Above 20% external quantum efficiency in green and white phosphorescent organic light-emitting diodes using an electron transport type green host material

Highly efficient green and white phosphorescent organic light emitting diodes were developed using a green phosphorescent host material based on phenyl substituted spirobifluorene. A high quantum efficiency of 25.3% was achieved in the green phosphorescent device and a high quantum efficiency of 21.6% was obtained in the white device with a stacked emitting structure of deep blue and red: green emitting layers. (C) 2011 Elsevier B.V. All rights reserved.