| It is a trend to effectively and rationally use solar energy as a way to solve the issues of the increasing worsening environmental pollution, global warming and depletion of fossil fuels. Solar cells can directly transform solar energy into electricity without mechanical and polluted by-products. Therefore, the study on solar cells has been attracted great interest, and developed rapidly.As a cheap, environmental friendly, simple fabrication process, and diversification of shape, dye-sensitized solar cells (DSSCs) have huge potential for replacing silicon-based solar cells. The structure of DSSCs is mainly composed of conductive substrate, photoelectrode, dye, electrolyte, and counter electrode. The conductive substrate determines the shape of DSSCs. Thus, the substrate and photoelectrode are extremely critical to DSSCs. Generally, photoelectrode materials, charge transfer, and dye-adsorbed amount are considered for constructing photoelectrode. Thus, the work has been done as followings:It is simple to build TiO2photoelectrode with long-path order and large specific surface area. Anatase TiO2tree-like nanoarrays were prepared on various metal wires through one-step facile hydrothermal reaction. The anatase TiO2tree-like nanoarrays consisting of long TiO2nanowire trunks and a large number of short TiO2nanorod branches have been employed as photoelectrodes for fiber DSSCs. The fiber DSSCs on Ti wires can achieve outstanding PCE of6.32%, while that based on W wires achieve lower one of3.24%due to the forming WO3layer, which might enhance charge recombination. When the substrate is a Nicole oxide wire, a novel P-N heterojunction can be obtained. This universal method is simple, facile, and low cost for preparing anatase TiO2treelike-nanoarrays on various metal wires, which may find potential applications in fabrication of optoelectronic devices.It is simple to build ZnO photoelectrode and it is the first time that the seed layer for ZnO nanowore arrays greatly influenced the performance of DSSCs. ZnO hierarchical nanostructures were in-situ deposited on Zn wires by hydrothermal growth, in which ZnO nanopaticle layers generated firstly and than served as seed for synthesis of ZnO nanowire arrays. The fiber DSSCs with ZnO photoelectrode at0.5h reaction time showed PCE of0.98%. However, the PCE decreases with reaction time of ZnO due to the seed layer of ZnO nanoparticles. The absorbed dye amount by ZnO nanoparticle layer reduced with reaction time when ZnO nanoparticle size grown larger; while the longer nanowire arrays absorbed more dye molecules, which enhanced charge recombination.SnO2hierarchical microsphere has been synthetized by microwave-assisted hydrothermal synthesis, which is cluster of nanorods and nanoparticles. SnO2hierarchical microsphere was further applied to photoanode in DSSCs. After TiO2modifing SnO2photoanode, PCE increased from1.40%to4.15%. This is because that SnO2conduction band edge is relatively lower that that of TiO2, resulting in larger charge recombination. SnO2and TiO2-modified SnO2photoanodes are applied to UV detector, which can operate at zero bias. The self-powered UV detectors have rectangular square wave signals of current with "on" and "off’UV illumination pulse. After TiO2modifing, the response has increased from91to6229, and the response time increased from0.15s to0.055s. The study may open a new way for next-generation photosensing applications.To substitute semiconductor for the dye molecules in DSSCs can realize semiconductor-sensitized solar cells (SSSCs). The low coverage of sensitizer on photoelectrode is a key issue to effect the performance of SSSCs. Bandgap-graded ZnO/(CdS)1-x(ZnS)x (0≤x≤1) coaxial nanowire arrays have been successfully fabricated by ion exchange reactions based on ZnO nanowire arrays. The (CdS)1-x(ZnS)x shells are thoroughly and tightly covered on the ZnO cores, and play the role of sensitizers. The photoelectrode based on the ZnO/CdS coaxial nanowire array shows good performance with power conversion efficiency of2.1%. |
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