Hostname: page-component-586b7cd67f-l7hp2 Total loading time: 0 Render date: 2024-11-29T05:06:05.691Z Has data issue: false hasContentIssue false
  • English
  • Français

Surface induced orientation and vertically layered morphology in thin films of poly(3-hexylthiophene) crystallized from the melt

Published online by Cambridge University Press:  11 April 2017

Jens Balko ,
Guiseppe Portale ,
Ruth H. Lohwasser ,
Mukundan Thelakkat  and
Thomas Thurn-Albrecht Open the ORCID record for Thomas Thurn-Albrecht [Opens in a new window]
Jens Balko
Affiliation:
Institute of Physics, Martin Luther University, 06120 Halle/Saale, Germany
Guiseppe Portale
Affiliation:
Zernike Institute for Adv. Materials, University of Groningen, NL-9747 AG Groningen, The Netherlands
Ruth H. Lohwasser
Affiliation:
Applied Functional Materials, Macromolecular Chemistry I, University of Bayreuth, 95440 Bayreuth, Germany
Mukundan Thelakkat
Affiliation:
Applied Functional Materials, Macromolecular Chemistry I, University of Bayreuth, 95440 Bayreuth, Germany
Thomas Thurn-Albrecht*
Affiliation:
Institute of Physics, Martin Luther University, 06120 Halle/Saale, Germany
*
a) Address all correspondence to this author. e-mail: [email protected]
Get access

Abstract

The presence of interfaces and geometrical confinement can have a strong influence on the structure and morphology of thin films of semicrystalline polymers. Using surface-sensitive grazing incidence wide angle X-ray scattering and atomic force microscopy to investigate the vertical structure of thin films of poly(3-hexylthiophene) crystallized from the melt, we show that highly oriented crystallites are induced at the air/polymer interface and not as sometimes assumed at the interface to the substrate. These crystallites are oriented with their crystallographic a-axis perpendicular to the plane of the film. While the corresponding orientation dominates in thinner films, for sufficiently thick films (>60 nm) a layer containing unoriented crystals is present below the surface layer. Due to the anisotropic charge transport properties, the observed effects are expected to be of special relevance for potential applications of semiconductor polymers in the field of organic photovoltaics for which vertical transport in thicker films plays an important role.

Keywords

polymernanostructuresemiconducting
Type
Invited Articles
Information
Journal of Materials Research , Volume 32 , Issue 10: Focus Issue: Microstructural Characterization for Emerging Photovoltaic Materials , 26 May 2017 , pp. 1957 - 1968
Check for updates
Copyright
Copyright © Materials Research Society 2017 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

b)

Present Address: Fraunhofer Institute for Applied Polymer Research, 14476 Potsdam, Germany

c)

