Enhanced thermal stability of a polymer solar cell blend induced by electron beam irradiation in the transmission electron microscope

Olof Bäcke; Camilla Lindqvist; Amaia Diaz de Zerio Mendaza; Stefan Gustafsson; Ergang Wang; Mats R Andersson; Christian Müller; Per Magnus Kristiansen; Eva Olsson

doi:10.1016/j.ultramic.2017.03.013

Enhanced thermal stability of a polymer solar cell blend induced by electron beam irradiation in the transmission electron microscope

Ultramicroscopy. 2017 May:176:23-30. doi: 10.1016/j.ultramic.2017.03.013. Epub 2017 Mar 15.

Authors

Olof Bäcke¹, Camilla Lindqvist², Amaia Diaz de Zerio Mendaza², Stefan Gustafsson³, Ergang Wang², Mats R Andersson², Christian Müller², Per Magnus Kristiansen⁴, Eva Olsson⁵

Affiliations

¹ Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg, Sweden. Electronic address: obacke@chalmers.se.
² Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg, Sweden.
³ Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg, Sweden.
⁴ 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.
⁵ Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg, Sweden. Electronic address: eva.olsson@chalmers.se.

PMID: 28341555
DOI: 10.1016/j.ultramic.2017.03.013

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.

Keywords: Crosslinking; Electron irradiation; In-situ transmission electron microscopy; Organic solar cells; Thermal stability.

Publication types

Research Support, Non-U.S. Gov't