| Abstract Scope |
We study the structural, electronic, optical, and thermoelectric properties of nine ternary chalcogenides, NaAX2, where A represents As, Sb, and Te, and X represents S, Se, and Te. Calculations based on density functional theory yield the following results: (i) phonon dispersion curves predict three of the compounds, NaAsS2, NaSbS2, and NaSbSe2, to be dynamically stable in the monoclinic, C2/c, structure, (ii) A-X electronic bonding features vary significantly with structural distortions arising from atomic size mismatch, therefore directly influencing stability, (iii) strong absorption is observed in the stable compounds, with coefficients ranging from 104 to 105 cm-1 in the visible-UV range, and (iv) remarkably high Seebeck coefficients exceeding 500 μV/K, at carrier concentrations commonly achieved in such materials, are found. From these results, we conclude that NaAsS2, NaSbS2, and NaSbSe2 are suitable candidates for both photovoltaic, particularly in tandem solar cells, and thermoelectric applications. Experimental synthesis and verification are suggested. |