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Chinese Journal of Polymer Science

, Volume 37, Issue 7, pp 664–673 | Cite as

Increasing the Content of β Phase of Poly(9,9-dioctylfluorene) by Synergistically Controlling Solution Aggregation and Extending Film-forming Time

  • Ya-Di Liu
  • Qiang Zhang
  • Xin-Hong Yu
  • Jian-Gang LiuEmail author
  • Yan-Chun HanEmail author
Article
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Abstract

For poly(9,9-dioctylfuorene) (PFO), β phase (coplanar conformation with the intra-chain torsion angle of 165°) has a greater conjugation length and higher degree of order compared to those of α phase, which favors charge carrier transport. However, the highest content of β phase obtained so far is 45%. We propose to increase the content of β phase by promoting the solution aggregation of PFO molecules and extending film-forming time. For this purpose, 1,8-diiodooctane (DIO) is added to PFO o-xylene solution, which enhances the interaction of PFO chains and improves the planarity of PFO backbone, resulting in the formation of ordered aggregation. The aggregates act as nucleation centers to promote the formation of β phase. The content of β phase increases with increasing DIO concentration and reaches a platform of 39% as DIO is more than 4 vol%. Furthermore, the film is kept in a sealed environment with o-xylene atmosphere for 3 h, thus the PFO molecules have enough time to diffuse to the crystallization front and achieve disorder-order transition. As a result, the crystallinity of PFO is improved significantly and the content of β phase increases to 52%, reaching the highest value reported so far.

Keywords

β Phase Ordered aggregation Film-forming time Disorder-order transition 

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Notes

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (Nos. 51890871, 91833306, and 51573185), and the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDB12020300).

