High Yield Ultrafast Intramolecular Singlet Exciton Fission in a Quinoidal Bithiophene.
We report the process of singlet exciton fission with high-yield upon photoexcitation of a quinoidal thiophene molecule. Efficient ultrafast triplet photogeneration and its yield are determined by photoinduced triplet-triplet absorption, flash photolysis triplet lifetime measurements, as well as by femtosecond time-resolved transient absorption and fluorescence methods. These experiments show that optically excited quinoidal bithiophene molecule undergoes ultrafast formation of the triplet-like state with the lifetime ∼57 μs. CASPT2 and RAS-SF calculations have been performed to support the experimental findings. To date, high singlet fission rates have been reported for crystalline and polycrystalline materials, whereas for covalently linked dimers and small oligomers it was found to be relatively small. In this contribution, we show an unprecedented quantum yield of intramolecular singlet exciton fission of ∼180% for a quinoidal bithiophene system.
†Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.
Oleg
O
Varnavski
†Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.
Neranga
N
Abeyasinghe
‡Instituto de Ciencia Molecular, Universidad de Valencia, 46980 Paterna, Spain.
Juan
J
Aragó
‡Instituto de Ciencia Molecular, Universidad de Valencia, 46980 Paterna, Spain.
Juan J
JJ
Serrano-Pérez
‡Instituto de Ciencia Molecular, Universidad de Valencia, 46980 Paterna, Spain.
Enrique
E
Ortí
§Department of Physical Chemistry, University of Malaga, 29071 Malaga, Spain.
Juan T
JT
López Navarrete
∥Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan.
Kazuo
K
Takimiya
⊥IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain.|∇Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU), P.K. 1072, 20080 Donostia, Spain.|¶Donostia International Physics Center (DIPC), 20018 Donostia, Spain.
David
D
Casanova
§Department of Physical Chemistry, University of Malaga, 29071 Malaga, Spain.
Juan
J
Casado
†Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.
Theodore
T
Goodson
Intramolecular; Organic photovoltaics; Quinoidal Oligothiophenes; Singlet exciton fission; Ultrafast spectroscopy