Present Address: BASF, Ludwigshafen, Germany

Contributing Editor: Chris Nicklin

References

REFERENCES

Liu, Y.X. and Chen, E.Q.: Polymer crystallization of ultrathin films on solid substrates. Coord. Chem. Rev. 254, 1011–1037 (2010).Google Scholar
Li, H.H. and Yan, S.K.: Surface-induced polymer crystallization and the resultant structures and morphologies. Macromolecules 44, 417–428 (2011).CrossRefGoogle Scholar
Carr, J.M., Langhe, D.S., Ponting, M.T., Hiltner, A., and Baer, E.: Confined crystallization in polymer nanolayered films: A review. J. Mater. Res. 27, 1326–1350 (2012).Google Scholar
Frank, C.W., Rao, V., Despotopoulou, M.M., Pease, R.F.W., Hinsberg, W.D., Miller, R.D., and Rabolt, J.F.: Structure in thin and ultrathin spin-cast polymer films. Science 273, 912–915 (1996).Google Scholar
Ma, Y., Hu, W.B., and Reiter, G.: Lamellar crystal orientations biased by crystallization kinetics in polymer thin films. Macromolecules 39, 5159–5164 (2006).Google Scholar
Löhmann, A.K., Henze, T., and Thurn-Albrecht, T.: Direct observation of prefreezing at the interface melt-solid in polymer crystallization. Proc. Natl. Acad. Sci. U. S. A. 111, 17368–17372 (2014).Google Scholar
Sear, R.P.: Nucleation: Theory and applications to protein solutions and colloidal suspensions. J. Phys.: Condens. Matter 19, 033101 (2007).Google Scholar
Napolitano, S. and Wübbenhorst, M.: Slowing down of the crystallization kinetics in ultrathin polymer films: A size or an interface effect? Macromolecules 39, 5967–5970 (2006).Google Scholar
Napolitano, S. and Wübbenhorst, M.: Deviation from bulk behaviour in the cold crystallization kinetics of ultrathin films of poly(3-hydroxybutyrate). J. Phys.: Condens. Matter 19, 205121 (2007).Google Scholar
Vanroy, B., Wübbenhorst, M., and Napolitano, S.: Crystallization of thin polymer layers confined between two adsorbing walls. ACS Macro Lett. 2, 168–172 (2013).CrossRefGoogle ScholarPubMed
Martinez-Tong, D.E., Vanroy, B., Wübbenhorst, M., Nogales, A., and Napolitano, S.: Crystallization of poly(L-lactide) confined in ultrathin films: competition between finite size effects and irreversible chain adsorption. Macromolecules 47, 2354–2360 (2014).Google Scholar
Wu, X.Z., Ocko, B.M., Sirota, E.B., Sinha, S.K., Deutsch, M., Cao, B.H., and Kim, M.W.: Surface tension measurements of surface freezing in liquid normal alkanes. Science 261, 1018–1021 (1993).Google Scholar
Ocko, B.M., Wu, X.Z., Sirota, E.B., Sinha, S.K., Gang, O., and Deutsch, M.: Surface freezing in chain molecules: Normal alkanes. Phys. Rev. E: Stat. Phys., Plasmas, Fluids, Relat. Interdiscip. Top. 55, 3164–3182 (1997).CrossRefGoogle Scholar
Gautam, K.S. and Dhinojwala, A.: Melting at alkyl side chain comb polymer interfaces. Phys. Rev. Lett. 88, 145501 (2002).Google Scholar
Gautam, K.S., Kumar, S., Wermeille, D., Robinson, D., and Dhinojwala, A.: Observation of novel liquid-crystalline phase above the bulk-melting temperature. Phys. Rev. Lett. 90, 215501 (2003).Google Scholar
Gang, O., Wu, X.Z., Ocko, B.M., Sirota, E.B., and Deutsch, M.: Surface freezing in chain molecules. II. Neat and hydrated alcohols. Phys. Rev. E: Stat. Phys., Plasmas, Fluids, Relat. Interdiscip. Top. 58, 6086–6100 (1998).CrossRefGoogle Scholar
Prasad, S., Jiang, Z., Sinha, S.K., and Dhinojwala, A.: Partial crystallinity in alkyl side chain polymers dictates surface freezing. Phys. Rev. Lett. 101, 065505 (2008).Google Scholar
