Effect of Broken Conjugation on the Stretchability of Semiconducting Polymers

Suchol Savagatrup, Xikang Zhao, Esther Chan, Jianguo Mei, Darren J. Lipomi

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

Increasing the flexibility of polymer chains is a common method of increasing the deformability of solid polymeric materials. Here, the effects of "conjugation-break spacers" (CBSs)-aliphatic units that interrupt the sp2 -hybridized backbone of semiconducting polymers-on the mechanical and photovoltaic properties of a diketopyrrolopyrrole-based polymer are described. Unexpectedly, the tensile moduli and cracking behavior of a series of polymers with repeat units bearing 0%, 30%, 50%, 70%, and 100% of the CBS are not directly related to the percent incorporation of the flexible unit. Rather, the mechanical properties are a strong function of the order present in the film as determined by grazing-incidence x-ray diffraction. The effect of the CBSs on the photovoltaic performance of these materials, on the other hand, is more intuitive: it decreases with increasing fraction of the flexible units. These studies highlight the importance of solid-state packing structure-as opposed to only the flexibility of the individual molecules-in determining the mechanical properties of a conjugated polymer film for stretchable, ultraflexible, and mechanically robust electronics.

Original languageEnglish (US)
Pages (from-to)1623-1628
Number of pages6
JournalMacromolecular Rapid Communications
Volume37
Issue number19
DOIs
StatePublished - Oct 1 2016
Externally publishedYes

Keywords

  • bulk heterojunctions
  • conjugated polymers
  • mechanical properties
  • stretchable electronics
  • structure-property relationships

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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