title: Enhanced thermal stability of a polymer solar cell blend induced by electron beam irradiation in the transmission electron microscope.
abstract: We show by in situ microscopy that the effects of electron beam irradiation during transmission electron microscopy can be used to lock microstructural features and enhance the structural thermal stability of a nanostructured polymer:fullerene blend. Polymer:fullerene bulk-heterojunction thin films show great promise for use as active layers in organic solar cells but their low thermal stability is a hindrance. Lack of thermal stability complicates manufacturing and influences the lifetime of devices. To investigate how electron irradiation affects the thermal stability of polymer:fullerene films, a model bulk-heterojunction film based on a thiophene-quinoxaline copolymer and a fullerene derivative was heat-treated in-situ in a transmission electron microscope. In areas of the film that exposed to the electron beam the nanostructure of the film remained stable, while the nanostructure in areas not exposed to the electron beam underwent large phase separation and nucleation of fullerene crystals. UV-vis spectroscopy shows that the polymer:fullerene films are stable for electron doses up to 2000kGy.
authors.affiliation: Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg, Sweden. Electronic address: obacke@chalmers.se.
authors.forename: Olof
authors.initials: O
authors.lastname: Bäcke
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg, Sweden.
authors.forename: Camilla
authors.initials: C
authors.lastname: Lindqvist
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg, Sweden.
authors.forename: Amaia Diaz
authors.initials: AD
authors.lastname: de Zerio Mendaza
authors.affiliation: Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg, Sweden.
authors.forename: Stefan
authors.initials: S
authors.lastname: Gustafsson
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg, Sweden.
authors.forename: Ergang
authors.initials: E
authors.lastname: Wang
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg, Sweden.
authors.forename: Mats R
authors.initials: MR
authors.lastname: Andersson
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg, Sweden.
authors.forename: Christian
authors.initials: C
authors.lastname: Müller
authors.affiliation: Institute of Polymer Nanotechnology (INKA), FHNW University of Applied Science and Arts Northwestern Switzerland, 5210 Windisch, Switzerland; Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, 5232 Villigen, Switzerland.
authors.forename: Per Magnus
authors.initials: PM
authors.lastname: Kristiansen
authors.affiliation: Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg, Sweden. Electronic address: eva.olsson@chalmers.se.
authors.forename: Eva
authors.initials: E
authors.lastname: Olsson
keywords: Crosslinking; Electron irradiation; In-situ transmission electron microscopy; Organic solar cells; Thermal stability