Enhancement of organic photovoltaic efficiency via nanomorphology control using conjugated polymers incorporating fullerene compatible side-chains

Sungmin Park, Dongkyun Seo, Tae In Ryu, Gukil Ahn, Kyungwon Kwak, Hyunjung Kim, Cheol-Hong Cheon, Nam Gyu Park, BongSoo Kim, Min Jae Ko, Doh Kwon Lee, Jin Young Kim, Honggon Kim, Hae Jung Son

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

We present controls of nanomorphology of polymer:fullerene BHJ films via synthesis of a series of push-pull-type copolymers with various molar percentages of side chains terminated with o-dichlorobenzyl (DCBZ) groups. As the molar percentage of the DCBZ-containing repeat units increases, the miscibility of the polymers in the series with PC71BM increases with respect to that of the polymer (PTBBO) that does not contain DCBZ. In the optimal film morphology, which consists of a polymer containing 25 mol % DCBZ-terminated side chains in the electron-pull unit (PTBDCB25), the polymer/PC71BM interface area is sufficiently large for efficient charge separation and percolated pathways is present for efficient charge carrier transport. In contrast, the BHJ film prepared from PTBBO has smaller interfaces and larger PC71BM aggregates. Furthermore, the intermolecular interaction between PC71BM and DCBZ induced changes in the PC71BM 's electronic structure at the polymer:PC71BM interface, resulting in an increase of the PC71BM's LUMO level and thereby the improved open-circuit voltage. As a result, the BHJ solar cell device fabricated with PTBDCB25 exhibits significantly improved performance with a PCE of 8.30%, whereas the PCE of PTBBO is 6.90%. (Chemical Equation Presented).

Original languageEnglish
Pages (from-to)337-345
Number of pages9
JournalMacromolecules
Volume48
Issue number2
DOIs
Publication statusPublished - 2015 Jan 27

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ASJC Scopus subject areas

  • Organic Chemistry
  • Materials Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry

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