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

Geoffrey A Rojas; Yanfei Wu; Greg Haugstad; C Daniel Frisbie

doi:10.1021/acsami.6b00367

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

ACS Appl Mater Interfaces. 2016 Mar 9;8(9):5772-6. doi: 10.1021/acsami.6b00367. Epub 2016 Feb 29.

Authors

Geoffrey A Rojas¹, Yanfei Wu¹, Greg Haugstad², C Daniel Frisbie¹

Affiliations

¹ Department of Chemical Engineering and Materials Science, University of Minnesota , 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States.
² Characterization Facility, University of Minnesota , 100 Union Street SE, Minneapolis, Minnesota 55455, United States.

PMID: 26890658
DOI: 10.1021/acsami.6b00367

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.

Keywords: band bending; charge generation layer; fullerene; polymer; scanning kelvin probe.

Publication types

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