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Free-triplet generation with improved efficiency in tetracene oligomers through spatially separated triplet pair states

Abstract

Singlet fission (SF) can potentially boost the efficiency of solar energy conversion by converting a singlet exciton (S1) into two free triplets (T1 + T1) through an intermediate state of a correlated triplet pair (TT). Although efficient TT generation has been recently realized in many intramolecular SF materials, their potential applications have been hindered by the poor efficiency of TT dissociation. Here we demonstrate that this can be overcome by employing a spatially separated 1(T…T) state with weak intertriplet coupling in tetracene oligomers with three or more chromophores. By using transient magneto-optical spectroscopic methods, we show that free-triplet generation can be markedly enhanced through the SF pathway that involves the spatially separated 1(T…T) state rather than the pathway mediated by the spatially adjacent TT state, leading to a marked improvement in free-triplet generation with an efficiency increase from 21% for the dimer to 85% (124%) for the trimer (tetramer).

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Fig. 1: Scenarios of the iSF processes involving different intermediate states.
Fig. 2: TA spectra revealing the iSF dynamics in the tetracene oligomers.
Fig. 3: MFE on the iSF dynamics in the tetracene oligomers.
Fig. 4: MFE on free-triplet generation in the tetracene oligomers.
Fig. 5: Solvent polarity effect on the iSF dynamics in the tetracene trimer.

Data availability

The data shown in the paper are available from the figshare repository at https://doi.org/10.6084/m9.figshare.13669820.

References

  1. 1.

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

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  2. 2.

    Smith, M. B. & Michl, J. Recent advances in singlet fission. Annu. Rev. Phys. Chem. 64, 361–386 (2013).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  3. 3.

    Casanova, D. Theoretical modeling of singlet fission. Chem. Rev. 118, 7164–7207 (2018).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  4. 4.

    Rao, A. & Friend, R. H. Harnessing singlet exciton fission to break the Shockley–Queisser limit. Nat. Rev. Mater. 2, 17063 (2017).

    CAS  Article  Google Scholar 

  5. 5.

    Miyata, K., Conrad-Burton, F. S., Geyer, F. L. & Zhu, X.-Y. Triplet pair states in singlet fission. Chem. Rev. 119, 4261–4292 (2019).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  6. 6.

    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  Article  PubMed Central  Google Scholar 

  7. 7.

    Tayebjee, M. J. Y., Gray-Weale, A. A. & Schmidt, T. W. Thermodynamic limit of exciton fission solar cell efficiency. J. Phys. Chem. Lett. 3, 2749–2754 (2012).

    CAS  Article  Google Scholar 

  8. 8.

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

    Article  CAS  Google Scholar 

  9. 9.

    Müller, A. M. et al. Exciton fission and fusion in bis(tetracene) molecules with different covalent linker structures. J. Am. Chem. Soc. 129, 14240–14250 (2007).

    PubMed  Article  CAS  PubMed Central  Google Scholar 

  10. 10.

    Zirzlmeier, J. et al. Singlet fission in pentacene dimers. Proc. Natl Acad. Sci. USA 112, 5325–5330 (2015).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  11. 11.

    Sanders, S. N. et al. Quantitative intramolecular singlet fission in bipentacenes. J. Am. Chem. Soc. 137, 8965–8972 (2015).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  12. 12.

    Lukman, S. et al. Tuneable singlet exciton fission and triplet–triplet annihilation in an orthogonal pentacene dimer. Adv. Funct. Mater. 25, 5452–5461 (2015).

    CAS  Article  Google Scholar 

  13. 13.

    Lukman, S. et al. Tuning the role of charge-transfer states in intramolecular singlet exciton fission through side-group engineering. Nat. Commun. 7, 13622 (2016).

    CAS  PubMed  PubMed Central  Article  Google Scholar 

  14. 14.

    Korovina, N. V. et al. Singlet fission in a covalently linked cofacial alkynyltetracene dimer. J. Am. Chem. Soc. 138, 617–627 (2016).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  15. 15.

    Basel, B. S. et al. Unified model for singlet fission within a non-conjugated covalent pentacene dimer. Nat. Commun. 8, 15171 (2017).

    CAS  PubMed  PubMed Central  Article  Google Scholar 

  16. 16.

    Korovina, N. V. et al. Linker-dependent singlet fission in tetracene dimers. J. Am. Chem. Soc. 140, 10179–10190 (2018).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  17. 17.

    Margulies, E. A. et al. Enabling singlet fission by controlling intramolecular charge transfer in π-stacked covalent terrylenediimide dimers. Nat. Chem. 8, 1120–1125 (2016).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  18. 18.

    Sung, J. et al. Direct observation of excimer-mediated intramolecular electron transfer in a cofacially-stacked perylene bisimide pair. J. Am. Chem. Soc. 138, 9029–9032 (2016).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  19. 19.

    Kumarasamy, E. et al. Tuning singlet fission in π-bridge-π chromophores. J. Am. Chem. Soc. 139, 12488–12494 (2017).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  20. 20.

