Length-dependent self-assembly of oligothiophene derivatives in thin films

Brian S. Rolczynski, Jodi M. Szarko, Byeongdu Lee, Joseph Strzalka, Jianchang Guo, Yongye Liang, Luping Yu*, Lin X Chen

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

2 Scopus citations

Abstract

Thin-film aggregation characteristics of a series of oligothiophenes with a central thieno[3,4-b] thiophene ester unit and 4 (M5), 8 (M9), and 16 (M17) regioregular hexylthiophene units were investigated. These oligomers exhibited length-dependent self-assembly characteristics upon spin coating. M9 formed long fibers, while M5 and M17 formed random domains. Grazing incidence x-ray diffraction was performed to understand the reason for this length dependence. The M5 had a dominant ester-ester interaction that disrupted long-range order. The M9 morphology was due to a balance of orthogonal backbone and ester effects, which imposed long-range order on the M9 aggregates. Meanwhile, the M17 ester chain had a smaller relative contribution to packing and functioned as a molecular defect, disrupting long-range order. As a result, though the local self-assembly between monomers was very similar for the molecules, backbone length dependent changes in intermolecular forces dominated long-range structure. The analysis of self-assembly characteristics in these materials provides guidance in the design of organic conjugated materials for use in semiconductor devices.

Original languageEnglish (US)
Pages (from-to)296-305
Number of pages10
JournalJournal of Materials Research
Volume26
Issue number2
DOIs
StatePublished - Jan 28 2011

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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