title: Quantitative Intramolecular Singlet Fission in Bipentacenes.
abstract: Singlet fission (SF) has the potential to significantly enhance the photocurrent in single-junction solar cells and thus raise the power conversion efficiency from the Shockley-Queisser limit of 33% to 44%. Until now, quantitative SF yield at room temperature has been observed only in crystalline solids or aggregates of oligoacenes. Here, we employ transient absorption spectroscopy, ultrafast photoluminescence spectroscopy, and triplet photosensitization to demonstrate intramolecular singlet fission (iSF) with triplet yields approaching 200% per absorbed photon in a series of bipentacenes. Crucially, in dilute solution of these systems, SF does not depend on intermolecular interactions. Instead, SF is an intrinsic property of the molecules, with both the fission rate and resulting triplet lifetime determined by the degree of electronic coupling between covalently linked pentacene molecules. We found that the triplet pair lifetime can be as short as 0.5 ns but can be extended up to 270 ns.
authors.affiliation: †Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors.forename: Samuel N
authors.initials: SN
authors.lastname: Sanders
authors.affiliation: †Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors.forename: Elango
authors.initials: E
authors.lastname: Kumarasamy
authors.affiliation: †Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Pun
authors.affiliation: †Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors.forename: M Tuan
authors.initials: MT
authors.lastname: Trinh
authors.affiliation: †Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors.forename: Bonnie
authors.initials: B
authors.lastname: Choi
authors.affiliation: †Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors.forename: Jianlong
authors.initials: J
authors.lastname: Xia
authors.affiliation: †Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors.forename: Elliot J
authors.initials: EJ
authors.lastname: Taffet
authors.affiliation: †Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors.forename: Jonathan Z
authors.initials: JZ
authors.lastname: Low
authors.forename: John R
authors.initials: JR
authors.lastname: Miller
authors.affiliation: †Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors.forename: Xavier
authors.initials: X
authors.lastname: Roy
authors.affiliation: †Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors.forename: X-Y
authors.initials: XY
authors.lastname: Zhu
authors.affiliation: †Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Steigerwald
authors.forename: Matthew Y
authors.initials: MY
authors.lastname: Sfeir
authors.affiliation: †Department of Chemistry, Columbia University, New York, New York 10027, United States.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Campos