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

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

본 연구에서는 자기장 하에서 증착 후 열처리된 NPD (4,4'-bis-[N-(1-napthyl)-N-phenyl-amino]biphenyl)박막의 토폴로지와 분자배열을 관찰하였다. NPD는 진공에서 열 증발법을 통하여 증착되었다. 분자 배열이 잘 되어진 유기/금속필름은 2전류밀도와 발광효율 같은 소자의 특성을 향상시키는 것이 특히 중요하다. 원자탐침현미경(AFM) 및 X선 회절 분석기(XRD)의 분석결과는 토폴로지와 NPD필름의 구조적 배열을 특성화하는데 사용되었다. 멀티소스미터는 ITO/NPD/Al 소자의 전류-전압 특성을 측정하는데 사용되었다. XRD 결과에 따르면 자기장 하에서 증착된 NPD 박막은 분자배열이 관찰되지 않았으나, $130^{\circ}C$에서 후(後)열처리한 NPD 박막에서는 고른 분자배열을 확인할 수 있었다. AFM 이미지에 따르면, 자기장 하에서 증착된 NPD 박막은 자기장 없이 증착된 박막보다 더 매끄러운 표면을 가졌다. NPD의 전류-전압 특성은 고른 분자 배열을 가진 NPD 필름의 더 높아진 전자이동도로 인해 향상되었다.

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.