Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

A molecular design principle of lyotropic liquid-crystalline conjugated polymers with directed alignment capability for plastic electronics

Abstract

Conjugated polymers with a one-dimensional p-orbital overlap exhibit optoelectronic anisotropy. Their unique anisotropic properties can be fully realized in device applications only when the conjugated chains are aligned. Here, we report a molecular design principle of conjugated polymers to achieve concentration-regulated chain planarization, self-assembly, liquid-crystal-like good mobility and non-interdigitated side chains. As a consequence of these intra- and intermolecular attributes, chain alignment along an applied flow field occurs. This liquid-crystalline conjugated polymer was realized by incorporating intramolecular sulphur–fluorine interactions and bulky side chains linked to a tetrahedral carbon having a large form factor. By optimizing the polymer concentration and the flow field, we could achieve a high dichroic ratio of 16.67 in emission from conducting conjugated polymer films. Two-dimensional grazing-incidence X-ray diffraction was performed to analyse a well-defined conjugated polymer alignment. Thin-film transistors built on highly aligned conjugated polymer films showed more than three orders of magnitude faster carrier mobility along the conjugated polymer alignment direction than the perpendicular direction.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Figure 1: The chemical structures of the designed CPs, their absorption spectra (in solution and as films) and the suggested mechanism for directed CP alignment.
Figure 2: The grooves generated from the flow of CP1 solution and their morphology analysis.
Figure 3: GIXRD with CP1.
Figure 4: Directed alignment and its optical/electrical anisotropic properties.

Similar content being viewed by others

References

  1. Kim, Y. et al. A strong regioregularity effect in self-organizing conjugated polymer films and high-efficiency polythiophene:fullerene solar cells. Nature Mater. 5, 197–203 (2006).

    Article  CAS  Google Scholar 

  2. Chen, H-Y. et al. Polymer solar cells with enhanced open-circuit voltage and efficiency. Nature Photon. 3, 649–653 (2009).

    Article  CAS  Google Scholar 

  3. Park, S. H. et al. Bulk heterojunction solar cells with internal quantum efficiency approaching 100%. Nature Photon. 3, 297–303 (2009).

    Article  CAS  Google Scholar 

  4. McCulloch, I. et al. Liquid-crystalline semiconducting polymers with high charge-carrier mobility. Nature Mater. 5, 328–333 (2006).

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  6. Ha, J. S., Kim, K. H. & Choi, D. H. 2,5-Bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4-(2H,5H)-dione-based donor–acceptor alternating copolymer bearing 5,5′-di(thiophen-2-yl)-2,2’-biselenophene exhibiting 1.5 cm2 V−1 s−1 hole mobility in thin-film transistors. J. Am. Chem. Soc. 133, 10364–10367 (2011).

    Article  CAS  Google Scholar 

  7. Gross, M. et al. Improving the performance of doped p-conjugated polymers for use in organic light-emitting diodes. Nature 405, 661–665 (2000).

    Article  CAS  Google Scholar 

  8. Lavastre, O., Illitchev, I., Jegou, G. & Dixneuf, P. H. Discovery of new fluorescent materials from fast synthesis and screening of conjugated polymers. J. Am. Chem. Soc. 124, 5278–5279 (2002).

    Article  CAS  Google Scholar 

  9. Thomas, S. W. III, Joly, G. D. & Swager, T. M. Chemical sensors based on amplifying fluorescent conjugated polymers. Chem. Rev. 107, 1339–1386 (2007).

    Article  CAS  Google Scholar 

  10. Forzani, E. S. et al. A conducting polymer nanojunction sensor for glucose detection. Nano Lett. 4, 1785–1788 (2004).

    Article  CAS  Google Scholar 

  11. Gibbons, W. M., Shannon, P. J., Sun, S-T. & Swetlin, B. J. Surface-mediated alignment of nematic liquid crystals with polarized laser light. Nature 351, 49–50 (1991).

    Article  CAS  Google Scholar 

  12. Grell, M. et al. A glass-forming conjugated main-chain liquid crystal polymer for polarized electroluminescence application. Adv. Mater. 9, 798–802 (1997).

    Article  CAS  Google Scholar 

  13. Grell, M. et al. A. Blue polarized electroluminescence from a liquid crystalline polyfluorene. Adv. Mater. 11, 671–675 (1999).

    Article  CAS  Google Scholar 

  14. Lee, J., Jun, H. & Kim, J. Polydiacetylene–liposome microarrays for selective and sensitive mercury(II) detection. Adv. Mater. 21, 3674–3677 (2009).

