Interconnected molybdenum disulfide@tin disulfide heterojunctions with different morphologies: a type of enhanced counter electrode for dye-sensitized solar cells

In this work, we successfully synthesized SnS 2 nanoparticles, a hollowed-out netty MoS 2 (nMoS 2 ) nanostructure, a flower-like MoS 2 (fMoS 2 ) nanostructure, an nMoS 2 @SnS 2 heterostructure, and an fMoS 2 @SnS 2 heterostructure via a simple and facile hydrothermal process. We used powder X-ray diffractograms to verify purity and crystalline phases of the as-prepared samples. Additionally, the structures and morphologies of as-prepared components were checked by X-ray photoelectron spectroscopy analysis (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). A dye-sensitized solar cell (DSSC) assembled with this original heterostructure as a counter electrode (CE) displayed a splendid power conversion efficiency (PCE) of 7.63% along with stable catalytic performance for triiodide reduction. This is better than other DSSCs including: SnS 2 CE (6.67%), nMoS 2 CE (5.78%), fMoS 2 CE (5.37%), and fMoS 2 @SnS 2 CE (7.08%). According to our experimental results, we believe that the outstanding performance of nMoS 2 @SnS 2 heterostructures for a DSSC is because of their characteristic crystal structure, which may contribute to playing a heterogeneous and synergistic effect between the active materials, optimize dispersity of the samples, avoid recombination of electron-hole pairs to accelerate velocity of triiodide reduction, and enhance stability in a I 3 − /I − electrolyte. Hence, the nMoS 2 @SnS 2 heterostructure can play a better role in DSSCs with excellent performance and superior stability as an efficient CE. The MoS 2 @SnS 2 heterojunctions have been synthesized and displayed the enhanced performance due to the specific crystal structure.