title: Effect of Annealing on Exciton Diffusion in a High Performance Small Molecule Organic Photovoltaic Material.
abstract: Singlet exciton diffusion was studied in the efficient organic photovoltaic electron donor material DTS(FBTTh2)2. Three complementary time-resolved fluorescence measurements were performed: quenching in planar heterojunctions with an electron acceptor, exciton-exciton annihilation, and fluorescence depolarization. The average exciton diffusivity increases upon annealing from 1.6 × 10-3to 3.6 × 10-3cm2s-1, resulting in an enhancement of the mean two-dimensional exciton diffusion length (LD= (4Dτ)1/2) from 15 to 27 nm. About 30% of the excitons get trapped very quickly in as-cast films. The high exciton diffusion coefficient of the material leads to it being able to harvest excitons efficiently from large donor domains in bulk heterojunctions.
authors.affiliation: Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9SS, United Kingdom.
authors.forename: Yun
authors.initials: Y
authors.lastname: Long
authors.affiliation: Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9SS, United Kingdom.
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Hedley
authors.affiliation: Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9SS, United Kingdom.
authors.forename: Arvydas
authors.initials: A
authors.lastname: Ruseckas
authors.affiliation: Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9SS, United Kingdom.
authors.forename: Mithun
authors.identifier: http://orcid.org/0000-0002-2513-6006
authors.initials: M
authors.lastname: Chowdhury
authors.affiliation: Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9SS, United Kingdom.
authors.forename: Thomas
authors.initials: T
authors.lastname: Roland
authors.affiliation: Glasgow Centre for Physical Organic Chemistry, WESTCHEM, School of Chemistry, University of Glasgow , Glasgow G12 8QQ, United Kingdom.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Serrano
authors.affiliation: Glasgow Centre for Physical Organic Chemistry, WESTCHEM, School of Chemistry, University of Glasgow , Glasgow G12 8QQ, United Kingdom.
authors.forename: Graeme
authors.initials: G
authors.lastname: Cooke
authors.affiliation: Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9SS, United Kingdom.
authors.forename: Ifor D W
authors.identifier: http://orcid.org/0000-0001-7821-7208
authors.initials: IDW
authors.lastname: Samuel
keywords: bulk heterojunctions; excitation energy transfer; light harvesting; organic semiconductors; organic solar cells