High power efficiency in blue phosphorescent organic light-emitting diodes using a spirobifluorene phosphine oxide compound

High power efficiency blue phosphorescent organic light-emitting diodes (PHOLEDs) were fabricated using a mixed host of 1,1-bis[(di-4-tolylamino)phenyl] cyclohexane (TAPC) and 2,7-bis(diphenylphosphoryl)-9,9'-spirobi[fluorene] (SPPO13) in the emitting layer. A maximum power efficiency of 33.7 lm/W and a high power efficiency of 28.4 lm/W at 1,000 cd/m² were achieved in the blue PHOLED with the mixed host emitting layer of TAPC and SPPO13. The efficiency roll-off of the device was also reduced by using the mixed host emitting layer.