Jeon, Y., Vaknin, D., Bu, W., Sung, J., Ouchi, Y., Sung, W., and Kim, D.: Surface nanocrystallization of an ionic liquid. Phys. Rev. Lett. 108, 055502 (2012).Google Scholar
Sirringhaus, H., Brown, P.J., Friend, R.H., Nielsen, M.M., Bechgaard, K., Langeveld-Voss, B.M.W., Spiering, A.J.H., Janssen, R.A.J., Meijer, E.W., Herwig, P., and de Leeuw, D.M.: Two-dimensional charge transport in self-organized, high-mobility conjugated polymers. Nature 401, 685–688 (1999).CrossRefGoogle Scholar
Sirringhaus, H., Tessler, N., and Friend, R.H.: Integrated optoelectronic devices based on conjugated polymers. Science 280, 1741–1744 (1998).Google Scholar
Forrest, S.R.: The path to ubiquitous and low-cost organic electronic appliances on plastic. Nature 428, 911–918 (2004).Google Scholar
Li, G., Shrotriya, V., Huang, J.S., Yao, Y., Moriarty, T., Emery, K., and Yang, Y.: High-efficiency solution processable polymer photovoltaic cells by self-organization of polymer blends. Nat. Mater. 4, 864–868 (2005).Google Scholar
Salleo, A.: Charge transport in polymeric transistors. Mater. Today 10, 38–45 (2007).Google Scholar
Bao, Z., Dodabalapur, A., and 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).Google Scholar
Müller-Buschbaum, P.: The active layer morphology of organic solar cells probed with grazing incidence scattering techniques. Adv. Mater. 26, 7692–7709 (2014).CrossRefGoogle ScholarPubMed
Hugger, S., Thomann, R., Heinzel, T., and Thurn-Albrecht, T.: Semicrystalline morphology in thin films of poly(3-hexylthiophene). Colloid Polym. Sci. 282, 932–938 (2004).Google Scholar
Wu, Z.Y., Petzold, A., Henze, T., Thurn-Albrecht, T., Lohwasser, R.H., Sommer, M., and Thelakkat, M.: Temperature, and molecular weight dependent hierarchical equilibrium structures in semiconducting poly(3-hexylthiophene). Macromolecules 43, 4646–4653 (2010).Google Scholar
Brinkmann, M. and Rannou, P.: Effect of molecular weight on the structure and morphology of oriented thin films of regioregular poly(3-hexylthiophene) grown by directional epitaxial solidification. Adv. Funct. Mater. 17, 101–108 (2007).Google Scholar
Prosa, T.J., Winokur, M.J., Moulton, J., Smith, P., and Heeger, A.J.: X-ray structural studies of poly(3-alkylthiophenes)—an example of an inverse comb. Macromolecules 25, 4364–4372 (1992).Google Scholar
Tashiro, K., Kobayashi, M., Kawai, T., and Yoshino, K.: Crystal structural change in poly(3-alkyl thiophene)s induced by iodine doping as studied by an organized combination of X-ray diffraction, infrared/Raman spectroscopy and computer simulation techniques. Polymer 38, 2867–2879 (1997).CrossRefGoogle Scholar
Joshi, S., Grigorian, S., Pietsch, U., Pingel, P., Zen, A., Neher, D., and Scherf, U.: Thickness dependence of the crystalline structure and hole mobility in thin films of low molecular weight poly(3-hexylthiophene). Macromolecules 41, 6800–6808 (2008).Google Scholar
Kline, R.J., Mcgehee, M.D., Kadnikova, E.N., Liu, J.S., and Frechet, J.M.J.: Controlling the field-effect mobility of regioregular polythiophene by changing the molecular weight. Adv. Mater. 15, 1519–1522 (2003).Google Scholar
Zen, A., Saphiannikova, M., Neher, D., Grenzer, J., Grigorian, S., Pietsch, U., Asawapirom, U., Janietz, S., Scherf, U., Lieberwirth, I., and Wegner, G.: Effect of molecular weight on the structure and crystallinity of poly(3-hexylthiophene). Macromolecules 39, 2162–2171 (2006).Google Scholar
