White organic light-emitting devices based on fac tris(2-phenylpyridine) iridium sensitized 5,6,11,12-tetraphenylnap-hthacene

Abstract

We have fabricated the white organic light-emitting devices (WOLEDs) based on 4,4′-bis(2,2-diphenyl vinyl)-1,1′ — biphenyl (DPVBi) and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene (rubrene). The device structure is ITO/2T-NATA (20 nm)/ NPBX (20 nm)/ CBP: x%Ir(ppy)₃:0.5% rubrene (8 nm)/ NPBX (5 nm)/DPVBi (30 nm)/ Alq(30 nm)/LiF(0.5 nm)/Al. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris (2-phenylpyridine) iridium [Ir(ppy)₃], acts as a yellow light-emitting layer, and N,N′-bis-(1-naphthyl)-N,N′-diphenyl-1, 1′-biphenyl-4,4′-diamine (NPBX) acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir (ppy)₃ is 6wt%, the maximum luminance is 24960 cd/m² at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.

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