Skip to main content

Connecting soft x-ray anisotropy with local order in conjugated polymers


Polarized resonant soft x-ray scattering (RSoXS) can leverage contrast between domains in mass, chemical bonds, and chain orientation to characterize polymer thin films. Although mass and chemical contrast can be predicted from the absorption spectra, the origins of orienta-tional contrast are not fully understood. For example, in the case where one domain is crystalline, it is not obvious how the total crystallinity will affect the anisotropy. Using a simple calculation, we predict polarized RSoXS of model structures and compare with experiment. Through experiments and simulations, we demonstrate that scattering anisotropy is not monotonically related to local order but instead peaks when 50% of domains have aligned chains, i.e., when the sample is 50% crystalline.

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

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5


  1. 1.

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

    CAS  Article  Google Scholar 

  2. 2.

    C. Guo, Y.-H. Lin, M.D. Witman, K.A. Smith, C. Wang, A. Hexemer, J. Strzalka, E.D. Gomez, and R. Verduzco: Conjugated block copolymer pho-tovoltaics with near 3% efficiency through microphase separation. Nano Lett. 13, 2957 (2013).

    CAS  Article  Google Scholar 

  3. 3.

    J.R. Tumbleston, B.A. Collins, L. Yang, A.C. Stuart, E. Gann, W. Ma, W. You, and H. Ade: The influence of molecular orientation on organic bulk heterojunction solar cells. Nat. Photonics 8, 385 (2014).

    CAS  Article  Google Scholar 

  4. 4.

    J. Zhao, Y. Li, G. Yang, K. Jiang, H. Lin, H. Ade, W. Ma, and H. Yan: Efficient organic solar cells processed from hydrocarbon solvents. Nat. Energy 1, 15027 (2016).

    CAS  Article  Google Scholar 

  5. 5.

    C.J. Schaffer, C. Wang, A. Hexemer, and P. Müller-Buschbaum: Grazing incidence resonant soft X-ray scattering for analysis of multi-component polymer-fullerene blend thin films. Polymer 105, 357 (2016).

    CAS  Article  Google Scholar 

  6. 6.

    S.V. Kesava, Z. Fei, A.D. Rimshaw, C. Wang, A. Hexemer, J.B. Asbury, M. Heeney, and E.D. Gomez: Domain compositions and fullerene aggregation govern charge photogeneration in polymer/fullerene solar cells. Adv. Energy Mater. 4, 1400116 (2014).

    Article  CAS  Google Scholar 

  7. 7.

    M. Zhang, X. Guo, W. Ma, H. Ade, and J. Hou: A large‐bandgap conjugated polymer for versatile photovoltaic applications with high performance. Adv. Mater. 27, 4655 (2015).

    CAS  Article  Google Scholar 

  8. 8.

    M. Zhang, X. Guo, W. Ma, H. Ade, and J. Hou: A polythiophene derivative with superior properties for practical application in polymer solar cells. Adv. Mater. 26, 5880 (2014).

    CAS  Article  Google Scholar 

  9. 9.

    D. Xie, T. Liu, W. Gao, C. Zhong, L. Huo, Z. Luo, K. Wu, W. Xiong, F. Liu, and Y. Sun: A novel thiophene‐fused ending group enabling an excellent small molecule acceptor for high‐performance fullerene‐free polymer solar cells with 11.8% efficiency. Solar RRL 1, 1700044 (2017).

    Article  CAS  Google Scholar 

  10. 10.

    S. Swaraj, C. Wang, T. Araki, G. Mitchell, L. Liu, S. Gaynor, B. Deshmukh, H. Yan, C. McNeill, and H. Ade: The utility of resonant soft x-ray scattering and reflectivity for the nanoscale characterization of polymers. Eur. Phys. J. Spec. Top. 167, 121 (2009).

    Article  Google Scholar 

  11. 11.

    C.R. McNeill and N.C. Greenham: Conjugated‐polymer blends for optoelectronics. Adv. Mater. 21, 3840 (2009).

    CAS  Article  Google Scholar 

  12. 12.

    F. Liu, M.A. Brady, and C. Wang: Resonant soft X-ray scattering for polymer materials. Eur. Polym. J. 81, 555 (2016).

    CAS  Article  Google Scholar 

  13. 13.

    X. Gu, H. Yan, T. Kurosawa, B.C. Schroeder, K.L. Gu, Y. Zhou, J.W. To, S. D. Oosterhout, V. Savikhin, and F. Molina‐Lopez: Comparison of the morphology development of polymer–fullerene and polymer–polymer solar cells during solution‐shearing blade coating. Adv. Energy Mater. 6, 1601225 (2016).

