title: Measuring the Thickness and Potential Profiles of the Space-Charge Layer at Organic/Organic Interfaces under Illumination and in the Dark by Scanning Kelvin Probe Microscopy.
abstract: Scanning Kelvin probe microscopy was used to measure band-bending at the model donor/acceptor heterojunction poly(3-hexylthiophene) (P3HT)/fullerene (C60). Specifically, we measured the variation in the surface potential of C60 films with increasing thicknesses grown on P3HT to produce a surface potential profile normal to the substrate both in the dark and under illumination. The results confirm a space-charge carrier region with a thickness of 10 nm, consistent with previous observations. We discuss the possibility that the domain size in bulk heterojunction organic solar cells, which is comparable to the space-charge layer thickness, is actually partly responsible for less than expected electron/hole recombination rates.
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota , 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Rojas
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota , 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Yanfei
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Characterization Facility, University of Minnesota , 100 Union Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Greg
authors.initials: G
authors.lastname: Haugstad
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota , 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States.
authors.forename: C Daniel
authors.initials: CD
authors.lastname: Frisbie
keywords: band bending; charge generation layer; fullerene; polymer; scanning kelvin probe