Analysis of ITO cleaning protocol on surface properties and polymer: Fullerene bulk heterojunction solar cell performance

In the traditional organic solar cell architecture, indium tin oxide (ITO) serves as the transparent electrode and substrate for solution-cast device layers. Hydrophobic contaminants are known to modify ITO wettability and other properties, making selection of an effective cleaning scheme essential. In this work, we demonstrate that certain solvent-based routines provide essentially equivalent surface properties as coupled solvent+UV-ozone protocols reported in literature. Surface energy analysis further reveals that solvent selection can effectively tune ITO charge transport. Fabricated devices showed comparable performance, indicating that interfacial resistances are not limiting factors in the model OSC system and that UV-ozone exposure could be eliminated to reduce commercialization costs. (C) 2013 Elsevier B.V. All rights reserved.