Aromatic polyazomethine belong to conjugated polymers with extended π-system having alternately CH=N group and benzene ring in the main chain. Since many years these polymers have been of interest due to their thermal stability and promising electro-, photoluminescent and nonlinear optical properties [1-3]. A series of four aromatic polyazomethine thin films have been obtained by thermal vacuum evaporation onto quartz substrates via polycondensation process. As initial monomers terephaldehyde (TPA) and four different amines i.e.: paraphenylene-diamine (PPDA); 7,2-diamino-fluorene; 1,1'-biphenyl-3,3',4,4' tetramine; 3-amino-4-(1-naphthyldiazenyl) phenylamine (fat brown RR) were used. The absorption spectra of investigated films cover the range from 200 to 2500 nm (6.2 - 0.496 eV) and reveal a few absorption bands. The feature at about 2.8 eV is attributed to transition between delocalized states with the electron-phonon interaction involved. The vibronic progression was deconvoluted with modified Fourier self-deconvolution and Finite Response Operator (FIRO) method. The bands in the range 3.8 - 4.9 eV are mainly attributed to the localized to delocalized states (and vice versa) transitions and Frenkel-type exciton formation. For all investigated films, the strongest absorption band, seen at 5.48 - 6.2 eV, is due to transitions between localized states. Changes of the position and intensity of the bands for different polyazomethine films are connected with the conformation of polymer chain. The energy gap of investigated films, following the relation typical for amorphous semiconductors (like in [4]), was found to change from 2.05 to 2.4 eV and is expected to be dependent on polyazomethine chain structure and the length of conjugated parts. These optical investigations seems to be useful to better understand electronic structure of different aromatic polyazomethine thin films as new optoelectronic materials.

[1] C. Y. Yang, S. A. Janekhe, Macromol. 1995, 28, 1180.

[2] A. Kubono, N. Okui,, Prog. Polym. Sci. 1994, 19, 389.

[3] F. Rohlfing, D. D. C. Bradley, Chem. Phys. 1998, 227, 133.

[4] B. Jarzabek, E. Schab-Balcerzak, T. Chamenko, D. Sęk, J. Cisowski, A. Volozhin, J. Non-Cryst. Solids 2002, 229, 1057.

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1. Azobenzene-Functionalized Polymers as Potential Materials for Fabrication of Nanostructures