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The Mechanism of Charge Generation in Charge-Generation Units Composed of p-Doped Hole-Transporting Layer/HATCN/n-Doped Electron-Transporting Layers

Authors

  • Sunghun Lee,

    1. WCU Hybrid Materials Program, Department of Materials Science and Engineering and the Center for Organic Light Emitting Diode, Seoul National University, Seoul, 151-744, Korea
    2. OLED Research Institute, Samsung Mobile Display Co., LTD., Giheung-Gu, Yongin-City, 446-711, Korea
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  • Jeong-Hwan Lee,

    1. WCU Hybrid Materials Program, Department of Materials Science and Engineering and the Center for Organic Light Emitting Diode, Seoul National University, Seoul, 151-744, Korea
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  • Jae-Hyun Lee,

    1. WCU Hybrid Materials Program, Department of Materials Science and Engineering and the Center for Organic Light Emitting Diode, Seoul National University, Seoul, 151-744, Korea
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  • Jang-Joo Kim

    Corresponding author
    1. WCU Hybrid Materials Program, Department of Materials Science and Engineering and the Center for Organic Light Emitting Diode, Seoul National University, Seoul, 151-744, Korea
    • WCU Hybrid Materials Program, Department of Materials Science and Engineering and the Center for Organic Light Emitting Diode, Seoul National University, Seoul, 151-744, Korea.

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Abstract

The rate-limiting step of charge generation in charge-generation units (CGUs) composed of a p-doped hole-transporting layer (p-HTL), 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HATCN) and n-doped electron-transporting layer (n-ETL), where 1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl)-cyclohexane (TAPC) was used as the HTL is reported. Energy level alignment determined by the capacitance–voltage (CV) measurements and the current density–voltage characteristics of the structure clearly show that the electron injection at the HATCN/n-ETL junction limits the charge generation in the CGUs rather than charge generation itself at the p-HTL/HATCN junction. Consequently, the CGUs with 30 mol% Rb2CO3-doped 4,7-diphenyl-1,10-phenanthroline (BPhen) formed with the HATCN layer generates charges very efficiently and the excess voltage required to generate the current density of ±10 mA cm−2 is around 0.17 V, which is extremely small compared with the literature values reported to date.

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