TY  - JOUR
AU  - Li, C.
AU  - Mishchenko, A.
AU  - Li, Z.
AU  - Pobelov, I.
AU  - Wandlowski, Th.
AU  - Li, X.Q.
AU  - Würthner, F.
AU  - Begrets, A.
AU  - Evers, F.
TI  - Electrochemical gate-controlled electron transport of redox-active single perylene bisimide molecular junctions
JO  - Journal of physics / Condensed matter
VL  - 20
SN  - 0953-8984
CY  - Bristol
PB  - IOP Publ.
M1  - PreJuSER-331
SP  - 374122
PY  - 2008
N1  - This work was supported by the HGF Project 'Molecular Switches', the SPP 1243, the Volkswagen Foundation and the University of Berne and the Research Center Julich. IP acknowledges support of the German Academic Exchange Agency for a PhD fellowship. FE, AA and AB acknowledge support from the SPP 1243 'Center for Functional Nanostructures' situated at Karlsruhe University.
AB  - We report a scanning tunneling microscopy (STM) experiment in an electrochemical environment which studies a prototype molecular switch. The target molecules were perylene tetracarboxylic acid bisimides modified with pyridine (P-PBI) and methylthiol (T-PBI) linker groups and with bulky tert-butyl-phenoxy substituents in the bay area. At a fixed bias voltage, we can control the transport current through a symmetric molecular wire Au|P-PBI(T-PBI)|Au by variation of the electrochemical 'gate' potential. The current increases by up to two orders of magnitude. The conductances of the P-PBI junctions are typically a factor 3 larger than those of T-PBI. A theoretical analysis explains this effect as a consequence of shifting the lowest unoccupied perylene level (LUMO) in or out of the bias window when tuning the electrochemical gate potential VG. The difference in on/off ratios reflects the variation of hybridization of the LUMO with the electrode states with the anchor groups. I(T)-E(S(T)) curves of asymmetric molecular junctions formed between a bare Au STM tip and a T-PBI (P-PBI) modified Au(111) electrode in an aqueous electrolyte exhibit a pronounced maximum in the tunneling current at -0.740, which is close to the formal potential of the surface-confined molecules. The experimental data were explained by a sequential two-step electron transfer process.
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:21694429
UR  - <Go to ISI:>//WOS:000258734700024
DO  - DOI:10.1088/0953-8984/20/37/374122
UR  - https://juser.fz-juelich.de/record/331
ER  -