|Prof. Aron Walsh and Dr. Keith Butler (University of Bath, UK)
|Semiconducting Materials Design by Structural and Chemical Analogy
|矢上キャンパス内 ディスカッションルーム2 (14-212)
|The periodic table offers an almost infinite number of possibilities for forming new materials, especially when multi-component systems are considered. Even given the rapid advances in high throughput experiment and computations, the compositional landscape will not be exhausted in the near or long-term.The theory of semiconducting materials is well developed, the most fundamental of which is based on the counting of electrons. Based on satisfying the octet rule in a covalent description, or equivalently local charge neutrality in an ionic picture, the existence of binary (e.g. II-VI and III-V) and ternary (e.g. I-III-VI2 and I-II-V) semiconductors can be understood. These ideas can be applied to more complex compositions, where there has been success in the development of quaternary semiconductors for use in solar cells, spin transport, thermoelectrics and as topological insulators. By maintaining either the lattice type (cation mutation) or chemical composition (polymorph engineering), the design of new materials with novel properties becomes a systematic and tractable process.The development and application of these ideas to designing new materials will be presented, including: (i) cation mutation in the diamond lattice (combining the related zinc-blende, chalcopyrite and kesterite crystal structures); (ii) compositional variance in the perovskite structure, which can be used to control lattice polarization and ionization potentials, and (iii) the design of conductive metal-organic frameworks. In addition, I will discuss recent progress in predicting the electron binding energy (ionization potentials and electron affinities of solid state materials). These ideas are being implemented into the code Semiconducting Materials by Analogy and Computational Techniques (SMACT).