References

  1. 1.
    Zhang, Q.; Chi, L.; Hai, G.; Fang, Y.; Li, X.; Xia, R.; Huang, W.; Gu, E. An easy approach to control β-phase formation in PFO films for optimized emission properties. Molecules 2017, 22, 315.CrossRefGoogle Scholar
  2. 2.
    Wu, F. I.; Shih, P. I.; Shu, C. F.; Tung, Y. L.; Chi, Y. Highly efficient light-emitting diodes based on fluorene copolymer consisting of triarylamine units in the main chain and oxadiazole pendent groups. Macromolecules 2005, 38, 9028–9036.CrossRefGoogle Scholar
  3. 3.
    Peet, J.; Brocker, E.; Xu, Y.; Bazan, G. C. Controlled β phase formation in poly(9,9-di-n-octylfluorene) by processing with alkyl additives. Adv. Mater. 2008, 20, 1882–1885.CrossRefGoogle Scholar
  4. 4.
    Chou, K. W.; Yan, B.; Li, R.; Li, E. Q.; Zhao, K.; Anjum, D. H.; Alvarez, S.; Gassaway, R.; Biocca, A.; Thoroddsen, S. T.; Hexemer, A.; Amassian, A. Spin-cast bulk heterojunction solar cells: A dynamical investigation. Adv. Mater. 2013, 25, 1923–1929.CrossRefGoogle Scholar
  5. 5.
    Günes, S.; Neugebauer, H.; Sariciftci, N. S. Conjugated polymer-based organic solar cells. Chem. Rev. 2007, 107, 1324–1338.CrossRefGoogle Scholar
  6. 6.
    Chen, H. Y.; Hou, J.; Zhang, S.; Liang, Y.; Yang, G.; Yang, Y.; Yu, L.; Wu, Y.; Li, G. Polymer solar cells with enhanced open-circuit voltage and efficiency. Nat. Photon. 2009, 3, 649–653.CrossRefGoogle Scholar
  7. 7.
    Wang, H.; Li, F.; Gao, B.; Xie, Z.; Liu, S.; Wang, C.; Hu, D.; Shen, F.; Xu, Y.; Shang, H. Doped organic crystals with high efficiency, color-tunable emission toward laser application. Cryst. Growth Des. 2009, 9, 4945–4950.CrossRefGoogle Scholar
  8. 8.
    Schneider, D.; Rabe, T.; Riedl, T.; Dobbertin, T.; Werner, O.; Kröger, M.; Becker, E.; Johannes, H. H.; Kowalsky, W.; Weimann, T. Deep blue widely tunable organic solid-state laser based on a spirobifluorene derivative. Appl. Phys. Lett. 2004, 84, 4693–4695.CrossRefGoogle Scholar
  9. 9.
    Lin, J. Y.; Zhu, W. S.; Liu, F.; Xie, L. H.; Zhang, L.; Xia, R.; Xing, G. C.; Huang, W. A rational molecular design of β phase polydiarylfluorenes: Synthesis, morphology, and organic lasers. Macromolecules 2014, 47, 1001–1007.CrossRefGoogle Scholar
  10. 10.
    Liu, B.; Lin, J.; Liu, F.; Yu, M.; Zhang, X.; Xia, R.; Yang, T.; Fang, Y.; Xie, L.; Huang, W. A highly crystalline and wide-bandgap polydiarylfluorene with β-phase conformation toward stable electroluminescence and dual amplified spontaneous emission. ACS Appl. Mater. Interfaces 2016, 8, 21648–21655.CrossRefGoogle Scholar
  11. 11.
    Lu, H. H.; Liu, C. Y.; Chang, C. H.; Chen, S. A. Self-dopant formation in poly(9,9-di-n-octylfluorene) via a dipping method for efficient and stable pure-blue electroluminescence. Adv. Mater. 2007, 19, 2574–2579.CrossRefGoogle Scholar
  12. 12.
    Liang, J.; Yu, L.; Zhao, S.; Ying, L.; Liu, F.; Yang, W.; Peng, J.; Cao, Y. Improving efficiency and color purity of poly(9,9-dioctylfluorene) through addition of a high boiling-point solvent of 1-chloronaphthalene. Nanotechnology 2016, 27, 284001.CrossRefGoogle Scholar
  13. 13.
    Teetsov, J.; Fox, M. A. Photophysical characterization of dilute solutions and ordered thin films of alkyl-substituted polyfluorenes. J. Mater. Chem. 1999, 9, 2117–2122.CrossRefGoogle Scholar
  14. 14.
    Zhu, B.; Han, Y.; Sun, M.; Bo, Z. Water-soluble dendronized polyfluorenes with an extremely high quantum yield in water. Macromolecules 2007, 40, 4494–4500.CrossRefGoogle Scholar
  15. 15.
    Cho, H. J.; Jung, B. J.; Cho, N. S.; Lee, J.; Shim, H. K. Synthesis and characterization of thermally stable blue light-emitting polyfluorenes containing siloxane bridges. Macromoecules 2003, 36, 6704–6710.CrossRefGoogle Scholar
  16. 16.
    Wang, P. H.; Ho, M. S.; Yang, S. H.; Chen, K. B.; Hsu, C. S. Synthesis of thermal-stable and photo-crosslinkable polyfluorenes for the applications of polymer light-emitting diodes. J. Polym. Sci., Part A: Polym. Chem. 2010, 48, 516–524.CrossRefGoogle Scholar
