Molecular donor-acceptor compounds as prospective organic electronics materials

The pi-electronic functionalities of molecular donor (D)-acceptor (A) compounds have been attracting subjects for the solid state science as well as for the prospective technological exploitation in organic electronics. In this review, it is shown that the novel neutral-ionic valence instability in the charge-transfer (CT) complexes is closely related to valuable electric properties such as the current-induced resistance switching, quantum phase transition, gigantic dielectric response, and relaxor ferroelectricity. Furthermore, the displacive-type ferroelectricity has recently been developed on the DA combinations in the hydrogen-bonded co-crystals. It is also discussed that the intermolecular CT mechanism in the molecular DA compounds is promising to advance the potential of organic field-effect transistors (FETs) that are envisioned as key components in future organic electronics.