Ballantyne, A.M., Chen, L., Dane, J., Hammant, T., Braun, F.M., Heeney, M., Duffy, W., McCulloch, I., Bradley, D.D.C., and Nelson, J.: The effect of poly(3-hexylthiophene) molecular weight on charge transport and the performance of polymer: Fullerene solar cells. Adv. Funct. Mater. 18, 2373–2380 (2008).Google Scholar
Kim, Y., Cook, S., Tuladhar, S.M., Choulis, S.A., Nelson, J., Durrant, J.R., Bradley, D.D.C., Giles, M., McCulloch, I., Ha, C.S., and Ree, M.: A strong regioregularity effect in self-organizing conjugated polymer films and high-efficiency polythiophene: Fullerene solar cells. Nat. Mater. 5, 197–203 (2006).Google Scholar
Brinkmann, M.: Structure, and morphology control in thin films of regioregular poly(3-hexylthiophene). J. Polym. Sci., Part B: Polym. Phys. 49, 1218–1233 (2011).Google Scholar
Schulz, G.L. and Ludwigs, S.: Controlled crystallization of conjugated polymer films from solution and solvent vapor for polymer electronics. Adv. Funct. Mater. 27, 1603083 (2017).Google Scholar
Virkar, A.A., Mannsfeld, S., Bao, Z.A., and Stingelin, N.: Organic semiconductor growth, and morphology considerations for organic thin-film transistors. Adv. Mater. 22, 3857–3875 (2010).Google Scholar
Boudouris, B.W., Ho, V., Jimison, L.H., Toney, M.F., Salleo, A., and Segalman, R.A.: Real-time observation of poly(3-alkylthiophene) crystallization and correlation with transient optoelectronic properties. Macromolecules 44, 6653–6658 (2011).Google Scholar
Woo, C.H., Piliego, C., Holcombe, T.W., Toney, M.F., and Frechet, J.M.J.: A quantitative correlation between the mobility and crystallinity of photo-cross-linkable P3HT. Macromolecules 45, 3057–3062 (2012).Google Scholar
Singh, C.R., Gupta, G., Lohwasser, R., Engmann, S., Balko, J., Thelakkat, M., Thurn-Albrecht, T., and Hoppe, H.: Correlation of charge transport with structural order in highly ordered melt-crystallized poly(3-hexylthiophene) thin films. J. Polym. Sci., Part B: Polym. Phys. 51, 943–951 (2013).Google Scholar
Factor, B.J., Russell, T.P., and Toney, M.F.: Grazing-incidence X-ray-scattering studies of thin-films of an aromatic polyimide. Macromolecules 26, 2847–2859 (1993).Google Scholar
Kawamoto, N., Mori, H., Nitta, K.H., Sasaki, S., Yui, N., and Terano, M.: Microstructural characterization of polypropene surfaces using grazing incidence X-ray diffraction. Macromol. Chem. Phys. 199, 261–266 (1998).Google Scholar
Jukes, P.C., Das, A., Durell, M., Trolley, D., Higgins, A.M., Geoghegan, M., Macdonald, J.E., Jones, R.A.L., Brown, S., and Thompson, P.: Kinetics of surface crystallization in thin films of poly(ethylene terephthalate). Macromolecules 38, 2315–2320 (2005).Google Scholar
Yakabe, H., Tanaka, K., Nagamura, T., Sasaki, S., Sakata, O., Takahara, A., and Kajiyama, T.: Grazing incidence X-ray diffraction study on surface crystal structure of polyethylene thin films. Polym. Bull. 53, 213–222 (2005).Google Scholar
Kline, R.J., Mcgehee, M.D., and Toney, M.F.: Highly oriented crystals at the buried interface in polythiophene thin-film transistors. Nat. Mater. 5, 222–228 (2006).CrossRefGoogle Scholar
Baker, J.L., Jimison, L.H., Mannsfeld, S., Volkman, S., Yin, S., Subramanian, V., Salleo, A., Alivisatos, A.P., and Toney, M.F.: Quantification of thin film crystallographic orientation using X-ray diffraction with an area detector. Langmuir 26, 9146–9151 (2010).Google Scholar
