title: Nafion-modified MoOx as effective room-temperature hole injection layer for stable, high-performance inverted organic solar cells.
abstract: We present a hole injection layer processed from solution at room temperature for inverted organic solar cells. Bis(2,4-pentanedionato) molybdenum(VI) dioxide (MoO2(acac)2) is used as the precursor for MoOx. Small amounts of Nafion in the precursor solution allow it to form continuous films with good wetting onto the active layers. The hydrolysis of MoO2(acac)2 and the effects of adding Nafion to the precursor solution are studied by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The devices with solution-processed MoOx including Nafion exhibited comparable performance to the reference devices based on the commonly used hole injection layers such as poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) or evaporated MoO3. Inverted poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methyl ester devices with Nafion-modified MoOx maintain 80% of their initial power conversion efficiency upon exposure to ambient air for ∼5000 h, outperforming devices with PEDOT:PSS or with evaporated MoO3.
authors.affiliation: Imec , Kapeldreef 75, 3001 Heverlee, Belgium.
authors.forename: Weiming
authors.initials: W
authors.lastname: Qiu
authors.forename: Robert
authors.initials: R
authors.lastname: Müller
authors.forename: Eszter
authors.initials: E
authors.lastname: Voroshazi
authors.forename: Bert
authors.initials: B
authors.lastname: Conings
authors.forename: Robert
authors.initials: R
authors.lastname: Carleer
authors.forename: Hans-Gerd
authors.initials: HG
authors.lastname: Boyen
authors.forename: Mathieu
authors.initials: M
authors.lastname: Turbiez
authors.forename: Ludo
authors.initials: L
authors.lastname: Froyen
authors.forename: Paul
authors.initials: P
authors.lastname: Heremans
authors.forename: Afshin
authors.initials: A
authors.lastname: Hadipour
keywords: MoOx; Nafion; hole injection layer; inverted solar cells; stability