Nanostructured Nitrogen Doping TiO Nanomaterials for Photoanodes of Dye-Sensitized Solar Cells - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 70

Fig. 14 a Open-circuit voltage decay transients of the dye-sensitized N-doped and pure TiO 2
solar cells; b calculated electron lifetime (Eq 1 ) versus open-circuit voltage [ 56 ]; c s e versus N/Ti
molar ratio [ 42 ]
Fig. 15 EIS spectra of
N-doped DSCs [ 44 ]
ions in the electrolyte and (2) the back reaction at the TiO 2 /electrolyte interface,
presented by the semicircle in intermediate-frequency regime. Dai et al. reported a
retarded electron recombination in the N-doped DSCs. This retarded electron
recombination may be due to the change in surface properties, e.g., the lattice
perfection (Fig. 15 ). The charge transfer resistances demonstrated dependency on
the N dopant amount. The electron lifetime of N-doped DSCs tended to decrease
as the N dopant increased.
Overall, fast electron transport, short electron lifetime, and retarded electron
recombination were found in N-doped DSCs. Moreover, a synergistic effect of
high dye uptake and efficient electron transport contributed to the improvement of
N-doped DSCs.
5 Summary and Outlook
In conclusion, the recent development of N-doped TiO 2 nanomaterials and its
application into DSCs is summarized. The different synthesis approaches, nitrogen
dopant types, and amount can affect the physical and chemical properties of
N-doped TiO 2 , thereby their performance in the photoanodes of DSCs. Moreover,
nitrogen doping can help charge separation and transport in QDSCs. Based on
these results, the synergistic effect of higher dye uptake, N dopant amount, and