    Article  CAS  Google Scholar 

  14. 14.

    Q. Fan, W. Su, Y. Wang, B. Guo, Y. Jiang, X. Guo, F. Liu, T.P. Russell, M. Zhang, and Y. Li: Synergistic effect of fluorination on both donor and acceptor materials for high performance non-fullerene polymer solar cells with 13.5% efficiency. Sci. China Chem. 61, 531 (2018).

    CAS  Article  Google Scholar 

  15. 15.

    D. Ye, S. Rongpipi, J.H. Litofsky, Y. Lee, T.E. Culp, S.H. Yoo, T.N. Jackson, C. Wang, E.W. Gomez, and E.D. Gomez: Aluminum oxide freestanding thin films to enable nitrogen edge soft x-ray scattering. MRS Commun. 9, 224 (2019).

    CAS  Article  Google Scholar 

  16. 16.

    M. Mezger, B. Jérôme, J.B. Kortright, M. Valvidares, E.M. Gullikson, A. Giglia, N. Mahne, and S. Nannarone: Molecular orientation in soft matter thin films studied by resonant soft X-ray reflectivity. Phys. Rev. B 83, 155406 (2011).

    Article  CAS  Google Scholar 

  17. 17.

    P. Mach, R. Pindak, A.-M. Levelut, P. Barois, H. Nguyen, H. Baltes, M. Hird, K. Toyne, A. Seed, and J. Goodby: Structures of chiral smectic-C mesophases revealed by polarization-analyzed resonant x-ray scattering. Phys. Rev. E 60, 6793 (1999).

    CAS  Article  Google Scholar 

  18. 18.

    E. Gann, B.A. Collins, M. Tang, J.R. Tumbleston, S. Mukherjee, and H. Ade: Origins of polarization-dependent anisotropic X-ray scattering from organic thin films. J. Synchrotron Radiat. 23, 219 (2016).

    CAS  Article  Google Scholar 

  19. 19.

    Y. Diao, Y. Zhou, T. Kurosawa, L. Shaw, C. Wang, S. Park, Y. Guo, J.A. Reinspach, K. Gu, and X. Gu: Flow-enhanced solution printing of all-polymer solar cells. Nat. Commun. 6, 7955 (2015).

    CAS  Article  Google Scholar 

  20. 20.

    T. Pham, A.P. Goldstein, J.P. Lewicki, S.O. Kucheyev, C. Wang, T.P. Russell, M.A. Worsley, L. Woo, W. Mickelson, and A. Zettl: Nanoscale structure and superhydrophobicity of sp2-bonded boron nitride aerogels. Nanoscale 7, 10449 (2015).

    CAS  Article  Google Scholar 

  21. 21.

    C.D. Liman, T.A. Germer, D.F. Sunday, D.M. DeLongchamp, and R.J. Kline: Modeling the polarized X‐ray scattering from periodic nanostruc-tures with molecular anisotropy. J. Appl. Crystallogr. 50, 1677 (2017).

    CAS  Article  Google Scholar 

  22. 22.

    J.H. Litofsky, Y. Lee, M.P. Aplan, B. Kuei, A. Hexemer, C. Wang, Q. Wang, and E.D. Gomez: Polarized soft X-ray scattering reveals chain orientation within nanoscale polymer domains. Macromolecules 52, 2803–2813 (2019).

    CAS  Article  Google Scholar 

  23. 23.

    B. Collins, J. Cochran, H. Yan, E. Gann, C. Hub, R. Fink, C. Wang, T. Schuettfort, C. McNeill, and M. Chabinyc: Polarized X-ray scattering reveals non-crystalline orientational ordering in organic films. Nat. Mater. 11, 536 (2012).

    CAS  Article  Google Scholar 

  24. 24.

    K. Vakhshouri, B.H. Smith, E.P. Chan, C. Wang, A. Salleo, C. Wang, A. Hexemer, and E.D. Gomez: Signatures of intracrystallite and intercrystal-lite limitations of charge transport in polythiophenes. Macromolecules 49, 7359 (2016).

    CAS  Article  Google Scholar 

  25. 25.

    E. Gann, A. Young, B. Collins, H. Yan, J. Nasiatka, H. Padmore, H. Ade, A. Hexemer, and C. Wang: Soft x-ray scattering facility at the Advanced Light Source with real-time data processing and analysis. Rev. Sci. Instrum. 83, 045110 (2012).

    CAS  Article  Google Scholar 

  26. 26.

