A new (TTF) ₁₁ I ₈ organic molecular conductor: from single crystals to flexible all-organic piezoresistive films

This paper reports selective synthesis of two iodine-containing TTF (tetrathiafulvalene) salts: one, (TTF)11I8, is a new molecular conductor while another is the known non-conducting (TTF)I3 compound. Single crystals of both salts were prepared using different amounts of iodine in the redox process between TTF and I2. X-ray data showed that the resulting conducting (TTF)11I8 salt might be considered as a new modulated phase of the non-stoichiometric (TTF)I0.7+δ salts. The electrical resistance of single crystals of (TTF)11I8 reveals a semiconducting-like behaviour. The paper presents also a study of electromechanical properties of organic conductive bi-layer (BL) films prepared by covering different organic polymeric films with a thin network of oriented submicrocrystals of (TTF)I0.7+δ phases. These BL films exhibit a combination of flexibility, lightweight, and high piezo-resistivity properties showing therefore a potential interest for electronic sensing applications where lightweight, large area coverage and flexibility are required.