Liquid phase deposition/anodizing of TiO2 nanotube working electrode for dye-sensitized solar cells

With a high carrier transfer rate, anodizing TiO2 nanotubes (TNTs) are often used as the working electrode in dye-sensitized solar cells (DSSCs). However, the TNT length is restricted by the thickness of the Ti foil, which in turn limits the dye adsorption efficiency of the working electrode. To combat this problem, this study used liquid-phase deposition (LPD) to fabricate a TiO2 film on anodizing TNT. LPD allows for more rapid and even deposition of TiO2 films on the anodizing TNT structure than does vacuum deposition. Analysis revealed that LPD-TiO2 films fabricated at 3.33 nm/s increased the length of the TNT from 17.76 to 24.80 μm, and the dye adsorption capacity rose from 9.8 × 10−7 to 1.07 × 10−6 mol/m3. Testing confirmed that the photoelectric conversion efficiency of the DSSC device of the LPD/anodizing TNT increased from 2.43% to 2.85%, that the interface impedance of the DSSC device (R2) decreased from 132 to 41.5 Ω, and that the electron lifetime (τe) increased. In sum, the LPD-TiO2 film increased the thickness, dye adsorption efficiency and reduced the oxygen vacancies in the anodizing TNT; in other words, the coating effectively enhanced the photoelectric conversion properties of the DSSC device of the working electrode.