Silver nanoparticle-embedded titania nanobelts with tunable electronic band structures and plasmonic resonance for photovoltaic application

Abstract

Metallic silver nanoparticle (NP)-embedded single-crystalline titania (Ag@TiO2) nanobelts have been prepared by a new process with use of sodium titanates sequentially from ion exchange, thermal hydrogenation to post-calcination. The structural transformation involved and their morphology were characterized. This work explored photovoltaic efficiency of these composite nanobelts as anode materials in dye-sensitized solar cells and their electronic and energy band properties, which correlate with the Ag content. Optical absorption and photoluminescence analyses reveal core Ag NP-induced localized surface plasmon resonance (LSPR) and mediated electron transfer within the titania shell. According to Mott-Schottky analysis, the Ag addition causes an increase in the donor density and an upshift in the flat-band potential of the oxide host. The investigated Ag@TiO2 cells produced higher photocurrents and open-circuit voltages than the bare TiO2 one, and the best performance was attained with a marked enhancement by 72% in the photovoltaic efficiency. As indicated by electrochemical impedance analysis, the Ag-added nanobelts are beneficial to rapid electron diffusion and electron lifetime, so that they promote charge collection efficiency. Synergistic combination of plasmonic resonance, electronic conduction and Fermi-level upshift is a plausible strategy to functionalize the one-dimensional core-shell Ag@TiO2 nanostructures for optoelectronic applications.