High Efficient Green Phosphorescent OLED with Emission Layer of TPBI Selectively Doped with Ir(ppy)₃

Abstract

A green phosphorescent organic light-emitting device with structure of N,N′-diphenyl-N,N′-bis-[4-(phenyl-m-tolylamino)-phenyl]-biphenyl-4,4′-diamine[DNTPD]/1,1-bis-(di-4-polyaminophenyl)cyclohexane[TAPC]/1,3,5-tris(N-phenylbenzimiazole-2-yl)benzene[TPBI] selectively doped with Ir(ppy)₃/SFC-137 between anode and cathode is newly reported in comparison with the devices entirely doped with Ir(ppy)₃ in TPBI with or without an additional exciton confining layer (ECL). The undoped region of TPBI in the proposed device functions itself as an effective ECL, and SFC-137 is an electron transporting material named by the proprietary company.

Electroluminescent characteristics of the device selectively doped in TPBI with an additional undoped layer, which showed the maximum current efficiency of 51 cd/A at 6 V and the central wavelength of 512 nm, were comparable to those of the device entirely doped in TPBI with an ECL of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline[BCP]. The device with an additional undoped layer of TPBI exhibited the better roll-off characteristics of current efficiency according to the increasing voltage than the device without a specific ECL.

Keywords:

• Exciton confining layer
• green PhOLED
• Ir(ppy)₃
• selective doping
• TPBI