title: Singlet exciton fission for solar cell applications: energy aspects of interchromophore coupling.
abstract: Singlet exciton fission, a process that converts one singlet exciton to a pair of triplet excitons, has the potential to enhance the efficiency of both bulk heterojunction and dye-sensitized solar cells and is understood in crystals but not well understood in molecules. Previous studies have identified promising building blocks for singlet fission in molecular systems, but little work has investigated how these individual chromophores should be combined to maximize triplet yield. We consider the effects of chemically connecting two chromophores to create a coupled chromophore pair and compute how various structural choices alter the thermodynamic and kinetic parameters likely to control singlet fission yield. We use density functional theory to compute the electron transfer matrix element and the thermodynamics of fission for several promising chromophore pairs and find a trade-off between the desire to maximize this element and the desire to keep the singlet fission process exoergic. We identify promising molecular systems for singlet fission and suggest future experiments.
authors.affiliation: Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Greyson
authors.forename: Brian R
authors.initials: BR
authors.lastname: Stepp
authors.forename: Xudong
authors.initials: X
authors.lastname: Chen
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Schwerin
authors.forename: Irina
authors.initials: I
authors.lastname: Paci
authors.forename: Millicent B
authors.initials: MB
authors.lastname: Smith
authors.forename: Akin
authors.initials: A
authors.lastname: Akdag
authors.forename: Justin C
authors.initials: JC
authors.lastname: Johnson
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Nozik
authors.forename: Josef
authors.initials: J
authors.lastname: Michl
authors.forename: Mark A
authors.initials: MA
authors.lastname: Ratner