A transferable model for singlet-fission kinetics

  • A Corrigendum to this article was published on 20 June 2014

Abstract

Exciton fission is a process that occurs in certain organic materials whereby one singlet exciton splits into two independent triplets. In photovoltaic devices these two triplet excitons can each generate an electron, producing quantum yields per photon of >100% and potentially enabling single-junction power efficiencies above 40%. Here, we measure fission dynamics using ultrafast photoinduced absorption and present a first-principles expression that successfully reproduces the fission rate in materials with vastly different structures. Fission is non-adiabatic and Marcus-like in weakly interacting systems, becoming adiabatic and coupling-independent at larger interaction strengths. In neat films, we demonstrate fission yields near unity even when monomers are separated by >5 Å. For efficient solar cells, however, we show that fission must outcompete charge generation from the singlet exciton. This work lays the foundation for tailoring molecular properties like solubility and energy level alignment while maintaining the high fission yield required for photovoltaic applications.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Figure 1: Kinetic model of singlet fission.
Figure 2: Summary of theoretical and experimental fission rates.
Figure 3: Prediction of fission rates for a variety of pentacene derivatives.
Figure 4: Impact of fission rate on solar cell performance.

Change history

  • 21 May 2014

    In the version of this Article originally published, the author name Moungi G. Bawendi was missing the middle initial. This has now been corrected in the online versions of the Article.

References

  1. 1

    Geacintov, N., Pope, M. & Vogel, F. Effect of magnetic field on the fluorescence of tetracene crystals: exciton fission. Phys. Rev. Lett. 22, 593–596 (1969).

    CAS  Google Scholar 

  2. 2

    Congreve, D. N. et al. External quantum efficiency above 100% in a singlet-exciton-fission-based organic photovoltaic cell. Science 340, 334–337 (2013).

    CAS  PubMed  Google Scholar 

  3. 3

    Hanna, M. C. & Nozik, A. J. Solar conversion efficiency of photovoltaic and photoelectrolysis cells with carrier multiplication absorbers. J. Appl. Phys. 100, 074510 (2006).

    Google Scholar 

  4. 4

    Smith, M. B. & Michl, J. Singlet fission. Chem. Rev. 110, 6891–6936 (2010).

    CAS  PubMed  Google Scholar 

  5. 5

    Chan, W-L. et al. Observing the multiexciton state in singlet fission and ensuing ultrafast multielectron transfer. Science 334, 1541–1545 (2011).

    CAS  PubMed  Google Scholar 

  6. 6

    Lee, J. et al. Singlet exciton fission in a hexacene derivative. Adv. Mater. 25, 1445–1448 (2013).

    CAS  PubMed  Google Scholar 

  7. 7

    Lee, J., Jadhav, P. & Baldo, M. A. High efficiency organic multilayer photodetectors based on singlet exciton fission. Appl. Phys. Lett. 95, 033301 (2009).

    Google Scholar 

  8. 8

    Wilson, M. W. B. et al. Ultrafast dynamics of exciton fission in polycrystalline pentacene. J. Am. Chem. Soc. 133, 11830–11833 (2011).

    CAS  PubMed  Google Scholar 

  9. 9

    Burdett, J. J. & Bardeen, C. J. Quantum beats in crystalline tetracene delayed fluorescence due to triplet pair coherences produced by direct singlet fission. J. Am. Chem. Soc. 134, 8597–8607 (2012).

    CAS  PubMed  Google Scholar 

  10. 10

    Johnson, J. C., Nozik, A. J. & Michl, J. High triplet yield from singlet fission in a thin film of 1,3-diphenylisobenzofuran. J. Am. Chem. Soc. 132, 16302–16303 (2010).

    CAS  PubMed  Google Scholar 

  11. 11

    Gradinaru, C. C. et al. An unusual pathway of excitation energy deactivation in carotenoids: singlet-to-triplet conversion on an ultrafast timescale in a photosynthetic antenna. Proc. Natl Acad. Sci. USA 98, 2364–2369 (2001).

    CAS  PubMed  Google Scholar 

  12. 12

    Zimmerman, P. M., Zhang, Z. & Musgrave, C. B. Singlet fission in pentacene through multi-exciton quantum states. Nature Chem. 2, 648–652 (2010).

    CAS  Google Scholar 

  13. 13

    Englman, R. & Jortner, J. The energy gap law for radiationless transitions in large molecules. Mol. Phys. 18, 145–164 (1970).

    CAS  Google Scholar 

  14. 14

    Greyson, E. C., Vura-Weis, J., Michl, J. & Ratner, M. A. Maximizing singlet fission in organic dimers: theoretical investigation of triplet yield in the regime of localized excitation and fast coherent electron transfer. J. Phys. Chem. B 114, 14168–14177 (2010).

    CAS  PubMed  Google Scholar 

  15. 15

    Beljonne, D., Yamagata, H., Brédas, J. L., Spano, F. C. & Olivier, Y. Charge-transfer excitations steer the Davydov splitting and mediate singlet exciton fission in pentacene. Phys. Rev. Lett. 110, 226402 (2013).

