三稀土离子共掺氟化钠钇的第一性原理计算和实验制备
发布时间：2019-06-07 12:52
【摘要】：上转换功能材料可以将吸收的红外光子转换为可见光子,如果将上转换功能材料与太阳能电池结合在一起,可以改善太阳能电池对太阳光谱的利用效率,从而提升太阳能电池的光电转换效率。目前,稀土离子掺杂的β-NaYF4是比较好的上转换功能材料,有望用于提高太阳能电池的转换效率。本文通过基于第一性原理方法的Material Studio软件模拟计算了三种不同稀土离子组合共掺的NaYF4的微观结构、电子以及光学等性质,并利用水热法实验制备NaYF4,研究了保温时间、反应温度及pH值对物相和形貌的影响。最后分别制备了三稀土离子共掺的上转换材料NaY(Er/Ho/Yb)F4,NaY(Er/Tm/Yb)F4及NaY(Tm/Ho/Yb)F4,研究了不同稀土离子组合共掺的上转换发光性质。通过对β-NaYF4以及三种不同稀土离子组合共掺β-NaYF4的第一性原理模拟计算发现稀土离子的引入虽然会使晶胞体积增大,但仍能保持体系的稳定性。由于稀土离子的电子排布特性会使β-NaYF4体系的带隙减小并变为直接带隙,最终增强对红外光的吸收。而且由于几种稀土离子的离子半径和电子排布都是非常相似的,所以不同稀土离子组合对β-NaYF4体系的影响也是非常一致的。采用水热法制备NaYF4时,适当延长保温时间以及调配偏酸性的溶液环境,有利于β-NaYF4(六方相)的生成。同时提高反应温度,会使α-NaYF4(立方相)逐渐转变为β-NaYF4(六方相),但是过高的反应温度会使产物中晶体表面缺陷增多,晶粒过度生长,均匀性变差。在保温时间为48h,反应温度为180℃,pH=3的实验条件下,制备的NaY(Er/Ho/Yb)F4,NaY(Er/Tm/Yb)F4及NaY(Tm/Ho/Yb)F4,均为单纯的β-NaYF4(六方相)结构,并且晶粒形貌完整、尺寸均匀、分散性良好。而且在980nm和1550nm激发光源的照射下,不同稀土离子共掺的β-NaYF4都可以检测到上转换发光现象。
[Abstract]:The upconversion functional material can convert the absorbed infrared photons into visible photons. If the upconversion functional material is combined with the solar cell, the utilization efficiency of the solar spectrum can be improved. In order to improve the photoelectric conversion efficiency of solar cells. At present, 尾-NaYF4 doped with rare earth ions is a good upconversion functional material, which is expected to be used to improve the conversion efficiency of solar cells. In this paper, the microstructure, electron and optical properties of NaYF4 co-doped with three different rare earth ions were simulated and calculated by Material Studio software based on the first principle method, and the holding time of NaYF4, was studied by hydrothermal experiment. Effects of reaction temperature and pH value on phase and morphology. Finally, NaY (Er/Ho/Yb) F _ 4, nay (Er/Tm/Yb) F _ 4 and NaY (Tm/Ho/Yb) F _ 4 co-doped with three rare earth ions were prepared, and the upconversion luminous properties of different rare earth ion combinations were studied. Through the first-principle simulation of 尾-NaYF4 and three different rare earth ion combinations co-doping 尾-NaYF4, it is found that the introduction of rare earth ions can increase the cell volume, but still maintain the stability of the system. Due to the electronic arrangement of rare earth ions, the band gap of 尾-NaYF4 system decreases and becomes direct band gap, and finally enhances the absorption of infrared light. Moreover, because the ion radius and electron arrangement of several rare earth ions are very similar, the effects of different rare earth ion combinations on 尾-NaYF4 system are also very consistent. When NaYF4 is prepared by hydrothermal method, the proper prolongation of holding time and the preparation of acidic solution environment are beneficial to the formation of 尾-NaYF4 (hexagonal phase). At the same time, increasing the reaction temperature will gradually change the 伪-NaYF4 (cubic phase) to 尾-NaYF4 (hexagonal phase), but too high the reaction temperature will increase the crystal surface defects, the grain growth is excessive, and the uniformity will become worse. Under the experimental conditions of holding time of 48 h, reaction temperature of 180 鈩，
本文编号：2494806
[Abstract]:The upconversion functional material can convert the absorbed infrared photons into visible photons. If the upconversion functional material is combined with the solar cell, the utilization efficiency of the solar spectrum can be improved. In order to improve the photoelectric conversion efficiency of solar cells. At present, 尾-NaYF4 doped with rare earth ions is a good upconversion functional material, which is expected to be used to improve the conversion efficiency of solar cells. In this paper, the microstructure, electron and optical properties of NaYF4 co-doped with three different rare earth ions were simulated and calculated by Material Studio software based on the first principle method, and the holding time of NaYF4, was studied by hydrothermal experiment. Effects of reaction temperature and pH value on phase and morphology. Finally, NaY (Er/Ho/Yb) F _ 4, nay (Er/Tm/Yb) F _ 4 and NaY (Tm/Ho/Yb) F _ 4 co-doped with three rare earth ions were prepared, and the upconversion luminous properties of different rare earth ion combinations were studied. Through the first-principle simulation of 尾-NaYF4 and three different rare earth ion combinations co-doping 尾-NaYF4, it is found that the introduction of rare earth ions can increase the cell volume, but still maintain the stability of the system. Due to the electronic arrangement of rare earth ions, the band gap of 尾-NaYF4 system decreases and becomes direct band gap, and finally enhances the absorption of infrared light. Moreover, because the ion radius and electron arrangement of several rare earth ions are very similar, the effects of different rare earth ion combinations on 尾-NaYF4 system are also very consistent. When NaYF4 is prepared by hydrothermal method, the proper prolongation of holding time and the preparation of acidic solution environment are beneficial to the formation of 尾-NaYF4 (hexagonal phase). At the same time, increasing the reaction temperature will gradually change the 伪-NaYF4 (cubic phase) to 尾-NaYF4 (hexagonal phase), but too high the reaction temperature will increase the crystal surface defects, the grain growth is excessive, and the uniformity will become worse. Under the experimental conditions of holding time of 48 h, reaction temperature of 180 鈩，
本文编号：2494806
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