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New electroluminescent, PPV-like, conjugated polymers containing bipyridylene−vinylene subunits were prepared and characterized with respect to their electrooptical properties. The polymers were found to exhibit reversible and tunable optical properties depending on protonation−deprotonation processes. pH sensitivity and reversible tunability of the polymers were observed by photo- and electroluminescence, optical absorption, photoinduced-absorption, and electroabsorption experiments. A luminescence red-shift of as much as 0.2 eV (∼60 nm) was observed upon full protonation of a free-base film. Films of the free-base form of the new polymers showed, in general, sharper spectra than the corresponding protonated films, probably due to increased disorder and stronger interchain interactions in the latter.

The application of conjugated polymers having electroactive pendant groups, such as poly(N-methyl-N‘-(3-pyrrol-1-ylpropyl)-4,4‘-bipyridinium), p-Pyr-V2+-Me, and poly(N-hydrogen-N‘-(3-pyrrol-1-ylpropyl)-4,4‘-bipyridinium), p-Pyr-V2+-H, as active photovoltaic and photoconducting media is investigated. Photoinduced charged species are characterized using photomodulated differential transmission spectroscopy and photoconductivity. The ability of using such media as active layers in photovoltaic cells is demonstrated.

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