High-Color-Quality White Top-Emitting Organic Electroluminescent Devices Based on Both Exciton and Electroplex Emission

A high-color-quality white top-emitting organic electroluminescent device (TOLED) with a simple structure was fabricated using both exciton and electroplex emission. White emission was achieved by combining the exciton emission of 4,4'-bis(2,2'-diphenylvinyl)-1,1'-biphenyl (DPVBi) and the broad band emission of electroplex generated between DPVBi and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP). The white emission spectra showed excellent stability at different bias voltages. By inserting a blend film of DPVBi: BCP and adjusting the ratio of DPVBi to BCP in the blend film, the CIE coordinates of the white emission can be tuned to (0.30; 0.33) and the electroluminescence efficiency can also be enhanced. (C) 2011 The Japan Society of Applied Physics