Polymer light-emitting diodes with novel environment-friendly alcohol-soluble conjugated copolymer

摘要

Polymer light-emitting diodes (PLEDs) were prepared using an environment-friendly alcohol-soluble quaternized aminoalkyl-substituted conjugated polyfluorene co-polymerizing 2,1,3-benzothiadiazole monomer (PFNBr-BTDZ05) as an emitter, a high work-function Au metal as a cathode. The device structure used here is indium-tin-oxide (ITO)/poly(N-vinylcarbazole) (PVK)/PFNBr-BTDZ05/Au, where PVK is an anode buffer layer acting as the hole injection. The maximal external quantum and luminance efficiencies of 0.73% and 0.86 cd/A are obtained, and the maximal luminance is nearly 700 cd/m~2 at 13 V, which was the highest brightness value reported in PLEDs with the Au metal cathode. This conjugated polyelectrolyte has such excellent electron injection ability that the device with the structure of ITO/poly(ethylene dioxythiophene)/ poly(2-(4-(3',7'-dimethyloctyloxy)-phenyl)-p-phenylenevinylene)/PFNBr-BTDZ05/Al exhibits a high external quantum efficiency of 7.0%. The electron-injecting mechanism of PFNBr-BTDZ05 was discussed.