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
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.
Molecular electronics, organosilicon chemistry, electronic structure, density functional theory
IdentifiersURN: urn:nbn:se:uu:diva-198705DOI: 10.1021/jp400062yISI: 000319896700005OAI: oai:DiVA.org:uu-198705DiVA: diva2:617501