High external quantum efficiency in yellow and white phosphorescent organic light-emitting diodes using an indoloacridinefluorene type host material

• Triplet host material for high efficiency yellow phosphorescent organic light-emitting diodes.
• Indoloacridine and spirofluorene derivative for bipolar charge transport properties.
• High quantum efficiency of 20.9% in two color white organic light-emitting diodes.

High efficiency yellow phosphorescent organic light-emitting diodes were developed using spiro[fluorene-9,8′-indolo[3,2,1-de]acridine]-2,7-dicarbonitrile (ACDCN) as the host material for yellow emitting iridium(III) bis(4-phenylthieno[3,2-c]pyridinato-N,C2′)acetylacetonate (PO-01). The ACDCN host showed bipolar charge transport properties and efficient energy transfer to PO-01 dopant. Maximum external quantum efficiency of 25.7% and external quantum efficiency of 21.9% at 1000 cd/m2 were obtained using ACDCN as the host material. In addition, high external quantum efficiency of 20.9% was achieved in the two color white phosphorescent organic light-emitting diodes with the PO-01 and iridium(III) bis[(4,6-difluorophenyl)-pyridinato-N,C2]picolinate doped ACDCN emitting layer.

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