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.

Polarized X-ray scattering reveals non-crystalline orientational ordering in organic films

Nature Materials volume 11, pages 536–543 (2012)Cite this article

Subjects

Abstract

Molecular orientation critically influences the mechanical, chemical, optical and electronic properties of organic materials. So far, molecular-scale ordering in soft matter could be characterized with X-ray or electron microscopy techniques only if the sample exhibited sufficient crystallinity. Here, we show that the resonant scattering of polarized soft X-rays (P-SoXS) by molecular orbitals is not limited by crystallinity and that it can be used to probe molecular orientation down to size scales of 10 nm. We first apply the technique on highly crystalline small-molecule thin films and subsequently use its high sensitivity to probe the impact of liquid-crystalline ordering on charge mobility in polymeric transistors. P-SoXS also reveals scattering anisotropy in amorphous domains of all-polymer organic solar cells where interfacial interactions pattern orientational alignment in the matrix phase, which probably plays an important role in the photophysics. The energy and q-dependence of the scattering anisotropy allows the identification of the composition and the degree of orientational order in the domains.

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

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Learn more

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

Figure 1: Mechanism and method of bond-orientation scattering.
Figure 2: Microscopy of and scattering from pentacene.
Figure 3: PBTTT X-ray results correlate with OTFT performance.
Figure 4: P-SoXS of P3HT:P(NDI2OD-T2) blend films.
Figure 5: Morphology and mechanism of scattering anisotropy in P3HT:P(NDI2OD-T2) films.

References

  1. Simmons, A. H., Michal, C. A. & Jelinski, L. W. Molecular orientation and two-component nature of the crystalline fraction of spider dragline silk. Science 271, 84–87 (1996).

    Article  CAS  Google Scholar 

  2. Vollrath, F. & Knight, D. P. Liquid crystalline spinning of spider silk. Nature 410, 541–548 (2001).

    Article  CAS  Google Scholar 

  3. Schmidt-Mende, L. et al. Self-organized discotic liquid crystals for high-efficiency organic photovoltaics. Science 293, 1119–1122 (2001).

    Article  CAS  Google Scholar 

  4. Chen, W., Qi, D-C., Huang, H., Gao, X. & Wee, A. T. S. Organic–organic heterojunction interfaces: Effect of molecular orientation. Adv. Funct. Mater. 21, 410–424 (2011).

    Article  CAS  Google Scholar 

  5. Salleo, A., Kline, R. J., DeLongchamp, D. M. & Chabinyc, M. L. Microstructural characterization and charge transport in thin films of conjugated polymers. Adv. Mater. 22, 3812–3838 (2010).

    Article  CAS  Google Scholar 

  6. Friend, R. H. et al. Electroluminescence in conjugated polymers. Nature 397, 121–128 (1999).

    Article  CAS  Google Scholar 

  7. Sirringhaus, H. Mobility enhancement in conjugated polymer field-effect transistors through chain alignment in a liquid-crystalline phase. Appl. Phys. Lett. 77, 406–408 (2000).

    Article  CAS  Google Scholar 

  8. Yan, H. et al. A high-mobility electron-transporting polymer for printed transistors. Nature 457, 679–686 (2009).

    Article  CAS  Google Scholar 

  9. Zhang, X. et al. In-plane liquid crystalline texture of high-performance thienothiophene copolymer thin films. Adv. Funct. Mater. 20, 4098–4106 (2010).

    Article  CAS  Google Scholar 

  10. Ade, H. & Hsiao, B. X-ray linear dichroism microscopy. Science 262, 1427–1429 (1993).

    Article  CAS  Google Scholar 

  11. Ade, H., Toledo-Crow, R., Vaez-Iravani, M. & Spontak, R. J. Observation of polymer birefringence in near-field optical microscopy. Langmuir 12, 231–234 (1996).

    Article  CAS  Google Scholar 

  12. Brauer, B. et al. X-ray microscopy imaging of the grain orientation in a pentacene field-effect transistor. Chem. Mater. 22, 3693–3697 (2010).

    Article  CAS  Google Scholar 

  13. Hub, C., Burkhardt, M., Halik, M., Tzvetkov, G. & Fink, R. In situ STXM investigations of pentacene-based OFETs during operation. J. Mater. Chem. 20, 4884–4887 (2010).

    Article  CAS  Google Scholar 

  14. McNeill, C. R. Imaging the domain structure of organic semiconductor films. J. Polymer Sci. B 49, 909–919 (2011).

    Article  CAS  Google Scholar 

  15. Günes, S., Neugebauer, H. & Sariciftci, N. S. Conjugated polymer-based organic solar cells. Chem. Rev. 107, 1324–1338 (2007).

    Article  Google Scholar 

  16. Dennler, G., Scharber, M. C. & Brabec, C. J. Polymer-fullerene bulk-heterojunction solar cells. Adv. Mater. 21, 1323–1338 (2009).

