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

摘要

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)/Ii2CO3(2 nm) as the electron-injection layer.The structure of this device is ITO/Al/Li2CO3/ SPPO13/SPPO13: Flrpic/TCTA/MoO3/Al ( SPPO13 :2,7-bis ( diphenylphosphoryl) -9,9'-spirobi [ fluorene ] ; Flrpic; 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.%在氧化铟锡(ITO)阴极上依次蒸镀2 nm铝和2 nm碳酸锂(Li2 CO3)薄膜作为电子注入层,成功制备出器件结构为ITO/Al/Li2 CO3/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4.2V,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/Li2 CO3可以作为反转有机发光二极管优良的电子注入层.