In this talk, two different strategies for the discovery of new two-dimensional (2D) materials with electro-active functionality will be introduced. Our new 2D materials are created based on the engineering of crystal structure dealing with electrons, showing unprecedented physical properties.
The first material, electride, which is regarded as a new electronic material, is ionic crystal in which interstitial electrons serve as anions. The physical properties of electrides are determined by the topology of cavities or channels which confine anionic electrons. The confining sites have been restricted to cavities or weakly linked channels of organic systems. Here, it will be highlighted that the two- dimensionally (2D) confined electron systems can show diverse physical properties as electrons are localized or delocalized.
The second material type is new 2D polymorphic layered materials based on Zintl phases. These systems can be exotic 2D materials for beyond graphene that allow unlimited extent of 2D material science in terms of the diversity of materials and physical properties. A new class of 2D materials was developed from a 3D structured material that has (1) a multicomponent system, (2) primary atomic bonds in three-dimensionality, (3) thermodynamic and chemical stability, and (4) diversity in chemical compositions. Paradoxically, these restrictions inevitably mean that it is possible to create 2D materials from all types of inorganic compounds. The recent experimental and theoretical studies on diverse physical properties obtained in the new 2D materials will be discussed.