High-efficiency dye-sensitized solar cells based on bilayer structured photoanode consisting of carbon nanofiber/TiO2 composites and Ag@TiO2 core-shell spheres

In this contribution, bilayer structured photoanode consisting of electron transport layer and light-scattering layer was elaborately designed for dye-sensitized solar cells (DSSCs). The electron transport layer was constructed by hierarchical carbon nanofiber/TiO2 (CF/TiO2) composites characterized by high electrical conductivity, while the light-scattering layer was assembled by Ag@TiO2 core-shell spheres with excellent light-scattering capacity. To demonstrate the potential application of such promising photoanode, the DSSC based on CF/TiO2-Ag@TiO2 bilayer structured photoanode was fabricated and characterized in detail. In stark contrast, the resultant DSSC exhibited a superior short-circuit photocurrent density of 16.51 mA cm−2, a prolonged electron lifetime of 93.7 ms, as well as a notable enhanced PCE up to 7.35%, which was about 41% higher than that of commercial P25-based DSSC. Along with the analysis of microstructure characteristics, light absorption/reflection spectra as well as electrochemical impedance spectroscopy, the significantly enhanced photovoltaic performance of DSSC based on the bilayer structured photoanode were believed to be related to the combined effect of sufficient dye loading endowed by the large specific surface area of photoanode materials, the outstanding light-harvesting capacity offered by the unique Ag@TiO2 light-scattering layer and the efficient electron transfer and/or negligible interfacial charge recombination benefited from the unique CF/TiO2 electron transport layer.