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Spin density encodes intramolecular singlet exciton fission in pentacene dimers

Krishnapriya, KC and Roy, Palas and Puttaraju, Boregowda and Salzner, Ulrike and Musser, Andrew J and Jain, Manish and Dasgupta, Jyotishman and Patil, Satish (2019) Spin density encodes intramolecular singlet exciton fission in pentacene dimers. In: NATURE COMMUNICATIONS, 10 .

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Official URL: https://doi.org/10.1038/s41467-018-07736-3

Abstract

The formation of two triplet excitons at the cost of one photon via singlet exciton fission in organic semiconductors can potentially enhance the photocurrent in photovoltaic devices. However, the role of spin density distribution in driving this photophysical process has been unclear until now. Here we present the significance of electronic spin density distribution in facilitating efficient intramolecular singlet exciton fission (iSEF) in pi-bridged pentacene dimers. We synthetically modulate the spin density distribution in a series of pentacene dimers using phenyl-, thienyl- and selenyl-flanked diketopyrrolopyrrole (DPP) derivatives as pi-bridges. Using femtosecond transient absorption spectroscopy, we find that efficient iSEF is only observed for the phenyl-derivative in similar to 2.4 ps while absent in the other two dimers. Electronic structure calculations reveal that phenyl-DPP bridge localizes alpha- and beta-spin densities on distinct terminal pentacenes. Upon photoexcitation, a spin exchange mechanism enables iSEF from a singlet state which has an innate triplet pair character.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to NATURE PUBLISHING GROUP
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Division of Physical & Mathematical Sciences > Physics
Depositing User: Id for Latest eprints
Date Deposited: 29 Jan 2019 06:30
Last Modified: 29 Jan 2019 06:30
URI: http://eprints.iisc.ac.in/id/eprint/61527

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