Photoelectrochemical Properties Study On Zn/ZnO/TiO₂and ZnO/SnO₂Composite Nanostructures

Nanomaterials has attracted extensive attention due to its special optical, electrical and magnetic property by scholars, especially the semiconductor property which presents bright application prospect in dye-sensitized solar cells(DSSCs). In this paper, the new nanomaterias:Zn/ZnO/TiO2and ZnO/SnO2composite nanostructures have been synthesized using direct sintering method, hydrothermal method, and a variety of chemical methods.These new nanostructures films have been enclosured as photoanode in DSSCs. The morphology and component of the sample were analyzed by varies electrical microscopy equipments, providing the evidence to deduce the growth mechanism.Then, the photoelectrochemical properties of the DSSCs based on composite nanostructures were tested. We discuss how the novel nanostructure influences the photoelectric performance of DSSCs, and study the electronic transport mechanism and recombination rate from micro level:1. The photoelectrochemical property study of the urchin-like Zn/ZnO/TiO2in dye-sensitized solar cellsA novel urchin-like Zn/ZnO hierarchical structure directly growing on fluorine-doped tin oxide (FTO) glass is prepared by a simple sintering process at550℃, instead of the tranditional spherical and1D nanowiire structure. SEM, XRD and TEM are used to deduce the growing process and mechanism of this new structure. The dye-sensitized solar cells (DSSCs) based on such structure present more desirable photoelectrochemical(PEC) properties than DSSCs based on ZnO nanowires by J-V and IPCE test. Furthermore, the TiO2layer is coated by ALD method, forming Zn/ZnO/TiO2composite structure. The origin of the striking difference in performance due to shell thickness is analyzed and discussed by electrochemical impedance spectrum testing. The study confirms that such novel photoanode structure can modify the energy band levels, suppress charge recombination, prolong the electron lifetime, and increase the conversion efficiency. The highest conversion efficiency of the cell can reach about0.82%. The open-circuit voltage is0.66V, as well as short-circuit at3.28mA.cm"2.2. The study of photoelectrochemiqal property of ZnO/SnO2core-shell structure in DSSCsThis paper describe the synthesis of ZnO nanowire, SnO2nanoparticle by hydrothermal/solvothermal method, and then ZnO nanowire/SnO2nanoparticle (ZnO NW/SnO2NP) core-shell composite electrode by spin coating method. The growing process of SnO2is analysed on account of principle of chemical synthesis. The integration of such nanocomposite photoanodes in dye-sensitized solar cells (DSSCs) leads to much better photovoltaic properties than bare ZnO NW or SnO2NP with the short-circuit photocurrent (Jsc), the open-circuit photovoltage (Voc) and the photo conversion efficiency as high as2.93mA/cm-2,0.64V and0.74%, respectively. By the characterization of the incident photon-to-electron conversion efficiency (IPCE) and intesnsity-modulated photocurrent/photovoltage spectroscopy, the results show that the formation of an energy barrier on the ZnO NW can prolong the electron lifetime and transmission time, reduce the rate of electron recombination at the ZnO/electrolyte interface and increase the conversion efficiency.