Effect of Spacer Length of Siloxane-Terminated Side Chains on Charge Transport in Isoindigo-Based Polymer Semiconductor Thin Films

Jianguo Mei, Hung Chin Wu, Ying Diao, Anthony Appleton, Hong Wang, Yan Zhou, Wen Ya Lee, Tadanori Kurosawa, Wen Chang Chen, Zhenan Bao

Research output: Contribution to journalArticle

Abstract

A series of isoindigo-based conjugated polymers (PII2F-CmSi, m = 3-11) with alkyl siloxane-terminated side chains are prepared, in which the branching point is systematically "moved away" from the conjugated backbone by one carbon atom. To investigate the structure-property relationship, the polymer thin film is subsequently tested in top-contact field-effect transistors, and further characterized by both grazing incidence X-ray diffraction and atomic force microscopy. Hole mobilities over 1 cm2 V-1 s-1 is exhibited for all soluble PII2F-CmSi (m = 5-11) polymers, which is 10 times higher than the reference polymer with same polymer backbone. PII2F-C9Si shows the highest mobility of 4.8 cm2 V-1 s-1, even though PII2F-C11Si exhibits the smallest π-π stacking distance at 3.379 Å. In specific, when the branching point is at, or beyond, the third carbon atoms, the contribution to charge transport arising from π-π stacking distance shortening becomes less significant. Other factors, such as thin-film microstructure, crystallinity, domain size, become more important in affecting the resulting device's charge transport.

Original languageEnglish (US)
Pages (from-to)3455-3462
Number of pages8
JournalAdvanced Functional Materials
Volume25
Issue number23
DOIs
StatePublished - Jun 1 2015

Keywords

  • charge transport
  • conjugated polymers
  • field-effect transistors
  • siloxane-terminated side chain
  • spacer length

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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