Highly Efficient p-i-n and Tandem Organic Light-Emitting Devices Using an Air-Stable and Low-Temperature-Evaporable Metal Azide as an n-Dopant

Authors

  • Kyoung Soo Yook,

    1. Department of Polymer Science and Engineering Dankook University Jukjeon-dong, Suji-gu, Yongin, Gyeonggi-do, 448-701 (Korea)
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  • Soon Ok Jeon,

    1. Department of Polymer Science and Engineering Dankook University Jukjeon-dong, Suji-gu, Yongin, Gyeonggi-do, 448-701 (Korea)
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  • Sung-Yong Min,

    1. Department of Materials Science and Engineering Pohang University of Science and Technology San 31 Hyoja-dong, Nam-gu, Pohang, Gyeongbuk 790-784 (Korea)
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  • Jun Yeob Lee,

    Corresponding author
    1. Department of Polymer Science and Engineering Dankook University Jukjeon-dong, Suji-gu, Yongin, Gyeonggi-do, 448-701 (Korea)
    • Department of Polymer Science and Engineering Dankook University Jukjeon-dong, Suji-gu, Yongin, Gyeonggi-do, 448-701 (Korea).
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  • Ha-Jin Yang,

    1. Samsung Mobile Displays Mt. 14-1, Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-712 (Korea)
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  • Taeyong Noh,

    1. Samsung Mobile Displays Mt. 14-1, Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-712 (Korea)
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  • Sung-Kee Kang,

    1. Samsung Mobile Displays Mt. 14-1, Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-712 (Korea)
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  • Tae-Woo Lee

    Corresponding author
    1. Department of Materials Science and Engineering Pohang University of Science and Technology San 31 Hyoja-dong, Nam-gu, Pohang, Gyeongbuk 790-784 (Korea)
    • Department of Materials Science and Engineering Pohang University of Science and Technology San 31 Hyoja-dong, Nam-gu, Pohang, Gyeongbuk 790-784 (Korea).
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Abstract

Cesium azide (CsN3) is employed as a novel n-dopant because of its air stability and low deposition temperature. CsN3 is easily co-deposited with the electron transporting materials in an organic molecular beam deposition chamber so that it works well as an n-dopant in the electron transport layer because its evaporation temperature is similar to that of common organic materials. The driving voltage of the p-i-n device with the CsN3-doped n-type layer and a MoO3-doped p-type layer is greatly reduced, and this device exhibits a very high power efficiency (57 lm W−1). Additionally, an n-doping mechanism study reveals that CsN3 was decomposed into Cs and N2 during the evaporation. The charge injection mechanism was investigated using transient electroluminescence and capacitance–voltage measurements. A very highly efficient tandem organic light-emitting diodes (OLED; 84 cd A−1) is also created using an n–p junction that is composed of the CsN3-doped n-type organic layer/MoO3 p-type inorganic layer as the interconnecting unit. This work demonstrates that an air-stable and low-temperature-evaporable inorganic n-dopant can very effectively enhance the device performance in p-i-n and tandem OLEDs, as well as simplify the material handling for the vacuum deposition process.

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