Dye-Sensitized Solar Cells Inspired Method to Modulate Photo-Induced Charge Transfer Efficiency for Enhancing the SERS Activity of Semiconductor

While the Lithium ion modification strategy is widely adopted in tuning the bandgap of semiconductors in dye-sensitized solar cells (DSSCs), such strategy is yet to be applied to semiconductor-based surface enhanced Raman scattering (SERS), which is also a photo-induced charge-transfer (CT) process. Here, a new DSSCs-inspired modification method is proposed for TiO2 nanoparticles (NPs): through the adsorption of Li+, the surface states of TiO2 NPs are more abundant, so that the SERS intensity and charge transfer of the adsorbed molecule are significantly enhanced. Similar to DSSCs systems, it is found that the conduction band edge and surface state energy level of TiO2 NPs shift downward with increasing Li+ concentration, which facilitates the CT interaction between the molecules and the SERS substrates. The EF can reach to 10(4), 1-2 degrees higher than previously reported pure semiconductors. This is the first time to use the DSSCs-inspired Li+ adsorption strategy on TiO2 NPs as SERS substrate to investigate its SERS enhancement effect, which may provide new ideas for the development of semiconductor nanomaterials in the research of SERS substrates.