The sandwiched- p-doped-layer hole injection structure to enhance the performance of inverted organic light-emitting diodes.

The performance of inverted organic light-emitting diodes (IOLEDs) has been improved based on MoO-doped N,N′-bis-(1-naphthyl)-diphenyl-1,1′-biphenyl-4,4′-diamine (2:1 NPB:MoO in mass ratio) and 4,4′-N,N′-dicarbazole-biphenyl (2:1 CBP:MoO in mass ratio). The sandwiched- p-doped-layer hole injection structure of CBP:MoO 10 nm/NPB:MoO 5 nm/CBP:MoO 5 nm/Al showed increased device performance via enhancing hole current into the CBP, compared to the single- p-doped-layer hole injection structure of CBP:MoO 20 nm/Al, mostly due to the higher conductivity of NPB:MoO than that of CBP:MoO; it also improved device current and thereby performance than the double- p-doped-layer hole injection structure of CBP:MoO 10 nm/NPB:MoO 10 nm/Al, mostly attributed to that the hole injection from Al to CBP:MoO was more efficient than that from Al to NPB:MoO. The current research provides some insights in reducing the power loss toward the commercialization of IOLEDs. [ABSTRACT FROM AUTHOR]