Thienoisoindigo (TII)-Based Quinoidal Small Molecules for High-Performance n-Type Organic Field Effect Transistors

Arulmozhi Velusamy, Chih Hsin Yu, Shakil N. Afraj, Chia Chi Lin, Wei Yu Lo, Chia Jung Yeh, Ya Wen Wu, Hsin Chun Hsieh, Jianhua Chen, Gene Hsiang Lee, Shih Huang Tung, Cheng Liang Liu*, Ming Chou Chen*, Antonio Facchetti*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


A novel quinoidal thienoisoindigo (TII)-containing small molecule family with dicyanomethylene end-capping units and various alkyl chains is synthesized as n-type organic small molecules for solution-processable organic field effect transistors (OFETs). The molecular structure of the 2-hexyldecyl substituted derivative, TIIQ-b16, is determined via single-crystal X-ray diffraction and shows that the TIIQ core is planar and exhibits molecular layers stacked in a “face-to-face” arrangement with short core intermolecular distances of 3.28 Å. The very planar core structure, shortest intermolecular N···H distance (2.52 Å), existence of an intramolecular non-bonded contact between sulfur and oxygen atom (S···O) of 2.80 Å, and a very low-lying LUMO energy level of −4.16 eV suggest that TIIQ molecules should be electron transporting semiconductors. The physical, thermal, and electrochemical properties as well as OFET performance and thin film morphologies of these new TIIQs are systematically studied. Thus, air-processed TIIQ-b16 OFETs exhibit an electron mobility up to 2.54 cm2 V−1 s−1 with a current ON/OFF ratio of 105–106, which is the first demonstration of TII-based small molecules exhibiting unipolar electron transport characteristics and enhanced ambient stability. These results indicate that construction of quinoidal molecule from TII moiety is a successful approach to enhance n-type charge transport characteristics.

Original languageEnglish (US)
Article number2002930
JournalAdvanced Science
Issue number1
StatePublished - Jan 6 2020


  • organic field effect transistors
  • organic semiconductors
  • quinoid
  • solution-shearing
  • thienoisoindigo

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Chemical Engineering(all)
  • Materials Science(all)
  • Biochemistry, Genetics and Molecular Biology (miscellaneous)
  • Engineering(all)
  • Physics and Astronomy(all)


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