Highly Conducting Ion‐Radical Salts of Tetrathiotetracene

TLDR: The electrical resistivity and thermoelectric power of the organic semiconductor tetrathiotetracene (TTT) and its chloride, bromide, iodide, and thiocyanate salts are reported as a function of temperature.

Abstract: The electrical resistivity and thermoelectric power of the organic semiconductor tetrathiotetracene (TTT) and its chloride, bromide, iodide, and thiocyanate salts are reported as a function of temperature. The ion–radical salts, of nearly 1:1 stoichiometry, were discovered to be highly conducting organic semiconductors and have resistivity values at room temperature ranging from 2.3 × 103 Ω·cm for TTT–chloride to 0.71 Ω·cm for TTT–iodide. The sign of the Seebeck coefficient of TTT–chloride corresponds to an n‐type semiconductor, while for TTT and the other salts it indicates p‐type behavior. Infrared absorption spectra of the solids, uv–visible spectra of solutions, preliminary x‐ray powder patterns and density measurements are correlated with electrical properties. The influence of constitution of the ion–radical salts on the electrical resistivity and possible mechanisms of conduction are discussed.