Influence of a Photoconductive Polymer Matrix on the Photoluminescence of Cationic Polymethine Dyes

Using symmetric cationic indopolycarbocyanines HIC and HIDC as an example, the authors detected the enhancement of their photoluminescence in films of photoconductive polymers poly–N–epoxypropyl carbazole and poly–N–vinyl carbazole as compared to nonphotoconductive polymers, i.e., polyvinyl butyral, polystyrene, and polyethylene. The excitation was carried out on the shortwave edge of the absorption band of the dye and did not affect the absorption region of the polymer. It is shown that the effect of enhancement of the luminescence increases with decrease in the excitation wavelength and becomes weaker with increase in the molecular mass of carbazole–containing polymers. Its enhancement is interpreted as the recombination luminescence of electron–hole pairs formed in photogeneration of charge from the dye molecules.