Article
  • Synthesis and Photovoltaic Properties of a Low Band Gap Polymer for Organic Solar Cell
  • Woo YH, Lee HS, Park S, Choi EJ, Kim BS
  • 유기태양전지를 위한 작은 밴드갭 고분자의 합성과 광전특성
  • 우용호, 이효상, 박성남, 최이준, 김봉수
Abstract
We synthesized a low band gap alternating copolymer containing electron-rich units (i.e. dithienosiloles and benzodithiophenes) and electron-deficient units (i.e. ifluorobenzothiadiazoles) 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: PC70BM/Al with five different blending ratios of polymer and PC70BM (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 PC70BM in the photoactive layer, and TEM revealed that there is an optimal nanoscale phase separation between polymer and PC70BM in the 1:3 ratio blend film.

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 PC70BM을 1:1.5, 1:2, 1:3, 1:3.5 및 1:4의 중량비로 혼합하여 ITO/PEDOT:PSS/polymer:PC70BM/Al의 구조로 유기태양전지 소자를 제작하여 그 광전특성을 조사하였다. 고분자:PC70BM의 혼합비율이 1:3에서 최고 1.0%의 광전변환효율이 달성되었다. TEM 실험을 통하여 1:3 혼합비율에서 유기태양전지에 가장 적합한 나노규모로 상분리가 일어났으며, 다른 혼합비율에서는 고분자와 PC70BM의 뭉침현상에 기인하여 태양전지 특성이 낮아졌다.

Keywords: organic solar cell; low band gap; Stille coupling reaction; alternating copolymer.

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  • Polymer(Korea) 폴리머
  • Frequency : Bimonthly(odd)
    ISSN 0379-153X(Print)
    ISSN 2234-8077(Online)
    Abbr. Polym. Korea
  • 2023 Impact Factor : 0.4
  • Indexed in SCIE

This Article

  • 2015; 39(1): 71-77

    Published online Jan 25, 2015

  • Received on May 24, 2013
  • Accepted on Jul 25, 2013