Singlet Fission in Rubrene Derivatives: Impact of Molecular Packing

Christopher Sutton, Naga Rajesh Tummala, David Beljonne, Jean Luc Bredas

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

We examine the properties of six recently synthesized rubrene derivatives (with substitutions on the side phenyl rings) that show vastly different crystal structures. In order to understand how packing in the solid state affects the excited states and couplings relevant for singlet fission, the lowest excited singlet (S1), triplet (T1), multiexciton (TT), and charge-transfer (CT) states of the rubrene derivatives are compared to known singlet fission materials [tetracene, pentacene, 5,12-diphenyltetracene (DPT), and rubrene itself]. While a small difference of less than 0.2 eV is calculated for the S1 and TT energies, a range of 0.50 to 1.2 eV in the CT energies and nearly 3 orders of magnitude in the electronic couplings are computed for the rubrene derivatives in their crystalline packings, which strongly affects the role of the CT state in facilitating SF. To rationalize experimental observations of singlet fission occurring in amorphous phases of rubrene, DPT, and tetracene, we use molecular dynamics (MD) simulations to assess the impact of molecular packing and orientations and to gain a better understanding of the parameters that control singlet fission in amorphous films compared to crystalline packings. The MD simulations point to a crystalline-like packing for thin films of tetracene; on the other hand, DPT, rubrene, and the rubrene derivatives all show various degrees of disorder with a number of sites that have larger electronic couplings than in the crystal, which can facilitate singlet fission in such thin films. Our analysis underlines the potential of these materials as promising candidates for singlet fission and helps understand how various structural motifs affect the critical parameters that control the ability of a system to undergo singlet fission.

Original languageEnglish (US)
Pages (from-to)2777-2787
Number of pages11
JournalChemistry of Materials
Volume29
Issue number7
DOIs
StatePublished - Apr 11 2017

Bibliographical note

Funding Information:
This work was supported by the National Science Foundation through the MRSEC Program under Award DMR-0819885 with computing resources provided by the CRIF Program under Award CHE-0946869. We thank Dr. Sukrit Mukhopadhyay for helpful discussions. D.B. is a FNRS Research Director.

Publisher Copyright:
© 2017 American Chemical Society.

Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.

How much support was provided by MRSEC?

  • Partial

Reporting period for MRSEC

  • Period 3

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