Conflicted effects of a solvent additive on PTB7:PC71BM bulk heterojunction solar cells

Wanjung Kim, Jung Kyu Kim, Eunchul Kim, Tae Kyu Ahn, Dong Hwan Wang, Jong Hyeok Park

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152 Citations (Scopus)


Recently, polymer-fullerene based bulk heterojunction (BHJ) solar cells, which contain blends of poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}) (PTB7) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM), have been widely studied due to exhibiting high power conversion efficiency (PCE) and well-defined nanomorphology. Because of the short exciton diffusion pathway (less than 10 nm) in organic thin films, the optimization of PTB7:PC71BM BHJ with optimized morphology is very important between the donor and acceptor. In order to increase nanoscale phase separation, the chemical additives of 1,8-diiodooctane (DIO) have been used in PTB7:PC71BM blend systems. However, the mechanism studies of DIO in BHJ solar cells and its effectiveness on device stability are unclear. In this study, we fabricated polymer solar cells (PSCs) based on PTB7:PC71BM BHJ with various DIO concentrations to investigate not only correlation between device performances and different morphologies, but also the influence of additives on device stabilities. Positive effects of DIO, which were induced by efficient charge separation in BHJ at optimized blending ratio, are proved by the results of time-resolved photoluminescence (TRPL), and negative effects of DIO on a device stability have been investigated according to the ISOS-D-1 protocol.

Original languageEnglish
Pages (from-to)5954-5961
Number of pages8
JournalJournal of Physical Chemistry C
Issue number11
Publication statusPublished - 2015 Mar 19

Bibliographical note

Publisher Copyright:
© 2015 American Chemical Society.

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films


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