    C.R. Snyder, R.C. Nieuwendaal, D.M. DeLongchamp, C.K. Luscombe, P. Sista, and S.D. Boyd: Quantifying crystallinity in high molar mass poly (3-hexylthiophene). Macromolecules 47, 3942 (2014).

    CAS  Article  Google Scholar 

  27. 27.

    F.P.V. Koch, M. Heeney, and P. Smith: Thermal and structural characteristics of oligo (3-hexylthiophene) s (3HT) n, n = 4–36. J. Am. Chem. Soc. 135, 13699 (2013).

    CAS  Article  Google Scholar 

  28. 28.

    C. Zhu, M.R. Tuchband, A. Young, M. Shuai, A. Scarbrough, D.M. Walba, J.E. Maclennan, C. Wang, A. Hexemer, and N.A. Clark: Resonant carbon K-edge soft X-ray scattering from lattice-free heliconical molecular ordering: soft dilative elasticity of the twist-bend liquid crystal phase. Phys. Rev. Lett. 116, 147803 (2016).

    Article  CAS  Google Scholar 

  29. 29.

    J.H. Carpenter, A. Hunt, and H. Ade: Characterizing morphology in organic systems with resonant soft X-ray scattering. J. Electron Spectrosc. Relat. Phenomena 200, 2 (2015).

    CAS  Article  Google Scholar 

  30. 30.

    K.H. Stone and J.B. Kortright: Molecular anisotropy effects in carbon $K $-edge scattering: depolarized diffuse scattering and optical anisotropy. Phys. Rev. B 90, 104201 (2014).

    Article  CAS  Google Scholar 

  31. 31.

    M. Born and E. Wolf: Principles of Optics (Cambridge University Press, Cambridge, 1999).

    Book  Google Scholar 

  32. 32.

    Y. Lee, M.P. Aplan, Z.D. Seibers, R. Xie, T.E. Culp, C. Wang, A. Hexemer, S.M. Kilbey, Q. Wang, and E.D. Gomez: Random copolymers allow control of crystallization and microphase separation in fully conjugated block copolymers. Macromolecules 51, 8844 (2018).

    CAS  Article  Google Scholar 

  33. 33.

    D.R. Kozub, K. Vakhshouri, L.M. Orme, C. Wang, A. Hexemer, and E.D. Gomez: Polymer crystallization of partially miscible polythiophene/fuller-ene mixtures controls morphology. Macromolecules 44, 5722 (2011).

    CAS  Article  Google Scholar 

  34. 34.

    M. Hallermann, I. Kriegel, E. Da Como, J.M. Berger, E. Von Hauff, and J. Feldmann: Charge transfer excitons in polymer/fullerene blends: the role of morphology and polymer chain conformation. Adv. Funct. Mater. 19, 3662 (2009).

    CAS  Article  Google Scholar 

  35. 35.

    O. Korovyanko, R. Österbacka, X. Jiang, Z. Vardeny, and R. Janssen: Photoexcitation dynamics in regioregular and regiorandom polythiophene films. Phys. Rev. B 64, 235122 (2001).

    Article  CAS  Google Scholar 

  36. 36.

    C. Poelking, K. Daoulas, A. Troisi, and D. Andrienko: Morphology and charge transport in P3HT: a theorist’s perspective. In P3HT Revisited–From Molecular Scale to Solar Cell Devices, edited by Sabine Ludwigs (Springer, Berlin, Germany, 2014), pp. 139.

    Google Scholar 

  37. 37.

    P. Vanlaeke, A. Swinnen, I. Haeldermans, G. Vanhoyland, T. Aernouts, D. Cheyns, C. Deibel, J. D’Haen, P. Heremans, and J. Poortmans: P3HT/ PCBM bulk heterojunction solar cells: relation between morphology and electro-optical characteristics. Sol. Energy Mater. Sol. Cells 90, 2150 (2006).

    CAS  Article  Google Scholar 

  38. 38.

    S. Hugger, R. Thomann, T. Heinzel, and T. Thurn-Albrecht: Semicrystalline morphology in thin films of poly (3-hexylthiophene). Colloid Polym. Sci. 282, 932 (2004).

    CAS  Article  Google Scholar 

  39. 39.

    W.C. Tsoi, S.J. Spencer, L. Yang, A.M. Ballantyne, P.G. Nicholson, A. Turnbull, A.G. Shard, C.E. Murphy, D.D. Bradley, and J. Nelson: Effect of crystallization on the electronic energy levels and thin film morphology of P3HT: PCBM blends. Macromolecules 44, 2944 (2011).

