Triplet Transfer Mediates Triplet Pair Separation during Singlet Fission in 6,13‐Bis(triisopropylsilylethynyl)‐Pentacene |
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| Authors: | Christopher Grieco Grayson S. Doucette Jason M. Munro Eric R. Kennehan Youngmin Lee Adam Rimshaw Marcia M. Payne Nichole Wonderling John E. Anthony Ismaila Dabo Enrique D. Gomez John B. Asbury |
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| Affiliation: | 1. Department of Chemistry, The Pennsylvania State University, State College, PA, USA;2. Intercollege Materials Science and Engineering Program, The Pennsylvania State University, Universtiy Park, PA, USA;3. Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA;4. Materials Research Institute, The Pennsylvania State University, University Park, PA, USA;5. Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA;6. Department of Chemistry, University of Kentucky, Lexington, KY, USA |
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| Abstract: | Triplet population dynamics of solution cast films of isolated polymorphs of 6,13‐bis(triisopropylsilylethynyl) pentacene (TIPS‐Pn) provide quantitative experimental evidence that triplet excitation energy transfer is the dominant mechanism for correlated triplet pair (CTP) separation during singlet fission. Variations in CTP separation rates are compared for polymorphs of TIPS‐Pn with their triplet diffusion characteristics that are controlled by their crystal structures. Since triplet energy transfer is a spin‐forbidden process requiring direct wavefunction overlap, simple calculations of electron and hole transfer integrals are used to predict how molecular packing arrangements would influence triplet transfer rates. The transfer integrals reveal how differences in the packing arrangements affect electronic interactions between pairs of TIPS‐Pn molecules, which are correlated with the relative rates of CTP separation in the polymorphs. These findings suggest that relatively simple computations in conjunction with measurements of molecular packing structures may be used as screening tools to predict a priori whether new types of singlet fission sensitizers have the potential to undergo fast separation of CTP states to form multiplied triplets. |
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| Keywords: | molecular electronics singlet fission structure– property relationships triplet transfer |
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