Simply structured, deep-blue phosphorescent organic light-emitting diode with bipolar host material

We developed an efficient, deep-blue phosphorescent organic light-emitting diode (POLED) with a simplified device structure using a new host material. There are only three organic layers in the deep-blue POLED, namely, a hole-transporting layer, an emitting layer and an electron-transporting layer. The new host material exhibits bipolar carrier transportability and high triplet energy. The POLED utilizes a phosphorescent guest material, iridium(III) bis(4′,6′,-difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate, that exhibits an external quantum efficiency of about 13% and a power efficiency of about 15 lm/W at a current density of 0.1 mA/cm2. The efficiencies of the POLED are comparable to those of conventional POLEDs consisting of at least four organic layers. The bipolar host material will be useful for simplifying the device structure of deep-blue POLEDs.

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► Simply structured, efficient deep-blue OLED.
► Novel host material with a bipolar carrier transportability and a high triplet energy.
► External quantum efficiency of about 13% and a power efficiency of about 15 lm/W in deep-blue phosphorescent OLED.