Color tunable electroluminescence from polymer blends containing carbazoleunit

The electro-optical properties of poly(phenylenevinylene-alt-N-hexyl-carbaz olevinylene) [Poly(PPV-N-hexylCvz)], poly[1',4'-phenylene-1 ", 4 "-(2 "-(2' '''-ethylhexyloxy))phenylene-2,5-(1''',4'''-phenylene)-1,3,4-oxadiazolyl](P PEPPO) and their blends were characterized. The photoluminescence and elect roluminescence spectra of the blend films composed of Poly(PPV-N-hexylCvz) and PPEPPO were mainly contributed from the luminance of Poly(PPV-N-hexylCv z) even at low Poly(PPV-N-hexylCvz) ratios. Remarkably enhanced EL efficien cy was observed as the ratio of PPEPPO increased. As the ratio of PPEPPO wa s increased from 50 to 83 %, the EL emission was changed from green to blue color.