Tetrathiafulvalene-based nanocrystals: site-selective formation, device fabrication, and electrical properties

Abstract

A tetrathiafulvalene(TTF)--based nanocrystal was site--selectively synthesized only in the gap between two electrochemical electrodes by using a nanoscale electrocrystallization method. Furthermore, the nanocrystal was directed to form a bridge between two electrodes using alternating current (AC) electrolysis. The nanocrystal was found to have a one--dimensional π--π stacking structure of TTF molecules, which is the source of its high electrical conductivity. Further, when we reused the two electrochemical electrodes as the source and drain electrodes, a two--terminal device could be readily obtained. The electrical conductivity of the nanocrystal was comparable to that of a partially oxidized bulk crystal. A bottom--gate--type FET was also obtained when the device was fabricated on a silicon substrate. A weak field effect was observed even though the nanocrystal has a metallic nature. The nanoscale electrocrystallization is considered to be applicable to nanocrystal fabrication using various organic molecules. We expect that further enhancement of this method will lead to the development of eco--friendly nanofabrication processes. 11-12We have reported site--selective fabrication of nanocrystals in the gap between two electrodes by alternating current (AC) electrolysis. Unlike the electrochemical fabrication of conductive organic bulk A tetrathafulvalene(TTF)-based nanocrystal was selectively synthesized only in the gap between two electrodes using a nanoscale electrocrystallization. A two-terminal TTF-based device and an FET could be readily obtained via an eco-friendly nanofabrication process.

Review—Micro/Nanoelectrodes and Their Use in Electrocrystallization: Historical Perspective and Current Trends

“…Hasegawa showed site-selective formation of TTF-based CTC nanocrystals between the source and drain electrodes. 98 Tapered and multi-tip electrodes were patterned by photolithography. The gap between the two electrodes was 5 μm.…”

Tetrathiafulvalene as a Conductive Film-Making Additive on High-Voltage Cathode

“…Therefore, it is an organic mixed-valence compound. High electrical conductivity has been observed in its oxidized form with various salts. − For example, TTF + Cl – is known as an outstanding organic semiconductor; its conductivity is 12 orders of magnitude higher than that of neutral TTF at room temperature. Therefore, significant research has been conducted on TTF and its derivatives in charge transfer complexes, nonlinear optics, and Langmuir–Blodgett films. , However, to the best of our knowledge, it has never been used as a functional electrolyte additive in lithium-ion cells.…”