Real-time observation of multiexcitonic states in ultrafast singlet fission using coherent 2D electronic spectroscopy
Author(s)
Type
Journal Article
Abstract
Singlet fission is the spin-allowed conversion of a spin-singlet exciton into a pair of spin-triplet excitons residing on neighbouring molecules. To rationalize this phenomenon, a multiexcitonic spin-zero triplet-pair state has been hypothesized as an intermediate in singlet fission. However, the nature of the intermediate states and the underlying mechanism of ultrafast fission have not been elucidated experimentally. Here, we study a series of pentacene derivatives using ultrafast two-dimensional electronic spectroscopy and unravel the origin of the states involved in fission. Our data reveal the crucial role of vibrational degrees of freedom coupled to electronic excitations that facilitate the mixing of multiexcitonic states with singlet excitons. The resulting manifold of vibronic states drives sub-100 fs fission with unity efficiency. Our results provide a framework for understanding singlet fission and show how the formation of vibronic manifolds with a high density of states facilitates fast and efficient electronic processes in molecular systems.
Date Issued
2016-01
Date Acceptance
2015-09-08
Citation
Nature Chemistry, 2016, 8, pp.16-23
ISSN
1755-4330
Publisher
Nature Publishing Group
Start Page
16
End Page
23
Journal / Book Title
Nature Chemistry
Volume
8
Identifier
https://www.nature.com/articles/nchem.2371
Subjects
Organic Chemistry
03 Chemical Sciences
Publication Status
Published
Date Publish Online
2015-10-26