纳米金/椭球三维有序复合结构的构筑及光学增强机理研究

How to improve the photoelectric conversion efficiency of solar cells is the core issue of utilizing the solar energy. The existence of ordered structures could obviously enhanced the optical properties of photoelectric materials, but the ellipsoid-type ordered structures process the better photo-controlled efficiency than sphere-type ordered structures. In this project, we would choose the nano-Au/ellipsoid three dimensional ordered structures for applying in the back reflected layers of solar cells as research object. Selecting the α-Fe2O3 nanoparticles as the cores, undergoing the SiO2 coating and reduction-oxidation thermal treatment, we could prepare the monodispersed γ-Fe2O3@SiO2 magnetic ellipsoid nanoparticles. Utilizing the air-liquid self assembly method induced by horizontal magnetic fields to control the orientation and packing efficiency of ellipsoid nanopartilce, the large area ellipsoid three dimensional ordered structures would be high effectively fabricated. Make the nano-Aus with different shapes and sizes embed into the intervals of ellipsoid three dimensional ordered structures, and fabricate the high-filling ratio nano-Au/ellipsoid three dimensional ordered structures. Utilize UV-Vis-NIR, Raman scattering and fluorescence spectra, etc. to evaluate the optical properties, and combine the physical effects of the Surface Plasmon Resonance and photoluminescence, etc., clarify the optical enhancement mechanism. This research would provide the high effective optical platform and designing ideas of new structural solar cells.

提高太阳能电池的光电转换效率是太阳能利用的核心问题。有序结构的存在能显著增强光电材料的光学特性，而椭球型有序结构比球型有序结构具有更好的光学调控作用。本项目以可用于太阳能电池背反射层的纳米金/椭球三维有序复合结构为研究对象。拟采用α-氧化铁纳米粒子为核心，经过二氧化硅包覆和还原-氧化热处理制备出单分散γ-Fe2O3@SiO2磁性椭球型粒子。利用水平磁场诱导气-液界面自组装法控制椭球型粒子的取向和组装效率，高效地构筑出大面积椭球型三维有序结构。将不同粒径和形貌的纳米金嵌入到椭球型三维有序结构的间隙，构筑出高填充率的纳米金/椭球三维有序复合结构。利用紫外-可见-近红外光谱、Raman光谱、荧光光谱等评价纳米金/椭球三维有序复合材料的光学性能，并结合表面等离子共振、光致发光等物理效应，阐明纳米金/椭球三维有序复合结构的光学增强机理。该研究将为新型结构的太阳能电池提供高效的光学平台和设计思路。

作为光电材料的背底，椭球有序结构的光学增强作用比球型有序结构等更具优势，有利于提高太阳能电池等的光电转化效率。本项目围绕椭球型有序结构的光学增强作用研究为重点，开展了γ-Fe2O3@SiO2磁性椭球型粒子的可控制备、不同形貌纳米金的可控合成、纳米金/椭球有序复合结构的构筑及拉曼增强效应和荧光作用等光学性能及增强作用方面的研究。主要研究结果包括：（1）成功掌握了壳厚可控的单分散性γ-Fe2O3@SiO2磁性椭球型粒子的制备工艺，实现了单分散的二氧化硅核壳椭球功能材料合成的拓展研究；（2）掌握了形貌均一、分散稳定的金纳米棒、金纳米颗粒和荧光金团簇的可控合成，进一步采用水平磁场诱导气-液界面组装法和纳米金嵌入方法相结合，成功制备出三维高度有序的纳米金/磁性椭球有序复合结构，建立了自组装条件、嵌入方法、椭球与金的几何参数等因素与复合结构有序度之间的影响关系模型；（3）利用拉曼光谱、荧光光谱等测试手段，发现了椭球有序结构对金纳米颗粒、金纳米棒的SERS效应及金纳米团簇的荧光效应均有显著的增强作用，并建立了结构类型、有序度与纳米金光学增强效果之间的关系模型，为椭球有序结构应用于光电材料领域起到重要的理论和实践支撑作用。