Since the first silicon transistor, the manufacture of transistors in electronics developed rapidly in size (smaller) and density (higher), following Moore’s law: ‘the number of transistors in a dense integrated circuits doubles every two years. The miniaturization of electronics continued following this development until the new millennium. Higher transistor densities and smaller transistor sizes have their ultimate limit at the atomic level. Feynman indicated in 1959 already that ‘there is plenty of room at the bottom’. Fabricating electronic devices based on atoms and molecules is referred to as molecular electronics.