Realization of high-efficiency/high-luminance small-molecule organic light-emitting diodes: synergistic effects of siloxane anode functionalization/hole-injection layers, and hole/exciton-blocking/electron-transport layers

Abstract

High-efficiency/high-luminance small-molecule organic light-emitting diodes (OLEDs) are fabricated by combining thin, covalently-bound triarylamine hole injection/adhesion interlayers with hole- and exciton-blocking/electron transport interlayers in tris(8-hydroxyquinolato)aluminum (III) (Alq)-based OLEDs. Power and forward external quantum efficiencies as high as 15.2 lm/W and 4.4±0.5%, respectively, and turn-on voltages ∼4.5 V are achieved in devices of the structure ITO/TPDSi2/NPB/Alq:DIQA/BCP/Li/MgAg [NPB=(N,N′-di(1-napthl)-N,N′-diphenyl benzidine)] TPDSi2 interlayers are straightforwardly fabricated by spin-casting N,N′-diphenyl-N,N′- bis(p-trichlorosilylpropylphenyl)(1,1′-biphenyl)-4,4′-diamine TPDSi2 onto the ITO surface, while 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) interlayers are introduced by thermal evaporation. High quantum efficiencies are attributed to the synergistic enhanced hole/electron injection and exciton confinement effects of the TPDSi2 and BCP interlayers, respectively.