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Metal-based semiconductor nanomaterials for thin-film solar cells 157

Fig. 8.3 TEM images of synthesized (A) spherical, (B) rod-like, and (C) wire-like TiO 2
nanocrystals; (D) HR-TEM image of wire-like TiO 2 .
Reprinted with permission from S. Lee et al., Two-step sol–gel method-based TiO 2
nanoparticles with uniform morphology and size for efficient photo-energy conversion
devices. Chem. Mater. 22 (2010) 1958–1965.

Ti (OH) ® TiO × x HO + ( 2 - x) HO ( Condensation)
2
2
4
2
Fig. 8.3 shows the TEM images of typical TiO 2 NPs obtained by the sol-gel
method [16].
8.2.1.2 Fabrication of TiO 2 NRs/NWs
Because of their high electron diffusivity, large specific surface area, and their ability to
restrain the redox reactions among carriers, TiO 2 NRs/NWs have been widely used as
one-dimensional (1D) photoanode materials in thin-film solar cells. Various techniques
have been employed to fabricate 1D nanomaterials for thin-film solar cells, including
chemical vapor deposition (CVD), electrodeposition, pulsed laser deposition (PLD),