Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Organic semiconductors

A little energy goes a long way

Nature Materials volume 9, pages 884–885 (2010)Cite this article

Subjects

Excitons in a highly ordered organic semiconductor are found to diffuse over distances of a few micrometres. This may pave the way towards designing efficient excitonic solar cells.

The idea of using triplets produced by singlet fission in photovoltaic devices is an intriguing one because it would represent a natural avenue for an energy up-conversion scheme that 'comes in the tin'. In this process, a single optical absorption event would produce two excitons that could in turn be separated into charges, enhancing the potential to achieve high-efficiency devices. With the advent of crystal growth techniques giving access to excellent crystal quality, as shown in the work by Podzorov and colleagues3, it should be possible to examine further the role of singlet fission in organic semiconductor crystals, and the photophysical mechanism that is responsible for it. In fact, the mechanism has been explored theoretically in pentacene by Zimmerman and co-workers5, who conclude that it involves rapid internal conversion of the photoexcited state into a dark state that has multi-exciton character and efficiently dissociates into two triplets. This can occur if the energy of the lowest optically allowed singlet state is greater than twice that of the lowest triplet state. Zimmerman notes that this is not the case in tetracene, because fission occurs in that material only through thermally activated processes. Can singlet fission therefore occur in rubrene crystals, which are chemical derivatives of tetracene, and if so, by what mechanism? In model tetracene dimers, the yield of this process depends sensitively on the molecular nature of a bridge linking the two molecules6. One might therefore expect that in rubrene the side-group substituents could increase the rate of singlet fission with respect to that in unsubstituted tetracene crystals. Further ultrafast spectroscopic measurements in high-purity rubrene crystals are thus warranted.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Learn more

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Molecular structure of rubrene (a) and schematic of the crystal structure (b) along the (a,b) crystallographic plane.
Figure 2: Illumination of a single rubrene crystal produces current at the surface of the crystal if the surface is functionalized with a layer that splits excitons.

References

  1. Gershenson, M. E., Podzorov, V. & Morpurgo, A. Rev. Mod. Phys. 78, 973–989 (2006).

    Article  CAS  Google Scholar 

  2. Sundar, V. C. et al. Science 303, 1644–1646 (2004).

    Article  CAS  Google Scholar 

  3. Najafov, H., Lee, B., Zhou, Q., Feldman, L. C. & Podzorov, V. Nature Mater. 9, 938–943 (2010).

    Article  CAS  Google Scholar 

  4. Pope, M. & Swenberg, C. E. Electronic Processes in Organic Crystals and Polymers (Oxford Univ. Press, 1999).

    Google Scholar 

  5. Zimmerman, P. M., Zhang, Z. & Musgrave, C. B. Nature Chem. 2, 648–652 (2010).

    Article  CAS  Google Scholar 

  6. Müller, A. M., Avlasevich, Y. S., Schoeller, W. W., Müllen, K. & Bardeen, C. J. J. Am. Chem. Soc. 129, 14240–14250 (2007).

    Article  Google Scholar 

  7. Rao, A. et al. J. Am. Chem. Soc. 132, 12698–12703 (2010).

    Article  CAS  Google Scholar 

  8. Yoo, S., Domercq, B. & Kippelen, B. Appl. Phys. Lett. 85, 5427–5429 (2004).

    Article  CAS  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Carlos Silva is in the Department of Physics and Regroupement québécois sur les matériaux de pointe, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal (Québec) H3C 3J7, Canada. carlos.silva@umontreal.ca,

    Carlos Silva

Authors
  1. Carlos Silva
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Silva, C. A little energy goes a long way. Nature Mater 9, 884–885 (2010). https://doi.org/10.1038/nmat2890

Download citation

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat2890

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing