title: Singlet exciton fission in solution.
abstract: Singlet exciton fission, the spin-conserving process that produces two triplet excited states from one photoexcited singlet state, is a means to circumvent the Shockley-Queisser limit in single-junction solar cells. Although the process through which singlet fission occurs is not well characterized, some local order is thought to be necessary for intermolecular coupling. Here, we report a triplet yield of 200% and triplet formation rates approaching the diffusion limit in solutions of bis(triisopropylsilylethynyl (TIPS)) pentacene. We observe a transient bound excimer intermediate, formed by the collision of one photoexcited and one ground-state TIPS-pentacene molecule. The intermediate breaks up when the two triplets separate to each TIPS-pentacene molecule. This efficient system is a model for future singlet-fission materials and for disordered device components that produce cascades of excited states from sunlight.
authors.affiliation: Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge, UK.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Walker
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Musser
authors.forename: David
authors.initials: D
authors.lastname: Beljonne
authors.forename: Richard H
authors.initials: RH
authors.lastname: Friend