Multiple nano-TiO2 layers to prevent dye/nano-TiO2 from photodegradation under a UV-exposure environment

A device of multiple nano-TiO2 layers was proposed and fabricated to prevent a dye/nano-TiO2 region from serious photo-degradation. In this device, the top of the dye/TiO2 region was designed to be coated using sol–gel nano-TiO2 thin films to shield UV irradiation from the photodegradation effect. The sol–gel TiO2 was prepared in a low temperature (75 8C) and verified as nano-sized particles and an anatase crystalline structure. Different devices of the multi-layer samples fabricated using different compositions of nano-TiO2 were produced and exposed for UV irradiation tests. Results show that the presence of the sol–gel TiO2 films coated on top of the dye/TiO2 region can significantly alleviate the dye photo-degradation under UV irradiation. This multi-layer device can effectively improve the photo-stability of the dye/TiO2 region in a UVexposure environment.