Hostname: page-component-586b7cd67f-r5fsc Total loading time: 0 Render date: 2024-11-30T10:39:44.205Z Has data issue: false hasContentIssue false
  • English
  • Français

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

Published online by Cambridge University Press:  07 September 2017

Annabel R. Chew  and
Alberto Salleo
Annabel R. Chew
Affiliation:
Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
Alberto Salleo*
Affiliation:
Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
*
Address all correspondence to Alberto Salleo at [email protected]
Get access

Abstract

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.

Type
Research Letters
Information
MRS Communications , Volume 7 , Issue 3 , September 2017 , pp. 728 - 734
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.)

References

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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
22.Noh, Y. and Sirringhaus, H.: Ultra-thin polymer gate dielectrics for top-gate polymer field-effect transistors. Org. Electron. 10, 174 (2009).Google Scholar
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).Google Scholar
24.Ghosh, R., Pochas, C.M., and Spano, F.C.: Polaron delocalization in conjugated polymer films. J. Phys. Chem. C 120, 11394 (2016).Google Scholar
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).Google Scholar
26.Heimel, G.: The optical signature of charges in conjugated polymers. ACS Cent. Sci. 2, 309 (2016).Google Scholar
27.Deng, Y.Y. and Sirringhaus, H.: Optical absorptions of polyfluorene transistors. Phys. Rev. B 72, 45207 (2005).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
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).Google Scholar
Supplementary material: File

Chew and Salleo supplementary material

Chew and Salleo supplementary material 1

Download Chew and Salleo supplementary material(File)
File 94.9 KB