Improvement of Electroluminescence Efficiency of Blue-Polymer-Light-Emitting Diodes Using Polymer Hole-Transporting and Electron-Transporting Layers

概要

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We improved the characteristics of blue-polymer-light-emitting diodes by introducing hole-transporting and electron-transporting layers. Poly[(9,9-dioctylfluorene-2,7-diyl)-alt-(triphenylamine-4,4$'$-diyl)] [PF8-TPA (50%)], poly[(9,9-dioctylfluorene-2,7-diyl)-co-(stilbene-4,4$'$-diyl)] [PF8-SB (10%)], and poly[(9,9-dioctylfluorene-2,7-diyl)-alt-(pyridine-2,6-diyl)] [PF8-Py (50%)] were used as the hole-transporting material, blue-light-emitting material and electron-transporting material, respectively. It was found that by introducing the hole-transporting layer, luminance and efficiency were greatly increased. At 1000 cd/m2, efficiency was increased from 0.60 cd/A for a single layer device to 1.29 cd/A for a bilayer device and external quantum efficiency was increased from 0.60% for a single layer device to 0.74% for a bilayer device. Efficiency and external quantum efficiency at 1000 cd/m2 can be further increased up to 1.50 cd/A and 0.95%, respectively, by introducing the electron-transporting layer. These improvements of efficiencies are supposed to be achieved by the good confinement of holes and electrons in the emitting layer by the hole-transporting layer and electron-transporting layer.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2006-04-30