Journal of Semiconductors, Volume. 44, Issue 9, 092602(2023)

Low-temperature conformal vacuum deposition of OLED devices using close-space sublimation

Bryan Siu Ting Tam1, Shou-Cheng Dong1,2、*, and Ching W. Tang1,2
Author Affiliations
  • 1State Key Laboratory of Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
  • 2Institute for Advanced Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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    Figures & Tables(6)
    (Color online) Process flow of CSS.
    (Color online) (a) CSS setup using an electrically heated Ta foil; (b) simulated temperature distribution of the Ta foil under constant current; (c) foil temperatures under different currents with 10 s heating time; (d) the temporal profile of the evaporation rate and Ta foil temperature; (e) CSS evaporation rate of NPB films of various thicknesses from 50 to 500 nm as a function of Ta foil temperatures; (f) AFM image of a CSS-deposited NPB thin film; (g) AFM image of a VTE-deposited NPB film; (h) simulated and measured thickness profile of a CSS-deposited film from a 25 mm donor at a 1 mm gap; (i) film uniformity dependence on the donor-substrate gap and the donor dimensions; and (j) simulated thickness profile of a CSS-deposited film from a 2.5 m donor at a 20 mm gap.
    (Color online) (a) CSS using a curved Ta foil; (b) schematics of CSS deposition on curved surfaces; (c) CSS-deposited NPB film on a curved stainless-steel piece; (d) fluorescent image of CSS-deposited NPB on PMMA; and (e) UV-Vis absorption spectra of CSS-deposited NPB at different locations of the PMMA substrate.
    (Color online) (a) Radiation-heating CSS setup using a halogen bulb for device fabrication; (b) large-area radiation-heating CSS apparatus with a halogen lamp module; and (c) heating profile of the setup in (a) with a 250 W halogen bulb.
    (Color online) (a) The molecular structure of materials used for device fabrication; (b) device energy diagrams; (c) EQE vs. current density and (d) current density vs. voltage of blue OLEDs using CSS- and VTE-deposited NPB layers; and (e) current density vs. voltage plot of hole-only devices.
    • Table 1. Peak temperatures and evaporation rates in CSS at different currents.

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      Table 1. Peak temperatures and evaporation rates in CSS at different currents.

      Current (A)Peak rate (Å/s)Tpeak (°C)
      5.40293
      5.7610142
      5.9430150
      6.30100166
      8.80489162
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    Bryan Siu Ting Tam, Shou-Cheng Dong, Ching W. Tang. Low-temperature conformal vacuum deposition of OLED devices using close-space sublimation[J]. Journal of Semiconductors, 2023, 44(9): 092602

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    Paper Information

    Category: Articles

    Received: May. 15, 2023

    Accepted: --

    Published Online: Oct. 25, 2023

    The Author Email: Dong Shou-Cheng (scdong@ust.hk)

    DOI:10.1088/1674-4926/44/9/092602

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