EFFICIENT MULTILAYER ELECTROLUMINESCENCE DEVICES WITH ENEVINYLENE-CO-2,5-DIOCTYLOXY-P-PHENYLENEVINYLENE) AS THE EMISSIVE LAYER

The use of a new highly luminescent conjugated polymer as an emissive layer in single and multilayer electroluminescence devices is reported . enevinylene-co-2,5-dioctyloxy-p-phenylenevinylene) [PmPV-co-DOctOPV] was prepared via a Wittig synthesis reaction. The resulting polymer h as a high photoluminescence quantum efficiency in the solid state with an emission spectrum peaked at 506 nm (2.45 eV) in the green. Electro luminescence devices were fabricated with an ITO anode and a MgAg cath ode. Three different structures were studied: (i) single layer devices containing only PmPV-co-DOctOPV; (ii) double layer devices with PmPV- co-DOctOPV and an evaporated film of 1,3-bis(4-tert-butylphenyl-1,3,4- oxadiazoyl) phenylene [OXD-7] as an electron transport layer; (iii) tr iple layer devices containing PmPV-co-DOctOPV. OXD-7 and in addition a polyvinylcarbazole hole transport layer. Electroluminescence external quantum efficiencies for these devices were found to be up to 0.08%, 0.55%, and 1%, respectively, corresponding to luminous efficiencies of approximate to 0.5, approximate to 3, and approximate to 6 lm/W and p ower efficiencies of 8.5X10(-5), 5.9X10(-4), and 6.0X10(-4) W/W. (C) 1 997 American Institute of Physics.