Single molecule switch devices: A minireview

Abstract

Electronic switches fabricated with single molecules are expected to break through the bottleneck in the development of semiconductor device miniaturization. However, at present time, most development on single molecule switches only provides one-way switching functions. Stable bidirectional reversible single-molecule switches are rarely reported. This paper reviews the recent studies on single-molecule switches. By applying an external stimulation, the bistable or polymorphic state between molecular switches can be activated, and the properties of molecules may be changed by changing conformation, dipole orientation, spin state, and charge state, so that the molecules and the supporting substrate can be coupled in parallel to the circuit. The break-junction technique can be connected to an external chemical electrode to change the conductance state. Common techniques include mechanically-controllable break-junction (MCBJ) and scanning tunneling microscope break-junction (STM-BJ). In addition, molecules may also be integrated into surface circuits at the molecular scale by the use of bottom-up surface self-assembly schemes. This paper introduces the concepts of single molecule switches from several parts and presents the potential application of these methods in the future. The purpose of this paper is to provide guidance for the study of stable bidirectional reversible single-molecule switches and to promote the role of molecular switches in the advances of miniaturization of conductor devices.