Oriented Epitaxial Films of (NMP) (TCNQ)

An important step in the characterization of organic conductors is the ability to correlate the solid state electrical properties of these materials with their composition and crystal structure. In many cases it has not been possible to grow single crystals of suitable size or purity for such investigations. The use of epitaxial films represents an alternative approach. In addition, such films may be potentially useful as larger area conductive surfaces. This paper describes the preparation of relatively large-area, oriented epitaxial films of the organic conductor N-methylphenazinium- 7,7,8,8-tetracyanoquinodimethanide (NMP) (TCNQ) by means of vacuum evaporation. Factors that appear to affect the degree of orientation, the film areas, and the chemical composition include the source temperature, the kind of evaporation (rapid or slow), the degree of lattice matching between the substrate and the organic material, and the substrate surface charge potential.