Issue 5, 2018

Femtosecond stimulated Raman evidence for charge-transfer character in pentacene singlet fission

Abstract

Singlet fission is a spin-allowed process in which an excited singlet state evolves into two triplet states. We use femtosecond stimulated Raman spectroscopy, an ultrafast vibrational technique, to follow the molecular structural evolution during singlet fission in order to determine the mechanism of this process. In crystalline pentacene, we observe the formation of an intermediate characterized by pairs of excited state peaks that are red- and blue-shifted relative to the ground state features. We hypothesize that these features arise from the formation of cationic and anionic species due to partial transfer of electron density from one pentacene molecule to a neighboring molecule. These observations provide experimental evidence for the role of states with significant charge-transfer character which facilitate the singlet fission process in pentacene. Our work both provides new insight into the singlet fission mechanism in pentacene and demonstrates the utility of structurally-sensitive time-resolved spectroscopic techniques in monitoring ultrafast processes.

Graphical abstract: Femtosecond stimulated Raman evidence for charge-transfer character in pentacene singlet fission

Supplementary files

Article information

Article type
Edge Article
Submitted
10 Aug 2017
Accepted
12 Dec 2017
First published
20 Dec 2017
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2018,9, 1242-1250

Femtosecond stimulated Raman evidence for charge-transfer character in pentacene singlet fission

Stephanie M. Hart, W. R. Silva and R. R. Frontiera, Chem. Sci., 2018, 9, 1242 DOI: 10.1039/C7SC03496B

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