TY - JOUR
T1 - Vacancy control in acene blends links exothermic singlet fission to coherence
AU - Zeiser, Clemens
AU - Cruz, Chad
AU - Reichman, David R.
AU - Seitz, Michael
AU - Hagenlocher, Jan
AU - Chronister, Eric L.
AU - Bardeen, Christopher J.
AU - Tempelaar, Roel
AU - Broch, Katharina
N1 - Funding Information:
We thank Frank Schreiber for access to equipment, the Soleil Synchrotron and the Diamond Light Source for beamtime allocation, and Alina Vlad, Rupak Banerjee, Lisa Egenberger, and the staff of beamlines SixS (Soleil) and I07 (Diamond Light Source) for support during the synchrotron experiments. This work was supported by the National Science Foundation grant CHE-1800187 (C.J.B.) and NSF-CHE—1954791 (D.R.R.), and the German Research Foundation grant HI 1927/1-1 (J.H.).
Publisher Copyright:
© 2021, The Author(s).
PY - 2021/12/1
Y1 - 2021/12/1
N2 - The fission of singlet excitons into triplet pairs in organic materials holds great technological promise, but the rational application of this phenomenon is hampered by a lack of understanding of its complex photophysics. Here, we use the controlled introduction of vacancies by means of spacer molecules in tetracene and pentacene thin films as a tuning parameter complementing experimental observables to identify the operating principles of different singlet fission pathways. Time-resolved spectroscopic measurements in combination with microscopic modelling enables us to demonstrate distinct scenarios, resulting from different singlet-to-triplet pair energy alignments. For pentacene, where fission is exothermic, coherent mixing between the photoexcited singlet and triplet-pair states is promoted by vibronic resonances, which drives the fission process with little sensitivity to the vacancy concentration. Such vibronic resonances do not occur for endothermic materials such as tetracene, for which we find fission to be fully incoherent; a process that is shown to slow down with increasing vacancy concentration.
AB - The fission of singlet excitons into triplet pairs in organic materials holds great technological promise, but the rational application of this phenomenon is hampered by a lack of understanding of its complex photophysics. Here, we use the controlled introduction of vacancies by means of spacer molecules in tetracene and pentacene thin films as a tuning parameter complementing experimental observables to identify the operating principles of different singlet fission pathways. Time-resolved spectroscopic measurements in combination with microscopic modelling enables us to demonstrate distinct scenarios, resulting from different singlet-to-triplet pair energy alignments. For pentacene, where fission is exothermic, coherent mixing between the photoexcited singlet and triplet-pair states is promoted by vibronic resonances, which drives the fission process with little sensitivity to the vacancy concentration. Such vibronic resonances do not occur for endothermic materials such as tetracene, for which we find fission to be fully incoherent; a process that is shown to slow down with increasing vacancy concentration.
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U2 - 10.1038/s41467-021-25395-9
DO - 10.1038/s41467-021-25395-9
M3 - Article
C2 - 34446726
AN - SCOPUS:85113691308
SN - 2041-1723
VL - 12
JO - Nature communications
JF - Nature communications
IS - 1
M1 - 5149
ER -