Effect of the Compact TiO₂ Layer on Charge Transfer between N3 Dyes and TiO₂ Investigated by Raman Spectroscopy

Abstract

The charge transfer between N3 dyes and TiO2 electrodes has been investigated by Raman spectroscopy. The TiO2 nanoparticles are synthesized at different temperatures to form the compact layer in the photoelectrode. The red shift of the Eg(3) mode of the TiO2 electrode increases with an increase in the synthesis temperature of TiO2 nanoparticles, which is also associated with its vibration mode and conversion efficiency. This indicates that the charge transfer between N3 dyes and the TiO2 electrode reaches optimal when TiO2 nanoparticles are synthesized at 190 °C. In electrochemical impedance spectroscopy measurements of the dye-sensitized solar cells (DSSC), the internal resistance of the cell decreases with an increase in the synthesis temperature, suggesting the improvement of the electron transfer from N3 dyes into the TiO2 electrode at higher synthesis temperature. Herein, we have established a relationship between the red shift of the Eg(3) mode of the TiO2 electrode and the energy conversion efficiency. This demonstrates that the Raman spectroscopic technique is a convenient and useful tool to investigate the charge transfer between N3 dyes into TiO2 electrode and its impact on the performance of DSSC.