In the research presented in this thesis, the effects of humidity on a series of Ru-complex molecular layers is investigated with the Conductive Atomic Force Microscopy technique. One specific... Show moreIn the research presented in this thesis, the effects of humidity on a series of Ru-complex molecular layers is investigated with the Conductive Atomic Force Microscopy technique. One specific molecule out of this series called '2-Ru-N' shows remarkable humidity sensitive diode behavior: in low humidity it behaves as a conventional resistive tunneling junction, wheras in high humidity, it behaves as a diode. The rectification ratios found for 2-Ru-N are among the highest reported for molecular junctions in the literature. By comparing the behavior of 2-Ru-N with its other counterparts, a model is presented that is based on two localized molecular orbitals that are misaligned during the addition of water. This is due to the water pulling on the counter-ions that are found in the molecular layer and hence, effectively gate one of the two localized molecular orbitals, resulting in a misalignment and thus, a diode-like behavior. Show less