A comprehensive study of extended tetrathiafulvalene cruciform molecules for molecular electronics: Synthesis and electrical transport measurements
| Autor: | Peter Bæch Abrahamsen, Thorbjørn J. Morsing, Bo W. Laursen, Tao Li, Riccardo Frisenda, Nicolás Agraït, Karsten Jennum, Emil Glibstrup, Christian R. Parker, Mogens Brøndsted Nielsen, Herre S. J. van der Zant, Maria Teresa Gonzalez, Mikkel A. Christensen, Marco Santella, Kasper Nørgaard, Gabino Rubio-Bollinger, Edmund Leary, Zhongming Wei, Eduardo Antonio Della Pia, Xingbin Jiang |
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| Jazyk: | angličtina |
| Rok vydání: | 2014 |
| Předmět: | |
| Zdroj: | Repositorio Institucional del Instituto Madrileño de Estudios Avanzados en Nanociencia instname |
| Popis: | Cruciform-like molecules with two orthogonally placed π-conjugated systems have in recent years attracted significant interest for their potential use as molecular wires in molecular electronics. Here we present synthetic protocols for a large selection of cruciform molecules based on oligo(phenyleneethynylene) (OPE) and tetrathiafulvalene (TTF) scaffolds, end-capped with acetyl-protected thiolates as electrode anchoring groups. The molecules were subjected to a comprehensive study of their conducting properties as well as their photophysical and electrochemical properties in solution. The complex nature of the molecules and their possible binding in different configurations in junctions called for different techniques of conductance measurements: (1) conducting-probe atomic force microscopy (CP-AFM) measurements on self-assembled monolayers (SAMs), (2) mechanically controlled break-junction (MCBJ) measurements, and (3) scanning tunneling microscopy break-junction (STM-BJ) measurements. The CP-AFM measurements showed structure-property relationships from SAMs of series of OPE3 and OPE5 cruciform molecules; the conductance of the SAM increased with the number of dithiafulvene (DTF) units (0, 1, 2) along the wire, and it increased when substituting two arylethynyl end groups of the OPE3 backbone with two DTF units. The MCBJ and STM-BJ studies on single molecules both showed that DTFs decreased the junction formation probability, but, in contrast, no significant influence on the single-molecule conductance was observed. We suggest that the origins of the difference between SAM and single-molecule measurements lie in the nature of the molecule-electrode interface as well as in effects arising from molecular packing in the SAMs. This comprehensive study shows that for complex molecules care should be taken when directly comparing single-molecule measurements and measurements of SAMs and solid-state devices thereof. |
| Databáze: | OpenAIRE |
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