Preparation of transparent TiO2 nanocrystalline film for UV sensor

Nanocrystalline TiO2 is a very important inorganic semiconductor function material with a wild band gap of 3.0-3.2 eV. Owing to its characteristics of selectiveabsorption for UV light, it has been extensively applied in photocatalysts, dye-sensitized sola…

Preparation of transparent TiO2 nanocrystalline film for UV sensor

The nanocrystalline TiO₂ film electrodes were prepared by sol-gel method at different calcining temperatures, which had characteristics of different film thickness, uniform transparency, as well as high photoelectric and mechanical stability. Photoelectric measurements show that calcining temperature and film thickness could remarkably influence the photoelectric properties of the electrodes. The film calcined at 450°C is anatase phase with high crystallinity and strong photoelectric activity, and shows the largest photocurrent. When the temperature is lower than 450°C, the film has weaker crystallinity because of a large number of defects in the film, and this is not favorable for the transport of the photogenerated carriers. And at a temperature higher than 450°C, the photocurrent of the electrode is decreased due to anatase-rutile phase transition in the film. The increase in film thickness is favorable to the enhancement of ultraviolet light (UV) absorption amount, which would improve the photoelectric activity of the film. But, excessive thickness will increase the recombination rate of the electron-hole pairs, and result in a reduction in electrode’s photoelectric activity. In addition, the response sensitivity and stability of the photocurrent produced in the electrode are related to bias potential. At a potential of 0.4 V, the electrode shows a saturated photocurrent of 30.8 μA and a response time of ∼1 s, suggesting that the prepared TiO₂ film electrode can be used for making UV sensors.