A triple-layered, hierarchical 1D core-shell nanostructure with a plasmonic Ag octahedral core for use in solid-state dye-sensitized solar cells

A triple-layered, core-shell nanostructure is prepared with Ag octahedra, a SnO₂ nanotube (SNT), and a TiO₂ nanosheet (TNS) via a combined process of electrospinning and solvothermal reaction. In particular, a facile one-step synthesis process for Ag octahedral nanocrystals is suggested. The Ag@SNT@TNS hetero-nanostructure is uniformly distributed in an organized TiO₂ film derived with the poly(vinyl chloride)-graft-poly(oxyethylene methacrylate) (PVC-g-POEM) graft copolymer and hydrophilically pretreated TiO₂ nanocrystals. The efficiency of solid-state dye-sensitized solar cells (ssDSSCs) fabricated with this hetero-nanostructure reaches 7.8% at 100 mW cm^-2, which is much greater than that of cells without a hetero-nanostructure (5.2%) or that prepared with commercially available Dyesol paste (4.4%). This higher efficiency is attributed to the one-dimensional (1D) tubular structure, the improved surface area, and the plasmonic effect of Ag octahedral nanocrystals, resulting in enhanced short-circuit current density (J_sc), as confirmed by the incident photon-to-current efficiency (IPCE), electrochemical impedance spectroscopy (EIS), and intensity modulated photocurrent/voltage spectroscopy (IMPS/IMVS).