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.
Highlights
Singlet fission (SF) is an exciton multiplication phenomenon in organic semiconductors where one spin-singlet exciton transforms into two spin-triplet excitons, conserving spin[1,2] in a process that can be ultrafast (
Journal of the American Chemical Society protect the reactive radical sites have opened a library of tunable, highly stable derivatives.[35−39] We investigated the smallest member of the class, six-ring zethrene (Z), larger heptazethrene (HZ) and octazethrene (OZ), and phenalenofluorene (PF)
We demonstrate their general ability to undergo rapid SF, via the same bound, spin-entangled, and surprisingly emissive triplet-pair state TT recently reported in acenes.[6,15]
Summary
Singlet fission (SF) is an exciton multiplication phenomenon in organic semiconductors where one spin-singlet exciton transforms into two spin-triplet excitons, conserving spin[1,2] in a process that can be ultrafast (
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
