Plasmon induced charge transfer mechanism in gold-TiO2 nanoparticle systems: The size effect of gold nanoparticle

The application of surface plasmon in the solar-cell design has become a hot topic in the field of photovoltaic research. The enhancement of the photoelectric conversion efficiency is due to charge transfer caused by photoinduced injection of electrons from the metal to the corresponding acceptors. Revealing the basic physical mechanism further is of very important practical significance. We used the femtosecond time-resolved IR ultrafast spectroscopy technology and chose to excite the plasmon band of gold while changing the size of the gold nanoparticle to regulate the complex nanoprocess of the separation and recombination of photogenerated electrons in gold assembled with TiO2 systems. Behavior of hot holes in gold was also considered. We found that larger gold particles resulted in longer charge recombination times. The mechanism is discussed in detail in terms of restricted carrier diffusion in the nanospace.