The Study On Interface Modification Of Flexible ITO Electrode

Flexible organic light-emitting diodes?FOLEDs?has the advantages of good mechanical flexibility,low power consumption,low driving voltage,high color gamut,wide viewing angle,fast response,etc.It shows a wide application in flexible display,lighting and wearable devices.prospect.Although the research and application of flexible OLEDs have made great progress,but the stability,efficiency and electrodes must be further improved to achieve industrialization.In this paper,PET/ITO was selected as the flexible electrode.The relationship between the modification of flexible ITO electrode and device performance was studied and the development trend of flexible OLED was prospected.1.The effect of molydium oxide?MoO₃?,1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile?HAT-CN?,HAT-CN/MoO₃ as hole injection layer?HIL?on the performance of FOLED based flexible ITO is investigated.The hybrid HAT-CN/MoO₃ leads to high hole injection efficiency and improvement in device performance due to the cleaning ability of HAT-CN and hole injection capability of MoO₃.The device with HAT-CN/MoO₃ as HIL shows a maximum current efficiency (CE_max)of 41.29 cd/A and maximum power current efficiency(PE_max)of 15.92 lm/W.The smooth current injection can be achieved by the HAT-CN's ability of cleaning ITO surface.And the hybrid HAT-CN/MoO₃ reduces the hole injection barrier and suppresses the space change accumulation in electrode/organic layer interface to enhance hole injection efficiently.2.The hydrophobicity of PET/ITO surface was investigated.The hydrophilia of PET/ITO surface is improved by using MoO₃.The hybrid MoO₃/PEDOT:PSS is used to improve the hydrophilia and roughness of PET/ITO.Meanwhile,MoO₃ is introduced between PEDPT:PSS and CBP.It has been proved that MoO₃/PEDOT:PSS/MoO₃ is the most effective to modify PET/ITO and the maximum current efficiency and power efficiency of device modified with MoO₃/PEDOT: PSS/MoO₃ are 58.90 cd/A and 42.44 lm/W,respectively.3.The defects of flexible ITO on electron injection are avoided due to carrier injection is effective and independent of the electrode by using organic p-n junctions.The fact that organic p-n junctions are independent of electrode is a major factor in improving device performance.And PEDOT:PSS which has a better modification effect on rough surface of flexible ITO can improve device performance.The devices with PEDOT:PSS/Bphen:Cs₂CO₃ and MoO₃/Bphen:Cs₂CO₃ show a maximum current efficiency(CE_max)of 78.31 cd/A and 51.66 cd/A,maximum power current efficiency(PE_max)of 60.08 lm/W and 38.07 lm/W,respectively.4.The effect of organic p-n junction modified PET/ITO on the performance of the device in the FOLED structure was studied.On the basis of the upright structure,the flexible ITO was modified using the n-p junction Bphen:Cs₂CO₃/MoO₃ as hole injection layer.The maximum current efficiency and power efficiency of PET/ITO devices modified with MoO₃/Bphen:Cs₂CO₃ reached 45.78 cd/A and 14.26 lm/W,respectively.