  17. 17.
    Li, X.; Bai, Z.; Liu, B.; Li, T.; Lu, D. From starting formation to the saturation content of the β phase in poly(9,9-dioctylfuorene) toluene solutions. J. Phys. Chem. C 2017, 121, 14443–14450.CrossRefGoogle Scholar
  18. 18.
    Huang, L.; Huang, X.; Sun, G.; Gu, C.; Lu, D.; Ma, Y. Study of β phase and chains aggregation degrees in poly(9,9-dioctylfuorene) (PFO) solution. J. Phys. Chem. C 2012, 116, 7993–7999.CrossRefGoogle Scholar
  19. 19.
    Chen, S.; Su, A.; Su, C.; Chen, S. Crystalline forms and emission behavior of poly(9,9-di-n-octyl-2,7-fluorene). Macromolecules 2005, 38, 379–385.CrossRefGoogle Scholar
  20. 20.
    Bradley, D. D. C.; Grell, M.; Long, X.; Mellor, H.; Grice, A. W.; Inbasekaran, M.; Woo, E. P. Influence of aggregation on the optical properties of a polyfluorene. Proc. SPIE 1997, 3145, 254–260.CrossRefGoogle Scholar
  21. 21.
    Grell, M.; Bradley, D. D. C.; Long, X.; Chamberlain, T.; Inbasekaran, M.; Woo, E. P.; Soliman, M. Chain geometry, solution aggregation and enhanced dichroism in the liquidcrystalline conjugated polymer poly(9,9-dioctylfuorene). Acta Polym. 1998, 49, 439–444.CrossRefGoogle Scholar
  22. 22.
    Grell, M.; Bradley, D. D. C.; Inbasekaran, M.; Woo, E. P. A glass-forming conjugated main-chain liquid crystal polymer for polarized electroluminescence applications. Adv. Mater. 1997, 9, 798–802.CrossRefGoogle Scholar
  23. 23.
    Perevedentsev, A.; Stavrinou, P. N.; Smith, P.; Bradley, D. D. C. Solution-crystallization and related phenomena in 9,9-dialkyl-fluorene polymers. II. Influence of side-chain structure. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1492–1506.CrossRefGoogle Scholar
  24. 24.
    Liu, B.; Lin, J. Y.; Yu, M. N.; Li, B.; Xie, L. H.; Ou, C. J.; Liu, F.; Li, T.; Lu, D.; Huang, W. Hereditary character of alkylchain length effect on β phase conformation from polydialkylfuorenes to bulky polydiarylfuorenes. J. Phys. Chem. C 2017, 121, 19087–19096.CrossRefGoogle Scholar
  25. 25.
    Liu, B.; Tao, L.; Hao, Z.; Ma, T.; Dan, L. Polyfluorene (PF) single-chain conformation, β conformation, and its stability and chain aggregation by side-chain length change in the solution dynamic process. J. Phys. Chem. C 2018, 122, 14814–14826.CrossRefGoogle Scholar
  26. 26.
    Grell, M.; Bradley, D. D. C.; Ungar, G.; Hill, J.; Whitehead, K. Interplay of physical structure and photophysics for a liquid crystalline polyfluorene. Macromolecules 1999, 32, 5810–5817.CrossRefGoogle Scholar
  27. 27.
    Yu, M. N.; Soleimaninejad, H.; Lin, J. Y.; Zuo, Z. Y.; Liu, B.; Bo, Y. F.; Bai, L. B.; Han, Y. M.; Smith, T. A.; Xu, M.; Wu, X. P.; Dunstan, D. E.; Xia, R. D.; Xie, L. H.; Bradley, D. D. C.; Huang, W. Photophysical and fluorescence anisotropic behavior of polyfluorene β-conformation films. J. Phys. Chem. Lett. 2018, 9, 364–372.CrossRefGoogle Scholar
  28. 28.
    Khan, A. L.; Sreearunothai, P.; Herz, L. M.; Banach, M. J.; Köhler, A. Morphology-dependent energy transfer within polyfluorene thin films. Phys. Rev. B 2004, 69, 085201.CrossRefGoogle Scholar
  29. 29.
    Bai, Z.; Liu, Y.; Li, T.; Li, X.; Liu, B.; Liu, B.; Lu, D. Quantitative study on β phase heredity based on poly(9,9-dioctylfluorene) from solutions to films and the effect on hole mobility. J. Phys. Chem. C 2016, 120, 27820–27828.CrossRefGoogle Scholar
  30. 30.
    Yu, M. N.; Liu, B.; Lin, J. Y.; Tao, L.; Dan, L.; Feng, L.; Zhu, W. S. Nondilute 1,2-dichloroethane solution of poly(9,9-dioctylfuorene-2,7-diyl): A study on the aggregation process. Chinese J. Polym. Sci. 2016, 34, 1311–1318.CrossRefGoogle Scholar
  31. 31.
    Yang, H.; Qu, K.; Li, H.; Cheng, H.; Zhang, J. An in situ investigation into the formation of the solvent-induced crystalline phase of poly(9,9-dioctylfluorene) in solvent vapor annealing. Macromol. Chem. Phys. 2016, 217, 1579–1585.CrossRefGoogle Scholar
  32. 32.
