Despite all these differences, we recognize similar desirable features in the band structures (visualized with the GPAW code ) of Ag 3 PS 4 and Ba 4 P 2 S (Fig. ). Band gaps are direct and lie in the visible (after applying the HSE correction), and both the CBM and the VBM have high band dispersion. Thus, both materials have significant potential for high α and high μ. Since the chemical origin of the band edges is completely different in the two materials, tuning the P/S ratio (or equivalently, the oxidation state of P) is a design knob unique to PSs. As the character of the band edges can be tuned as a demonstration of the unique chemical versatility of PSs. The crystal structure, electronic band structure, and orbital-resolved electronic density of states (DOS) are shown for Ag3PS4 (top row) and Ba4P2S (bottom row). Most of this information is already available elsewhere. For the sake of consistency, we have recalculated the band structures and DOS at the PBE level using the GPAW code. Even though the character of the band edges is entirely different in the two materials (see DOS), the resulting band structures have similar features (direct band gaps, disperse bands). The same color code is used for atoms and for electronic states. Silver is displayed in grey, sulfur in yellow, phosphorus in purple and barium in green.