Blue electroluminescence in blend of polymers containing carbazole and 1,3,4-oxadiazole units

The electro-optical properties of novel polymers such as poly(2,5-dihexyl p henylene-alt N-ethyl-3,6-carbazolevinylene) (PDPCVz) and poly[1',4'-phenyle ne-1 ",4 "-(2 "-(2''''-ethylhexyloxy))phenylene-2,5-(1"',4'"-phenylene)-1,3 ,4-oxadiazolyl] (PPEPPO) were characterized. The photoluminescence and elec troluminescence spectra of the blend films composed of PDPCVz and PPOPPD we re mainly contributed from the luminance of PDPCVz even at low PDPCVz ratio s. Remarkably enhanced blue EL was shown, which probably results form the e nergy transfer in the exited state from PPEPPO, with a larger bandgap, to P DPCVz with a smaller bandgap. Furthermore, by incorporation of Alq(3) as th e electron transporting layer to the EL devices, remarkable improvements in charge injection and EL efficiency were observed. (C) 2000 Published by El sevier Science S.A.