High efficiency tandem organic light-emitting devices with Al∕WO3∕Au interconnecting layer

An interconnecting layer of Al (2nm)∕WO3 (3nm)∕Au (16nm) was studied for application in tandem organic light-emitting devices. It can be seen that the Al∕WO3∕Au structure plays the role of an excellent interconnecting layer. The introduction of WO3 in the connection unit significantly improves the device efficiency as compared to the case of Al∕Au. Thus, the current efficiency of the two-unit tandem devices is enhanced by two factors with respect to the one-unit devices. The green two-unit tandem device of indium tin oxide/MoO3∕4,4′-N,N′-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl(NPB)/tris(8-hydroxylquinoline) aluminum (Alq3):10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolizin-11-one (C545T)∕Alq3∕LiF∕Al∕WO3∕Au∕MoO3∕NPB∕Alq3:C545T∕Alq3∕LiF∕Al showed a maximum current efficiency of 33.9cd∕A and a power efficiency of 12.0lm∕W.