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 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
Journal article, 2017

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 2000 kGy.

In-situ transmission electron microscopy

Organic solar cells

Thermal stability

Crosslinking

Electron irradiation

Author