Optimization of antireflective zinc oxide nanorod arrays on seedless substrate for bulk-heterojunction organic solar cells

We report on the enhanced performance of hybrid photovoltaic devices consisting of poly (3-hexylthiophene), (6,6)-phenyl C-61 butyric acid methyl ester, and zinc oxide (ZnO) nanorod arrays grown on seedless indium tin oxide (ITO) glass in aqueous zinc chloride solution. Introduction of optimized-length ZnO nanorod arrays between hole injection and ITO layers increased photocurrent density from 8.0 to 8.8 mA/cm(2) and fill factor from 42% to 47%. The absence of a seed layer significantly reduced incident light reflection on the ITO glass and resulted in an overall 10% increase in photocurrent. A photovoltaic device based on a ZnO nanostructure length of 100 nm exhibited a maximum power conversion efficiency of 2.4%, 15% higher than that of an equivalent device without ZnO nanorods. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4757997]