| As is known to all, photoanode material which was used to absorb dye and transfer the photoelectrons into the SnO2conductive layer is very important to the final photoelectric conversion efficiency in the study of dye sensitized solar cell (DSSC). At present, nanometer TiO2is the best photoanode material, and the TiO2multiporous nanoparticle film was used most extensively. But on one hand, the TiO2multiporous nanoparticle film has too much interface to impede the transmission of photoelectrons, and there are many lattice defects to make some photoelectrons disappear, which both reduce the photoelectric conversion efficiency of DSSC. On the other hand, the TiO2multiporous nanoparticle film poor adhesion and fall easily off FTO substrates when it was printed on a large area, which hindered the development of large area DSSC. So it is very important and urgent to find and study new morphological photoanode material deeply, expecially the photoanode material which can separate the electron hole pair and transfer the photoelectrons fastly. Studies as follows were finished based on the fact that low dimensional materials could offer high-speed channel for electrons:TiO2nanorod array film was prepared under different conditions with hydrothermal method which was low cost and simple. It was found that this type of TiO2film grew on the FTO substrate was homogeneous and had good adhesion the tetragonal rutile phase from the FESEM images a nd the XRD patterns. And diameters of TiO2nanorods with length about4.5μm were about in the range of100nm-900nm. The growth of this TiO2nanorod array film could be affected by reaction temperature, initial reactant concentration and growth time. This TiO2nanorod array film could not grow when the reaction temperature was too low temperature, initial reactant concentration too small or growth time too short, and FTO substrate would be corroded at too high temperature. But Without any modification treatment, only a light-to-electricity conversion efficiency of0.41%(AM1.5G) was achieved by using this TiO2nanorod array film as the photoanode in a DSSC, possibly there was too small space between a TiO2nanorod and its neighboring nanorods for adsorbing more dye.One type of novel and thick TiO2array-cluster film was prepared also with hydrothermal method based on the study of TiO2nanorod array film to improve the photoelectric conversion efficiency of DSSC. It was found that this type of TiO2film on the FTO substrate was a structure of two-layer and had the tetragonal rutile phase from the FESEM images and the XRD patterns. However, the subjacent layer of the two layers was TiO2array, while the supernatant layer was TiO2clusters, and both of them were formed from TiO2rods which developed from finer TiO2nanorods. This two-layer structure was advantageous for TiO2film to adsorb more dye and could provide a fast circulation channel for photon-generated electrons, and the more the clusters were, the higher the light-to-electricity conversion efficiency was. The thickness of this type of TiO2film could reach to beyond40μm and the number of the clusters of supernatant layer could be varied by changing initial reactant concentration, growth time or angles of FTO placed. Without any modification treatment, a light-to-electricity conversion efficiency of1.24%was achieved by using22.9μm-thick TiO2array-cluster film which was prepared under the0.06mol/L-dosage of tetrabutyl titanate (TBOT), at140℃for72h and the FTO substrates placed at180-degree angle as the photoanode in a Dye-Sensitized Solar Cell (DSSC). And the photoelectric conversion efficiency of DSSC with TiO2array-cluster film used as photoanode was twice as more as that of DSSC with TiO2nanorod array film, for there was larger space for adsorbing dye between a TiO2nanorod of clusters and its neighboring nanorods, so this novel TiO2array-cluster film has very much potential for DSSC. |
PDF Full Text Request