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Generally, tetrahedrally coordinated Ag-based chalcogenides have wider band gaps than their Cu-based counterparts. Recent studies have suggested Cu3SbS4 as the absorber in low-cost and low-toxicity photovoltaic (PV), however its band gap is ∼0.5 eV smaller than the ideal value of ∼1.3 eV. In this work, we investigate Ag3SbS4 by first-principles means, since one can anticipate improved optical properties for this compound. The results indeed demonstrate that enargite Ag3SbS4 is a direct-gap semiconductor with a band gap of 1.38 eV, thus optimal for single-junction solar cells. Furthermore, its carrier effective masses, optical coefficients and spectroscopic limited maximum efficiency are comparable to well-established PV compounds. The compound exhibits also thermodynamical and dynamical stability. Hence, based on the present theoretical study we predict that Ag3SbS4 could be a candidate for absorber in high-efficient thin-film PVs., QC 20231009

The electronic structure of AgGaSe2 has been investigated as a photocatalyst candidate by first-principles calculation. Our results demonstrate that the band edge positions of bulk AgGaSe2 straddle the water redox potentials. From the band offset calculation, we find that Al-doping of AgGaSe2 shifts the conduction band minimum upwards, whereas Cu-doping of AgGaSe2 shifts the valence band maximum upwards. By (Ag, Cu)(Ga, Al)Se-2 alloying one can thereby tailor both the band edge positions and the band gap energy, and this effect provides an approach to optimize the band properties for overall water splitting. Moreover, AgGaSe2 forms a suitable junction with CuGaSe2 with a type-II band offset, which facilitates electron-hole separation. The AgGaSe2 and CuGaSe2 junction can be designed as a tandem photoelectrochemical device to improve the photocatalytic properties of the system., QC 20140425