Skip to content
BY-NC-ND 3.0 license Open Access Published by De Gruyter Open Access December 1, 2007

Energy up-conversion in dilute polyfluorene solutions

Alexander Kuehne, Allan Mackintosh, David Armstrong and Richard Pethrick
From the journal Open Chemistry

Abstract

Poly(9,9-dioctylfluorene) (PFO) shows highly efficient blue emission with photo excitation occurring between 340–400 nm. Here we show that PFO can in dilute solution emit at a wavelength well below that at which it is being exited. This, we propose is related to an energy transfer from conjugated parts of the polymer chain into more localised states which then emit at a lower wavelength. These localised states can be considered as defects in the conjugation of the polymer or as chain ends. These may produce quasi monomer or quasi dimer species within the chain, which will have a HOMO-LUMO gap of higher energy than the conjugated polymer. These then fluoresce at the lower wavelength; essentially causing, by energy transfer, a process of energy up-conversion.

[1] J.H. Burroughes, D.D.C. Bradley, A.R. Brown, R.N. Marks, K. Mackay, R.H. Friend, P.L. Burn and A.B. Holmes: “Light emitting-diodes based on conjugated polymers”, Nature, Vol. 347, (1990), pp. 539–541. http://dx.doi.org/10.1038/347539a010.1038/347539a0Search in Google Scholar

[2] M. Gross, D.C. Müller, H.G. Nothofer, U. Scherf, D. Neher, C. Bräuchle and K. Meerholz: “Improving the performance of doped π-conjugated polymers for use in organic light-emitting diodes”, Nature, Vol. 405, (2000), pp. 661–665. http://dx.doi.org/10.1038/3501503710.1038/35015037Search in Google Scholar

[3] Y. Ohmori, M. Uchida, K. Muro and K. Yoshino: “Blue electroluminescent diodes utilizing poly(alkylfluorene)”, Jpn. J. Appl. Phys., Vol. 30, (1991), pp. L1941–L1943. http://dx.doi.org/10.1143/JJAP.30.L194110.1143/JJAP.30.L1941Search in Google Scholar

[4] E. Gu, H.X. Zhang, H.D. Sun, M.D. Dawson, A.R. Mackintosh, A.J. C. Kuehne, R.A. Pethrick, C. Belton and D.D.C. Bradley: “Hybrid inorganic/organic microstructured light-emitting diodes produced using photocurable polymer blends”, Appl. Phys. Lett., Vol. 90, (2007), art. 031116. Search in Google Scholar

[5] C. Chi, C. Im and G. Wegner: “Lifetime determination of fluorescence and phosphorescence of a series of oligofluorenes”, J. Chem. Phys., Vol. 124, (2006), art. 024907. Search in Google Scholar

[6] E. Somma, B. Loppinet, C. Chi, G. Fytas and G. Wegner: “Static and dynamic solution properties of monodisperse oligofluorenes”, Phys. Chem. Chem. Phys., Vol. 8, (2006), pp. 2773–2778. http://dx.doi.org/10.1039/b601531j10.1039/b601531jSearch in Google Scholar

[7] V. Marcon, N. van der Vegt, G. Wegner and G. Raos: “Modeling of molecular packing and conformation in oligofluorenes”, J. Phys. Chem. B, Vol. 110, (2006), pp. 5253–5261. http://dx.doi.org/10.1021/jp056858y10.1021/jp056858ySearch in Google Scholar

[8] M.A. Stevens, C. Silva, D.M. Russell and R.H. Friend: “Exciton dissociation mechanisms in the polymeric semiconductors poly.9,9-dioctylfluorene and poly.9,9-dioctylfluorene-co-benzothiadiazole”, Phys. Rev. B, Vol. v, (2001), art. 165213. Search in Google Scholar

[9] S. Baluschev, T. Mteva, V. Yakutin, G. Nelles, A Yasuda and G. Wegner: “Upconversion fluorescence: Noncoherent excitation by sunlight”, Phys. Rev. Lett., Vol. 97, (2006), art. 143903. Search in Google Scholar