    CAS  PubMed  Google Scholar 

  16. 16

    Berkelbach, T. C., Hybertsen, M. S. & Reichman, D. R. Microscopic theory of singlet exciton fission. II. Application to pentacene dimers and the role of superexchange. J. Chem. Phys. 138, 114103 (2013).

    PubMed  Google Scholar 

  17. 17

    Johnson, J. C., Nozik, A. J. & Michl, J. The role of chromophore coupling in singlet fission. Acc. Chem. Res. 46, 1290–1299 (2013).

    CAS  PubMed  Google Scholar 

  18. 18

    Chan, W-L., Ligges, M. & Zhu, X. Y. The energy barrier in singlet fission can be overcome through coherent coupling and entropic gain. Nature Chem. 4, 840–845 (2012).

    CAS  Google Scholar 

  19. 19

    Wu, Q., Cheng, C. L. & Van Voorhis, T . Configuration interaction based on constrained density functional theory: a multireference method. J. Chem. Phys. 127, 164119 (2007).

    PubMed  Google Scholar 

  20. 20

    Feng, X., Luzanov, A. & Krylov, A. I. Fission of entangled spins: an electronic structure perspective. J. Phys. Chem. Lett. 4, 3845–3852 (2013).

    CAS  Google Scholar 

  21. 21

    Yost, S. R., Hontz, E., Yeganeh, S. & Van Voorhis, T. Triplet versus singlet energy transfer in organic semiconductors: the tortoise and the hare. J. Phys. Chem. C 116, 17369–17377 (2012).

    CAS  Google Scholar 

  22. 22

    Zimmerman, P. M., Bell, F., Casanova, D. & Head-Gordon, M. Mechanism for singlet fission in pentacene and tetracene: from single exciton to two triplets. J. Am. Chem. Soc. 133, 19944–19952 (2011).

    CAS  PubMed  Google Scholar 

  23. 23

    Berkelbach, T. C., Hybertsen, M. S. & Reichman, D. R. Microscopic theory of singlet exciton fission. I. General formulation. J. Chem. Phys. 138, 114102 (2013).

    PubMed  Google Scholar 

  24. 24

    Casanova, D. Electronic structure study of singlet fission in tetracene derivatives. J. Chem. Theory Comput. ASAP 10, 324–334 (2014).

    CAS  Google Scholar 

  25. 25

    Renaud, N., Sherratt, P. A. & Ratner, M. A. Mapping the relation between stacking geometries and singlet fission yield in a class of organic crystals. J. Phys. Chem. Lett. 4, 1065–1069 (2013).

    CAS  PubMed  Google Scholar 

  26. 26

    Dreuw, A. & Head-Gordon, M. Single-reference ab initio methods for the calculation of excited states of large molecules. Chem. Rev. 105, 4009–4037 (2005).

    CAS  PubMed  Google Scholar 

  27. 27

    Kaduk, B., Kowalczyk, T. & Van Voorhis, T . Constrained density functional theory. Chem. Rev. 112, 321–370 (2011).

    Google Scholar 

  28. 28

    Yamagata, H. et al. The nature of singlet excitons in oligoacene molecular crystals. J. Chem. Phys. 134, 204703 (2011).

    CAS  PubMed  Google Scholar 

  29. 29

    Tiago, M. L., Northrup, J. E. & Louie, S. G. Ab initio calculation of the electronic and optical properties of solid pentacene. Phys. Rev. B 67, 115212 (2003).

    Google Scholar 

  30. 30

    Sharifzadeh, S., Darancet, P., Kronik, L. & Neaton, J. B. Low-energy charge-transfer excitons in organic solids from first-principles: the case of pentacene. J. Phys. Chem. Lett. 4, 2197–2201 (2013).

    CAS  Google Scholar 

  31. 31

    Jortner, J. & Bixon, M. Intramolecular vibrational excitations accompanying solvent-controlled electron transfer reactions. J. Chem. Phys. 88, 167–170 (1988).

    CAS  Google Scholar 

  32. 32

    Sparpaglione, M. & Mukamel, S. Adiabatic vs. nonadiabatic electron transfer and longitudinal solvent dielectric relaxation: beyond the Debye model. J. Phys. Chem. 91, 3938–3943 (1987).

    CAS  Google Scholar 

  33. 33

    Marcus, R. On the theory of oxidation—reduction reactions involving electron transfer. I. J. Chem. Phys. 24, 966–978 (1956).

    CAS  Google Scholar 

  34. 34

    Piland, G. B., Burdett, J. J., Kurunthu, D. & Bardeen, C. J. Magnetic field effects on singlet fission and fluorescence decay dynamics in amorphous rubrene. J. Phys. Chem. C 117, 1224–1236 (2012).

    Google Scholar 

  35. 35

    Thorsmølle, V. K. et al. Morphology effectively controls singlet–triplet exciton relaxation and charge transport in organic semiconductors. Phys. Rev. Lett. 102, 017401 (2009).

