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Liquid-crystalline semiconducting polymers with high charge-carrier mobility

Abstract

Organic semiconductors that can be fabricated by simple processing techniques and possess excellent electrical performance, are key requirements in the progress of organic electronics. Both high semiconductor charge-carrier mobility, optimized through understanding and control of the semiconductor microstructure, and stability of the semiconductor to ambient electrochemical oxidative processes are required. We report on new semiconducting liquid-crystalline thieno[3,2-b ]thiophene polymers, the enhancement in charge-carrier mobility achieved through highly organized morphology from processing in the mesophase, and the effects of exposure to both ambient and low-humidity air on the performance of transistor devices. Relatively large crystalline domain sizes on the length scale of lithographically accessible channel lengths (200 nm) were exhibited in thin films, thus offering the potential for fabrication of single-crystal polymer transistors. Good transistor stability under static storage and operation in a low-humidity air environment was demonstrated, with charge-carrier field-effect mobilities of 0.2–0.6 cm2 V−1 s−1 achieved under nitrogen.

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Figure 1: Chemical structure of poly(2,5-bis(3-alkylthiophen-2-yl) thieno[3,2-b]thiophene).
Figure 2: AFM images of polymer C12 (annealed at 180 C).
Figure 3: X-ray scattering pattern of polymer C12 (annealed at 180 C).
Figure 4: Field-effect transistor device characteristics in N2 atmosphere with polymer C14 semiconductor.
Figure 5: Stability of FET devices.

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References

  1. Katz, H. E. Recent advances in semiconductor performance and printing processes for organic transistor-based electronics. Chem. Mater. 16, 4748–4756 (2004).

    Article  Google Scholar 

  2. Chabinyc, M. L. & Salleo, A. Materials requirements and fabrication of active matrix arrays of organic thin film transistors for displays. Chem. Mater. 16, 4509–4521 (2004).

    Article  Google Scholar 

  3. Sirringhaus, H. et al. Two-dimensional charge transport in self-organized, high-mobility conjugated polymers. Nature 401, 685–688 (1999).

    Article  Google Scholar 

  4. Jurchescu, O. D., Baas, J. & Palstra, T. T. M. Effect of impurities on the mobility of single crystal pentacene. Appl. Phys. Lett. 84, 3061–3063 (2004).

    Article  Google Scholar 

  5. Podzorov, V., Sysoev, S. E., Loginova, E., Pudalov, V. M. & Gershenson, M. E. Single-crystal organic field effect transistors with the hole mobility. Approx. 8 cm2/Vs . Appl. Phys. Lett. 83, 3504–3505 (2003).

    Article  Google Scholar 

  6. Baude, P. F. et al. Pentacene-based radio-frequency identification circuitry. Appl. Phys. Lett. 82, 3964–3966 (2003).

    Article  Google Scholar 

  7. Payne, M. M., Parkin, S. R., Anthony, J. E., Kuo, C. C. & Jackson, T. N. Organic field-effect transistors from solution-deposited functionalized acenes with mobilities as high as 1 cm2/V·s . J. Am. Chem. Soc. 127, 4986–4987 (2005).

    Article  Google Scholar 

  8. Sirringhaus, H., Tessler, N. & Friend, R. H. Integrated optoelectronic devices based on conjugated polymers. Science 280, 1741–1744 (1998).

    Article  Google Scholar 

  9. Bao, Z., Dobabalapur, A. & Lovinger, A. J. Soluble and processable regioregular poly(3-hexylthiophene) for thin film field-effect transistor applications with high mobility. Appl. Phys. Lett. 69, 4108–4110 (1996).

    Article  Google Scholar 

  10. Prosa, T. J., Wimokur, M. J., Moulton, J., Smith, P. & Heeger, A. J. X-ray structural studies of poly(3-alkylthiophenes): An example of an inverse comb. Macromolecules 25, 4364–4372 (1992).

    Article  Google Scholar 

  11. Ong, B. S., Wu, Y., Liu, P. & Gardner, S. High-performance semiconducting polythiophenes for organic thin-film transistors. J. Am. Chem. Soc. 126, 3378–3379 (2004).

    Article  Google Scholar 

  12. McCulloch, I. et al. Influence of molecular design on field-effect transistor characteristics of terthiophene polymers. Chem. Mater. 17, 1381–1385 (2005).

    Article  Google Scholar 

  13. Zhao, N. et al. Microscopic studies on liquid crystal poly(3,3′′′ -dialkylquaterthiophene) semiconductor. Macromolecules 37, 8307–8312 (2004).

    Article  Google Scholar 

  14. Street, R. A., Northrup, J. E. & Salleo, A. Transport in polycrystalline polymer thin-film transistors. Phys. Rev. B 71, 165202 (2005).

    Article  Google Scholar 

  15. McCullough, R. The chemistry of conducting polythiophenes. Adv. Mater. 10, 93–116 (1998).

    Article  Google Scholar 

  16. Brennan, D. J. et al. Recent advances in the synthesis of polyfluorenes as organic semiconductors. Mater. Res. Soc. Symp. Proc. 814, 1–12 (2004).

    Article  Google Scholar 

  17. Heeney, M. et al. Alkylidene fluorene liquid crystalline semiconducting polymers for organic field effect transistor devices. Macromolecules 37, 5250–5256 (2004).

    Article  Google Scholar 

  18. Kline, J. R., McGehee, M. D., Kadnikova, E. N., Liu, J. & Frechet, J. M. J. Controlling the field-effect mobility of regioregular polythiophene by changing the molecular weight. Adv. Mater. 15, 1519–1522 (2003).

    Article  Google Scholar 

  19. Babel, A. & Jenekhe, S. A. Field-effect mobility of charge carriers in blends of regioregular poly(3-alkylthiophene)s. J. Phys. Chem. B 107, 1749–1754 (2003).

    Article  Google Scholar 

  20. Yang, H. C. et al. Effect of mesoscale crystalline structure on the field-effect mobility of regioregular poly(3-hexylthiophene) in thin-film transistors. Adv. Funct. Mater. 15, 671–676 (2005).

    Article  Google Scholar 

  21. Kline, R. J. et al. Dependence of regioregular poly(3-hexylthiophene) film morphology and field-effect mobility on molecular weight. Macromolecules 38, 3312–3319 (2005).

    Article  Google Scholar 

  22. Heeney, M. et al. Stable polythiophene semiconductors incorporating thieno[2,3-b]thiophene. J. Am. Chem. Soc. 127, 1078–1079 (2005).

    Article  Google Scholar 

  23. Salleo, A. et al. Intrinsic hole mobility and trapping in a regioregular poly(thiophene). Phys. Rev. B 70, 115311 (2004).

    Article  Google Scholar 

  24. Meijer, E. J. et al. Dopant density determination in disordered organic field-effect transistors. J. Appl. Phys. 93, 4831–4835 (2003).

    Article  Google Scholar 

  25. Leeuw, D. M. d., Simenon, M. M. J., Brown, A. R. & Einerhand, R. E. F. Stability of n-type doped conducting polymers and consequences for polymeric microelectronic devices. Synth. Met. 87, 53–59 (1997).

    Article  Google Scholar 

  26. Xia, Y., Rogers, J. A., Paul, K. E. & Whitesides, G. M. Unconventional methods for fabricating and patterning nanostructures. Chem. Rev. 99, 1823–1848 (1999).

    Article  Google Scholar 

  27. Sele, C. W., von Werne, T., Friend, R. H. & Sirringhaus, H. Lithography-free, self-aligned inkjet printing with sub-hundred nanometer resolution. Adv. Mater. 17, 997–1001 (2005).

    Article  Google Scholar 

  28. Tierney, S., Heeney, M. & McCulloch, I. Microwave-assisted synthesis of polythiophenes via the stille coupling. Synth. Met. 148, 195–198 (2005).

    Article  Google Scholar 

  29. Toney, M. F. & Wiesler, D. G. Instrumental effects on measurements of surface x-ray diffraction rods: Resolution function and active sample area. Acta Crystallogr. A 49, 624–642 (1993).

    Article  Google Scholar 

  30. Sano, T., Hamada, Y. & Shibata, K. Energy-band schemes of highly stable organic electroluminescent devices. IEEE J. Sel. Top. Quantum Electron. 4, 34–39 (1998).

    Article  Google Scholar 

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Acknowledgements

Portions of this research were carried out at the Stanford Synchrotron Radiation Laboratory, a user facility operated by Stanford University on behalf of the US Department of Energy, Office of Basic Energy Sciences.

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Correspondence to Iain McCulloch.

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McCulloch, I., Heeney, M., Bailey, C. et al. Liquid-crystalline semiconducting polymers with high charge-carrier mobility. Nature Mater 5, 328–333 (2006). https://doi.org/10.1038/nmat1612

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