Superconducting super-organized nanoparticles of the superconductor (BEDT-TTF)2Cu(NCS)2

The synthesis of (BEDT-TTF)2Cu(NCS)2 in the presence of poly(ethylene glycol) leads to super-organized nanoparticles of 2–8 nm size. Samples contain crystalline nanoparticles of the κ-(BEDT-TTF)2Cu(NCS)2 phase. The electrical conductivity at room temperature is about 0.08 S · cm–1, a typical value for nanopowders of tetrathiafulvalene-based conducting compounds. The current-voltage characteristic for an individual nanoparticle aggregate is fitted with a Shockley diode model. A saturation current of 4.1 pA and a threshold voltage of 0.45 V are extracted. N1s and S2p lines in X-ray photoelectron spectroscopy evidence a charge transfer, characteristic for tetrathiafulvalene-based conducting salts. Magnetic susceptibility studies show a superconducting transition at 9.1 K, a characteristic value for the κ-(BEDT-TTF)2Cu(NCS)2 phase. The thermoelectric power of the nanopowder is represented by the average //c and //b values for the single-crystal. Finally, resistivity for the nanopowder is nearly flat in the metallic region.