Abstract
Singlet fission and triplet–triplet annihilation represent two highly promising ways of increasing the efficiency of photovoltaic devices. Both processes are believed to be mediated by a biexcitonic triplet-pair state, 1(TT). Recently however, there has been debate over the role of 1(TT) in triplet–triplet annihilation. Here we use intensity-dependent, low-temperature photoluminescence measurements, combined with kinetic modelling, to show that distinct 1(TT) emission arises directly from triplet–triplet annihilation in high-quality pentacene single crystals and anthradithiophene (diF-TES-ADT) thin films. This work demonstrates that a real, emissive triplet-pair state acts as an intermediate in both singlet fission and triplet–triplet annihilation and that this is true for both endo- and exothermic singlet fission materials.
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Data availability
The datasets generated during and/or analysed during the current study are available in the University of Sheffield’s ORDA repository (hosted by figshare; https://doi.org/10.15131/shef.data.12943496). Source data are provided with this paper.
Code availability
The code used to perform the kinetic modelling shown in Figs. 4 and 6 is available at https://github.com/davidbossanyi/sfmodelling. The TRPL data processing was performed using an application available at https://github.com/fast-spectroscopy-sheffield/iCCD-kinetics. Additional code used in the data analysis is available from D.G.B. on request.
Change history
16 December 2020
A Correction to this paper has been published: https://doi.org/10.1038/s41557-020-00622-w
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Acknowledgements
D.G.B. and J.A.S. thank the EPSRC Centre for Doctoral Training in New and Sustainable Photovoltaics (EP/L01551X/1) for studentship support. J.Z. and M.M. acknowledge funding by the Deutsche Forschungsgemeinschaft via the Collaborative Research Center ‘N-Heteropolycycles as Functional Materials’ (SFB 1249, C06). J.D.S. thanks the Grantham Centre for Sustainable Futures for studentship support. J.E.A. and E.H. thank the US NSF (CHE-1609974) for support of material synthesis. J.C., A.J.M. and S.W. thank EPSRC for funding (EP/S002103/1 and EP/M025330/1). We thank EPSRC for a Capital Equipment award (EP/L022613/1 and EP/R042802/1), which provided the Lord Porter Laser Laboratory Facility used in this study. We further thank Xenocs for their ongoing support through the X-ray scattering user programme at the University of Sheffield and we thank the EPSRC for funding the purchase of this instrument. We thank R. Jayaprakash for assistance with the polarized absorption measurement. Finally, we thank P. Green and M.W.B. Wilson from the University of Toronto for providing us with inorganic semiconductor nanocrystals for triplet sensitization.
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J.C. conceived the project. D.G.B., A.J.M. and J.C. designed the experiments. D.G.B. made the diF-TES-ADT samples and performed all of the spectroscopic measurements, data analysis and kinetic modelling. S.W. performed the magnetic field-dependent measurements. M.M. fabricated and characterized the pentacene single crystals under the supervision of J.Z. J.A.S. and R.C.K. performed the GIWAXS and AFM measurements. J.D.S. and D.C. assisted with transient absorption measurements. E.H. and J.E.A. provided the diF-TES-ADT. D.G.B. and J.C. wrote the manuscript with input from A.J.M.
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Bossanyi, D.G., Matthiesen, M., Wang, S. et al. Emissive spin-0 triplet-pairs are a direct product of triplet–triplet annihilation in pentacene single crystals and anthradithiophene films. Nat. Chem. 13, 163–171 (2021). https://doi.org/10.1038/s41557-020-00593-y
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