Thin-film phases of organic charge-transfer complexes formed by chemical vapor deposition

Thin films of organic charge-transfer salts, (TTF)(TCNQ) and (TTF)(DMDCNQI), are prepared by the chemical vapor deposition method, where TTF is tetrathiafulvalene, TCNQ is tetracyanoquinodimethane, and DMDCNQI is dimethyldicyanoquinonediimine. Depending on the substrate temperatures, we have obtained randomly oriented polycrystalline phases composed of relatively large crystals and microcrystalline thin-film phases, which sometimes contain well-grown nanowires. The latter shows much different conducting properties from the bulk crystals, and particularly the (TTF)(DMDCNQI) film is nearly as conductive as the (TTF)(TCNQ) film in spite of the bulk insulating property coming from the mixed-stack crystal structure.