Highly efficient p-i-n white organic light emitting devices with tandem structure

Highly efficient tandem p-i-n white organic light emitting devices have been fabricated. Utilizing an optical transparent bilayer with doped organic p-n junction that consists of 4,7-diphenyl-1,10-phenanthroline: 2% cesium carbonate (Cs2CO3)/N,N-'-bis(1-naphthyl)-N,N-'-diphenyl-1,1(')-biphenyl-4,4(')-diamine: 50% v/v tungsten oxide (WO3) as the connecting layer, the tandem p-i-n white device achieved an electroluminescence efficiency of 23.9 cd/A and a power efficiency of 7.8 lm/W at 20 mA/cm(2) with a Commission Internationale de l'Eclairage coordinates of (0.30, 0.43). The electroluminescent color of this tandem p-i-n white organic light-emitting diode device will not change significantly with respect to drive current variation and forward viewing angle. (c) 2007 American Institute of Physics.