Analysis of alternating current driven electroluminescence in organic light emitting diodes: A comparative study

Le Zhang, Hajime Nakanotani, Kou Yoshida, Chihaya Adachi

研究成果: ジャーナルへの寄稿学術誌査読

18 被引用数 (Scopus)


The alternating current (AC) responses of double-injection and double-insulated organic light-emitting diodes (OLEDs) were investigated and compared. To reveal the electroluminescent (EL) processes in these devices, the AC voltage and frequency dependence of the EL intensity and capacitive current were studied in the time domain with a focus on phase difference analysis. It was found that the voltage-dependent transit time and frequency-dependent carrier distribution were important for the AC-driven performance of the double-injection OLEDs. In contrast, although the double-insulated OLEDs shared some similarities with the double-injection OLEDs, they had some unique characteristics, which were the absence of resistive current and phase shift of EL profiles. It was revealed that the EL in the double-insulated OLEDs was driven by the displacement current generated by the ionization of the doped layers, which, however, formed space charge regions and undermined the EL emission. The space charge redistributed the electric field across the devices after the initiation of EL, making the EL maintain for a limited time interval. This effect was significant under low frequency and high AC voltage. Comparing the phase difference between both devices, it was indicated that the space charge effect was responsible for the observed EL phase shift and the asymmetric EL profiles at low frequency and high AC voltage in the double-insulated OLEDs. The proposed model was also of help to understand the EL saturation phenomena with AC frequency and voltage in those devices.

ジャーナルOrganic Electronics
出版ステータス出版済み - 8月 2014

!!!All Science Journal Classification (ASJC) codes

  • 電子材料、光学材料、および磁性材料
  • 生体材料
  • 化学 (全般)
  • 凝縮系物理学
  • 材料化学
  • 電子工学および電気工学


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