High power efficiency in simplified two layer blue phosphorescent organic light-emitting diodes

High power efficiency blue phosphorescent organic light-emitting diodes (PHOLEDs) with only two organic layers were developed using a spirobifluorene based phosphine oxide (SPPO13) host material. Two layer blue PHOLEDs with only 1,1-bis[(di-4-tolylamino) phenyl] cyclohexane (TAPC) hole transport layer and TAPC: SPPO13: blue dopant mixed host emitting layer were fabricated. A high power efficiency of 26.0 lm/W at 1000 cd/m(2) were achieved in the simple blue device due to the high quantum efficiency of 17.5% and a low driving voltage of 4.1 V at 1000 cd/m(2). In addition, a maximum power efficiency of 48.5 lm/W and a high quantum efficiency of 19.6% were demonstrated from the simple blue PHOLEDs with only two organic layers. (C) 2010 Elsevier B.V. All rights reserved.