Luminescence and absorption spectra of BEDT-TTF and its ion radical salt

• Published in: Chemical physics letters Vol. 223; no. 4; pp. 318 - 322
• Main Authors: Kozlov, M.E., Tanaka, Y., Tokumoto, M., Tani, T.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 24.06.1994; Elsevier Science
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Photoluminescence; Physics; Solid organic materials; BEDT-TTF; Photoluminescence; Dimers; Energy-level splitting; Absorption spectra; Experimental study; Organic compounds
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/0009-2614(94)00464-1

Photoluminescence spectra of the organic donor compound, bis (ethylenedithio)tetrathiafulvalene (BEDT-TTF), has been observed in crystals and rigid solution at liquid He temperature. The spectra have similar shapes with a maximum at 1.96 eV and an intense side-band near 1.79 eV. A solid state effect reveals itself in low-temperature excitation spectra. A drastic increase in the excitation efficiency in the low-energy region (2.1–3.1 eV) compared to the high-energy one (3.1–4.0 eV) appears in the crystalline sample. The emission of BEDT-TTF is quenched by a modification of the degree of oxidation of molecules forming the crystal and is weak in the case of monovalent (BEDT-TTF)Br salt. The shapes of the luminescence spectra correlate with the absorption data of the substances. The recorded spectra are interpreted assuming a dimer-like arrangement of molecules in the investigated compounds.