Preparation Of Au/TiO₂ Composite Films And Research On Photoelectric Properties Of Solar Cells

Dye-sensitized solar cells(DSSC) have been rapid developed and have been become a hot topic of scientific research of renewable energy because of its low price, light quality, easy fabrication and working under low light. As a multi-component chemical structure of the system there are many questions in this new type of photovoltaic solar cells. Based on surface plasmon resonance (SPR) of noble metal nanoparticles and the semiconductor surface resonant coupling of electromagnetic field to increase the absorption of incident light and the transmission of electrons in the solar cells, thus improving the photoelectric conversion efficiency of DSSC.Nano TiO₂ sol for coating film was prepared by cooperating hydrothermal colloidal sol with organic polymer dispersing agent (PVA) in this paper. Nanocrystalline TiO₂ films of a porous structure with excellent performance were prepared by electro-hydrodynamic technique (EHD) and investigated by using XRD, TEM, SEM and UV-visible absorption spectra. etc. The results show TiO₂ nano-powder by hydrothermal synthesis is well distributed. The porous nanocrystalline TiO₂ films prepared by EHD technique have continuous distribution and multilevel hierarchical structure, therefore, they have better optical scattering properties. After successfully synthesized Au NPs with different sizes by the reduction of Citrate, we tried to coat the TiO₂ porous films with Au NPs using a simple solvent-assembling method. TEM characterized Au's sizes and SEM photos shown the Au NPs were dispersed on porous TiO₂ films. It showed that most of the Au nanoparticles had been assembled evenly on the TiO₂ films surface by UV-Vis spectrometer (UV-vis), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. DSSC was assembled by positive electrode with Au nanoparticles, sensitized dyes, electrolytes and counter electrode. It was proved that coupling of the electromagnetic field of porous TiO₂ films with surface plasmon resonance (SPR) of Au NPs enhanced the light absorption and charge transfer through the IV curve, IPCE curves and electrochemical impedance Nyquist curve. And photoelectric conversion efficiency was increased by adding Au NPs. We obtained that the total conversion efficiency was 6.70% under 100mW/cm² sunlight intensity.