LB films of TCNQ in a mixed valence state incorporated from the aqueous subphase: preparation and characterisation

A positively charged monolayer of diphenylbis(octadecylamino)phosphonium was prepared and the tetracyanoquinodimethane (TCNQ) moiety was incorporated as the counterion from a subphase containing an aqueous solution of (CH3CH2)3NH(TCNQ)2. The isotherm shape, the area per molecule, the collapse pressure and the monolayer stability were dependent on the subphase concentration, the spreading process and the temperature. The degree of order and architecture of the films were studied by means of scanning electron microscopy (SEM), infrared (IR) and ultraviolet–visible (UV–VIS) spectroscopy.