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유기태양전지를 위한 작은 밴드갭 고분자의 합성과 광전특성

Synthesis and Photovoltaic Properties of a Low Band Gap Polymer for Organic Solar Cell

  • 우용호 (금오공과대학교 고분자공학과) ;
  • 이효상 (한국과학기술연구원) ;
  • 박성남 (고려대학교 그린스쿨) ;
  • 최이준 (금오공과대학교 고분자공학과) ;
  • 김봉수 (한국과학기술연구원)
  • Woo, Yong-Ho (Department of Polymer Science and Engineering, Kumoh National Institute of Technology) ;
  • Lee, Hyo-Sang (Korea Institute of Science and Technology) ;
  • Park, Sungnam (Green School, Korea University) ;
  • Choi, E-Joon (Department of Polymer Science and Engineering, Kumoh National Institute of Technology) ;
  • Kim, BongSoo (Korea Institute of Science and Technology)
  • 투고 : 2013.05.24
  • 심사 : 2013.07.25
  • 발행 : 2015.01.25

초록

본 연구에서는 전자가 풍부한 구조단위(dithienosilole 및 benzodithiophene)와 전자가 부족한 구조단위(difluorobenzothiadiazole)를 주사슬에 교대로 갖는 작은 밴드갭 공중합체를 Stille 짝지움 반응을 이용하여 합성하였다. $^1H$ NMR을 통하여 각 단계별 화합물과 고분자의 구조를 확인하였다. GPC, TGA, UV-vis 분광분석기 및 cyclic voltammetry를 이용하여 합성한 고분자의 특성을 조사하였다. 합성한 공액고분자와 $PC_{70}BM$을 1:1.5, 1:2, 1:3, 1:3.5 및 1:4의 중량비로 혼합하여 ITO/PEDOT:PSS/polymer:$PC_{70}BM/Al$의 구조로 유기태양전지 소자를 제작하여 그 광전특성을 조사하였다. 고분자:$PC_{70}BM$의 혼합비율이 1:3에서 최고 1.0%의 광전변환효율이 달성되었다. TEM 실험을 통하여 1:3 혼합비율에서 유기태양전지에 가장 적합한 나노규모로 상분리가 일어났으며, 다른 혼합비율에서는 고분자와 $PC_{70}BM$의 뭉침현상에 기인하여 태양전지 특성이 낮아졌다.

We synthesized a low band gap alternating copolymer containing electron-rich units (i.e. dithienosiloles and benzodithiophenes) and electron-deficient units (i.e. difluorobenzothiadiazoles) for high performance organic solar cells. The polymer was prepared by the Stille coupling reaction and characterized using $^1H$ NMR, GPC, TGA, UV-visible absorption spectroscopy, and cyclic voltammetry. Solar cells were fabricated in a structure of ITO/PEDOT:PSS/polymer: $PC_{70}BM/Al$ with five different blending ratios of polymer and $PC_{70}BM$ (1:1.5, 1:2, 1:3, 1:3.5 and 1:4 by weight ratio). The best efficiency was achieved from the 1:3 ratio of polymer and $PC_{70}BM$ in the photoactive layer, and TEM revealed that there is an optimal nanoscale phase separation between polymer and $PC_{70}BM$ in the 1:3 ratio blend film.

키워드

과제정보

연구 과제번호 : 화학인재양성사업단

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