First-Principles\nStudy of the Mechanical, Electronic,\nand Optical Properties of Ternary Chalcogenide Compounds

First-principles calculations are performed to study\nthe structural,\nmechanical, electronic, and optical properties of seven ternary chalcogenides,\nincluding the monoclinic Ba<sub>2</sub>GeSe<sub>4</sub> and Ba<sub>2</sub>SiSe<sub>4</sub>, triclinic AgScS<sub>2</sub>, AgYS<sub>2</sub>, and AuAlS<sub>2</sub>, as well as cubic NbCu<sub>3</sub>S<sub>4</sub> and Al<sub>2</sub>ZnS<sub>4</sub>. Our calculations show that these\nmaterials are stable. Ba<sub>2</sub>GeSe<sub>4</sub>, Ba<sub>2</sub>SiSe<sub>4</sub>, AgScS<sub>2</sub>, AgYS<sub>2</sub>, and AuAlS<sub>2</sub> are ductile, while NbCu<sub>3</sub>S<sub>4</sub> is brittle.\nMost of them possess a small hole-effective mass and high transparency\nin the visible-light region. The branch-point energy shows that Ba<sub>2</sub>GeSe<sub>4</sub>, Ba<sub>2</sub>SiSe<sub>4</sub>, AuAlS<sub>2</sub>, and Al<sub>2</sub>ZnS<sub>4</sub> are inclined to n-type\ndoping while AgScS<sub>2</sub>, AgYS<sub>2</sub>, and NbCu<sub>3</sub>S<sub>4</sub> tend to form p-type doping and are all potential candidates\nfor transparent conducting materials (TCMs). Based on these properties,\ntheir possible applications are analyzed. It is hoped that this work\ncould guide the exploration of TCMs.