Nanoparticle (NP) and nanotube (NT) morphologies consisting of mixed-phase (anatase and rutile) TiO2 photoanode were prepared to investigate electron transport and photovoltaic performance for dye-sensitized solar cell (DSSC) application. Agglomeration and condensation of TiO2 nanostructures combined with phase change were observed during 650 C sinter. The longer electron lifetime (τ) 53 ms with 5 × 1018 cm -3 of electron density (ns) in pure anatase NT photoanode could not achieve high solar conversion efficiency because rich surface states and oxygen vacancies trigger recombination of back-electrons and reduce the resistance (Rk) between TiO2 photoanode and electrolyte interface. In contrast, 12% rutile content of NP TiO2 photoanode with shorter τ and lower ns could improve light harvesting and achieve overall solar conversion efficiency to 5.1%. It is speculated that the high Rk value inhibits the recombination of back-electron and increases high open circuit voltage. Moreover, high efficiency of electron migrated from rutile conduction band to anatase trapping sites contribute to the overall solar energy conversion.
All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry