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Molecular Weight-Induced Structural Transition of Liquid-Crystalline Polymer Semiconductor for High-Stability Organic Transistor

  1. Do Hwan Kim1,†,‡,
  2. Jiyoul Lee1,‡,
  3. Jeong-Il Park1,
  4. Jong Won Chung1,
  5. Wi Hyoung Lee2,
  6. Gaurav Giri3,
  7. Byungwook Yoo1,
  8. Bonwon Koo1,
  9. Joo Young Kim1,
  10. Yong Wan Jin1,
  11. Kilwon Cho2,
  12. Bang-Lin Lee1,*,
  13. Sangyoon Lee1,*

Article first published online: 21 SEP 2011

DOI: 10.1002/adfm.201101021

Issue

Advanced Functional Materials

Advanced Functional Materials

Volume 21, Issue 23, pages 4442–4447, December 6, 2011

Additional Information

How to Cite

Kim, D. H., Lee, J., Park, J.-I., Chung, J. W., Lee, W. H., Giri, G., Yoo, B., Koo, B., Kim, J. Y., Jin, Y. W., Cho, K., Lee, B.-L. and Lee, S. (2011), Molecular Weight-Induced Structural Transition of Liquid-Crystalline Polymer Semiconductor for High-Stability Organic Transistor. Adv. Funct. Mater., 21: 4442–4447. doi: 10.1002/adfm.201101021

Author Information

  1. 1

    Display Device Laboratory, Samsung Advanced Institute of Technology, Yongin 446-712, Korea

  2. 2

    Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, 790-784, Korea

  3. 3

    Department of Chemical Engineering, Stanford University, Stanford, California 94305-5025, USA

  1. †

    Department of Chemical Engineering, Stanford University, Stanford, California 94305-5025, USA

  1. ‡

    D.H.K. and J.L. contributed equally to this work.

*Display Device Laboratory, Samsung Advanced Institute of Technology, Yongin 446-712, Korea.

Publication History

  1. Issue published online: 30 NOV 2011
  2. Article first published online: 21 SEP 2011
  3. Manuscript Received: 8 MAY 2011

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Keywords:

  • liquid-crystalline polymer semiconductor;
  • organic transistor;
  • crystalline microstructure;
  • molecular weight;
  • bias stability

Abstract

In order to fabricate polymer field-effect transistors (PFETs) with high electrical stability under bias-stress, it is crucial to minimize the density of charge trapping sites caused by the disordered regions. Here we report PFETs with excellent electrical stability comparable to that of single-crystalline organic semiconductors by specifically controlling the molecular weight (MW) of the donor-acceptor type copolymer semiconductors, poly (didodecylquaterthiophene-alt-didodecylbithiazole). We found that MW-induced thermally structural transition from liquid-crystalline to semi-crystalline phases strongly affects the device performance (charge-carrier mobility and electrical bias-stability) as well as the nanostructures such as the molecular ordering and the morphological feature. In particular, for the polymer with a MW of 22 kDa, the transfer curves varied little (ΔVth = 3∼4 V) during a period of prolonged bias stress (about 50 000 s) under ambient conditions. This enhancement of the electrical bias-stability can be attributed to highly ordered liquid-crystalline nanostructure of copolymer semiconductors on dielectric surface via the optimization of molecular weights.

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