卤化物—二氧化硅纳米复合结构双功能薄膜的结构调控和发光特性研究

The fluoride was prepared by our group, by using the sol-gel method without halogen-containing atmosphere. The quantum-cutting (QC) properties of the glass ceramics involving the fluoride nano-crystalline doped with rare earth ions were also studied. In this project, we will investigate three parts based on the previous research. First, the composite film consisting of halide doped with rare earth ion pair (Tb3+-Yb3+, Pr3+-Yb3+, Tm3+-Yb3+, etc.) and porous silica is prepared by the sol-gel method. The main choice of the halide is the fluoride and bromide containing rare earth ions. A high QC efficiency can be achieved by the combination of the halide with low phonon energy and appropriate ions. Second, the rate equations are created aiming at different QC mechanisms. With the rate equations and Monte-Carlo simulation, the main mechanism is distinguished and investigated. Then, the actual QC efficiency can be calculated and optimized by the experiments. Third, the structure of the halide nano-crystalline and the porous silica is adjusted via the control of preparation conditions of the film. The structure parameters contain the size and surface topography of the nano-crystalline, the thickness and porosity of the film, etc.. Thus, the transmittance of the film in the range of solar spectrum is increased via the anti-reflection, without decreasing the QC efficiency. Finally, the obtained composite nano-structured film is bi-functional: QC & anti-reflection. The film can be applied as the down-converting layer to enhance the light conversion efficiency of the thin-film solar cells greatly.

在溶胶凝胶法（无含卤气氛）制备氟化物、以及对稀土掺杂的氟化物纳米晶玻璃陶瓷的量子剪裁特性研究基础上，用溶胶凝胶法制备稀土离子对掺杂的卤化物纳米晶-多孔二氧化硅基体的复合结构薄膜。稀土离子对选用Tb3+-Yb3+、Pr3+-Yb3+、Tm3+-Yb3+等，卤化物基质主要选用含稀土离子的氟化物和溴化物。利用低声子能量的卤化物结合稀土离子对，实现高量子剪裁效率。针对材料中离子对的各种量子剪裁机制建立速率方程。在此基础上结合蒙特卡洛模拟，研究量子剪裁主要机制，计算实际量子剪裁效率，并结合实验优化。通过薄膜制备条件调控卤化物纳米晶-多孔二氧化硅的复合结构，如纳米晶尺寸和形貌、薄膜厚度和孔隙度，在保证卤化物高发光效率的前提下，提高薄膜在太阳光谱波段的透射率，实现增透效果。最终所得的量子剪裁-增透双功能纳米复合薄膜，可作为光转换片应用于薄膜硅太阳能电池，极大提高其光转换效率。

本研究采用溶胶凝胶法制备了KYF4: Tb3+, Yb3+量子剪裁发光材料，研究其量子剪裁发光性质。在该材料中报道Tb3+高能级激发的量子剪裁，并进一步研究了其量子剪裁机制。将化学还原法制备的Ag纳米颗粒掺入该材料，观测到了Ag纳米颗粒对量子剪裁发光的表面波等离子体增强，首次报道了贵金属纳米颗粒对量子剪裁发光的表面波等离子体增强效应。本效应有利于量子剪裁发光材料在太阳能电池中的进一步应用。本研究对NaBaPO4:Eu2+,Yb3+的宽带量子剪裁发光性质做了深入研究，发现这种材料具有高量子剪裁效率（197.4%），表明该材料有望用于太阳能电池来大大提高其光电转换效率。掺入Ag纳米颗粒时，同样观测到了量子剪裁发光的增强。本研究还对低声子能量的氟氯化物基质的稀土发光性质做了研究。引入Li+作为电荷补偿剂增强发光，并包覆SiO2壳层，克服了CaFCl:Tb3+纳米颗粒吸湿性强的缺点。另外，本研究以微阵列图形为模板，用自组装电化学法获得具有良好表面等离子激元增强特性的Au/Ag纳米材料微阵列，以期用于增强稀土离子发光。