An organic light-emitting devices of highly efficient white phosphor using an electron/exciton blocker

Abstract

Highly efficient white phosphorescent organic light-emitting devices (WOLEDs) was fabricated using an electron/exciton blocker. The device structure is ITO/2T-NATA(25 nm)/ NPBX(25-dnm)/CBP:5%Ir(ppy)₃:0.5%Rubrene(8 nm)/NPBX(dnm)/DPVBi(30 nm)/TPBi(20 nm)/Alq(10nm)/LiF(1nm)/Al, in which N,N′-bis-(1-naphthyl)-N,N′-diphenyl-1, 1′-biphenyl-4,4′-diamine (NPBX) functions as a hole transport layer and electron/exciton blocker, 4,4,N,N′-dicarbazolebiphenyl (CBP) is host, 4,4′-bis(2,2-diphenyl vinyl)-1,1′-biphenyl (DPVBi) is blue fluorescent dye, 5,6,11,12,-tetraphenylnaphthacene (rubrene) is fluorescent dye, factris (2-phenylpyridine) iridium (Ir(ppy)₃) is phosphorescent sensitizer and tris(8-hydroxyquinoline) aluminum (Alq₃) is an electron transport layer. The WOLEDs have obtained white light emission by adjusting the thickness of NPBX, when the concentration of Ir(ppy)₃ is 5-wt% and rubrene is 0.5-wt%, respectively, the thickness of the doped emissive layer is 8 nm, the WOLEDs show a maximum luminous efficiency is 11.2 cd/A with d of 10 nm at 7 V and a maximum luminance of 28170 cd/m² at 17 V, the CIE coordinates is (0.37.0.42), which is in white region.

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