Hydrogen-bonding tetrathiafulvalene (TTF) conductors: Carrier generation by self-doping

• Published in: Physica. B, Condensed matter Vol. 405; no. 11; pp. S23 - S26
• Main Authors: Kobayashi, Y., Yoshioka, M., Saigo, K., Hashizume, D., Ogura, T.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Kidlington Elsevier 01.06.2010
• Subjects: Arrays; Carriers; Charge carriers: generation, recombination, lifetime, and trapping; Charge transfer; Condensed matter; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity of specific materials; Conductivity phenomena in semiconductors and insulators; Conductors; Electronic transport in condensed matter; Exact sciences and technology; Hydrogen bonding; Isotope effect; Networks; Physics; Polymers; organic compounds (including organic semiconductors); Salt-bridge hydrogen bond; Electrical conductivity; Frontier orbital; Organic conductors; Doping; Tetrathiafulvalene derivatives; Intermolecular interaction; Isotope effect; Hydrogen bonds; Protonation of TTF; AC conductivity; Charge carrier generation; Property structure relationship; Protic doping; Crystal structure
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2009.10.049

A salt-bridge-type hydrogen bonding salt, ammonium tetrathiafulvalene-2-carboxylate has a conductivity of 2.2x10 super(-4 S/cm at 300 K. [inlineimage] is neither a charge transfer complex nor an ion-radical salt, suggesting that it is a new type of molecular conductor. The carrier generation mechanism in [inlineimage] was investigated using spectroscopic analysis. The crystal structure of [inlineimage] was determined using powder X-ray crystallography. The TTF moiety is stacked in one dimension with a helical columnar hydrogen-bonded network and S...S contacts, forming a two-dimensional intermolecular interaction in a supramolecular TTF array. Molecular orbital calculations showed that the SOMO of the embedded radical is in a quasi-closed shell configuration (an f-electron-like configuration), suggesting a stabilization of the unpaired electron in the molecular array in the solid. The AC conductivity of [inlineimage] and the deuterium-substituted [inlineimage] compound shows a large isotope effect below 200 K, implying a correlation between the salt-bridge hydrogen bonding moiety and the transport phenomena.)