Single-molecule electronic components based on molecular design

In downscaling the size of electronic components, molecules are viewed as promising alternatives as they can have additional functionality built-in by chemical design. We have developed several techniques to create solid-state, single-molecule devices in which molecules are deposited from solution. These include mechanical controlled break junctions, molecular transistors made by a self-breaking electromigration technique, and room-temperature stable molecular transistors by electroburning of few-layer graphene. With these techniques in place, we are investigating the electronic properties of a wide variety of molecules, with a special emphasis to use the intrinsic molecular structure (e.g. the orbital structure) to create electronic functionalities. Functionality can be based on quantum interference effects or on the creation of barriers for transport within the molecule over which substantial voltage drops occur when biasing the molecules. In this way, quantum-interference switches, negative differential resistance devices and single-molecule rectifiers can be created.