Heavy-atom effects on intramolecular singlet fission in a conjugated polymer.

Andrew J Musser,Martin Heeney,Jenny Clark,Mohammed Al-Hashimi

doi:10.1063/1.5110269

Abstract

A chief aim in singlet fission research is to develop new materials concepts for more efficient singlet fission. The typical approaches such as tuning π-overlap and charge-transfer interactions, enhancing delocalization, altering diradical character, or extending the conjugation length have profound effects simultaneously on the singlet and triplet energetics and the couplings between them. While these strategies have resulted in a handful of high-efficiency materials, the complex interplay of these factors makes systematic materials development challenging, and it would be useful to be able to selectively manipulate the properties and dynamics of just part of the singlet fission pathway. Here, we investigate the potential of heteroatom substitution as just such a selective tool. We explore the influence of heavy atoms within the main backbone of polythienylenevinylene and its selenophene and tellurophene derivatives. We find no significant effects on the prompt <300 fs intramolecular singlet fission dynamics but a clear heavy-atom effect on longer time scales.

Highlights

The field of singlet fission has seen remarkable progress in the last decade, with an increasingly sophisticated understanding of the underlying mechanism1–5 and spin physics.6–8 despite many attempts at systematic study in a range of materials systems,9–12 a detailed picture of the structure-property relationships that define the intermolecular singlet fission dynamics relevant to devices remains elusive
The synthesis, purification, and basic physical and chemical characterization of P3TV, P3SV, and P3TeV are presented in a previous report
In our previous study of the photophysics of P3TV,31 we found that singlet fission could be best identified from the excitation wavelength dependence in transient absorption, and that the photophysics could not be fully understood without consideration of the excitation wavelength dependence

Summary

Introduction

The field of singlet fission has seen remarkable progress in the last decade, with an increasingly sophisticated understanding of the underlying mechanism1–5 and spin physics.6–8 despite many attempts at systematic study in a range of materials systems,9–12 a detailed picture of the structure-property relationships that define the intermolecular singlet fission dynamics relevant to devices remains elusive.

Results

Conclusion