Preferentially oriented large antimony trisulfide single-crystalline cuboids grown on polycrystalline titania film for solar cells

Photovoltaic conversion of solar energy into electricity is an alternative way to use renewable energy for sustainable energy production. The great demand of low-cost and efficient solar cells inspires research on solution-processable light-harvesting materials. Antimony trisulfide (Sb 2 S 3 ) is a promising light-harvester for photovoltaic purposes. Here we report on the in situ grown monolayer of preferentially oriented, large Sb 2 S 3 single-crystalline cuboids on a polycrystalline titania (TiO 2 ) nanoparticle film. A facile, oriented seed-assisted solution-processing method is used, providing the Sb 2 S 3 /TiO 2 -based bulk/nano-planar heterojunction with a preferred structure for efficient planar solar cells. An orientation-competing-epitaxial nucleation/growth mechanism is proposed for understanding the growth of the Sb 2 S 3 single-crystalline cuboids. With an organic hole transporting material, the stable solar cell of the heterojunction yields a power conversion efficiency of 5.15% (certified as 5.12%). It is found that the [221]-oriented Sb 2 S 3 cuboids provide highly effective charge transport channels inside the Sb 2 S 3 layer.