title: Is the Chemical Strategy for Imbuing "Polyene" Character in Diketopyrrolopyrrole-Based Chromophores Sufficient for Singlet Fission?
abstract: In this work, we have rationally designed and synthesized a novel thiophene-diketopyrrolopyrrole (TDPP)-vinyl-based dimer. We have investigated the optical and electronic properties and have probed the photophysical dynamics using transient absorption to investigate the possibility of singlet exciton fission. These revealed extremely rapid decay to the ground state (<50 ps), which we confirm is due to intramolecular excitonic processes rather than large-scale conformational change enabled by the vinyl linker. In all cases, the main excited state appears to be "dark", suggesting rapid internal conversion into a dark 2Ag-type singlet state. We found no evidence of triplet formation in TDPP-V-TDPP under direct photoexcitation. This may be a consequence of significant singlet stabilization in the dimer, bringing it below the energy needed to form two triplets. Our studies on this model compound set valuable lessons for design of novel triplet-forming materials and highlight the need for more broadly applicable design principles.
authors.affiliation: Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore 560012, India.
authors.forename: Tushita
authors.initials: T
authors.lastname: Mukhopadhyay
authors.affiliation: Department of Physics and Astronomy, University of Sheffield , Sheffield, United Kingdom.|Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom.
authors.forename: Andrew J
authors.identifier: http://orcid.org/0000-0002-4600-6606
authors.initials: AJ
authors.lastname: Musser
authors.affiliation: Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore 560012, India.
authors.forename: Boregowda
authors.initials: B
authors.lastname: Puttaraju
authors.affiliation: Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore 560012, India.
authors.forename: Joydeep
authors.initials: J
authors.lastname: Dhar
authors.affiliation: Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom.
authors.forename: Richard H
authors.initials: RH
authors.lastname: Friend
authors.affiliation: Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore 560012, India.
authors.forename: Satish
authors.initials: S
authors.lastname: Patil