular junction is a system that consists ofone or several molecules sandwiched between two electrodes.The charge transport in molecular junctions is a very complex processthat is affected by the interaction between molecules and electrodes,the surroundings, as well as electron-electron (e-e) andelectron-phonon (e-p) couplings. When the molecule-electrode couplingis strong, the transport process can be very quick. If the e-p couplingis weak, the inelastic tunneling has only negligible contributions to thetotal current and the elastic electron tunneling plays the dominant role.Furthermore, the hopping process becomes dominant in the case of strong e-pcoupling, for which the geometric relaxation of the molecule needsto be considered. In this thesis, we have examined these three kinds oftransport processes separately.

The first studied system is a molecular junction consisting of aromaticallycoupled bimolecules. Its elastic electron tunneling property is simulatedusing Green's functional theory at density functional theory level.The dependence of the conductance of bimolecular junctions on the vertical distances,horizontal distances and the tilt angles has been systematically studied. Theinelastic electron tunneling spectra (IETS) of molecular junctions have beencalculated for several systems that were experimentally measured with conflictingresults and controversial assignments. Our calculations provide the reliableassignments for the experimental spectra and revealed unprecedented detailsabout the molecular conformations within the junctions under different conditions.It demonstrates that a combined theoretical and experimental IETS study is capableof accurately determining the structure of a single molecule inside the junction.The hopping process is a dominant charge transfer process in organic molecularcrystals. We have studied the charge transport ability of four kinds of n-typeorganic semiconductor materials to find out the related structure-to-propertyrelationship. It is done by adopting the quantum charge transfer rate equationcombined with the random walk approach.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. x, 68 p.
Trita-BIO-Report, ISSN 1654-2312 ; 2012:15
charge transport, molecular junction, organic molecular materials, Green's function, first-principles simulation
National Category
Physical Chemistry
Research subject
SRA - Transport
urn:nbn:se:kth:diva-94103 (URN)978-91-7501-371-8 (ISBN)
Public defence
2012-06-05, FA32, AlbaNova University Center, Roslagstullsbacken 21, Stockholm, 10:00 (English)
TrenOp, Transport Research Environment with Novel Perspectives
QC 20120515Available from: 2012-05-15 Created: 2012-05-07 Last updated: 2012-05-15Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Lin, Li-LiSong, Xiu-NengLuo, Yi
By organisation
Theoretical Chemistry
In the same journal
Journal of Physics: Condensed Matter
Condensed Matter Physics

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: 39 hits
ReferencesLink to record
Permanent link

Direct link