Synthesis of Au nanoparticle-incorporated mesoporous TiO₂ composite thin films and their electrical properties

Mesoporous TiO2 thin films containing Au nanoparticles were synthesized via sol–gel and evaporation-induced self-assembly processes. In this work, the effect of surfactant concentration on the pore structure of mesoporous TiO2 thin films was investigated and Au nanoparticles were introduced to enhance the electrical conductivity of mesoporous TiO2 without collapse of the pore structure. Pore structure was analyzed with small angle X-ray diffraction and grazing incidence small angle X-ray scattering. Crystallization of TiO2 was analyzed with wide angle X-ray diffraction. Increased surfactant concentration led to a corresponding increase in the porosity of mesoporous TiO2 thin films, but pore ordering in the mesoporous structure was still enhanced. The increasing rate of electrical resistivity associated with increased porosity was reduced in response to decreases in the electron scattering probability, which are strongly dependent on the pore ordering of mesoporous structures. Furthermore, the electrical conductivity of mesoporous TiO2 composite thin films was enhanced by the incorporation of Au nanoparticles due to the surface plasmon effect of Au nanoparticles.