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Spectroscopic studies of dopant-induced conformational changes in poly(3-hexylthiophene) thin films

  • Annabel R. Chew (a1) and Alberto Salleo (a1)

The effect of p-type doping at ultra-low concentrations (~10−4–10−5 monomer mol fraction) of the polymer poly(3-hexylthiophene) (P3HT) is studied using charge modulation (CM) spectroscopy. Quantitative analysis of CM spectra of doped P3HT show that dopants induce measurable changes in the P3HT local chain conformation. We find that the dopants reside in both the aggregate and amorphous regions of the polymer, not just in the amorphous regions, as previously assumed. With increased doping, the P3HT intrachain disorder grows, causing the P3HT chains to become more oligomer-like, which we postulate leads to the drop in mobility commonly observed in literature.

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Address all correspondence to Alberto Salleo at
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1.Arias, A.C., MacKenzie, J.D., McCulloch, I., Rivnay, J., and Salleo, A.: Materials and applications for large area electronics: solution-based approaches. Chem. Rev. 110, 3 (2010).
2.Duong, D.T., Wang, C., Antono, E., Toney, M.F., and Salleo, A.: The chemical and structural origin of efficient p-type doping in P3HT. Org. Electron. 14, 1330 (2013).
3.Méndez, H., Heimel, G., Opitz, A., Sauer, K., Barkowski, P., Oehzelt, M., Soeda, J., Okamoto, T., Takeya, J., Arlin, J.-B., Balandier, J.-Y., Geerts, Y., Koch, N., and Salzmann, I.: Doping of organic semiconductors: impact of dopant strength and electronic coupling. Angew. Chem. Int. Ed. 52, 7751 (2013).
4.Wang, C., Duong, D.T., Vandewal, K., Rivnay, J., and Salleo, A.: Optical measurement of doping efficiency in poly(3-hexylthiophene) solutions and thin films. Phys. Rev. B 91, 85205 (2015).
5.Gao, J., Stein, B.W., Thomas, A.K., Garcia-Galvez, J.A., Yang, J., Kirk, M.L., and Grey, J.K.: Enhanced charge transfer doping efficiency in J-aggregate poly(3-hexylthiophene) nanofibers. J. Phys. Chem. C 119, 16396 (2015).
6.Scholes, D.T., Hawks, S.A., Yee, P.Y., Wu, H., Lindemuth, J.R., Tolbert, S.H., and Schwartz, B.J.: Overcoming film quality issues for conjugated polymers doped with F4TCNQ by solution sequential processing: hall effect, structural, and optical measurements. J. Phys. Chem. Lett. 6, 4786 (2015).
7.Jacobs, I.E., Aasen, E.W., Oliveira, J.L., Fonseca, T.N., Roehling, J.D., Li, J., Zhang, G., Augustine, M.P., Mascal, M., and Moulé, A.J.: Comparison of solution-mixed and sequentially processed P3HT:F4TCNQ films: effect of doping-induced aggregation on film morphology. J. Mater. Chem. C 4, 3454 (2016).
8.Glaudell, A.M., Cochran, J.E., Patel, S.N., and Chabinyc, M.L.: Impact of the doping method on conductivity and thermopower in semiconducting polythiophenes. Adv. Energy Mater. 5, 1401072 (2015).
9.Olthof, S., Mehraeen, S., Mohapatra, S.K., Barlow, S., Coropceanu, V., Brédas, J.L., Marder, S.R., and Kahn, A.: Ultralow doping in organic semiconductors: evidence of trap filling. Phys. Rev. Lett. 109, 176601 (2012).
10.Pingel, P., Schwarzl, R., and Neher, D.: Effect of molecular p-doping on hole density and mobility in poly(3-hexylthiophene). Appl. Phys. Lett. 100, 143303 (2012).
11.Shang, Z., Heumueller, T., Prasanna, R., Burkhard, G.F., Naab, B.D., Bao, Z., McGehee, M.D., and Salleo, A.: Trade-off between trap filling, trap creation, and charge recombination results in performance increase at ultralow doping levels in bulk heterojunction solar cells. Adv. Energy Mater. 6, 1601149 (2016).
12.Said, M.M., Zhang, Y., Dasari, R.R., Anjum, D.H., Munir, R., Hu, H., Amassian, A., Barlow, S., and Marder, S.R.: Ultra-low p-doping of poly(3-hexylthiophene) and its impact on polymer aggregation and photovoltaic performance. Org. Photonics Photovolt. 4, 1 (2016).