    Cadby, A.; Lane, P.; Mellor, H.; Martin, S.; Grell, M.; Giebeler, C.; Bradley, D. D. C.; Wohlgenannt, M.; An, C.; Vardeny, Z. Film morphology and photophysics of polyfluorene. Phys. Rev. B 2000, 62, 15604.CrossRefGoogle Scholar
  33. 33.
    Zhang, X.; Lei, Z.; Hu, Q.; Lin, J.; Chen, Y.; Xie, L.; Lai, W.; Huang, W. Stable pure-blue polymer light-emitting devices based on β phase poly(9,9-dioctylfluorene) induced by 1,2-dichloroethane. Appl. Phys. Express 2014, 7, 101601.CrossRefGoogle Scholar
  34. 34.
    Bright, D. W.; Galbrecht, F.; Scherf, U.; Monkman, A. P. β phase formation in poly(9,9-di-n-decylfluorene) thin films. Macromolecules 2010, 43, 7860–7863.CrossRefGoogle Scholar
  35. 35.
    Li, T.; Liu, B.; Zhang, H.; Ren, J.; Bai, Z.; Li, X.; Ma, T.; Lu, D. Effect of conjugated polymer poly(9,9-dioctylfluorene) (PFO) molecular weight change on the single chains, aggregation and β phase. Polymer 2016, 103, 299–306.CrossRefGoogle Scholar
  36. 36.
    Li, T.; Huang, L.; Bai, Z.; Li, X.; Liu, B.; Lu, D. Study on the forming condition and mechanism of the β conformation in poly(9,9-dioctylfluorene) solution. Polymer 2016, 88, 71–78.CrossRefGoogle Scholar
  37. 37.
    Cheng, G.; Shi, T.; Bing, Y.; Liu, S.; Ying, L.; Wang, H.; Yang, S.; Hanif, M.; Dan, L.; Shen, F. Almost completely dedoped electrochemically deposited luminescent films exhibiting excellent LED performance. Electrochim. Acta 2009, 54, 7006–7011.CrossRefGoogle Scholar
  38. 38.
    Ng, M. F.; Sun, S. L.; Zhang, R. Q. A comparative study of optical properties of poly(9,9-dioctylfluorene) and poly(p-phenylenevinylene) oligomers. J. Appl. Phys. 2005, 97, 103513–103516.CrossRefGoogle Scholar
  39. 39.
    Hohenberg, P.; Kohn, W. Inhomogeneous electron gas. Phys. Rev. B 1964, 136, 864–871.CrossRefGoogle Scholar
  40. 40.
    Runge, E.; Gross, E. K. U. Density-functional theory for timedependent systems. Phys. Rev. Lett. 1984, 52, 997–1000.CrossRefGoogle Scholar
  41. 41.
    Hirata, S.; Lee, T. J.; Headgordon, M. Time-dependent density functional study on the electronic excitation energies of polycyclic aromatic hydrocarbon radical cations of naphthalene, anthracene, pyrene, and perylene. J. Chem. Phys. 1999, 111, 8904–8912.CrossRefGoogle Scholar
  42. 42.
    Lee, C.; Yang, W.; Parr, R. G. Development of the Colle-Salvetti correlation energy formula into a functional of the electron density. Phys. Rev. B: Condens. Matter 1988, 37, 785–789.CrossRefGoogle Scholar
  43. 43.
    Cao, X.; Du, Z.; Liang, C.; Zhao, K.; Li, H.; Liu, J.; Han, Y. Long diketopyrrolopyrrole-based polymer nanowires prepared by decreasing the aggregate speed of the polymer in solution. Polymer 2017, 118, 135–142.CrossRefGoogle Scholar
  44. 44.
    Liang, C.; Zhao, K.; Cao, X.; Liu, J.; Yu, X.; Han, Y. Nanowires of conjugated polymer prepared by tuning the interaction between the solvent and polymer. Polymer 2018, 149, 23–29.CrossRefGoogle Scholar
  45. 45.
    Chen, L.; Zhao, K.; Cao, X.; Liu, J.; Yu, X.; Han, Y. Diketopyrrolopyrrole-based polymer fibrils formation by changing molecular conformation during film formation. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 1079–1086.CrossRefGoogle Scholar
  46. 46.
    Liang, C.; Chi, S.; Zhao, K.; Liu, J.; Yu, X.; Han, Y. Aligned films of the DPP-based conjugated polymer by solvent vapor enhanced drop casting. Polymer 2016, 104, 123–129.CrossRefGoogle Scholar
  47. 47.
    Cao, X.; Chen, L.; Zhao, K.; Liu, J.; Han, Y. Diketopyrrolopyrrole-based polymer nanowires: Control of chain conformation and nucleation. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 833–841.CrossRefGoogle Scholar
  48. 48.
    Xu, Y.; Liu, J.; Wang, H.; Yu, X.; Xing, R.; Han, Y. Formation of parallel aligned nano-fibrils of a donor-acceptor conjugated copolymer via controlling J-aggregates and post treatment. Soft Matter 2013, 9, 9849–9856.CrossRefGoogle Scholar
  49. 49.
