Toward a new world of molecular devices: Making metallic contacts to molecules

The incorporation of molecular layers into electronic devices has many applications from sensing to energy harvesting. While many devices have been demonstrated and some are close to market, there are many challenges that must be overcome before molecular assemblies are incorporated in every device. Perhaps the most important is the development of reliable, reproducible metallic contacts to connect molecular layers with other device components. In order for this to happen, the following must be developed: an understanding of the interaction between the electrode and the different parts of the molecular layer, methods for the large-scale integration of molecules into devices, and eliminate variability in the contact. In this paper, the progress and remaining challenges in making metallic contacts to molecules will be discussed. Methods employed range from those that measure single molecules to ensembles of molecules, as well as those that could be employed in manufacturing processes.