Study On Nanocrystalline ZnO Based Dye-sensitized Solar Cells

Compared with traditional silicon solar cells, nanocrystalline dye-sensitized solar cell has been getting more and more attention with its low cost and simple production process. In the paper, fistly ZnO nanopowders with different morphologies were prepared, then the dye-sensitized solar cells were prepared, lastly composite and optimization of battery's photonaode structure were researched. The main experimental contents and results are as following:(1) With PEG as the soft template, the ZnO nanoparticles and ZnO nanorods were prepared by hydrothermal synthesis under certain conditions. When the molar ration of [Zn²⁺]/[OH-] is 0.5, ZnO nanoparticles with diamatere 150nm were prepared. With increase of the molar ratio of [Zn²⁺]/[OH-], ZnO morophology changed from nanoparticle to nanorod. With the increaseing of PEG molecular weight, the diameter of ZnO nanoparticles decreased.(2) Hydrothemal sysnthesis temperature is 220℃. When the molar concentrations of NaOH were 0.05mol/L, 1mol/L and 2mol/L, the micron-size of ZnO nanopowders were obtained. With the increase of the molar concentration of NaOH, the aspect ratio of ZnO decresed. ZnO nanorods which the length and diameter were 500nm and 100nm respectively were got when the molar concentrations of NaOH was 4mol/L.(3) When Hydrothemal sysnthesis temperature and the molar concentrations of NaOH were respectively100℃and 1mol/L, columnar ZnO was obtained. With the increase of the molar concentration of NaOH, the size of ZnO changed from micron-size to nanos-size. when the molar concentrations of NaOH were 4mol/L, ZnO nano-sheets which length, width and thickness were 800nm, 500nm, 80nm respectively were obtained.(4) ZnO nano-microspheres were prepared by heating under reflux with zinc acetate and alcohols as raw materials. The influences of different synthesis temperatures and different alcohols on ZnO properties were studied. ZnO nanospheres which the ranges of sphere diameter were 100⁸00nm were prepared. ZnO nanospheres doped with Li+ ions and IO3- ions were prepared. The diameters of ZnO nanospheres became uniform and smaller by doped Li+ ions and IO3- ions. When added molar comcemtration of lithium acetate or periodic acid was 0.001mol, the ZnO nanospheres were uniform and their diameter about 400nm.(5) The ZnO dye-sensitized solar cells were prepared by using ZnO nanopowders with different morophologies as photoanode. The morophology and the particles sizes of ZnO had a great impact on cell properties. The photoelectric conversion efficiency of the cell which ZnO nanospheres with diameter 500nm as photoanode was highest, the photoelectric conversion efficiency was 2.15%, the open circuit voltage of battery was 0.64V, short-circuit current was 6.47mA·cm^-2, and the fill factor was 0.52.(6)The influence of ZnO photoanode structure on dye-sensitized solar cell were studied. The optimal properties of ZnO DSSC were obtained, when ZnO photoanode is composed of two layers; which the upper and under layer were nanoparticles and nanospheres the photoelectric conversion efficiency was 1.74%, the open circuit voltage was 0.62V, short-circuit current was 6.66mA·cm^-2, and the fill factor was 0.42.