Molecular rotational conformation controls the rate of singlet fission and triplet decay in pentacene dimers
Artikel i vetenskaplig tidskrift, 2022

Three pentacene dimers have been synthesized to investigate the effect of molecular rotation and rotational conformations on singlet fission (SF). In all three dimers, the pentacene units are linked by a 1,4-diethynylphenylene spacer that provides almost unimpeded rotational freedom between the pentacene- and phenylene-subunits in the parent dimer. Substituents on the phenylene spacer add varying degrees of steric hindrance that restricts both the rotation and the equilibrium distribution of different conformers; the less restricted conformers exhibit faster SF and more rapid subsequent triplet-pair recombination. Furthermore, the rotational conformers have small shifts in their absorption spectra and this feature has been used to selectively excite different conformers and study the resulting SF. Femtosecond transient absorption studies at 100 K reveal that the same dimer can have orders of magnitude faster SF in a strongly coupled conformer compared to a more weakly coupled one. Measurements in polystyrene further show that the SF rate is nearly independent of viscosity whereas the triplet pair lifetime is considerably longer in a high viscosity medium. The results provide insight into design criteria for maintaining high initial SF rate while suppressing triplet recombination in intramolecular singlet fission.


Rasmus Ringström

Chalmers, Kemi och kemiteknik, Kemi och biokemi

Fredrik Edhborg

Chalmers, Kemi och kemiteknik, Kemi och biokemi

Zachary W. Schroeder

University of Alberta

Lan Chen

University of Alberta

Michael J. Ferguson

University of Alberta

Rik R. Tykwinski

University of Alberta

Bo Albinsson

Chalmers, Kemi och kemiteknik, Kemi och biokemi

Chemical Science

2041-6520 (ISSN) 2041-6539 (eISSN)

Vol. In Press

Uppkonvertering av fotonenergier i fastfas: Nya material för att bryta Shockley-Queisser gränsen

Energimyndigheten (46526-1), 2019-01-01 -- 2023-12-31.


Atom- och molekylfysik och optik


Organisk kemi



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