(Semi)ladder-Type Bithiophene Imide-Based All-Acceptor Semiconductors: Synthesis, Structure-Property Correlations, and Unipolar n-Type Transistor Performance

Yingfeng Wang, Han Guo, Alexandra Harbuzaru, Mohammad Afsar Uddin, Iratxe Arrechea-Marcos, Shaohua Ling, Jianwei Yu, Yumin Tang, Huiliang Sun, Juan Teodomiro López Navarrete, Rocio Ponce Ortiz, Han Young Woo, Xugang Guo

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174 Citations (Scopus)


Development of high-performance unipolar n-type organic semiconductors still remains as a great challenge. In this work, all-acceptor bithiophene imide-based ladder-type small molecules BTIn and semiladder-type homopolymers PBTIn (n = 1-5) were synthesized, and their structure-property correlations were studied in depth. It was found that Pd-catalyzed Stille coupling is superior to Ni-mediated Yamamoto coupling to produce polymers with higher molecular weight and improved polymer quality, thus leading to greatly increased electron mobility (μe). Due to their all-acceptor backbone, these polymers all exhibit unipolar n-type transport in organic thin-film transistors, accompanied by low off-currents (10-10-10-9 A), large on/off current ratios (106), and small threshold voltages (∼15-25 V). The highest μe, up to 3.71 cm2 V-1 s-1, is attained from PBTI1 with the shortest monomer unit. As the monomer size is extended, the μe drops by 2 orders to 0.014 cm2 V-1 s-1 for PBTI5. This monotonic decrease of μe was also observed in their homologous BTIn small molecules. This trend of mobility decrease is in good agreement with the evolvement of disordered phases within the film, as revealed by Raman spectroscopy and X-ray diffraction measurements. The extension of the ladder-type building blocks appears to have a large impact on the motion freedom of the building blocks and the polymer chains during film formation, thus negatively affecting film morphology and charge carrier mobility. The result indicates that synthesizing building blocks with more extended ladder-type backbone does not necessarily lead to improved mobilities. This study marks a significant advance in the performance of all-acceptor-type polymers as unipolar electron transporting materials and provides useful guidelines for further development of (semi)ladder-type molecular and polymeric semiconductors for applications in organic electronics.

Original languageEnglish
Pages (from-to)6095-6108
Number of pages14
JournalJournal of the American Chemical Society
Issue number19
Publication statusPublished - 2018 May 16

Bibliographical note

Funding Information:
X.G. thanks the National Science Foundation of China (51573076) Shenzhen Peacock Plan Project (KQTD20140630110339343), Shenzhen Basic Research Fund (JCYJ20160530185244662), Shenzhen Key Lab funding (ZDSYS201505291525382), Guangdong Natural Science Foundation (2015A030313900), and South University of Science and Technology of China (FRG-SUSTC1501A-72). H.G. is grateful to the Shenzhen Basic Research Fund (JCYJ20160530190226226). S.L. acknowledges the USI Training Program (2016S11). M.A.U. and H.Y.W. are grateful to the financial support from the NRF of Korea (2016M1A2A2940911 and 20100020209).

Publisher Copyright:
© 2018 American Chemical Society.

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry


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