title: Role of Macromolecular Structure in the Ultrafast Energy and Electron Transfer Dynamics of a Light-Harvesting Polymer.
abstract: Ultrafast energy and electron transfer (EnT and ET, respectively) are characterized in a light-harvesting assembly based on a π-conjugated polymer (poly(fluorene)) functionalized with broadly absorbing pendant organic isoindigo (iI) chromophores using a combination of femtosecond transient absorption spectroscopy and large-scale computer simulation. Photoexcitation of the π-conjugated polymer leads to near-unity quenching of the excitation through a combination of EnT and ET to the iI pendants. The excited pendants formed by EnT rapidly relax within 30 ps, whereas recombination of the charge-separated state formed following ET occurs within 1200 ps. A computer model of the excited-state processes is developed by combining all-atom molecular dynamics simulations, which provides a molecular-level view of the assembly structure, with a kinetic model that accounts for the multiple excited-state quenching pathways. Direct comparison of the simulations with experimental data reveals that the underlying structure has a dramatic effect on the partitioning between EnT and ET in the polymer assembly, where the distance and orientation of the pendants in relation to the backbone serve to direct the dominant quenching pathway.
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.
authors.forename: Zachary A
authors.initials: ZA
authors.lastname: Morseth
authors.affiliation: School of Chemistry and Biochemistry, School of Materials Science and Engineering, Center for Organic Photonics and Electronics, Georgia Tech Polymer Network, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Toan V
authors.initials: TV
authors.lastname: Pho
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.
authors.forename: Alexander T
authors.initials: AT
authors.lastname: Gilligan
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Dillon
authors.affiliation: Department of Chemistry, Center for Macromolecular Science and Engineering, University of Florida , Gainesville, Florida 32611, United States.
authors.forename: Kirk S
authors.initials: KS
authors.lastname: Schanze
authors.affiliation: School of Chemistry and Biochemistry, School of Materials Science and Engineering, Center for Organic Photonics and Electronics, Georgia Tech Polymer Network, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: John R
authors.initials: JR
authors.lastname: Reynolds
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.
authors.forename: John M
authors.initials: JM
authors.lastname: Papanikolas