    Busby, E. et al. A design strategy for intramolecular singlet fission mediated by charge-transfer states in donor–acceptor organic materials. Nat. Mater. 14, 426–433 (2015).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  21. 21.

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

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  22. 22.

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

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  23. 23.

    Pace, N. A. et al. Controlling long-lived triplet generation from intramolecular singlet fission in the solid state. J. Phys. Chem. Lett. 8, 6086–6091 (2017).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  24. 24.

    Schrauben, J. N. et al. Excitation localization/delocalization isomerism in a strongly coupled covalent dimer of 1,3-diphenylisobenzofuran. J. Phys. Chem. A 120, 3473–3483 (2016).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  25. 25.

    Wu, Y. et al. Intramolecular singlet fission in an antiaromatic polycyclic hydrocarbon. Angew. Chem. Int. Ed. 56, 9400–9404 (2017).

    CAS  Article  Google Scholar 

  26. 26.

    Wakasa, M. et al. What can be learned from magnetic field effects on singlet fission: role of exchange interaction in excited triplet pairs. J. Phys. Chem. C 119, 25840–25844 (2015).

    CAS  Article  Google Scholar 

  27. 27.

    Wan, Y. et al. Cooperative singlet and triplet exciton transport in tetracene crystals visualized by ultrafast microscopy. Nat. Chem. 7, 785–792 (2015).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  28. 28.

    Pensack, R. D. et al. Observation of two triplet-pair intermediates in singlet exciton fission. J. Phys. Chem. Lett. 7, 2370–2375 (2016).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  29. 29.

    Breen, I. et al. Triplet separation drives singlet fission after femtosecond correlated triplet pair production in rubrene. J. Am. Chem. Soc. 139, 11745–11751 (2017).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  30. 30.

    Pun, A. B. et al. Ultrafast intramolecular singlet fission to persistent multiexcitons by molecular design. Nat. Chem. 11, 821–828 (2019).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  31. 31.

    Bayliss, S. L. et al. Spin signatures of exchange-coupled triplet pairs formed by singlet fission. Phys. Rev. B 94, 045204 (2016).

    Article  Google Scholar 

  32. 32.

    Bayliss, S. L. et al. Site-selective measurement of coupled spin pairs in an organic semiconductor. Proc. Natl Acad. Sci. USA 115, 5077–5082 (2018).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  33. 33.

    Liu, H. et al. A covalently linked tetracene trimer: synthesis and singlet exciton fission property. Org. Lett. 19, 580–583 (2017).

    PubMed  Article  CAS  PubMed Central  Google Scholar 

  34. 34.

    Wang, X. et al. Intramolecular singlet fission in a face-to-face stacked tetracene trimer. Phys. Chem. Chem. Phys. 20, 6330–6336 (2018).

    CAS  PubMed  Article  Google Scholar 

  35. 35.

    Pensack, R. D. et al. Exciton delocalization drives rapid singlet fission in nanoparticles of acene derivatives. J. Am. Chem. Soc. 137, 6790–6803 (2015).

    CAS  PubMed  Article  Google Scholar 

  36. 36.

    Pun, A. B. et al. Triplet harvesting from intramolecular singlet fission in polytetracene. Adv. Mater. 29, 1701416 (2017).

    Article  CAS  Google Scholar 

  37. 37.

    Johnson, J. C. & Merrifield, R. E. Effects of magentic fields on the mutual annihilation of triplet excitons in anthracene crystals. Phys. Rev. B 1, 896–902 (1970).

    Article  Google Scholar 

  38. 38.

    Burdett, J. J., Piland, G. B. & Bardeen, C. J. Magnetic field effects and the role of spin states in singlet fission. Chem. Phys. Lett. 585, 1–10 (2013).

    CAS  Article  Google Scholar 

  39. 39.

    Johnson, R. C., Merrifield, R. E., Avakian, P. & Flippen, R. B. Effects of magnetic fields on mutual annihilation of triplet excitons in molecular crystals. Phys. Rev. Lett. 19, 285–287 (1967).

    CAS  Article  Google Scholar 

  40. 40.

    Bayliss, S. L. et al. Geminate and nongeminate recombination of triplet excitons formed by singlet fission. Phys. Rev. Lett. 112, 238701 (2014).

    PubMed  Article  CAS  PubMed Central  Google Scholar 

  41. 41.

    Wang, R. et al. Magnetic dipolar interaction between correlated triplets created by singlet fission in tetracene crystals. Nat. Commun. 6, 8602 (2015).

    CAS  PubMed  PubMed Central  Article  Google Scholar 

  42. 42.

    Yago, T., Ishikawa, K., Katoh, R. & Wakasa, M. Magnetic field effects on triplet pair generated by singlet fission in an organic crystal: application of radical pair model to triplet pair. J. Phys. Chem. C 120, 27858–27870 (2016).

    CAS  Article  Google Scholar 

  43. 43.

    Roberts, S. T. et al. Efficient singlet fission discovered in a disordered acene film. J. Am. Chem. Soc. 134, 6388–6400 (2012).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  44. 44.

