Viability of stretchable poly(3-heptylthiophene) (P3HpT) for organic solar cells and field-effect transistors

Suchol Savagatrup, Adam D. Printz, Haosheng Wu, Kirtana M. Rajan, Eric J. Sawyer, Aliaksandr V. Zaretski, Christopher J. Bettinger, Darren J. Lipomi

Research output: Contribution to journalArticlepeer-review

75 Scopus citations


Mechanical compliance is a critical attribute for organic semiconductors in flexible, stretchable, mechanically robust, and biologically integrated electronics. This paper substantially develops the observation that a small change in the length of the alkyl side chain of regioregular poly(3-alkylthiophene)s has a dramatic effect on the interplay between their mechanical and charge-transport properties. Specifically, the thermal, mechanical, and charge-transport properties of poly(3-heptylthiophene) (P3HpT, n = 7), which we found to be an unusual example of a stretchable semiconducting thermoplastic, are described in comparison to those of poly(3-hexylthiophene) (P3HT, n = 6) and poly(3-octylthiophene) (P3OT, n = 8). Neat P3HpT was found to have mechanical properties similar to that of P3OT, and when mixed in 1:1 blends with the fullerene [6,6]-phenyl C61 butyric acid methyl ester (PCBM), exhibited electronic properties comparable to P3HT. However, the charge-carrier mobility of neat P3HpT is substantially inferior to that of P3HT; the good performance of P3HpT-based solar cells is the result of improved mobility in P3HpT:PCBM blends compared to the neat material. While P3HpT may be a favorable alternative to P3HT in ultra-flexible, stretchable, and mechanically robust organic solar cells, P3HpT would only make a good field-effect transistor in situations in which mechanical compliance was more important than high mobility.

Original languageEnglish (US)
Pages (from-to)208-214
Number of pages7
JournalSynthetic Metals
StatePublished - May 2015
Externally publishedYes


  • Mechanical properties
  • Organic solar cells
  • P3HpT
  • Poly(3-alkylthiophene)
  • Stretchable electronics

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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