title: Oxygen-Induced Degradation in C60-Based Organic Solar Cells: Relation Between Film Properties and Device Performance.
abstract: Fullerene-based molecules are the archetypical electron-accepting materials for organic photovoltaic devices. A detailed knowledge of the degradation mechanisms that occur in C60 layers will aid in the development of more stable organic solar cells. Here, the impact of storage in air on the optical and electrical properties of C60 is studied in thin films and in devices. Atmospheric exposure induces oxygen-trap states that are 0.19 eV below the LUMO of the fullerene C60. Moreover, oxygen causes a 4-fold decrease of the exciton lifetime in C60 layers, resulting in a 40% drop of short-circuit current from optimized planar heterojunction solar cells. The presence of oxygen-trap states increases the saturation current of the device, resulting in a 20% loss of open-circuit voltage. Design guidelines are outlined to improve air stability for fullerene-containing devices.
authors.affiliation: imec , Kapeldreef 75, B-3001, Leuven, Belgium.|ESAT, Katholieke Universiteit Leuven , Kasteelpark Arenberg 10, B-3001, Leuven, Belgium.
authors.forename: João P
authors.initials: JP
authors.lastname: Bastos
authors.affiliation: imec , Kapeldreef 75, B-3001, Leuven, Belgium.
authors.forename: Eszter
authors.initials: E
authors.lastname: Voroshazi
authors.affiliation: Department of Chemistry, Katholieke Universiteit Leuven , Celestijnenlaan 200G-F, B-3001 Heverlee, Belgium.
authors.forename: Eduard
authors.initials: E
authors.lastname: Fron
authors.affiliation: imec , Kapeldreef 75, B-3001, Leuven, Belgium.
authors.forename: Guy
authors.initials: G
authors.lastname: Brammertz
authors.affiliation: Hasselt University, Institute for Materials Research & IMEC-Associated Lab IMOMEC , Wetenschapspark 1, B-3590 Diepenbeek, Belgium.
authors.forename: Tim
authors.initials: T
authors.lastname: Vangerven
authors.affiliation: Department of Chemistry, Katholieke Universiteit Leuven , Celestijnenlaan 200G-F, B-3001 Heverlee, Belgium.
authors.forename: Mark
authors.initials: M
authors.lastname: Van der Auweraer
authors.affiliation: imec , Kapeldreef 75, B-3001, Leuven, Belgium.|ESAT, Katholieke Universiteit Leuven , Kasteelpark Arenberg 10, B-3001, Leuven, Belgium.
authors.forename: Jef
authors.initials: J
authors.lastname: Poortmans
authors.affiliation: imec , Kapeldreef 75, B-3001, Leuven, Belgium.
authors.forename: David
authors.initials: D
authors.lastname: Cheyns
keywords: degradation; fullerenes; organic solar cells; oxygen; stability