Properties of viologen-TCNQ (2-2) Langmuir-Blodgett films

In conducting systems based on Langmuir-Blodgett(LB) films, TCNQ derivatives have been extensively studied as electron acceptor molecules. We have investigated the optical, electrical, and magnetic properties of viologen-(TCNQ)/sub 2/ LB films. In UV/visible absorption measurements, we have observed a TCNQ peak at 381 nm and a dimer peak at 626 nm. Iodine doping affects the degree of charge transfer and increases the conductivity of the films. The UV/visible absorption spectra of the LB film doped with I/sub 2/ show a peak at 400/spl sim/430 nm and there is no dimer absorption peak. Electron spin resonance (ESR) measurements suggest that the viologen-(TCNQ)/sub 2/ LB film exhibits an anisotropic property, i.e. the ESR signal shows angular dependence. The in-plane electrical conductivity of the undoped film is approximately 4.3/spl times/10/sup -6/ S/cm at room temperature.