Jimison, L.H., Himmelberger, S., Duong, D.T., Rivnay, J., Toney, M.F., and Salleo, A.: Vertical confinement and interface effects on the microstructure and charge transport of P3HT thin films. J. Polym. Sci., Part B: Polym. Phys. 51, 611–620 (2013).Google Scholar
Skrypnychuk, V., Boulanger, N., Yu, V., Hilke, M., Mannsfeld, S.C.B., Toney, M.F., and Barbero, D.R.: Enhanced vertical charge transport in a semiconducting P3HT thin film on single layer graphene. Adv. Funct. Mater. 25, 664–670 (2015).Google Scholar
Schmidt-Hansberg, B., Sanyal, M., Klein, M.F.G., Pfaff, M., Schnabel, N., Jaiser, S., Vorobiev, A., Müller, E., Colsmann, A., Scharfer, P., Gerthsen, D., Lemmer, U., Barrena, E., and Schabel, W.: Moving through the phase diagram: Morphology formation in solution cast polymer–fullerene blend films for organic solar cells. ACS Nano 5, 8579–8590 (2011).Google Scholar
Kim, D.H., Jang, Y., Park, Y.D., and Cho, K.: Layered molecular ordering of self-organized poly(3-hexylthiophene) thin films on hydrophobized surfaces. Macromolecules 39, 5843–5847 (2006).Google Scholar
Choi, D., Jin, S., Lee, Y., Kim, S.H., Chung, D.S., Hong, K., Yang, C., Jung, J., Kim, J.K., Ree, M., and Park, C.E.: Direct observation of interfacial morphology in poly(3-hexylthiophene) transistors: Relationship between grain boundary and field-effect mobility. ACS Appl. Mater. Interfaces 2, 48–53 (2010).Google Scholar
Anglin, T.C., Speros, J.C., and Massari, A.M.: Interfacial ring orientation in polythiophene field-effect transistors on functionalized dielectrics. J. Phys. Chem. C 115, 16027–16036 (2011).Google Scholar
Anglin, T.C., Lane, A.P., and Massari, A.M.: Real-time structural evolution at the interface of an organic transistor during thermal annealing. J. Mater. Chem. C 2, 3390–3400 (2014).Google Scholar
Huang, B.Y., Glynos, E., Frieberg, B., Yang, H.X., and Green, P.F.: Effect of thickness-dependent microstructure on the out-of-plane hole mobility in poly(3-hexylthiophene) films. ACS Appl. Mater. Interfaces 4, 5204–5210 (2012).Google Scholar
Yimer, Y.Y., Dhinojwala, A., and Tsige, M.: Interfacial properties of free-standing poly(3-hexylthiophene) films. J. Chem. Phys. 137, 044703 (2012).Google Scholar
Balko, J., Rinscheid, A., Wurm, A., Schick, C., Lohwasser, R.H., Thelakkat, M., and Thurn-Albrecht, T.: Crystallinity of poly(3-hexylthiophene) in thin films determined by fast scanning calorimetry. J. Polym. Sci., Part B: Polym. Phys. 54, 1791–1801 (2016).Google Scholar
Breiby, D.W., Bunk, O., Andreasen, J.W., Lemke, H.T., and Nielsen, M.M.: Simulating X-ray diffraction of textured films. J. Appl. Crystallogr. 41, 262–271 (2008).Google Scholar
Dosch, H., Batterman, B.W., and Wack, D.C.: Depth-controlled grazing-incidence diffraction of synchrotron X radiation. Phys. Rev. Lett. 56, 1144–1147 (1986).Google Scholar
Tolan, M.: X-ray Scattering From Soft-matter Thin Films, Vol. 148 (Springer-Verlag, Berlin-Heidelberg, 1999).Google Scholar
A. Hammersley: Fit2D. http://www.esrf.eu/computing/scientific/FIT2D (accessed September 09, 2015).Google Scholar
Scherrer, P.: Bestimmung der Größe und der inneren Struktur von Kolloidteilchen mittels Röntgenstrahlen. Nachrichten von der Gesellschaft der Wissenschaften zu Göttingen 1918, 98–100 (1918).Google Scholar
Langford, J.I. and Wilson, A.J.C.: Scherrer after sixty years: A survey and some new results in the determination of crystallite size. J. Appl. Crystallogr. 11, 102–113 (1978).Google Scholar
