Unlocking the potential of p-doped hole transport layers in inverted organic light emitting diodes.

The MoO 3 doped N,N′-bis-(1-naphthyl)-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB:MoO 3 in 2:1 mass ratio) and 4,4′-N,N′-dicarbazole-biphenyl (CBP:MoO 3 in 2:1 mass ratio) as p -doped hole transport layers have been used in inverted organic light emitting diodes (IOLEDs). Compared to the NPB/20 nm NPB:MoO 3 structure, the NPB/10 nm CBP:MoO 3 /10 nm NPB:MoO 3 structure showed increased device performance, mostly because the hole transport barrier from CBP:MoO 3 to NPB was smaller than that from NPB:MoO 3 to NPB; it also presented improved device performance than the NPB/20 nm CBP:MoO 3 structure, ascribed to the higher conductivity of NPB:MoO 3 than that of CBP:MoO 3 . We provide a manageable way to unlock the merits of p -doped hole transport layers for markedly increasing the performance of IOLEDs. [ABSTRACT FROM AUTHOR]