    Article  CAS  Google Scholar 

  17. Facchetti, A. π-conjugated polymers for organic electronics and photovoltaic cell applications. Chem. Mater. 23, 733–758 (2011).

    Article  CAS  Google Scholar 

  18. Street, R. A. Thin-film transistors. Adv. Mater. 21, 2007–2022 (2009).

    Article  CAS  Google Scholar 

  19. Glatter, O. & Kratky, O. Small Angle X-Ray Scattering (Academic, 1982).

    Google Scholar 

  20. Roe, R. J. Methods of X-Ray and Neutron Scattering in Polymer Science (Oxford Univ. Press, 2000).

    Google Scholar 

  21. Stribeck, N. X-Ray Scattering of Soft Matter (Springer, 2007).

    Google Scholar 

  22. Materlik, G., Sparks, C. J. & Fischer, K. Resonant Anomalous X-Ray Scattering: Theory and Applications (North-Holland, 1994).

    Google Scholar 

  23. Swaraj, S. et al. Nanomorphology of bulk heterojunction photovoltaic thin films probed with resonant soft X-ray scattering. Nano Lett. 10, 2863–2869 (2010).

    Article  CAS  Google Scholar 

  24. Virgili, J. M., Tao, Y. F., Kortright, J. B., Balsara, N. P. & Segalman, R. A. Analysis of order formation in block copolymer thin films using resonant soft X-ray scattering. Macromolecules 40, 2092–2099 (2007).

    Article  CAS  Google Scholar 

  25. Mitchell, G. E. et al. Molecular bond selective X-ray scattering for nanoscale analysis of soft matter. Appl. Phys. Lett. 89, 044101 (2006).

    Article  Google Scholar 

  26. Yan, H. et al. Correlating the efficiency and nanomorphology of polymer blend solar cells utilizing resonant soft X-ray scattering. ACS Nano 6, 677–688 (2012).

    Article  CAS  Google Scholar 

  27. Stöhr, J. NEXAFS Spectroscopy (Springer, 1992).

    Book  Google Scholar 

  28. Mezger, M. et al. Molecular orientation in soft matter thin films studied by resonant soft X-ray reflectivity. Phys. Rev. B 83, 155406 (2011).

    Article  Google Scholar 

  29. Mach, P. et al. Structures of chiral smectic-C mesophases revealed by polarization-analyzed resonant X-ray scattering. Phys. Rev. E 60, 6793–6802 (1999).

    Article  CAS  Google Scholar 

  30. Wang, C. et al. Resonant soft X-ray scattering of polymers with a 2D detector: Initial results and system developments at the Advanced Light Source. IOP Conf. Ser.: Mater. Sci. Eng. 14, 012016 (2010).

    Article  Google Scholar 

  31. Kilcoyne, A. L. D. et al. Interferometer-controlled scanning transmission X-ray microscopes at the Advanced Light Source. J. Synchrotron. Radiat. 10, 125–136 (2003).

    Article  CAS  Google Scholar 

  32. Kim, C., Facchetti, A. & Marks, T. J. Polymer gate dielectric surface viscoelasticity modulates pentacene transistor performance. Science 318, 76–80 (2007).

    Article  CAS  Google Scholar 

  33. Chabinyc, M. L. et al. Lamination method for the study of interfaces in polymeric thin film transistors. J. Am. Chem. Soc. 126, 13928–13929 (2004).

    Article  CAS  Google Scholar 

  34. Watts, B., Schuettfort, T. & McNeill, C. R. Mapping of domain orientation and molecular order in polycrystalline semiconducting polymer films with soft X-ray microscopy. Adv. Funct. Mater. 21, 1122–1131 (2011).

    Article  CAS  Google Scholar 

  35. Kline, R. J. et al. Significant dependence of morphology and charge carrier mobility on substrate surface chemistry in high performance polythiophene semiconductor films. Appl. Phys. Lett. 90, 062117 (2007).

    Article  Google Scholar 

  36. Bronstein, H. et al. Thieno[3,2-b]thiophene-diketopyrrolopyrrole-containing polymers for high-performance organic field-effect transistors and organic photovoltaic devices. J. Am. Chem. Soc. 133, 3272–3275 (2011).

    Article  CAS  Google Scholar 

  37. Moore, J. R. et al. Polymer blend solar cells based on a high-mobility naphthalenediimide-based polymer acceptor: Device physics, photophysics and morphology. Adv. Energ. Mater. 1, 230–240 (2011).

    Article  CAS  Google Scholar 

  38. Lee, M. J. et al. Anisotropy of charge transport in a uniaxially aligned and chain-extended, high-mobility, conjugated polymer semiconductor. Adv. Funct. Mater. 21, 932–940 (2011).

    Article  CAS  Google Scholar 

  39. Rivnay, J. et al. Unconventional face-on texture and exceptional in-plane order of a high mobility n-type polymer. Adv. Mater. 22, 4359–4363 (2010).

