Organic crystals containing highly conducting cation-anion-mixed sheets

Abstract We synthesized the new organic crystalline material ɛ-BETS2(IBr2)2TCE (BETS = bis(ethylenedithio)tetraselenafulvalene, TCE = 1,1,2-trichloroethane) and performed the single-crystal X-ray structural analysis, electrical resistivity measurement, and band calculation to elucidate the electronic properties. We reveal the possibility that the close interactions between cations and anions in the same sheets enable high conductivity. The findings indicate that evidently weak interactions in molecular crystals can almost qualitatively alter the electrical properties.