Light-emitting copolymers of cyano-containing PPV-based chromophores and aflexible spacer

Conjugated-non-conjugated alternating block copolymers containing cyano-mod ified distirylbenzene units as emitting chromophores were synthesized via K noevenagel and Wittig reactions; the non-conjugated block was an alkylene s pacer. The polymers were differentiated with respect to the location of the cyano groups in the chromophoric block (double bond or phenylene ring). Wh en photoluminescence and electroluminescence spectra of these materials wer e compared with those of a similar structure without the cyano group, a str ong bathochromic effect was observed. A more pronounced red shift and a hig her electroluminescence efficiency was observed in the polymer with the cya no group attached to the aromatic ring. (C) 1999 Elsevier Science Ltd. All rights reserved.