Journal of the Korean institute of surface engineering (한국표면공학회지)

The Korean Institute of Surface Engineering (한국표면공학회)
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Electroluminescent Characteristics of Fluorescent OLED with Alternating Current Negative Voltage

교류 음 전압에 따른 형광 OLED의 전계 발광 특성

  • Seo, Jung-Hyun (Department of Advanced Materials Science & Engineering, Daejin University) ;
  • Yang, Jae-Woong (Department of Advanced Materials Science & Engineering, Daejin University) ;
  • Paek, Kyeong-Kap (Department of Electronic Engineering, Daejin University) ;
  • Ju, Sung-Hoo (Department of Advanced Materials Science & Engineering, Daejin University)
  • Received : 2018.06.08
  • Accepted : 2019.03.24
  • Published : 2019.04.30
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Abstract

To study the characteristics of AC driven OLED, we fabricated the fluorescent OLEDs and analyzed the electroluminescence characteristics of OLEDs with AC negative voltage. The luminance and the current density of the OLED decreased, and the number and size of the dark spots increased in proportion to the duration time and level of the applied AC negative voltage. The current efficiency of the OLED was improved when high AC negative voltage was applied within a short time. When the AC negative voltage of 10 V was applied for 1 minute, the efficiency was improved by 12.4%. Also, the degradation of luminance and current efficiency due to the duration of light emission was improved in the case of OLED applied for 1 minute with 10 V AC negative voltage. These are expected as a result of the improvement of the leakage current characteristics by eliminating the short-circuit region formed by the defect of the OLED at the AC negative high voltage. As a result, the continuous application of AC negative voltage reduced the luminance and the current density of OLED, but the temporary application of AC negative voltage with the proper time and voltage could improve the efficiency and lifetime of OLED.

Keywords

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Fig. 1. Structure of fluorescent OLED.

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Fig. 2. AC negative voltage supply circuit board for OLED (a) schematic diagram, (b) board image.

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Fig. 3. Current density and luminance of OLED with AC negative voltage application time

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Fig. 4. Light emitting image of OLED with AC negative voltage application time.

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Fig. 5. Current efficiency of OLED with AC negative voltage application time.

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Fig. 6. Characteristics of OLED with reverse aging. (a) luminance, (b) current efficiency.

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