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Institute of Korean Electrical and Electronics Engineers (한국전기전자학회)
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Improved charge balance in quantum dot light-emitting diodes using self-assembled monolayer

자기조립단분자막을 이용한 양자점 발광다이오드의 전하 균형도 개선

  • Sangwook Park (Dept. of Electrical Engineering, Pusan National University) ;
  • Woon Ho Jung (Dept. of Energy Science, Centre for Artificial Atoms, Sungkyunkwan University (SKKU)) ;
  • Yeyun Bae (Dept. of Electrical Engineering, Pusan National University) ;
  • Jaehoon Lim (Dept. of Energy Science, Centre for Artificial Atoms, Sungkyunkwan University (SKKU)) ;
  • Jeongkyun Roh (Dept. of Electrical Engineering, Pusan National University)
  • Received : 2023.01.28
  • Accepted : 2023.02.16
  • Published : 2023.03.31
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Abstract

To improve the efficiency and stability of colloidal quantum dot light-emitting diodes (QD-LEDs), it is essential to achieve charge balance within the QD emissive layer. Zinc oxide (ZnO) is widely used for constructing an electron transport layer in the state-of-the-art QD-LEDs, but spontaneous electron injection from ZnO often results in excessive electrons in QDs that significantly deteriorate the performance of QD-LEDs. In this study, we demonstrated the improved performance of QD-LEDs by modifying the electron injection property of ZnO with self-assembled monolayer (SAM)-treatment. As a result of improved charge balance, the external quantum efficiency and maximum luminance of QD-LEDs with SAM-treatment were improved by 25% and 200%, respectively, compared to the devices without SAM-treatment.

양자점 발광 다이오드(QD-LED)의 효율과 안정성 향상을 위해서 QD 발광층에 주입되는 전하의 균형을 이루는 것은 필수이다. 산화 아연(ZnO)은 최신 QD-LED에서 전자수송층(electron transport layer, ETL)을 구성하기 위해 가장 많이 사용되고 있으나, ZnO의 자발적인 전자 주입은 QD-LED의 성능을 크게 열화시키는 과도한 전자 주입을 유발한다. 본 연구에서는 자기조립단분자막(self-assembled monolayer, SAM) 처리를 통해 ZnO의 전자 주입 특성을 조절하여 QD-LED의 성능을 향상시켰다. 전하 균형도를 향상시킨 결과, SAM을 처리한 QD-LED는 SAM을 처리 안한 소자와 비교하여 내부 양자 효율(external quantum efficiency, EQE)이 25%, 최대 휘도는 200% 향상되었다.

Keywords

Acknowledgement

This work was supported by a 2-Year Research Grant of Pusan National University

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