Dye-sensitized solar cells based on TiO2-B nanobelt/TiO2nanoparticle sandwich-type photoelectrodes with controllable nanobelt length

Abstract

The TiO₂-B nanobelt (NB)/TiO₂ nanoparticle (NP) sandwich-type structure photoelectrode, with controllable nanobelt length, has been used to fabricate high-efficiency dye-sensitized solar cells (DSSCs), which combine the advantages of the rapid electron transport in TiO₂-B NBs and the high surface area of TiO₂ NPs. The results indicate that the sandwich-type photoelectrode achieves higher photoelectrical conversion efficiency when compared with the TiO₂ nanoparticulate electrode. Increasing the length of TiO₂-B NBs has been demonstrated to improve the photoelectric conversion efficiency (η). DSSCs with the longest (10 μm) TiO₂-B NBs yield the highest η of 7.94%. The interfacial electron transport of DSSCs with different lengths of TiO₂-B NBs has been quantitatively investigated using the photovoltage transient and the electrochemical impedance spectra, which demonstrates that the DSSCs with longest TiO₂-B NBs display the highest electron collection efficiency and the fastest interfacial electron transfer.