A new cubic prototype structure in the IV-VI monochalcogenide system: a DFT study

作者：Segev Elad; Argaman Uri; Abutbul Ran E; Golan Yuval; Makov Guy^*

来源：CrystEngComm, 2017, 19(13): 1751-1761.

DOI：10.1039/c7ce00038c

A new cubic binary phase was recently discovered in the IV-VI monochalcogenides: tin monosulfide and tin monose-lenide. Here, we explored the possible materials design space for this phase across groups IVVI. The structure and properties of this new phase, the pi phase, including mechanical and thermodynamic stability and band gap width, were studied using density functional theory across the monochalcogenide systems of groups IV-VI. The structure of the new pi phase was interpreted in terms of a distorted rock-salt structure, and the bonding between the 64 atoms of the unit cell was elucidated. It was found that the pi phase is mechanically stable in germanium sulfide and germanium selenide and unstable in the tellurides. The energy differences between the pi phase and the stable orthorhombic structures were very small, suggesting that the pi phase could be thermodynamically accessible in monochalcogenide nanoparticles. The band gaps of the new phase were found to range from 1.0-1.4 eV, which may be attractive for a variety of photovoltaic and photosensing applications, in particular for GeS, which uniquely has a direct band gap in the pi phase.

• 出版日期2017-4-7