    CAS  Article  Google Scholar 

  40. 40.

    R.A. Marsh, J.M. Hodgkiss, S. Albert-Seifried, and R.H. Friend: Effect of annealing on P3HT: PCBM charge transfer and nanoscale morphology probed by ultrafast spectroscopy. Nano Lett. 10, 923 (2010).

    CAS  Article  Google Scholar 

  41. 41.

    R. Mauer, M. Kastler, and F. Laquai: The impact of polymer regioregularity on charge transport and efficiency of P3HT: PCBM photovoltaic devices. Adv. Funct. Mater. 20, 2085 (2010).

    CAS  Article  Google Scholar 

  42. 42.

    K. Tremel and S. Ludwigs: Morphology of P3HT in thin films in relation to optical and electrical properties. In P3HT Revisited–From Molecular Scale to Solar Cell Devices, edited by Sabine Ludwigs (Springer, Berlin, Germany, 2014), pp. 39.

    Google Scholar 

  43. 43.

    C. Wang, J. Rivnay, S. Himmelberger, K. Vakhshouri, M.F. Toney, E.D. Gomez, and A. Salleo: Ultrathin body poly(3-hexylthiophene) transistors with improved short-channel performance. ACS Appl. Mater. Interfaces 5, 2342 (2013).

    CAS  Article  Google Scholar 

  44. 44.

    P.-H. Chu, G. Wang, B. Fu, D. Choi, J.O. Park, M. Srinivasarao, and E. Reichmanis: Synergistic effect of regioregular and regiorandom poly (3-hexylthiophene) blends for high performance flexible organic field effect transistors. Adv. Electron. Mater. 2, 1500384 (2016).

    Article  CAS  Google Scholar 

  45. 45.

    S. Pankaj and M. Beiner: Long-term behavior and side chain crystallization of poly (3-alkyl thiophenes). Soft Matter 6, 3506 (2010).

    CAS  Article  Google Scholar 

  46. 46.

    R. Steyrleuthner, R. Di Pietro, B.A. Collins, F. Polzer, S. Himmelberger, M. Schubert, Z. Chen, S. Zhang, A. Salleo, and H. Ade: The role of regiore-gularity, crystallinity, and chain orientation on electron transport in a high-mobility n-type copolymer. J. Am. Chem. Soc. 136, 4245 (2014).

    CAS  Article  Google Scholar 

  47. 47.

    K. Vakhshouri and E.D. Gomez: Effect of crystallization kinetics on micro-structure and charge transport of polythiophenes. Macromol. Rapid Commun. 33, 2133 (2012).

    CAS  Article  Google Scholar 

  48. 48.

    S. Malik and A.K. Nandi: Crystallization mechanism of regioregular poly (3‐alkyl thiophene) s. J. Polym. Sci. B Polym. Phys. 40, 2073 (2002).

    CAS  Article  Google Scholar 

  49. 49.

    C. Müller, M. Aghamohammadi, S. Himmelberger, P. Sonar, M. Garriga, A. Salleo, and M. Campoy‐Quiles: One‐step macroscopic alignment of conjugated polymer systems by epitaxial crystallization during spin‐coating. Adv. Funct. Mater. 23, 2368 (2013).

    Article  CAS  Google Scholar 

  50. 50.

    T. Agostinelli, S. Lilliu, J.G. Labram, M. Campoy‐Quiles, M. Hampton, E. Pires, J. Rawle, O. Bikondoa, D.D. Bradley, and T.D. Anthopoulos: Real‐ time investigation of crystallization and phase‐segregation dynamics in P3HT: PCBM solar cells during thermal annealing. Adv. Funct. Mater. 21, 1701 (2011).

    CAS  Article  Google Scholar 

  51. 51.

    L.H. Jimison, S. Himmelberger, D.T. Duong, J. Rivnay, M.F. Toney, and A. Salleo: Vertical confinement and interface effects on the microstructure and charge transport of P3HT thin films. J. Polym. Sci. B Polym. Phys. 51, 611 (2013).

    CAS  Article  Google Scholar 

Download references


Financial support from the National Science Foundation under Award DMR-1626566 is acknowledged. Financial support from the Office of Naval Research under Grant N000141410532 is also acknowledged. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Author information



Corresponding author

Correspondence to Enrique D. Gomez.

Electronic Supplementary Material

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Litofsky, J.H., Gomez, E.D. Connecting soft x-ray anisotropy with local order in conjugated polymers. MRS Communications 9, 1168–1173 (2019).

Download citation