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A design strategy for intramolecular singlet fission mediated by charge-transfer states in donor–acceptor organic materials

Nature Materials volume 14, pages 426–433 (2015)Cite this article

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Abstract

The ability to advance our understanding of multiple exciton generation (MEG) in organic materials has been restricted by the limited number of materials capable of singlet fission. A particular challenge is the development of materials that undergo efficient intramolecular fission, such that local order and strong nearest-neighbour coupling is no longer a design constraint. Here we address these challenges by demonstrating that strong intrachain donor–acceptor interactions are a key design feature for organic materials capable of intramolecular singlet fission. By conjugating strong-acceptor and strong-donor building blocks, small molecules and polymers with charge-transfer states that mediate population transfer between singlet excitons and triplet excitons are synthesized. Using transient optical techniques, we show that triplet populations can be generated with yields up to 170%. These guidelines are widely applicable to similar families of polymers and small molecules, and can lead to the development of new fission-capable materials with tunable electronic structure, as well as a deeper fundamental understanding of MEG.

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Figure 1: Design template for singlet-fission-capable molecular and polymeric materials.
Figure 2: Structures and absorption spectra of singlet-fission-exhibiting and control materials.
Figure 3: Transient absorption data and global analysis for PBTDO1.
Figure 4: TA and PRTT for all TDO-containing materials.
Figure 5: Bleach recovery in transient absorption measurements.

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Acknowledgements

This project was funded through the Center for Re-Defining Photovoltaic Efficiency Through Molecular-Scale Control, an Energy Frontier Research Center funded by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences under Award DE-SC0001085. L.M.C. thanks 3M Non-Tenured Faculty Award and the NSF CAREER (DMR-1351293) for funding the synthesis of the small molecules and control materials. X-Y.Z. acknowledges support by the National Science Foundation, DMR-1321405. We wish to thank M. Vengris (Vilnius University) for graciously providing his global analysis software package for our use. We also thank S. Wei for a sample of PFTDO1 and J. Hoy for additional cyclic voltammetry measurements. 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, under Contract No. DE-AC02-98CH10886, and in the Chemistry Department, Brookhaven National Laboratory through Grant #DE-AC02-98-CH10886, which also supports the LEAF Facility of the BNL Accelerator Center for Energy Research.

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  1. Erik Busby and Jianlong Xia: These authors contributed equally to this work.

Authors and Affiliations

  1. Energy Frontier Research Center, Columbia University, New York, New York 10027, USA

    Erik Busby, Jianlong Xia, X-Y. Zhu & Luis M. Campos

  2. Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA

    Erik Busby, Qin Wu & Matthew Y. Sfeir

  3. Department of Chemistry, Columbia University, New York, New York 10027, USA

    Jianlong Xia, Jonathan Z. Low, Rui Song, X-Y. Zhu & Luis M. Campos

  4. Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, USA

    John R. Miller

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Contributions

E.B., J.X., L.M.C. and M.Y.S. conceived the experiments. L.M.C. and M.Y.S. supervised the project. J.X., J.Z.L. and R.S. synthesized and characterized the materials. E.B. performed transient absorption data acquisition and analysis. Q.W. provided theoretical support. J.R.M. and E.B. performed pulse radiolysis experiments. E.B., L.M.C. and M.Y.S. wrote the manuscript with input from all authors.

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Correspondence to Luis M. Campos or Matthew Y. Sfeir.

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Busby, E., Xia, J., Wu, Q. et al. A design strategy for intramolecular singlet fission mediated by charge-transfer states in donor–acceptor organic materials. Nature Mater 14, 426–433 (2015). https://doi.org/10.1038/nmat4175

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