title: Photoinduced Dynamics of Charge Separation: From Photosynthesis to Polymer-Fullerene Bulk Heterojunctions.
abstract: Understanding charge separation and charge transport is crucial for improving the efficiency of organic solar cells. Their active media are based on organic molecules and polymers, serving as both light-absorbing and transport layers. The charge-transfer (CT) states play an important role, being intermediate for free carrier generation and charge recombination. Here, we use light-induced electron paramagnetic resonance spectroscopy to study the CT dynamics in blends of the polymers P3HT, PCDTBT, and PTB7 with the fullerene derivative C60-PCBM. Time-resolved EPR measurements show strong spin-polarization patterns for all polymer-fullerene blends, confirming predominant generation of singlet CT states and partial orientation ordering near the donor-acceptor interface. These observations allow a comparison with charge separation processes in molecular donor-acceptor systems and in natural and artificial photosynthetic assemblies, and thus the elucidation of the initial steps of sequential CT in organic photovoltaic materials.
authors.affiliation: †Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States.
authors.forename: Jens
authors.initials: J
authors.lastname: Niklas
authors.affiliation: ‡Department of Chemistry, Laval University, Quebec City, Quebec G1V 0A6, Canada.
authors.forename: Serge
authors.initials: S
authors.lastname: Beaupré
authors.affiliation: ‡Department of Chemistry, Laval University, Quebec City, Quebec G1V 0A6, Canada.
authors.forename: Mario
authors.initials: M
authors.lastname: Leclerc
authors.affiliation: §Department of Chemistry and James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States.
authors.forename: Tao
authors.initials: T
authors.lastname: Xu
authors.affiliation: §Department of Chemistry and James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States.
authors.forename: Luping
authors.initials: L
authors.lastname: Yu
authors.affiliation: ∥University of Würzburg and Bavarian Centre for Applied Energy Research (ZAE Bayern), D-97074 Würzburg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Sperlich
authors.affiliation: ∥University of Würzburg and Bavarian Centre for Applied Energy Research (ZAE Bayern), D-97074 Würzburg, Germany.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Dyakonov
authors.affiliation: †Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States.
authors.forename: Oleg G
authors.initials: OG
authors.lastname: Poluektov
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport / Q000528:radiation effects; D037741:Fullerenes / Q000737:chemistry*; D015394:Molecular Structure; D010788:Photosynthesis; D011108:Polymers / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D037741:Fullerenes; D011108:Polymers