Contact and medium effects on molecular electronics

The initial aim of this project was to form a single-pot molecular spintronics technique. To achieve such a goal an understanding of the effect of measurement environment, and the of the metal-molecule contact are important. While the gold-thiol system has been well studied, little work has been done on the ferromagnetic contacts needed for molecular spintronics. It was therefore necessary to measure not only different metals but also different molecular anchors to work towards the best possible combination. A broadening of the understanding of the effect of the metal contact was initially performed by using PM-IRRAS to investigate molecular monolayers formed on Ni through potential assisted assembly. Co was also investigated as a possible metal for molecular spintronics. As a means of achieving a single-pot molecular spintronics setup deposition of Co from ionic liquids was investigated, although this was unsuccessful. Although a single-pot molecular spintronic system was ruled out for the time being, when used in tandem with an ionic liquid environment, Co allowed for successful single molecule conductance measurements. Furthermore these measurements showed similar conductance values to the analogous Au systems. The potential of the ionic liquid environment in molecular electronics was investigated in depth. Through the use of single molecule conductance measurements and electrochemical measurements ionic liquids were seen to be an exciting opportunity for molecular electronics. Ionic liquids extend the abilities of molecular electronics compared to more traditional environments. Furthermore the characteristics of ionic liquids can be exploited to allow desirable molecular traits to be witnessed. For example when viologen containing molecules were previously investigated in aqueous electrolytes an off-on switching was seen, whereas in ionic liquids analogous molecules showed off-on-off switching, likely as a result of the ionic liquid locking the ring conformation. This project has shown that when performing molecular electronics measurements both the environment and the metal-molecule contact are important. These findings are important to note because it means that when forming a molecular electronic system the entire junction should be carefully considered, rather than just the molecular backbone. Through careful choice of the entire molecular electronic junction a system rivaling those of traditional electronics may be formed.