Preparation and Current-Voltage Characteristics of Well-Aligned NPD (4,4' bis[N-(1-napthyl)-N-phenyl-amino] biphenyl) Thin Films

분자배열된 4,4' bis[N-(1-napthyl)-N-phenyl-amino] biphenyl 증착박막 제조와 전기적 특성

  • Oh, Sung (Department of Chemical Engineering, Pusan National University) ;
  • Kang, Do-Soon (Department of Chemical Engineering, Pusan National University) ;
  • Choe, Youngson (Department of Chemical Engineering, Pusan National University)
  • 오성 (부산대학교 화학공학과) ;
  • 강도순 (부산대학교 화학공학과) ;
  • 최영선 (부산대학교 화학공학과)
  • Received : 2006.05.01
  • Accepted : 2006.10.31
  • Published : 2006.12.10

Abstract

Topology and molecular ordering of NPD(4,4'-bis-[N-(1-naphthyl)-N-phenyl-amino]biphenyl) thin films deposited under magnetic field with post-deposition annealing were investigated. NPD was deposited onto ITO glass substrates via thermal evaporation process in vacuum. It is of great importance for highly oriented organic/metal films to have improved device performances such as higher current density and luminance efficiency. AFM (Atomic Force Microscope) and XRD (X-Ray Diffraction) analyses were used to characterize the topology and structure of oriented NPD films. The multi-source meter was used to observe the current-voltage characteristics of the ITO (Indium-Tin Oxide) / NPD (4,4'bis[N-(1-napthyl)-N-phenyl-amino]-biphenyl) / Al (Aluminum) device. While NPD thin films deposited under magnetic field were not molecularly well aligned according to the XRD results, the films after post-deposition annealing at $130^{\circ}C$ were well-oriented. AFM images show that NPD thin films deposited under magnetic field had a smoother surface than those deposited without magnetic field. The current-voltage performance of NPD thin films was improved due to the enhanced electron mobility in the well-aligned NPD films.

Keywords

NPD;molecular alignment;molecular stacking;magnetic field;OLED

Acknowledgement

Supported by : 부산대학교

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