Improved efficiency for green and red emitting electroluminescent devices using the same cohost composed of 9,10-di(2-naphthyl) anthracene and tris-(8-hydroxyquinolinato) aluminum

We demonstrate highly efficient green and red fluorescence dyes-doped electroluminescent devices using cohost strategy. The cohost system is composed of tris-(8-hydroxyquinolinato) aluminum (Alq) and 9,10-di(2-naphthyl) anthracene (ADN). The maximum current efficiencies are increased by 54% and 104% for green and red devices by optimizing the ratio between ADN and Alq in the cohost compared to the conventional Alq single-host devices, respectively. We attribute the improvement of efficiencies to balanced hole and electron injection into the emitting layer, the enlarged width of recombination region and the multiple emission processes.