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 ( Cs 2 C O 3 ) ∕ N , N ′ -bis(1-naphthyl)- N , N ′ -diphenyl- 1 , 1 ′ -biphenyl- 4 , 4 ′ -diamine: 50% v/v tungsten oxide ( W O 3 ) 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.