Defect-Engineered SnS2@Nitrogen-Doped Carbon Spheres as High-Efficiency Pt-Free Counter Electrodes for Dye-Sensitized Solar Cells

This study presents the development of nitrogen-doped carbon sphere/SnS 2 nanocomposites (SnS 2 @NCS) as efficient platinum-free counter electrodes for dye-sensitized solar cells (DSSCs). Nitrogen doping introduces topological defects into the carbon matrix, facilitating the epitaxial growth of ultrathin SnS 2 nanosheets into hierarchical architectures. The optimized SnS 2 @NCS electrode exhibits significantly enhanced catalytic activity, demonstrated by a low charge–transfer resistance of 1.070 Ω cm −2 (representing a 74.6% reduction compared to the undoped SnS 2 @CS) and achieves a power conversion efficiency of 8.18%, rivaling that of platinum-based counterparts. The improved performance is attributed to synergistic effects arising from C  N bonds and SnS 2 nanosheets, which collectively enhance interfacial charge transport and electrolyte infiltration. This work demonstrates a cost-effective strategy for fabricating high-performance DSSCs.