ZnO-TiO2多维阵列与核-壳复合结构的制备及其染料敏化太阳能电池性能研究

Dye sensitized solar cells (DSSCs) have attracted extensive recent research attention as a potential alternative to Si-based photovoltaic cells primarily due to their low manufacturing costs,relatively high energy conversion efficiencies, convenient fabrication and remarkable stability under the prolonged thermal and light-soaking dual stress. To date,the highest solar-to-electric conversion efficiency, over 12%, was achieved using a photoelectrode containing TiO2 nanoparticles film sensitized by a ruthenium-based dye. Considerable efforts have been made to improve the energy conversion efficiency of DSSCs by developing novel dyes, photoelectrodes, and electrolytes. However,further increase in conversion.efficiency has been limited by energy loss due to recombination between electrons and either the oxidized dye molecules or electron-accepting species in the electrolyte during the chargetransport process.In this project, well-aligned screw-like and center hollow ZnO arrays with large specific surface area will be prepared by a solvothermal process/supercritical solvothermal process through controling crystal morphology by optimizing synthesis experimental condition.This special morphology has the channels parallel to each other and vertically, superior photo-to-electric performance, higher photocurrent and photoelectrical conversion efficiency are promising. With this specific structure as a support for the TiO2-ZnO core-shell nanoparticles, ZnO and TiO2 spacial complex structure combining screw-like arrays and core-shell nanoparticles will be prepared. Furthermore, as an application of this special structure, dye sensitized solar cells based on them will be fabricated and the cell performances will be characterized.In this structure system, highly ordered crew-like and center hollow ZnO arrays provide a large surface area, allowing absorption of enough dye molecules to achieve significant optical density, have superior electron lifetimes and provide excellent pathways for electron percolation; And meanwhile the ZnO-TiO2 core-shell structure slowes down the recombination processes by the formation of anenergy barrier at the TiO2 surface.As a result,the energy conversion efficiency should be increased. The purpose of this project is to focuse on the research the effect of the supercritical hydrothermal synthesis experimental conditionals on the structure, morphology, spacial orientation and particle size of the product, as well as their growth mechanism. Furthermore, with the product as the photoelectrode,the effect of structure,morphology, spacial orientation of the photoelectrode on the dye-sensized solar cell properties and its mechanism will be researched. Through this research, an effective way to develop the energy conversion efficiency of the DSSCs by controling the morphology of the photoelectrode should be found.

纳米结构染料敏化太阳能电池具有原料丰富、成本低、环境友好，工艺简单等突出优点，有望取代硅太阳能电池成为未来光伏产业主导。本项目拟采用超临界溶剂热等方法，从各组件的结构、形貌等微观元素入手，通过优化实验条件，合成高度有序且并有超大比表面积的多维中空螺丝状ZnO 阵列，并将其作为TiO2-ZnO核-壳纳米结构载体，制备ZnO/TiO2空间复合结构作为染料化太阳能电池光阳极并测试其性能；利用其特殊形貌减少由于电荷复合而产生的能量损耗，增大染料吸附表面和吸附量，使入射光能够在晶体结构内多次折射，增加光能利用率，从而达到提高光电转换效率的目的。本项目重点研究溶剂热/超临界溶剂热法合成空间有序复合氧化物体系时，结晶形貌、生长方向、生长尺寸与实验条件的依赖关系，揭示其生长机理，并进一步揭示纳米结构形貌与染料敏化太阳能电池光伏特性之间的关系及内在机理，为从形貌出发提高电池光伏特性提供理论依据和实验基础。

本项目围绕第三代太阳能电池-纳米结构染料敏化太阳能电池，开展了针对性的研究，虽然染料敏化太阳能电池具有原料丰富、成本低、环境友好，工艺简单等突出优点，然而TiO2基染料敏化太阳能电池中光电转换效率的进一步提高却被电子在金属氧化物/染料敏化分子/电解质界面处的电荷再次复合而导致的能量损耗所限制，因此利用掺杂或表面改性，制备规整有序的纳米结构半导体阵列等技术提高TiO2的光电转换效率，抑制能量损耗成为目前对TiO2的研究热点和未来发展趋势。本项目从光阳极和对电极的结构、形貌等微观要素入手，用水热，溶剂热，溶液，固相等方法合成了具有多种形貌的ZnO及TiO2粉体，通过优化实验条件，材料表面改性，后处理，制备复合结构等方法制备了大比表面积的ZnO 结构及TiO2-ZnO 核-壳纳米结构，通过XRD、SEM、EDX、EIS和紫外-可见漫反射等测试手段对所得样品的结构、形貌、组成成分、阻抗、比表面积和染料吸附等特性进行表征并将其作为染料化太阳能电池光阳极测试其性能。结果显示利用其特殊形貌可以减少由于电荷复合而产生的能量损耗，增大染料吸附表面和吸附量，使入射光能够在晶体结构内多次折射，增加光能利用率，从而达到提高光电转换效率的目的。本项目同时也揭示了纳米结构形貌与染料敏化太阳能电池光伏特性之间的关系及内在机理，为从形貌出发提高电池光伏特性提供理论依据和实验基础。本项目完成学术论文12篇，其中SCI收录学术研究论文10篇，国内核心期刊论文2篇，参加国内学术会议3人次，国际会议1人次，培养硕士研究生毕业1人，在读4人。