13.Pingel, P. and Neher, D.: Comprehensive picture of p-type doping of P3HT with the molecular acceptor F4TCNQ. Phys. Rev. B 87, 115209 (2013).
14.Keum, C.-M., Liu, S., Al-Shadeedi, A., Kaphle, V., Bunge, S.D., and Lussem, B.: Charge trapping in doped organic Zener diodes. Org. Electron. 39, 77 (2016).
15.Arkhipov, V., Heremans, P., Emelianova, E., and Bässler, H.: Effect of doping on the density-of-states distribution and carrier hopping in disordered organic semiconductors. Phys. Rev. B 71, 45214 (2005).
16.Ma, L., Lee, W.H., Park, Y.D., Kim, J.S., Lee, H.S., and Cho, K.: High performance polythiophene thin-film transistors doped with very small amounts of an electron acceptor. Appl. Phys. Lett. 92, 63310 (2008).
17.Spano, F.C.: Absorption in regio-regular poly(3-hexyl)thiophene thin films: Fermi resonances, interband coupling and disorder. Chem. Phys. 325, 22 (2006).
18.Beljonne, D., Cornil, J., Sirringhaus, H., Brown, P.J., Shkunov, M., Friend, R.H., and Brédas, J.-L.: Optical signature of delocalized polarons in conjugated polymers. Adv. Funct. Mater. 11, 229 (2001).
19.Brown, P., Thomas, D., Köhler, A., Wilson, J., Kim, J.-S., Ramsdale, C., Sirringhaus, H., and Friend, R.: Effect of interchain interactions on the absorption and emission of poly(3-hexylthiophene). Phys. Rev. B 67, 64203 (2003).
20.Österbacka, R., An, C.P., Jiang, X.M., and Vardeny, Z.V.: Two-dimensional electronic excitations in self-assembled conjugated polymer nanocrystals. Science 287, 839 (2000).
21.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 (1999).
22.Noh, Y. and Sirringhaus, H.: Ultra-thin polymer gate dielectrics for top-gate polymer field-effect transistors. Org. Electron. 10, 174 (2009).
23.Zhao, N., Noh, Y.-Y., Chang, J.-F., Heeney, M., McCulloch, I., and Sirringhaus, H.: Polaron localization at interfaces in high-mobility microcrystalline conjugated polymers. Adv. Mater. 21, 3759 (2009).
24.Ghosh, R., Pochas, C.M., and Spano, F.C.: Polaron delocalization in conjugated polymer films. J. Phys. Chem. C 120, 11394 (2016).
25.Winkler, S., Amsalem, P., Frisch, J., Oehzelt, M., Heimel, G., and Koch, N.: Probing the energy levels in hole-doped molecular semiconductors. Mater. Horiz. 2, 427 (2015).
26.Heimel, G.: The optical signature of charges in conjugated polymers. ACS Cent. Sci. 2, 309 (2016).
27.Deng, Y.Y. and Sirringhaus, H.: Optical absorptions of polyfluorene transistors. Phys. Rev. B 72, 45207 (2005).
28.Noriega, R., Rivnay, J., Vandewal, K., Koch, F.P.V., Stingelin, N., Smith, P., Toney, M.F., and Salleo, A.: A general relationship between disorder, aggregation and charge transport in conjugated polymers. Nat. Mater. 12, 1038 (2013).
29.Turner, S.T., Pingel, P., Steyrleuthner, R., Crossland, E.J.W., Ludwigs, S., and Neher, D.: Quantitative analysis of bulk heterojunction films using linear absorption spectroscopy and solar cell performance. Adv. Funct. Mater. 21, 4640 (2011).
30.Zuo, G., Abdalla, H., and Kemerink, M.: Impact of doping on the density of states and the mobility in organic semiconductors. Phys. Rev. B 93, 235203 (2016).
31.Clark, J., Silva, C., Friend, R.H., and Spano, F.C.: Role of intermolecular coupling in the photophysics of disordered organic semiconductors: aggregate emission in regioregular polythiophene. Phys. Rev. Lett. 98, 206406 (2007).
32.Arkhipov, V.I., Emelianova, E.V., Heremans, P., and Bässler, H.: Analytic model of carrier mobility in doped disordered organic semiconductors. Phys. Rev. B 72, 235202 (2005).
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MRS Communications
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