(1) Preparation of ITO fibre
Melted spinning, liquid crystallized spinning and colloidal spinning is generally between 5 to 500μm. The diameter of a fibre made by any traditional method such as, whereas the diameter of fibre made by electrospinning is roughly between 3 nm to 5μm. Electrospinning is regarded as the essential fundamental method for manufacturing nanometer fibres. Electrospinning is the technology of making polymer fibres by applying electric field to a polymer solution. The electrospinning technology is utilized in multiple polymer materials including nylon and polyvinyl acetate. ITO is a transparent conducting electrode because of its unique properties of high transmittance, low resistivity and excellent adhesion to substrates. This studied is used a sol-gel composition for producing conductive fibres in an electrospinning process. The sol-gel composition comprises an indium tin oxide and a polyethylene oxide; wherein they are mixed in a ratio of about 8.5:1.5 (w/w) that conductivity is 1000Ω/□。
(2) Preparation of a hybrid layer of TiO2 and its precursor
In a solar cell system, it is important that the active layer of the solar cell absorbs as many photons as possible to produce more carrier electrons. In other words, the same photocurrent may be produced with a thinner film, and additional enhancement is also expected in thinner solar cells owing to the suppressed carrier recombination and decreased internal resistance. The essential requirement for the production of DSSC modules is to produce thin nanocrystalline TiO2 films with higher surface area, together with a better light scattering layer (400-500 nm sized TiO2), so that the production cost can be reduced by lowering the dye consumption without sacrificing the cell performance. Although the small size of the TiO2 nanoparticles (∼20 nm) employed to ensure a high surface area makes conventional nanocrystalline TiO2 films as poor light scatters, mixing the nanoparticles with larger particles or applying a scattering layer to the nanocrystalline film has been shown in simulations and increase of light harvesting by enhancing the scattering of light is feasible. The efficiency of hybrid TiO2 film by P25 and titanium tetraisopropoxide is better than that of P25 and that of two layers made by P25 and titanium tetraisopropoxide respectively. Besides that, hybrid TiO2 film can be made by electrospinning, less time and lower production cost. We believe the simple and cheap merit of electrospinning will have wide application in DSSC and help then move quickly to commercialisation.