Synthesis of electroluminescent copoly(aryl ether)s containing alternate 1,4-distyrylbenzene derivatives and aromatic 1,3,4-oxadiazole or 3,3"-terphenyldicarbonitrile segments

New copoly(aryl ether)s (P1-P3) containing alternate 2,5-dihexyloxy-1,4-di(m-ethoxystyryl)benzene (P1, P2) or 2,5-dihexyloxy-1,4-distyrylbenzene (P3) chromophores and aromatic 1,3,4-oxadiazole (Pl) or 3,3 ''-terphenyldicarbonitrile (P2, P3) segments were prepared by Horner reaction (P1 and P2) or nucleophilic displacement reaction (P3). They are basically amorphous materials with 5% weight-loss temperature above 410 degrees C. Their absorption, photoluminescence spectra, and quantum yields are dependent on the composition of the isolated fluorophores. The emissions are exclusively dominated by 1,4-distyrylbenzene segments via excitation energy transfer from electron-transporting 1,3,4-oxadiazole (Pl) or 3,3 ''-terphenyldicarbonitrile (P2, P3) chromophores. The HOMO and LUMO energy levels have been estimated from their cyclic voltammograms, and the observations confirm that oxidation and reduction start from the emitting 1,4-distyrylbenzene and electron-transporting segments, respectively, indicating that both carriers affinity can be enhanced simultaneously. Among the two-layer PLED devices (ITO/PEDOT/P1-P3/Al), P1 exhibits the best performance with a turn-on field of 4 x 10(5) V/cm and a maximum luminance of 225 cd/m(2). However, P2 emits green-yellow light (555 nm), owing to the excimer emission. (c) 2005 Wiley Periodicals, Inc.