Nanostructured ZnO/Conjugated Polymer for p-n Heterojunctions

High-density vertically aligned ZnO nanotubes (NTs) were prepared by etching ZnO nanorods (NRs) in aqueous solution, which were grown from ZnO sol-gel-derived seeds coated on transparent conductive glass substrate. We investigated the preparation of nanostructured oxide/conjugated polymer hybrid solar cells, where the regioregular poly(3-hexylthiophene) was infiltrated into transparent ZnO nanorod or nanotube films. The hybrid can take advantage of the high electron mobility attainable in oxide semiconductors and can be fabricated using low temperature aqueous solution growth techniques. Additionally, the morphology of the hybrid can be controlled in a systematic way through growth of the nanostructured ZnO to obtain a large amount of surface area. Because of the increased specific surface area, the power efficiency of cells based on ZnO NTs enhances twice as that of ZnO NRs. In other words, the nanotubes can offer a highly ordered material architecture with efficient charge generation and collection of electron in hybrid solar cells. A relation between efficiency and surface area is demonstrated. (C) 2011 The Japan Society of Applied Physics