New class of molecular conductance switches based on the [1,3]-silyl migration from silanes to silenes
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
On the basis of first-principles density functional theory calculations, we propose a new molecular photoswitch which exploits a photochemical [1,3]-silyl(germyl) shift leading from a silane to a silene (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. The silenes, on the other hand, have conjugated paths spanning over the complete molecules and thus act as the ON state. We calculate ON/OFF conductance ratios in the range of 10-50 at 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 silene being slightly higher in relative energy than the silane. The calculated activation barriers for the 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 with a simple one-level model show that the high ON/OFF ratio in the molecule assembled in a solid state device is due to changes in the energy position of the frontier molecular orbitals compared to the Fermi energy of the electrodes, in combination with an increased effective coupling between the molecule and the electrodes for the ON state.
Place, publisher, year, edition, pages
2013. Vol. 117, no 21, 10909-10918 p.
Activation barriers, Effective coupling, First-principles calculation, First-principles density functional theory, Frontier molecular orbitals, Molecular conductance, Relative energies, Reverse reactions, Calculations, Density functional theory, Electrodes, Molecular orbitals, Molecules, Solid state devices, Silanes
IdentifiersURN: urn:nbn:se:kth:diva-134450DOI: 10.1021/jp400062yISI: 000319896700005ScopusID: 2-s2.0-84878370074OAI: oai:DiVA.org:kth-134450DiVA: diva2:676701
FunderSwedish Research CouncilCarl Tryggers foundation Swedish Energy AgencySwedish Foundation for Strategic Research
QC 201312062013-12-062013-11-252013-12-06Bibliographically approved