High-quality SnO2@SnS2 core–shell heterojunctions: Designed construction, mechanism and photovoltaic applications

Abstract

High-quality SnO2@SnS2 core–shell heterojunctions have been constructed through sulfurization of SnO2 nanoflowers self-sacrificial templates with H2S gas at relatively low temperature in this paper. The unreacted SnO2 core and the in-situ synthesized SnS2 shell are in good crystallinity with a low lattice mismatch interface. The formation mechanism of the core–shell heterostructures have been examined by experiments and theoretic computation from the perspectives of both adsorption and diffusion. When used as photoanode in all-solid-state semiconductor-sensitized solar cells, the SnO2@SnS2 core–shell heterojunctions based hybrid solar cell shows a promising conversion efficiency of 1.45% under 1 sun illumination, which is over 5 times than that of SnS2 quantum dot sensitized SnO2 electrode made by the common chemistry bath deposition method. The enhanced photovoltaic performance is contributed to the unique structure of SnO2@SnS2 core–shell heterojunctions which provide highly covered sensitizers and favored interface for suppressing the charge recombination from SnO2 to electrolyte. This strategy and understanding can be extended to other nanostructure core–shell architecture and fields.