ZnSnS3 : Structure Prediction, Ferroelectricity, and Solar Cell Applications

The rapid growth of the solar energy industry has produced a strong demand for high performance, efficient photoelectric materials. Many ferroelectrics, composed of earth-abundant elements, are useful for solar cell applications due to their large internal polarization. However, their wide band gaps prevent them from absorbing light in the visible to mid-infrared range. Here, we address the band gap issue by investigating, in particular, the substitution of sulphur for oxygen in the perovskite structure ZnSnO3 . Using evolutionary methods we identify the stable and metastable structures of ZnSnS3 and compare them to those previously characterized for ZnSnO3 . Our results suggest that ZnSnS3 forms a monoclinic structure followed by metastable ilmenite and lithium-niobate structures. The latter structure is highly polarized and it possesses a significantly reduced band gap of 1.28 eV. These desirable characteristics make it a prime candidate for solar cell applications.