Abstract: Four methods to prepare thin films of charge-transfer complexes have been reviewed and the structural characterization of the related CT films was studied. In the LB films of the complex of N,N,N’,N’-tetramethylbenzidine (N-TMB) and 2-octadecyl-7,7,8,8- tetracyanoquinodimethane (C18H37TCNQ), the chromophore planes for both C18H37TCNQ and N-TMB are nearly parallel to the substrate surface while the hydrocarbon chain is considerably tilted with respect to the substrate normal. By dipping the mixed LB films of stearic acid and C18H37TCNQ into a petroleum ether solution of 3,3’,5,5’-tetramethylbenzidine(TMB), the thin films of charge-transfer complex can also be formed. In that case, the chromophore plane of TMB is nearly perpendicular to the substrate surface with its long axis lying on the substrate. If dipping LB films of pure C18H37TCNQ into a petroleum ether solution of TMB, we can also obtain the thin films of TMB•C18H37TCNQ and the orientation of the chromophore plane of TMB keeps nearly unchanged compared with the CT complexe thin films prepared from mixed LB films. The orientation of the hydrocarbon chain of the CT complexes, however, depends on the preparation methods undoubtedly.

Key words: Charge transfer complex, Langmuir-Blodgett technology, Thin films, 　Preparation method, Structural characterization