ELECTROLUMINESCENCE PROPERTIES OF A NONCONJUGATED POLYMER -BENZOXAZOLEDIYL[2,5-BIS(DECYLOXY)-1,4-PHENYLENE]] (6FPBO-OD)

Light-blue-emitting devices were fabricated from a non-conjugated poly mer poly -benzoxazolediyl[2,5-bis(decyloxy)-1,4-phenylene]] (6FPBO-OD) . Top brightness and electroluminescence (EL) internal quantum yield r each 204 cd/m(2) (at 17 V with a Mg:Ag cathode) and 0.86% (at 12 V wit h an Al cathode), respectively, in the double-layer devices with polym er poly(9-vinylcarbazole) (PVK) used as a hole-transporting layer. Thi s competitive performance, especially for a bluish polymer Light-emitt ing device (LED), was achieved against the fact that the photoluminesc ence yields of this polymer are unusually low, which is explained in t erms of fluorescence quenching excimer formation and intramolecular ch arge transfer. The understanding of the photophysical nature of this p olymer and its link to the polymer structure provides significant impl ications for improving the electroluminescent properties of this type of non-conjugated polymer. (C) 1998 Elsevier Science S.A. All rights r eserved.