    PubMed  Google Scholar 

  36. 36

    Burdett, J. J. & Bardeen, C. J. The dynamics of singlet fission in crystalline tetracene and covalent analogs. Acc. Chem. Res. 46, 1312–1320 (2013).

    CAS  PubMed  Google Scholar 

  37. 37

    Anthony, J. E., Brooks, J. S., Eaton, D. L. & Parkin, S. R. Functionalized pentacene: improved electronic properties from control of solid-state order. J. Am. Chem. Soc. 123, 9482–9483 (2001).

    CAS  PubMed  Google Scholar 

  38. 38

    Miao, Q. et al. Organization of acenes with a cruciform assembly motif. J. Am. Chem. Soc. 128, 1340–1345 (2006).

    CAS  PubMed  Google Scholar 

  39. 39

    Purushothaman, B., Parkin, S. R. & Anthony, J. E. Synthesis and stability of soluble hexacenes. Org. Lett. 12, 2060–2063 (2010).

    CAS  PubMed  Google Scholar 

  40. 40

    Bulgarovskaya, I., Vozzhennikov, V. & Aleksandrov, S. V. Belsky in Latv. PSR Zinat. Akad. Vestis Fiz. Teh. Zinat. Ser 4, 53 (1983).

    Google Scholar 

  41. 41

    Holmes, D., Kumaraswamy, S., Matzger, A. J. & Vollhardt, K. P. C. On the nature of nonplanarity in the [N]phenylenes. Chem. Eur. J. 5, 3399–3412 (1999).

    CAS  Google Scholar 

  42. 42

    Ruiz, R. et al. Structure of pentacene thin films. Appl. Phys. Lett. 85, 4926–4928 (2004).

    CAS  Google Scholar 

  43. 43

    Manzoni, C., Polli, D. & Cerullo, G. Two-color pump–probe system broadly tunable over the visible and the near infrared with sub-30 fs temporal resolution. Rev. Sci. Instrum. 77, 023103 (2006).

    Google Scholar 

  44. 44

    Wu, Q. & Van Voorhis, T. Direct calculation of electron transfer parameters through constrained density functional theory. J. Phys. Chem. A 110, 9212–9218 (2006).

    CAS  PubMed  Google Scholar 

  45. 45

    Woodcock, H. L. et al. Interfacing Q-Chem and CHARMM to perform QM/MM reaction path calculations. J. Comput. Chem. 28, 1485–1502 (2007).

    CAS  PubMed  Google Scholar 

  46. 46

    Nelsen, S. F., Blackstock, S. C. & Kim, Y. Estimation of inner shell Marcus terms for amino nitrogen compounds by molecular orbital calculations. J. Am. Chem. Soc. 109, 677–682 (1987).

    CAS  Google Scholar 

  47. 47

    Peumans, P., Yakimov, A. & Forrest, S. R. Small molecular weight organic thin-film photodetectors and solar cells. J. Appl. Phys. 93, 3693–3723 (2003).

    CAS  Google Scholar 

  48. 48

    Nitsche, R. & Fritz, T. Determination of model-free Kramers–Kronig consistent optical constants of thin absorbing films from just one spectral measurement: application to organic semiconductors. Phys. Rev. B 70, 195432 (2004).

    Google Scholar 

Download references

Acknowledgements

This work was supported as part of the Center for Excitonics, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences (award no. DE-SC0001088, MIT). The measurements on pentacene, TIPS-P and DTP were supported by the Engineering and Physical Sciences Research Council. A.R. thanks Corpus Christi College, Cambridge, for a research fellowship. Research was carried out in part at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the US Department of Energy, Office of Basic Energy Sciences (contract no. DE-AC02-98CH10886). The authors thank E. Hontz for discussions, C. Hanson for assistance with spectroscopy and B. Fernandez, T. L. Andrew and L. Liufor help with sample preparation and crystallization.

Author information

Affiliations

Authors

Contributions

T.V.V., M.A.B., J.Y., M.W.B.W. and S.R.Y. designed the experiment and co-wrote the paper. S.R.Y. and D.P.M. performed the density functional theory calculations. J.L., M.W.B.W., A.R., K.J. and M.Y.S. performed the spectroscopy. R.R.P. contributed material synthesis. T.W., N.J.T. and D.N.C. characterized the solar cells. All authors discussed the results and commented on the manuscript.

Corresponding authors

Correspondence to Richard H. Friend or Marc A. Baldo or Troy Van Voorhis.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary information (PDF 1219 kb)

Supplementary information

Crystallographic data for compound DBP (CIF 20 kb)

Supplementary information

Crystallographic data for compound DBTP (CIF 16 kb)

Supplementary information

Crystallographic data for compound DTT (CIF 17 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Yost, S., Lee, J., Wilson, M. et al. A transferable model for singlet-fission kinetics. Nature Chem 6, 492–497 (2014). https://doi.org/10.1038/nchem.1945

Download citation

Further reading

Search

Sign up for the Nature Briefing newsletter for a daily update on COVID-19 science.
Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing