Preparation And Photoelectric Properties Of Zinc Oxide Nano-structured Solar Cells

The solar cell is a set that thransforms directly the energy of light into the electrical energy. It provides low-cost, near-eternal power. It is almost no pollution. Therefore, in space and on earth are very wide range of applications. Since long-term, the researchers dedicated to the study of silicon-based solar cells. But the silicon-based solar cell is very difficult to substitute for conventional energy source truly to be widely used due to its high cost. Dye-sensitized solar cell (DSC) has become an arresting point of academy in the world due to its qualities such as continuability of development, friendliness to environment, simpleness of preparation and low cost. The photovoltaic efficiency of DSC is affected by anode, electrolyte and cathode. In this paper, we synthesized the ZnO nanowire arrays with buffer layer on the FTO glass substrate by using chemical vapor deposition. And then they were used as photoanode. During the experiment, we have analyzed samples of the morphology and structure. At the same time, one-dimensional nanostructure on the photoelectric properties of solar cells was preliminarily studied. Accordingly, the main work and main results are summarized as followings:First of all, ZnO nanowire arrays (NWs) with buffer layer were produced by using chemical vapor deposition. The reaction temperature is lower than traditional CVD method and the cataltst-free and without ZnO seed in this process. High density ZnO NWs are grown on the buffer layers in a large scale. Every single NW is self-aligned perpendicular to the substrate and there is no bending or interconnects along the NW, which make them perfect candidates for a DSC property study. The location of the substrate and the vacuum the impact on the morphology in the study were discussed. And the best experimental conditions were received.Secondly, ZnO nanowire array film and ZnO nanoparticles film were used as photoanode of solar cells. Reserchs have shown that the photoelectric properties on nanowire array is better than nanoparticles film. The reason is that nanowires provides the direct path to transport electrons. And nanowires avoid photoelectrons to be trap within grain boundaries and reduce the photoelectron recombination between grain boundaries and I3- in the electrolyte. In this paper, the electrical properties about the different morphology of the anode material were compared. And the electron transport mechanism among nanoparticles and in nanowire array were resolved.Thirdly, we investigatedthe electrical properties of the different size nanowire arrays solar cells. As it turned out, the photoelectric properties were improved with the increase length of nanowire. The density of increase also improved the photoelectric properties. And the reasons why the photoelectric properties were diverse with the change size were given.Then, ZnO nanowire array buffer layers were assembled as solar cells. We discussed the effect thickness of buffer layers on the photoelectric properties of solar cells. The buffer layer is too thick, a part of incident light was reflected and absorped. Then the photoelectric properties of solar cells is low. The proper thickness of BL can block the photoelectron recombination at the TCO glass/electrolyte interface, thus improve the photovoltaic performance of the solar cells. When the active area of the solar cell is 1cm2, ZnO nanowire array buffer layers were used as photoanodes. The solar cell has high Isc, Voc and FF. The corresponding values were 0.153 mA,0.93 V,66.2%。The active area of the solar cell is reduced to 4 mm2, the short-circuit current density (Jsc) is 4.3 mA·cm-2Last, CuSCN and different sizes of Cu2O nanoparticles were synthesized. Then they assembled into heterojunction solar cell with ZnO nanoparticles. And we measured the photovoltaic performance of CuSCN/ZnO and Cu2O/ZnO heterojunction solar cell. Studies have shown that the smaller the size of Cu2O is, the better the photovoltaic performance becomes. And the photovoltaic performance of CuSCN/ZnO was better than Cu2O/ZnO. In this paper, the corresponding explanations were given.