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Vacancy control in acene blends links exothermic singlet fission to coherence

DOI: 10.1038/s41467-021-25395-9 DOI Help

Authors: Clemens Zeiser (Universität Tübingen) , Chad Cruz (University of California at Riverside) , David R. Reichman (Columbia University) , Michael Seitz (University of Tübingen) , Jan Hagenlocher (University of Tübingen) , Eric L. Chronister (University of Nevada) , Christopher J. Bardeen (University of California at Riverside) , Roel Tempelaar (Columbia University; Northwestern University) , Katharina Broch (University of Tübingen)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Communications , VOL 12

State: Published (Approved)
Published: August 2021
Diamond Proposal Number(s): 21899

Open Access Open Access

Abstract: 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.

Journal Keywords: Excited states

Subject Areas: Materials, Physics

Instruments: I07-Surface & interface diffraction

Other Facilities: SixS at Soleil

Added On: 31/08/2021 10:24


Discipline Tags:

Surfaces Physics Materials Science interfaces and thin films

Technical Tags:

Diffraction X-ray Reflectivity (XRR)