LANGMUIR-BLODGETT SUPERCONDUCTORS BASED ON C-60, NEW DONOR-ACCEPTOR SYSTEMS, AND A NEW CONDUCTING POLYMER

Pure C-60 forms Langmuir-Blodgett (LB) multilayers; a hysteretic low-f ield signal in an EPR spectrometer in a K-doped 50-layer LB multilayer of C-60 appears at or below 8.1 K, due to flux exclusion (Meissner-Oc hsenfeld effect) by K3C60 i.e. due to superconductivity: this is the f irst LB film superconductor. The crystal structure of BDMT-TTeF (1) wi th C-60 and a molecule of CS2, an electrical insulator, has been deter mined. Other donors, such as DTDAF(2), form a 1:1 insulating and a 2:5 semiconducting (0.01 S/cm) complex with TCNQ, with evidence far TCNQ( --) dianions in the solid state. A conducting polymer, poly-(naphtho-[ 2,3-c]thiophene-alt-bithiophene) (3) has a band gap of only 0.65 eV, a nd a conductivity of 0.002 S/cm.