Multinary Chalcogenides: a Fruitful Playground for Property Tuning via Cation Substitution

Multinary chalcogenides offer a vast selection of materials with diverse properties due to flexibility of structure, morphology, composition, doping, and other factors. By employing a hierarchical strategy based on cross-cation substitution we can build complex ternary and quaternary systems starting with simpler II-VI binary materials. Within this fruitful approach, I₂-II-IV-VI₄, I-II₂-III-VI₄, and I-III-IV-VI₄ classes of materials can be obtained. While I₂-II-IV-VI₄ has been extensively explored in the past, I-II₂-III-VI₄ and I-III-IV-VI₄ systems are much less studied. In this presentation, we present first principles simulations to examine the structural diversity of these newer classes of materials. Several metastable phases that are also dynamically stable, are found for I-II₂-III-VI₄. Compositions from the I-III-IV-VI₄ class are also studied showing highly defective chalcopyrite-like structures among others. Simulations for the electronic and phonon properties are also conducted, which help us find common features and mechanisms that limit the transport in these materials. Given the inherently low thermal conductivity, electronic property tuning possibilities, and earth-abundant constituents in many compositions, these materials are examined in the context of thermoelectricity as potential candidates for environmentally friendly energy conversion devices.<br/><br/>Support from the US National Science Foundation under Grant No. DMR-1748188 is acknowledged.