Holzwarth, U. and Gibson, N.: The Scherrer equation versus the ‘Debye-Scherrer equation’. Nat. Nanotechnol. 6, 534 (2011).Google Scholar
Sheina, E.E., Liu, J.S., Iovu, M.C., Laird, D.W., and McCullough, R.D.: Chain growth mechanism for regioregular nickel-initiated cross-coupling polymerizations. Macromolecules 37, 3526–3528 (2004).Google Scholar
Balko, J., Lohwasser, R.H., Sommer, M., Thelakkat, M., and Thurn-Albrecht, T.: Determination of the crystallinity of semicrystalline poly(3-hexylthiophene) by means of wide-angle X-ray scattering. Macromolecules 46, 9642–9651 (2013).Google Scholar
French, P.J., Sarro, P.M., Mallee, R., Fakkeldij, E.J.M., and Wolffenbuttel, R.F.: Optimization of a low-stress silicon nitride process for surface-micromachining applications. Sens. Actuators, A 58, 149–157 (1997).Google Scholar
Aiyama, T., Fukunaga, T., Niihara, K., Hirai, T., and Suzuki, K.: An X-ray diffraction study of the amorphous structure of chemically vapor-deposited silicon nitride. J. Non-Cryst. Solids 33, 131–139 (1979).Google Scholar
Crossland, E.J.W., Rahimi, K., Reiter, G., Steiner, U., and Ludwigs, S.: Systematic control of nucleation density in poly(3-hexylthiophene) thin films. Adv. Funct. Mater. 21, 518–524 (2011).Google Scholar
Kohn, P., Rong, Z.X., Scherer, K.H., Sepe, A., Sommer, M., Müller-Buschbaum, P., Friend, R.H., Steiner, U., and Hüttner, S.: Crystallization-induced 10-nm structure formation in P3HT/PCBM blends. Macromolecules 46, 4002–4013 (2013).Google Scholar
Koch, F.P.V., Rivnay, J., Foster, S., Müller, C., Downing, J.M., Buchaca-Domingo, E., Westacott, P., Yu, L.Y., Yuan, M.J., Baklar, M., Fei, Z.P., Luscombe, C., McLachlan, M.A., Heeney, M., Rumbles, G., Silva, C., Salleo, A., Nelson, J., Smith, P., and Stingelin, N.: The impact of molecular weight on microstructure and charge transport in semicrystalline polymer semiconductors—poly(3-hexylthiophene), a model study. Prog. Polym. Sci. 38, 1978–1989 (2013).Google Scholar
Kayunkid, N., Uttiya, S., and Brinkmann, M.: Structural model of regioregular poly(3-hexylthiophene) obtained by electron diffraction analysis. Macromolecules 43, 4961–4967 (2010).Google Scholar
Werzer, O. and Resel, R.: Model-independent X-ray reflectivity fitting for structure analysis of poly(3-hexylthiophene) films. Macromolecules 46, 3529–3533 (2013).Google Scholar
Yimer, Y.Y. and Tsige, M.: Static and dynamic properties of poly(3-hexylthiophene) films at liquid/vacuum interfaces. J. Chem. Phys. 137, 204701 (2012).Google Scholar
Koch, F.P.V., Heeney, M., and Smith, P.: Thermal, and structural characteristics: Of oligo(3-hexylthiophene)s (3HT) n , n = 4–36. J. Am. Chem. Soc. 135, 13699–13709 (2013).CrossRefGoogle Scholar
Gurau, M.C., Delongchamp, D.M., Vogel, B.M., Lin, E.K., Fischer, D.A., Sambasivan, S., and Richter, L.J.: Measuring molecular order in poly(3-alkylthiophene) thin films with polarizing spectroscopies. Langmuir 23, 834–842 (2007).Google Scholar
Oosterbaan, W.D., Bolsee, J.C., Gadisa, A., Vrindts, V., Bertho, S., D’Haen, J., Cleij, T.J., Lutsen, L., McNeill, C.R., Thomsen, L., Manca, J.V., and Vanderzande, D.: Alkyl-chain-length-independent hole mobility via morphological control with poly(3-alkylthiophene) nanofibers. Adv. Funct. Mater. 20, 792–802 (2010).Google Scholar
Supplementary material: PDF

Balko supplementary material

Balko supplementary material 1

Download Balko supplementary material(PDF)
PDF 743.1 KB