A Charge-transfer Phenomenon between 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyano- p-quinodimethane (F4TCNQ) and a Tetrathiafulvalene-based Self-assembled Monolayer Using an Indium-Tin Oxide Electrode

摘要

Tetrathiafulvalene (TTF: C6H4S4) is a well-known two-electron donor molecule that is electrochemically active, showing two reversible redox cycles at E_(1/2)~1 = 0.33 V and E_(1/2)~2 =0.71 V (vs SCE). It reacts with 7,7,8,8-tetracyanoquinodimethane (TCNQ) to form an electrically conductive TTF-TCNQ charge-transfer (CT) complex with metallic conductivity at room temperature. Thereafter, many kinds of TTF-TCNQ-family CT complexes composed of, for example, ethylenedithio-tetrathia-fulvalene (EDT-TTF) and 2,3,5,6-tetrafluoro-7,7,8,8-tetra-cyanoquinodimethane (F4TCNQ), have followed, In the early stage, the CT complexes in the form of a single crystal were investigated with respect to their bulk properties such as crystal structure, electrical conductivity, and optical properties. With many techniques such as LB-film, chemical vapor deposition (CVD), and self-assembled monolayers (SAM), having been applied in this research field, the properties of CT complexes with a mono- or multi-layer have been intensively investigated. Among these techniques, it is relatively easy to prepare SAM film and highly promising to construct such molecular architectures on metal and semiconductor surfaces. For example, a Au surface modified with a dodecanethiol chain with an EDT-TTF functional-group has already been reported.