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Professor Jyotishman Dasgupta, Tata Institute of Fundamental Research, India
Tuesday, October 26, 2021, 11:00am - 12:00pm

 Jyotishman DasguptaTracking Correlated Triplet-Triplet Pairs in Singlet Exciton Fission

Singlet fission1-2 (SF) is a process by which an excited molecular chromophore in its singlet state shares its excitation energy with an unexcited proximal neighbour leading to formation of two triplet excitons through a spin-allowed process. Due to the high singlet-to-triplet conversion quantum efficiencies up to 200%, SF chromophores have potential application in boosting solar cell efficiencies beyond the Shockley-Queisser limit3. However molecular triplet excitons produced through SF usually have shorter triplet lifetimes due to exciton-exciton recombination and relaxation pathways, thereby resulting in complex device architectures for SF-boosted solar cells. In order to elucidate the fundamental mechanism of SF and the triplet-triplet recombination pathways it is essential to understand the intrinsic electronic nature of the intermediate correlated T-T pair states delocalized over the two chromophores. In this talk, I will demonstrate that coupling the chromophores in optimal morphologies/geometries allow for efficient SF as well as an unequivocal spectroscopic detection of the correlated T-T pair state.4 At the end, I will touch upon the significance of understanding the T-T pair state in enabling a testable structure-function relationship for next generation SF-boosted solar cells.

  1. Smith, M. B.; Michl, J., Singlet fission. Chemical reviews 2010, 110, 6891-6936.
  2. Smith, M. B.; Michl, J., Recent advances in singlet fission. Annual review of physical chemistry
    2013, 64, 361-386.
  3. Rao, A.; Friend, R. H., Harnessing singlet exciton fission to break the Shockley-Queisser limit. Nature reviews materials 2017, 2, 1-12.
  4. Krishnapriya, K.C.; Roy, P.; Puttaraju, B.; Salzner, U.; Musser, A. J.; Jain, M.; Dasgupta, J.; Patil, S.; “Spin density encodes intramolecular singlet exciton fission in pentacene dimers”, Nature Communications 2019, 10, 33.
  5. Kundu, A.; Dasgupta, J., Photogeneration of Long-Lived Triplet States through Singlet Fission in Lycopene H-Aggregates. J. Phys. Chem. Lett. 2021, 12, 5, 1468–1474.

Hosted by Professor Charles Dismukes

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