EFFECT OF PROTONATION-DEPROTONATION PROCESSES ON THE ELECTROOPTICAL PROPERTIES OF BIPYRIDINE-CONTAINING POLY(P-PHENYLENE-VINYLENE) DERIVATIVES

New electroluminescent, PPV-like, conjugated polymers containing bipyr idylene-vinylene subunits were prepared and characterized with respect to their electrooptical properties. The polymers were found to exhibi t reversible and tunable optical properties depending on protonation-d eprotonation processes. pH sensitivity and reversible tunability of th e polymers were observed by photo- and electroluminescence, optical ab sorption, photoinduced-absorption, and electroabsorption experiments. A luminescence red-shift of as much as 0.2 eV (similar to 60 nm) was o bserved upon full protonation of a flee-base film. Films of the free-b ase 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.