    Article  CAS  Google Scholar 

  40. Westenhoff, S. et al. Charge recombination in organic photovoltaic devices with high open-circuit voltages. J. Am. Chem. Soc. 130, 13653–13658 (2008).

    Article  CAS  Google Scholar 

  41. Huang, Y-s. et al. Electronic structures of interfacial states formed at polymeric semiconductor heterojunctions. Nature Mater. 7, 483–489 (2008).

    Article  CAS  Google Scholar 

  42. Morteani, A. C., Sreearunothai, P., Herz, L. M., Friend, R. H. & Silva, C. Exciton regeneration at polymeric semiconductor heterojunctions. Phys. Rev. Lett. 92, 247402 (2004).

    Article  Google Scholar 

  43. Price, S. C., Stuart, A. C., Yang, L., Zhou, H. & You, W. Fluorine substituted conjugated polymer of medium band gap yields 7% efficiency in polymer-fullerene solar cells. J. Am. Chem. Soc. 133, 4625–4631 (2011).

    Article  CAS  Google Scholar 

  44. Shapiro, D. et al. Biological imaging by soft X-ray diffraction microscopy. Proc. Natl Acad. Sci. USA 102, 15343–15346 (2005).

    Article  CAS  Google Scholar 

  45. Thibault, P. et al. High-resolution scanning X-ray diffraction microscopy. Science 321, 379–382 (2008).

    Article  CAS  Google Scholar 

  46. Dierolf, M. et al. Ptychographic X-ray computed tomography at the nanoscale. Nature 467, 436–439 (2010).

    Article  CAS  Google Scholar 

  47. Zhu, D. et al. High-resolution X-ray lensless imaging by differential holographic encoding. Phys. Rev. Lett. 105, 043901 (2010).

    Article  Google Scholar 

Download references

Acknowledgements

Discussions with and help from A. L. D. Kilcoyne, T. Tyliszczak, T. Young, A. Hexemer, G. Cody, S. Kevan and J. Kortright are gratefully acknowledged. P-SoXS development and blend film characterization by B.A.C., H.Y., E.G. and H.A. are supported by DOE (DE-FG02-98ER45737), GAANN Fellowship (E.G.) and ALS Fellowship (H.Y.). Characterization of PBTTT films by B.A.C., H.Y. and H.A. are supported by NSF (DMR-0906457, ARRA). M.L.C. and J.E.C. are supported by NSF (DMR-0906224, ARRA). C.H. and R.F. are supported by BMBF (contract 05 K10WEA). C.R.M. acknowledges support from the EPSRC (EP/E051804/1) and ARC (FT100100275). We graciously thank I. McCulloch and M. Heeney (Imperial College, UK) for samples of PBTTT. Part of this research was undertaken on the soft X-ray beamline at the Australian Synchrotron, Victoria, Australia. Data were acquired at beamlines 11.0.1.2., 7.3.3. and 5.3.2.2. at the ALS, which is supported by DOE (DE-AC02-05CH1123) and the LDRD programme under DOE (DE-AC02-05CH11231).

Author information

Authors and Affiliations

  1. Department of Physics, NCSU, Raleigh, North Carolina 27695-8202, USA

    B. A. Collins, H. Yan, E. Gann & H. Ade

  2. Materials Department, University of California, Santa Barbara, California 93106-5050, USA

    J. E. Cochran & M. L. Chabinyc

  3. Physikalische Chemie II and ICMM, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany

    C. Hub & R. Fink

  4. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

    C. Wang

  5. Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, UK

    T. Schuettfort

  6. Department of Materials Engineering, Monash University, Clayton, Victoria 3800, Australia

    C. R. McNeill

Authors
  1. B. A. Collins
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. J. E. Cochran
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. H. Yan
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. E. Gann
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. C. Hub
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. R. Fink
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. C. Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. T. Schuettfort
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. C. R. McNeill
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. M. L. Chabinyc
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. H. Ade
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

B.A.C., H.Y., E.G. and H.A. conceived and executed the P-SoXS experiments, J.E.C. and M.L.C. contributed to the scientific goals and experimental protocols, made the PBTTT-based samples and measured device performance. C.H. and R.F. made the pentacene samples and contributed the pentacene NEXAFS. C.W. built the scattering facility and helped with the experiments. C.R.M. and T.S. made the P3HT: P(NDI2OD-T2) samples and contributed the P(NDI2OD-T2) NEXAFS spectra. All authors contributed to the interpretation of the results and the writing of the manuscript.

Corresponding authors

Correspondence to M. L. Chabinyc or H. Ade.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 943 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Collins, B., Cochran, J., Yan, H. et al. Polarized X-ray scattering reveals non-crystalline orientational ordering in organic films. Nature Mater 11, 536–543 (2012). https://doi.org/10.1038/nmat3310

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat3310

This article is cited by

Search

Advanced 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