    Devir-Wolfman, A. H. et al. Short-lived charge-transfer excitons in organic photovoltaic cells studied by high-field magneto-photocurrent. Nat. Commun. 5, 4529 (2014).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  45. 45.

    Chen, M. et al. Quintet-triplet mixing determines the fate of the multiexciton state produced by singlet fission in a terrylenediimide dimer at room temperature. Proc. Natl Acad. Sci. USA 116, 8178–8183 (2019).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  46. 46.

    Weiss, L. R. et al. Strongly exchange-coupled triplet pairs in an organic semiconductor. Nat. Phys. 13, 176–181 (2016).

    Article  CAS  Google Scholar 

  47. 47.

    Tayebjee, M. J. Y. et al. Quintet multiexciton dynamics in singlet fission. Nat. Phys. 13, 182–188 (2016).

    Article  CAS  Google Scholar 

  48. 48.

    Stern, H. L. et al. Vibronically coherent ultrafast triplet-pair formation and subsequent thermally activated dissociation control efficient endothermic singlet fission. Nat. Chem. 9, 1205–1212 (2017).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  49. 49.

    Miyata, K. et al. Coherent singlet fission activated by symmetry breaking. Nat. Chem. 9, 983–989 (2017).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  50. 50.

    Dover, C. B. et al. Endothermic singlet fission is hindered by excimer formation. Nat. Chem. 10, 305–310 (2018).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  51. 51.

    Bakulin, A. A. et al. Real-time observation of multiexcitonic states in ultrafast singlet fission using coherent 2D electronic spectroscopy. Nat. Chem. 8, 16–23 (2016).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  52. 52.

    Yost, S. R. et al. A transferable model for singlet-fission kinetics. Nat. Chem. 6, 492–497 (2014).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  53. 53.

    Le, A. K. et al. Singlet fission involves an interplay between energetic driving force and electronic coupling in perylenediimide films. J. Am. Chem. Soc. 140, 814–826 (2018).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  54. 54.

    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, 114102 (2013).

    PubMed  Article  CAS  PubMed Central  Google Scholar 

  55. 55.

    Ambrosio, F. & Troisi, A. Singlet fission in linear chains of molecules. J. Chem. Phys. 141, 204703 (2014).

    PubMed  Article  CAS  PubMed Central  Google Scholar 

  56. 56.

    Alvertis, A. M. et al. Switching between coherent and incoherent singlet fission via solvent-induced symmetry breaking. J. Am. Chem. Soc. 141, 17558–17570 (2019).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  57. 57.

    Tamura, H. et al. First-principles quantum dynamics of singlet fission: coherent versus thermally activated mechanisms governed by molecular pi stacking. Phys. Rev. Lett. 115, 107401 (2015).

    PubMed  Article  CAS  PubMed Central  Google Scholar 

  58. 58.

    Xie, X. et al. Exciton–phonon interaction model for singlet fission in prototypical molecular crystals. J. Chem. Theory Comput. 15, 3721–3729 (2019).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  59. 59.

    Korovina, N. V., Chang, C. H. & Johnson, J. C. Spatial separation of triplet excitons drives endothermic singlet fission. Nat. Chem. 12, 391–398 (2020).

    CAS  PubMed  Article  PubMed Central  Google Scholar 

  60. 60.

    Trinh, M. T. et al. Distinct properties of the triplet pair state from singlet fission. Sci. Adv. 3, e1700241 (2017).

    PubMed  PubMed Central  Article  CAS  Google Scholar 

  61. 61.

    Wang, R. et al. Ultrafast hole transfer mediated by polaron pairs in all-polymer photovaltaic blends. Nat. Commun. 10, 398 (2019).

    CAS  PubMed  PubMed Central  Article  Google Scholar 

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Acknowledgements

This work was supported by the National Key R&D Program of China (2017YFA0303703 and 2018YFA0209100), the National Natural Science Foundation of China (21922302, 21873047, 91850105, 91833305, 21722302 and 21673109), Jiangsu Provincial Funds for Distinguished Young Scientists (BK20160019), the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) and the Fundamental Research Funds for the Central Universities (0204-14380126). C.Z. acknowledges financial support from the Tang Scholar programme. We thank X. Wu for technical assistance. We are grateful to the High-Performance Computing Center of Nanjing University for performing the numerical calculations in this paper on its blade cluster system.

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C.Z. and M.X. initiated the project. Z.W., R.W. and L.C. performed the optical experiments. H.L. and X.L. synthesized the molecules. C.Z., Z.W. and X.W. analysed the data. Y.X., H.M., X.X., W.F. and Y.Y. performed the quantum chemical calculations. C.Z., Z.W. and M.X. co-wrote the manuscript with help from all the other authors.

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Correspondence to Chunfeng Zhang or Haibo Ma or Xiyou Li or Min Xiao.

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Peer review information Nature Chemistry thanks T. Schmidt and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Figs. 1–25, discussion and Tables 1–10.

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Wang, Z., Liu, H., Xie, X. et al. Free-triplet generation with improved efficiency in tetracene oligomers through spatially separated triplet pair states. Nat. Chem. (2021). https://doi.org/10.1038/s41557-021-00665-7

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