Super helical Au/TiO₂ nanocomposites based on plasmid DNA for efficiency dye-sensitized solar cells

Super helical Au/TiO₂ nanocomposites were synthesized using plasmid DNA and incorporated into photoanode of dye-sensitized solar cells (DSSCs). The performance of photoanode films and DSSCs was investigated. Plasmid DNA can not only support as bio scaffold to synthesize Au/TiO₂ nanocomposites, but also act as an effective reducing agent under ultraviolet (UV) irradiation. Compared with TiO₂-only DSSCs, the light harvesting (LH), corresponding photocurrent and power conversion efficiency (PCE) of DSSCs were enhanced by incorporating of mechanically mixed Au-TiO₂ NPs and Au/TiO₂ nanocomposites. Compared to the TiO₂-only DSSCs samples (5.12%), the PCE of DSSCs with mechanically mixed Au-TiO₂ nanoparticles (NPs) (6.41%) increased by 25.20%, and DSSCs with Au/TiO₂ nanocomposites (8.17%) increased by 59.57%. The best PCE (8.24%) of DSSCs was obtained with the incorporation of Au/TiO₂ nanocomposites. Two reasons were presented for the best performance of DSSCs with Au/TiO₂ nanocomposites. Firstly, the localized surface plasmon resonance (LSPR) effect of Au NPs enhanced the absorption visible light. Secondly, the super helical structure of Au/TiO₂ nanocomposites provided a path for the transmission of photoelectrons.