Deposition of lead iodide films on Rh(1 0 0) electrodes from colloidal solutions––the effect of an iodine adlayer

The growth of PbI2 precipitates on single crystal substrates from colloidal solutions has been investigated with in air scanning tunneling microscopy and synchrotron-based X-ray photoelectron spectroscopy. The PbI2 growth on Rh(1 0 0) results in nano-clusters with lateral dimensions between 30 and 60 Å, consistent with earlier reports. However, the growth of PbI2 on a well-ordered iodinated Rh(1 0 0), denoted as (√2×√2)R45°-I, leads to atomically smooth PbI2 films having a hexagonal symmetry with lattice constant identical to the bulk value of 4.5 Å. The heteroepitaxy is believed to be effected by the atomic iodine monolayer that helps to accommodate large lattice mismatch between PbI2 and Rh surface with short-range van der Waals interaction.