超薄铝/碳酸锂修饰氧化铟锡阴极制备蓝色磷光反转底发光有机发光二极管

在氧化铟锡（ITO）阴极上依次蒸镀2 nm铝和2 nm碳酸锂（Li2CO3）薄膜作为电子注入层，成功制备出器件结构为ITO/Al/Li2CO3/SPPO13/SPPO13∶FIrpic/TCTA/MoO3/Al(SPPO13：2,7-双（二苯基磷）-9,9′-螺二[芴];FIrpic：双(4,6-二氟苯基吡啶-N,C2)吡啶甲酰合铱;TCTA：4,4′,4″-三(咔唑-9-基)三苯胺)的蓝色磷光反转底发光有机发光二极管（IBOLED）。 结果表明，Al/Li2CO3作为电子注入层可以有效降低ITO与有机材料之间的电子注入势垒，蓝色磷光IBOLED的起亮电压由11 V降至4.2 V，器件的发光效率也得到有效提高。 蓝光磷光IBOLED的最大电流效率与功率效率分别达到了28.2 cd/A和19.6 lm/W，制备出的反转结构器件性能可与传统正置结构比美，说明Al/Li2CO3可以作为反转有机发光二极管优良的电子注入层。

Ultrathin Al/Li2CO3 Modified Indium Tin Oxide Cathode for Blue Phosphorescent Inverted Bottom-emission Organic Light-emitting Diodes

Efficient blue phosphorescent inverted bottom-emission organic light-emitting diode(IBOLED) based on indium tin oxide(ITO) cathode has been successfully fabricated by thermal evaporation using Al(2 nm)/Li2CO3(2 nm) as the electron-injection layer. The structure of this device is ITO/Al/Li2CO3/SPPO13/SPPO13∶FIrpic/TCTA/MoO3/Al(SPPO13:2,7-bis(diphenylphosphoryl)-9,9′-spirobi[fluorene]; FIrpic:bis(4,6-difluorophenylpyridinato-N,C2)picolinatoiridium; TCTA:4,4′,4″-tri(9-carbazoyl)triphenylamine). It is found that the electron injection barrier between ITO and the organic layer can be significantly reduced with the presence of Al/Li2CO3, leading to the reduction of the turn-on voltage from 11 V to 4.2 V and the significant enhancement of efficiencies. The inverted device exhibits a maximum current efficiency of 28.2 cd/A and a maximum power efficiency of 19.6 lm/W, which are comparable with the conventional device. This suggests that Al/Li2CO3 has the potential to be used as the electron injection layer for inverted OLEDs.