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Singlet fission in pentacene through multi-exciton quantum states

Nature Chemistry volume 2, pages 648652 (2010) | Download Citation

Abstract

Multi-exciton generation—the creation of multiple charge carrier pairs from a single photon—has been reported for several materials and may dramatically increase solar cell efficiency. Singlet fission, its molecular analogue, may govern multi-exciton generation in a variety of materials, but a fundamental mechanism for singlet fission has yet to be described. Here, we use sophisticated ab initio calculations to show that singlet fission in pentacene proceeds through rapid internal conversion of the photoexcited state into a dark state of multi-exciton character that efficiently splits into two triplets. We show that singlet fission to produce a pair of triplet excitons must involve an intermediate state that (i) has a multi-exciton character, (ii) is energetically accessible from the optically allowed excited state, and (iii) efficiently dissociates into multiple electron–hole pairs. The rational design of photovoltaic materials that make use of singlet fission will require similar ab initio analysis of multi-exciton states such as the dark state studied here.

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Acknowledgements

The authors would like to thank the National Nanotechnology Infrastructure Network (NNIN) for providing computational time for this project. Z.Z. acknowledges partial support from NNIN.

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Affiliations

  1. Department of Chemical Engineering, Stanford University, 380 Roth Way, Stanford, California 94305, USA

    • Paul M. Zimmerman
  2. Stanford Nanofabrication Facility, Stanford University, 420 Via Palou Mall, Stanford, California 94305, USA

    • Zhiyong Zhang
  3. Department of Chemical and Biological Engineering, University of Colorado at Boulder, Boulder, Colorado 80309, USA

    • Charles B. Musgrave

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Contributions

P.M.Z. and Z.Z. completed the computations and analysis. All authors contributed to writing the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Paul M. Zimmerman or Zhiyong Zhang or Charles B. Musgrave.

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DOI

https://doi.org/10.1038/nchem.694

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