    Article  CAS  Google Scholar 

  15. Brinkmann, M & Wittmann, J-C. Orientation of regioregular poly(3-hexylthiophene) by directional solidification: A simple method to reveal the semicrystalline structure of a conjugated polymer. Adv. Mater. 18, 860–863 (2006).

    Article  CAS  Google Scholar 

  16. Cremer, L. D., Verbiest, T. & Koeckelberghs, G. Influence of the substituent on the chiroptical properties of poly(thieno[3,2-b]thiophene)s. Macromolecules 41, 568–578 (2008).

    Article  Google Scholar 

  17. Cimrová, V., Remmers, M., Neher, D. & Wegner, G. Polarized light emission from LEDs prepared by the Langmuir–Blodgett technique. Adv. Mater. 8, 146–149 (1996).

    Article  Google Scholar 

  18. Kim, J., McHugh, S. K. & Swager, T. M. Nanoscale fibrils and grids: Aggregated structures from rigid-rod conjugated polymers. Macromolecules 32, 1500–1507 (1999).

    Article  CAS  Google Scholar 

  19. Weder, C., Sarwa, C., Montali, A., Bastiaansen, C. & Smith, P. Incorporation of photoluminescent polarizers into liquid crystal displays. Science 279, 835–837 (1998).

    Article  CAS  Google Scholar 

  20. Montali, A., Bastiaansen, C., Smith, P. & Weder, C. Polarizing energy transfer in photoluminescentmaterials for display applications. Nature 392, 261–264 (1998).

    Article  CAS  Google Scholar 

  21. Tsao, H. N. et al. The influence of morphology on high-performance polymer field-effect transistors. Adv. Mater. 21, 209–212 (2009).

    Article  CAS  Google Scholar 

  22. Zheng, Z. et al. Uniaxial alignment of liquid-crystalline conjugated polymers by nanoconfinement. Nano Lett. 7, 987–992 (2007).

    Article  CAS  Google Scholar 

  23. Subramanian, S. et al. Chromophore fluorination enhances crystallization and stability of soluble anthradithiophene semiconductors. J. Am. Chem. Soc. 130, 2706–2707 (2008).

    Article  CAS  Google Scholar 

  24. Gundlach, D. J. et al. Contact-induced crystallinity for high-performance soluble acene-based transistors and circuits. Nature Mater. 7, 216–221 (2008).

    Article  CAS  Google Scholar 

  25. Kim, J. & Swager, T. M. Control of conformational and interpolymer effects in conjugated polymers. Nature 411, 1030–1034 (2001).

    Article  CAS  Google Scholar 

  26. Tsao, H. N. et al. Ultrahigh mobility in polymer field-effect transistors by design. J. Am. Chem. Soc. 133, 2605–2612 (2011).

    Article  CAS  Google Scholar 

  27. Lemaur, V. et al. Charge transport properties in discotic liquid crystals: A quantum-chemical insight into structure-property relationships. J. Am. Chem. Soc. 126, 3271–3279 (2004).

    Article  CAS  Google Scholar 

  28. Yuen, J. D. et al. Nonlinear transport in semiconducting polymers at high carrier densities. Nature Mater. 8, 572–575 (2009).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

The authors thank E-H. Sohn at Seoul National University (SNU) for the 2D GIXRD measurement and J. Kieffer and X. Ma for the calculation of the polymer conformation. This work was supported by the US Department of Energy (DOE), Office of Basic Energy Sciences, as part of the Center for Solar and Thermal Energy Conversion, an Energy Frontier Research Center (DE-SC0000957). E.J.J. was partly supported by the WCU (World Class University) programme through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (R31-2008-000-10075-0) and S.S. was supported by an NSF CAREER Award (DMR 0644864).

Author information

Authors and Affiliations

Authors

Contributions

J.K. designed and directed the project. B-G.K. and E.J.J. synthesized the series of polymers. B-G.K. prepared and analysed the aligned CP films, B-G.K., J.W.C. and B.K. fabricated the organic thin-film transistors, and S.S. performed the X-ray measurements. B-G.K. and J.K. wrote the manuscript, and all other authors had input.

Corresponding author

Correspondence to Jinsang Kim.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 1355 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Kim, BG., Jeong, E., Chung, J. et al. A molecular design principle of lyotropic liquid-crystalline conjugated polymers with directed alignment capability for plastic electronics. Nature Mater 12, 659–664 (2013). https://doi.org/10.1038/nmat3595

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat3595

This article is cited by

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing