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

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. (C) 2014 Elsevier B.V. All rights reserved.