Mechanically controlled binary conductance switching of a single-molecule junction.
Molecular-scale components are expected to be central to the realization of nanoscale electronic devices. Although molecular-scale switching has been reported in atomic quantum point contacts, single-molecule junctions provide the additional flexibility of tuning the on/off conductance states through molecular design. To date, switching in single-molecule junctions has been attributed to changes in the conformation or charge state of the molecule. Here, we demonstrate reversible binary switching in a single-molecule junction by mechanical control of the metal-molecule contact geometry. We show that 4,4'-bipyridine-gold single-molecule junctions can be reversibly switched between two conductance states through repeated junction elongation and compression. Using first-principles calculations, we attribute the different measured conductance states to distinct contact geometries at the flexible but stable nitrogen-gold bond: conductance is low when the N-Au bond is perpendicular to the conducting pi-system, and high otherwise. This switching mechanism, inherent to the pyridine-gold link, could form the basis of a new class of mechanically activated single-molecule switches.
Quek
Su Ying
SY
Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Kamenetska
Maria
M
Steigerwald
Michael L
ML
Choi
Hyoung Joon
HJ
Louie
Steven G
SG
Hybertsen
Mark S
MS
Neaton
J B
JB
Venkataraman
Latha
L
D003198:Computer Simulation; D004553:Electric Conductivity; D004563:Electrochemistry / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D008839:Microelectrodes; D008956:Models, Chemical; D036103:Nanotechnology / Q000379:methods*; D012666:Semiconductors; D013314:Stress, Mechanical; D014159:Transducers
D006046:Gold