Iodine induced structures on Cu(100)

Abstract: Replacing the expensive platinum layer in the dye-sensitized solar cells (DSSC) with cheaper materials can reduce the cost of these types of solar cells dramatically. In this study, the possibility of replacing the Pt layer with Cu is investigated. For this purpose, iodine which is used as electrolyte in dye-sensitized solar cells was deposited on the Cu(100) surface. Different amounts of Iodine was adsorbed on the surface, and consequently different iodine structures are observed. Low Energy Electron Diffraction (LEED) and Scanning Tunneling Microscopy (STM) are implemented to observe and verify the atomic structure on the Cu(100) substrate. LEED and STM images showed that iodine arranges in p(2x2), c(6x2) and c(4x2) phases on the Cu(100) surface. The study of the interface electronic properties has been done by use of photoelectron spectroscopy. Coverage dependent I4d spectra do not show any chemically shifted peaks, but a collective shift toward lower binding energy (at increasing surface concentration). The Cu3p spectra are found to be insensitive to the amount of iodine and heating; no iodide is formed on this surface. The spectroscopic results indicate a moderate Cu-I interaction and the surface atomic and electronic structure is strongly influenced by the iodine-iodine interaction in the surface layer.