Preparation And Characteristics Of TiO₂ Nanocrystals And Thin Film And Study On Its Conversion Of Light To Electricity

TiO₂ is an important inorganic material, and it has been paid close attention to distinct properties in physics and chemistry. Since the anatase has a forbidden bandwidth of 3.2eV and can absorb UV whose wavelength is less than 387.5nm, it can be a potential material for detecting UV. In this paper, the nanometer technology, the physical and chemical properties of nano-TiO₂, and the preparation of TiO₂ nanocrystals and TiO₂ thin film are reviewed. The experimental study on application of TiO₂ nanocrystals and TiO₂ thin film has also been developed in the respect of photo-electric conversion.Among many preparation technologies of TiO₂ nanocrystals, chemical methods are widely adopted in laboratory for simple equipment. There are many materials for synthesizing TiO₂. TiCl₄ and C₁₆H₃₆O₄Ti are commonly used, and TiCl₄ is welcome for its lower price. In this paper, by means of hydrolysis method and Sol-Gel process, TiO₂ nanocrystals was synthesized with TiCl₄;TiO₂ nano thin film was prepared on ITO glass substrate by dip coating and spin coating process.TiO₂ nanocrystals, synthesized by the hydrolysis method of TiCl₄, has low weight loss and high thermal stability. Anatase can be obtained at low temperature, and the particle size is less than 10nm under 400℃. Using the Sol-Gel process of TiCl₄, TiO₂ nanocrystals, whose particle size is big, appears the phase transformation from anatase to rutile occurs at the ambient temperature of 800℃, and turns rutile at 1000℃.The TiO₂ nano thin film prepared by spin coating process is white, while the TiO₂ nano thin film made by dip coating process is colorless and transparent. When the baking temperature is too low, the TiO₂ is amorphous;whereas the temperature is too high, the size of the power growing bigger, the hole between the power is recede, so the photocurrent is low. If the film is too thick, the rate of electron meet cavity is increase, it can also decrease the photocurrent. By the experimental observation, the thin film, made by dip coating process with heat treatment at 400℃ for 1h, has the highest photocurrent. Dye of coumarin can increase photocurrent efficiently.