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Efficient Singlet Fission and Triplet-Pair Emission in a Family of Zethrene Diradicaloids.

Published version
Peer-reviewed

Change log

Authors

Lukman, Steven 
Richter, Johannes M 
Yang, Le 
Hu, Pan 

Abstract

Singlet fission offers the potential to overcome thermodynamic limits in solar cells by converting the energy of a single absorbed photon into two distinct triplet excitons. However, progress is limited by the small family of suitable materials, and new chromophore design principles are needed. Here, we experimentally vindicate the design concept of diradical stabilization in a tunable family of functionalized zethrenes. All molecules in the series exhibit rapid formation of a bound, spin-entangled triplet-pair state TT. It can be dissociated by thermally activated triplet hopping and exhibits surprisingly strong emission for an optically "dark" state, further enhanced with increasing diradical character. We find that the TT excited-state absorption spectral shape correlates with the binding energy between constituent triplets, providing a new tool to understand this unusual state. Our results reveal a versatile new family of tunable materials with excellent optical and photochemical properties for exploitation in singlet fission devices.

Description

Keywords

0306 Physical Chemistry (incl. Structural), 0912 Materials Engineering

Journal Title

J Am Chem Soc

Conference Name

Journal ISSN

0002-7863
1520-5126

Volume Title

139

Publisher

American Chemical Society (ACS)
Sponsorship
Engineering and Physical Sciences Research Council (EP/M005143/1)
Engineering and Physical Sciences Research Council (EP/G060738/1)