Three families of linear shaped TiO2 anatase nanocrystals with variable aspect ratio (4, 8, 16) and two sets of branched TiO2 anatase nanocrystals (in the form of open-framework sheaf-like nanorods and compact braid-like nanorod bundles, respectively) were employed to fabricate high-quality mesoporous photoelectrodes and then implemented into dye-sensitized solar cells to elucidate the intrinsic correlation holding between the photovoltaic performances and the structure of the nanocrystal building blocks. To this aim, the chemical capacitance and the charge-transfer resistance of the photoelectrodes were extrapolated from electrochemical impedance spectroscopy measurements and used to draw a quantitative energy diagram of the dye-sensitized solar cells realized, on the basis of which their photovoltaic performances have been discussed. It has thus been revealed that photoanodes made from braid-like branched-nanorod bundles exhibited the most favorable conditions to minimize recombination at the interface with the electrolyte due to their deep distribution of trap states, whereas linear-shaped nanorods with higher aspect-ratios result in more remarkable downshift of the conduction band edge.
Electrochemical Assessment of the Band-Edge Positioning in Shape-Tailored TiO2-Nanorod-Based Photoelectrodes for Dye Solar Cells
Roberto Giannuzzi;COZZOLI, Pantaleo Davide;GIGLI, Giuseppe
2013-01-01
Abstract
Three families of linear shaped TiO2 anatase nanocrystals with variable aspect ratio (4, 8, 16) and two sets of branched TiO2 anatase nanocrystals (in the form of open-framework sheaf-like nanorods and compact braid-like nanorod bundles, respectively) were employed to fabricate high-quality mesoporous photoelectrodes and then implemented into dye-sensitized solar cells to elucidate the intrinsic correlation holding between the photovoltaic performances and the structure of the nanocrystal building blocks. To this aim, the chemical capacitance and the charge-transfer resistance of the photoelectrodes were extrapolated from electrochemical impedance spectroscopy measurements and used to draw a quantitative energy diagram of the dye-sensitized solar cells realized, on the basis of which their photovoltaic performances have been discussed. It has thus been revealed that photoanodes made from braid-like branched-nanorod bundles exhibited the most favorable conditions to minimize recombination at the interface with the electrolyte due to their deep distribution of trap states, whereas linear-shaped nanorods with higher aspect-ratios result in more remarkable downshift of the conduction band edge.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