[10] G. Klaerner and R.D. Miller: “Polyfluorene derivatives: Effective conjugation length from well defined oligomers”, Macromolecules, Vol. 31, (1998), pp. 2007–2009. http://dx.doi.org/10.1021/ma971073e10.1021/ma971073eSearch in Google Scholar

[11] L.-O. Pålsson, C.S. Wang, D.L. Russell, A.P. Monkman, M.R. Bryce, G. Rumbles and I.D.W. Samuel: “Photophysics of a fluorene co-polymer in solution and films”, Chem. Phys., Vol. 279, (2002), pp. 229–237. http://dx.doi.org/10.1016/S0301-0104(02)00407-X10.1016/S0301-0104(02)00407-XSearch in Google Scholar

[12] G. Fytas, H.G. Nothofer, U. Scherf, D. Vlassopoulos and G. Meier: “Structure and dynamics of nondilute polyfluorene solutions”, Macromolecules, Vol. 35, (2002), pp. 481–488. http://dx.doi.org/10.1021/ma011416f10.1021/ma011416fSearch in Google Scholar

[13] J. Duhamel, A. Yekta, M.A, Winnik, T.C. Jao, M.K. Mishra and I.D. Rubin: “A blob model to study polymer-chain dynamics in solution”, J. Phys. Chem., Vol. 97, (1993), pp. 13708–13712. http://dx.doi.org/10.1021/j100153a04610.1021/j100153a046Search in Google Scholar

[14] W. Chunwaschirasiri, B. Tanto, D.L. Huber and M.J. Winokur: “Chain conformations and photoluminescence of poly(di-n-octylfluorene)”, Phys. Rev. Lett., Vol. 94, (2005), art. 107402. Search in Google Scholar

[15] M. Annia, M.E. Caruso, S. Lattante and R. Cingolani: “The role of excitons’ quasiequilibrium in the temperature dependence of the poly,9,9-dioctylfluorene tphase photoluminescence”, J. Chem. Phys., Vol. 124, (2006), art. 134707. Search in Google Scholar

[16] O. Worsfold, J. Hill, S.Y. Heriot, A.M. Fox, D.D.C. Bradley and T.H. Richardson: “Langmuir and Langmui-Blodgett (LB) film properties of poly(9,9-dioctylfluorene)”, Mater. Sci. Eng. C, Vol. 23, (2003), pp. 541–544. Search in Google Scholar

[17] O. J. Korovyanko and Z.V. Vardeny: “Film morphology and ultrafast photoexcitation dynamics in polyfluorene”, Chem. Phys. Lett., Vol. 356, (2002), pp. 361–367. http://dx.doi.org/10.1016/S0009-2614(02)00349-410.1016/S0009-2614(02)00349-4Search in Google Scholar

[18] X. Gong, D. Moses, A.J. Heeger and S. Xiao: “Excitation energy transfer from polyfluorene to fluorene defects”, Synth. Met., Vol. 141, (2004), pp. 17–20. http://dx.doi.org/10.1016/j.synthmet.2003.06.00310.1016/j.synthmet.2003.06.003Search in Google Scholar

[19] J. Frahn, B. Karakaya, A. Schäfer and A.D. Schlüter: “Suzuki polycondensation: “On catalyst derived phosphorus incorporation and reproducibility of molecular weights”, Tetrahedron, Vol. 53 (1997), pp. 15459–15467. http://dx.doi.org/10.1016/S0040-4020(97)00973-310.1016/S0040-4020(97)00973-3Search in Google Scholar

[20] T.P. Nguyen: “Defect analysis in organic semiconductors”, Mater. Sci. Semicond. Process, Vol. 9, (2006), pp. 198–203. http://dx.doi.org/10.1016/j.mssp.2006.01.06010.1016/j.mssp.2006.01.060Search in Google Scholar

Published Online: 2007-12-1
Published in Print: 2007-12-1

© 2007 Versita Warsaw

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Scroll Up Arrow