Marina R. Filip, Christopher E. Patrick, Feliciano Giustino
We present first-principles calculations of the quasiparticle band structures of four isostructural semiconducting metal chalcogenides A$_2$B$_3$ (with A = Sb, Bi and B = S, Se) of the stibnite family within the G$_0$W$_0$ approach. We perform extensive convergence tests and identify a sensitivity of the quasiparticle corrections to the structural parameters and to the semicore $d$ electrons. Our calculations indicate that all four chalcogenides exhibit direct band gaps, if we exclude some indirect transitions marginally below the direct gap. Our converged quasiparticle band gaps are 1.6 eV (Sb$_2$S$_3$), 1.3 eV (Sb$_2$Se$_3$), 1.7 eV (Bi$_2$S$_3$) and 1.2 eV (Bi$_2$Se$_3$). By comparing our calculated gaps with the ideal Shockley-Queisser value we find that all four chalcogenides are promising as light sensitizers for nanostructured photovoltaics.
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http://arxiv.org/abs/1301.6571
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