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

Abstract

In this work, we successfully synthesized SnS₂ nanoparticles, a hollowed-out netty MoS₂ (nMoS₂) nanostructure, a flower-like MoS₂ (fMoS₂) nanostructure, an nMoS₂@SnS₂ heterostructure, and an fMoS₂@SnS₂ 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: SnS₂ CE (6.67%), nMoS₂ CE (5.78%), fMoS₂ CE (5.37%), and fMoS₂@SnS₂ CE (7.08%). According to our experimental results, we believe that the outstanding performance of nMoS₂@SnS₂ 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 I₃⁻/I⁻ electrolyte. Hence, the nMoS₂@SnS₂ heterostructure can play a better role in DSSCs with excellent performance and superior stability as an efficient CE.