Journal of the Korean Institute of Electrical and Electronic Material Engineers (한국전기전자재료학회논문지)

The Korean Institute of Electrical and Electronic Material Engineers (한국전기전자재료학회)
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Enhancement of Electrical Properties of Organic Light-Emitting Diodes Using F4-TCNQ Molecule as a Hole-Transport Layer

F4-TCNQ 분자를 정공 수송층에 이용한 유기 발광 소자의 전기적 특성 향상

  • Na, Su Hwan (Department of Information Display Engineering, Hongik university) ;
  • Lee, Won Jae (Department of Electronic Engineering, Gachon university)
  • 나수환 (홍익대학교 정보디스플레이공학과) ;
  • 이원재 (가천대학교 전자공학과)
  • Received : 2017.10.11
  • Accepted : 2017.10.16
  • Published : 2017.11.01
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Abstract

We studied the performance enhancement of organic light-emitting diodes (OLEDs) using 2,3,5,6-fluoro-7,7,8,8-tetracyanoquinodimethane ($F_4-TCNQ$) as the hole-transport layer. To investigate how $F_4-TCNQ$ affects the device performance, we fabricated a reference device in an ITO (170 nm)/TPD(40 nm)/$Alq_3$(60 nm)/LiF(0.5 nm)/Al(100 nm) structure. Several types of test devices were manufactured by either doping the $F_4-TCNQ$ in the TPD layer or forming a separate $F_4-TCNQ$ layer between the ITO anode and TPD layer. N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine (TPD), tri(8-hydroxyquinoline) aluminum ($Alq_3$), and $F_4-TCNQ$ layers were formed by thermal evaporation at a pressure of $10_{-6}$ torr. The deposition rate was $1.0-1.5{\AA}/s$ for TPD and $Alq_3$. The LiF was subsequently thermally evaporated at a deposition rate of $0.2{\AA}/s$. The performance of the OLEDs was considered with respect to the turn-on voltage, luminance, and current efficiency. It was found that the use of $F_4-TCNQ$ in OLEDs enhances the performance of the device. In particular, the use of a separate layer of $F_4-TCNQ$ realizes better device performance than other types of OLEDs.

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