White organic light-emitting devices employing phosphorescent iridium complex as RGB dopants

摘要

Efficient phosphorescent white organic light-emitting diodes (WOLEDs) were realized by using a bright blue-emitting layer, iridium (III) bis-[(4,6-di-fluoropheny)-pyridinato-N, C2'] picolinate doped 4.4'-bis-(9-carbazolyl)-2, 2'-dimethyl-biphenyl doped, together with tris-(2-phenylpyridine) iridium and bis-(1-phenyl-isoquinoline) acetylacetonate iridium (III) are codoped into a 4,4'-N,N'-dicarbazole-biphenyl layer to provide blue, green and red emission for colour mixing. The device emission colour is controlled by varying dopant concentrations and the thicknesses of blue and green-red layers as well as tuning the thickness of an exciton-blocking layer. The maximum luminance and power efficiency of the WOLED are 42700 cd m~(-2) at 17 V and 8.48 lm W~(-1) at 5 V, respectively. The Commission Internationale de l'Eclairage (CIE) chromaticity coordinate changes from (0.41, 0.42) to (0.37, 0.39) when the luminance ranges from 1000 cd m~(-2) to 30000 cd m~(-2).