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Photo-induced Charge Transfer and Relaxation of Persistent Charge Carriers in Polymer/Nanocrystal Composites for Applications in Hybrid Solar Cells

  1. Marc Daniel Heinemann1,
  2. Karsten von Maydell2,
  3. Folker Zutz1,
  4. Joanna Kolny-Olesiak1,
  5. Holgert Borchert1,*,
  6. Ingo Riedel1,
  7. Jürgen Parisi1

Article first published online: 9 NOV 2009

DOI: 10.1002/adfm.200900852

Issue

Advanced Functional Materials

Advanced Functional Materials

Volume 19, Issue 23, pages 3788–3795, December 9, 2009

Additional Information

How to Cite

Heinemann, M. D., von Maydell, K., Zutz, F., Kolny-Olesiak, J., Borchert, H., Riedel, I. and Parisi, J. (2009), Photo-induced Charge Transfer and Relaxation of Persistent Charge Carriers in Polymer/Nanocrystal Composites for Applications in Hybrid Solar Cells. Adv. Funct. Mater., 19: 3788–3795. doi: 10.1002/adfm.200900852

Author Information

  1. 1

    University of Oldenburg, Department of Physics, Energy and Semiconductor Research Laboratory Carl-von-Ossietzky-Str. 9-11, 26129 Oldenburg (Germany)

  2. 2

    EWE Research Center for Energy Technology – NEXT ENERGY Carl-von-Ossietzky-Str. 15, 26129 Oldenburg (Germany)

*University of Oldenburg, Department of Physics, Energy and Semiconductor Research Laboratory Carl-von-Ossietzky-Str. 9-11, 26129 Oldenburg (Germany).

Publication History

  1. Issue published online: 3 DEC 2009
  2. Article first published online: 9 NOV 2009
  3. Manuscript Received: 15 MAY 2009

Funded by

  • EWE Research Group “Thin Film Photovoltaics” by the EWE AG, Oldenburg

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Keywords:

  • Hybrid materials;
  • Solar cells;
  • Conjugated polymers;
  • CdSe nanocrystals;
  • Charge transfer

Abstract

The photo-induced charge transfer and the dynamics of persistent charge carriers in blends of semiconducting polymers and nanocrystals are investigated. Regioregular poly(3-hexylthiophene) (P3HT) is used as the electron donor material, while the acceptor moiety is established by CdSe nanocrystals (nc-CdSe) prepared via colloidal synthesis. As a reference system, organic blends of P3HT and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) are studied as well. The light-induced charge transfer between P3HT and the acceptor materials is studied by photoluminescence (PL), photo-induced absorption (PIA) and light-induced electron spin resonance spectroscopy (LESR). Compared to neat P3HT samples, both systems show an intensified formation of polarons in the polymer upon photo-excitation, pointing out successful separation of photogenerated charge carriers. Additionally, relaxation of the persistent charge carriers is investigated, and significant differences are found between the hybrid composite and the purely organic system. While relaxation, reflected in the transient signal decay of the polaron signal, is fast in the organic system, the hybrid blends exhibit long-term persistence. The appearance of a second, slow recombination channel indicates the existence of deep trap states in the hybrid system, which leads to the capture of a large fraction of charge carriers. A change of polymer conformation due to the presence of nc-CdSe is revealed by low temperature LESR measurements and microwave saturation techniques. The impact of the different recombination behavior on the photovoltaic efficiency of both systems is discussed.

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