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Generally, tetrahedrally coordinated Ag-based chalcogenides have wider band gaps than their Cu-based counterparts. Recent studies have suggested Cu 3 SbS 4 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 Ag 3 SbS 4 by first-principles means, since one can anticipate improved optical properties for this compound. The results indeed demonstrate that enargite Ag 3 SbS 4 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 Ag 3 SbS 4 could be a candidate for absorber in high-efficient thin-film PVs. • Enargite phase is the ground state of Ag 3 SbS 4. • Enargite Ag 3 SbS 4 has a wider band gap than famatinite Cu 3 SbS 4. • Enargite Ag 3 SbS 4 has the suitable band gap to be as PV absorber. • Enargite Ag 3 SbS 4 exhibits thermodynamical and dynamical stability. [ABSTRACT FROM AUTHOR]

I–III–VI 2 chalcopyrite compounds (I = Cu or Ag; III = Al, Ga, or In; VI = S, Se, or Te), especially sulfides and selelides, were studied as the promising photocathodes for water splitting. In this work, tellurides with a proper band gap [ i.e. CuAlTe 2 (2.06 eV) and AgAlTe 2 (2.27 eV)] had been investigated as the photocathode candidates by our first-principles calculations. Our results show that the band edge positions of AgAlTe 2 straddle the water redox potentials. In combination with the suitable band gap energy and light carrier effective masses along [001]-direction, AgAlTe 2 has the capacity of being a good candidate for water splitting. Moreover, to increase the absorbing ability on visible light, Ga-doping can adjust the band gap of AgAlTe 2 to an appropriate value and remain the reasonable band edge positions of AgAlTe 2 , which is suggested as an effective approach to optimize its electronic structure for water splitting. [ABSTRACT FROM AUTHOR]

Chalcopyrite compounds like Cu(In,Ga)(S,Se) 2 have been widely studied as the absorber for single-junction solar cell. Other wide band gap Chalcopyrite compounds like CuGaS 2 have been utilized as the host of the absorber for intermediate band solar cell (IBSC). Here, a Chalcopyrite compound LiGaTe 2 with a suitable band gap as the host of the absorber for IBSC has been investigated by HSE06 first-principles calculations. Our results revealed that a partially-filled and isolated intermediate band (IB) is generated in the forbidden band gap of LiGaTe 2 after group ⅣA elements (i.e., Si, Ge and Sn) substituting at Ga site and three-photon absorption can be achieved in the doped systems. Combining the suitable IB position induced by Sn-doping and its low formation energy, Sn-doped LiGaTe 2 as a promising candidate has been proposed to be the absorber for IBSC. [ABSTRACT FROM AUTHOR]