    Wang, H. Y.; Liu, J. G.; Xu, Y. Z.; Yu, X. H.; Xu, R. B.; Han, Y. C. Ordered fibrillar morphology of donor-acceptor conjugated copolymers at multiple scales via blending with flexible polymers and solvent vapor annealing: Insight into photophysics and mechanism. Phys. Chem. Chem. Phys. 2014, 16, 1441–1450.CrossRefGoogle Scholar
  50. 50.
    Xu, Y.; Liu, J.; Wang, H.; Zheng, L.; Han, Y. Formation of parallel aligned nano-fibrils of poly(3,3″′-didodecylquaterthiophene) induced by the unimer coils in solution. RSC Adv. 2013, 3, 12069–12074.CrossRefGoogle Scholar
  51. 51.
    Wang, H. Y.; Liu, J. G.; Xu, Y. Z.; Han, Y. C. Fibrillar mor-phology of derivatives of poly(3-alkylthiophene)s by solvent vapor annealing: Effects of conformational transition and conjugate length. J. Phys. Chem. B 2013, 117, 5996–6006.CrossRefGoogle Scholar
  52. 52.
    Bright, D. W.; Dias, F. B.; Galbrecht, F.; Scherf, U.; Monkman, A. P. The influence of alkyl-chain length on β-phase formation in polyfluorenes. Adv. Funct. Mater. 2009, 19, 67–73.CrossRefGoogle Scholar
  53. 53.
    Dias, F. B.; Morgado, J.; Macanita, A. L.; da Costa, F. P.; Burrows, H. D.; Monkman, A. P. Kinetics and thermodynamics of poly(9,9-dioctylfluorene) β phase formation in dilute solution. Macromolecules 2006, 39, 5854–5864.CrossRefGoogle Scholar
  54. 54.
    Knaapila, M.; Bright, D. W.; Stepanyan, R.; Torkkeli, M.; Almásy, L.; Schweins, R.; Vainio, U.; Preis, E.; Galbrecht, F.; Scherf, U. Network structure of polyfluorene sheets as a function of alkyl side chain length. Phys. Rev. E: Stat., Nonlinear, Soft Matter Phys. 2011, 83, 051803.CrossRefGoogle Scholar
  55. 55.
    Lin, Z. Q.; Shi, N. E.; Li, Y. B.; Qiu, D.; Zhang, L.; Lin, J. Y.; Zhao, J. F.; Wang, C.; Xie, L. H.; Huang, W. Preparation and characterization of polyfluorene-based supramolecular π-conjugated polymer gels. J. Phys. Chem. C 2011, 115, 4418–4424.CrossRefGoogle Scholar
  56. 56.
    Ariu, M.; Sims, M.; Rahn, M. D.; Hill, J.; Fox, A. M.; Lidzey, D. G.; Oda, M.; Cabanillas-Gonzalez, J.; Bradley, D. D. C. Exciton migration in β phase poly(9,9-dioctylfluorene). Phys. Rev. B 2003, 67, 195333.CrossRefGoogle Scholar
  57. 57.
    Montilla, F.; Ruseckas, A.; Samuel, I. D. W. Exciton-polaron interactions in polyfluorene films with β phase. J. Phys. Chem. C 2018, 122, 9766–9772.CrossRefGoogle Scholar
  58. 58.
    Ling, H.; Lin, J.; Yi, M.; Liu, B.; Li, W.; Lin, Z.; Xie, L.; Bao, Y.; Guo, F.; Huang, W. Synergistic effects of self-doped nanostructures as charge trapping elements in organic field effect transistor memory. ACS Appl. Mater. Interfaces 2016, 8, 18969–18977.CrossRefGoogle Scholar
  59. 59.
    Zhang, X.; Hu, Q.; Lin, J.; Lei, Z.; Guo, X.; Xie, L.; Lai, W.; Huang, W. Efficient and stable deep blue polymer light-emitting devices based on β phase poly(9,9-dioctylfluorene). Appl. Phys. Lett. 2013, 103, 153301.CrossRefGoogle Scholar
  60. 60.
    Liu, C.; Wang, Q.; Tian, H.; Liu, J.; Geng, Y.; Yan, D. Morphology and structure of the β phase crystals of monodisperse polyfluorenes. Macromolecules 2013, 46, 3025–3030.CrossRefGoogle Scholar
  61. 61.
    Chen, S. H.; Su, A. C.; Chen, S. A. Noncrystalline phases in poly(9,9-di-n-octyl-2,7-fluorene). J. Phys. Chem. B 2005, 109, 10067.CrossRefGoogle Scholar
  62. 62.
    Chen, S. H.; Chou, H. L.; Su, A. C. Molecular packing in crystalline poly(9,9-di-n-octyl-2,7-fluorene). Macromolecules 2004, 37, 6833–6838.CrossRefGoogle Scholar
  63. 63.
    Liu, C.; Wang, Q.; Tian, H.; Liu, J.; Geng, Y.; Yan, D. Control of crystal morphology in monodisperse polyfluorenes by solvent and molecular weight. J. Phys. Chem. B 2013, 117, 8880–8886.CrossRefGoogle Scholar

Copyright information

© Chinese Chemical Society Institute of Chemistry, Chinese Academy of Sciences Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchunChina
  2. 2.University of Science and Technology of ChinaHefeiChina

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