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Charge carrier mobility, bimolecular recombination and trapping in polycarbazole copolymer:fullerene (PCDTBT:PCBM) bulk heterojunction solar cells

Journal Article


Abstract


  • Organic photovoltaic devices based on the donor:acceptor blend of poly[N-9 ''-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl C-61 butyric acid methyl ester (PCBM) have received considerable attention in recent years due to their high power conversion efficiencies and the ability to achieve close to 100% internal quantum efficiency. However, the highest efficiencies were all attained using active layers of less than 100 nm, which is not ideal for either maximised potential performance or commercial viability. Furthermore, more recent reports have documented significant charge carrier trapping in these devices. In this paper two charge extraction techniques (photo-CELIV and time-of-flight) have been used to investigate the mobility and recombination behaviour in a series of PCDTBT:PCBM devices. The results not only confirm significant charge carrier trapping in this system, but also reveal close to Langevin-type bimolecular recombination. The Langevin recombination causes a short charge carrier lifetime that results in a short drift length. The combination of these two characteristics (trapping and fast bimolecular recombination) has a detrimental effect on the charge extraction efficiency when active layers greater than similar to 100 nm are used. This accounts for the pronounced decrease in fill factor with increasing active layer thickness that is typically observed in PCDTBT:PCBM devices.

Authors


  •   Clarke, Tracey M.
  •   Peet, Jeff (external author)
  •   Nattestad, Andrew
  •   Drolet, Nicolas (external author)
  •   Dennler, Gilles (external author)
  •   Lungenschmied, Christoph (external author)
  •   Leclerc, Mario (external author)
  •   Mozer, Attila J.

Publication Date


  • 2012

Citation


  • Clarke, T. M., Peet, J., Nattestad, A., Drolet, N., Dennler, G., Lungenschmied, C., Leclerc, M. & Mozer, A. J. (2012). Charge carrier mobility, bimolecular recombination and trapping in polycarbazole copolymer:fullerene (PCDTBT:PCBM) bulk heterojunction solar cells. Organic Electronics, 13 (11), 2639-2646.

Scopus Eid


  • 2-s2.0-84865469858

Ro Metadata Url


  • http://ro.uow.edu.au/aiimpapers/505

Has Global Citation Frequency


Number Of Pages


  • 7

Start Page


  • 2639

End Page


  • 2646

Volume


  • 13

Issue


  • 11

Place Of Publication


  • Netherlands

Abstract


  • Organic photovoltaic devices based on the donor:acceptor blend of poly[N-9 ''-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl C-61 butyric acid methyl ester (PCBM) have received considerable attention in recent years due to their high power conversion efficiencies and the ability to achieve close to 100% internal quantum efficiency. However, the highest efficiencies were all attained using active layers of less than 100 nm, which is not ideal for either maximised potential performance or commercial viability. Furthermore, more recent reports have documented significant charge carrier trapping in these devices. In this paper two charge extraction techniques (photo-CELIV and time-of-flight) have been used to investigate the mobility and recombination behaviour in a series of PCDTBT:PCBM devices. The results not only confirm significant charge carrier trapping in this system, but also reveal close to Langevin-type bimolecular recombination. The Langevin recombination causes a short charge carrier lifetime that results in a short drift length. The combination of these two characteristics (trapping and fast bimolecular recombination) has a detrimental effect on the charge extraction efficiency when active layers greater than similar to 100 nm are used. This accounts for the pronounced decrease in fill factor with increasing active layer thickness that is typically observed in PCDTBT:PCBM devices.

Authors


  •   Clarke, Tracey M.
  •   Peet, Jeff (external author)
  •   Nattestad, Andrew
  •   Drolet, Nicolas (external author)
  •   Dennler, Gilles (external author)
  •   Lungenschmied, Christoph (external author)
  •   Leclerc, Mario (external author)
  •   Mozer, Attila J.

Publication Date


  • 2012

Citation


  • Clarke, T. M., Peet, J., Nattestad, A., Drolet, N., Dennler, G., Lungenschmied, C., Leclerc, M. & Mozer, A. J. (2012). Charge carrier mobility, bimolecular recombination and trapping in polycarbazole copolymer:fullerene (PCDTBT:PCBM) bulk heterojunction solar cells. Organic Electronics, 13 (11), 2639-2646.

Scopus Eid


  • 2-s2.0-84865469858

Ro Metadata Url


  • http://ro.uow.edu.au/aiimpapers/505

Has Global Citation Frequency


Number Of Pages


  • 7

Start Page


  • 2639

End Page


  • 2646

Volume


  • 13

Issue


  • 11

Place Of Publication


  • Netherlands