發(fā)布時(shí)間：2019-06-07 12:52

【摘要】：上轉(zhuǎn)換功能材料可以將吸收的紅外光子轉(zhuǎn)換為可見(jiàn)光子,如果將上轉(zhuǎn)換功能材料與太陽(yáng)能電池結(jié)合在一起,可以改善太陽(yáng)能電池對(duì)太陽(yáng)光譜的利用效率,從而提升太陽(yáng)能電池的光電轉(zhuǎn)換效率。目前,稀土離子摻雜的β-NaYF4是比較好的上轉(zhuǎn)換功能材料,有望用于提高太陽(yáng)能電池的轉(zhuǎn)換效率。本文通過(guò)基于第一性原理方法的Material Studio軟件模擬計(jì)算了三種不同稀土離子組合共摻的NaYF4的微觀結(jié)構(gòu)、電子以及光學(xué)等性質(zhì),并利用水熱法實(shí)驗(yàn)制備NaYF4,研究了保溫時(shí)間、反應(yīng)溫度及pH值對(duì)物相和形貌的影響。最后分別制備了三稀土離子共摻的上轉(zhuǎn)換材料NaY(Er/Ho/Yb)F4,NaY(Er/Tm/Yb)F4及NaY(Tm/Ho/Yb)F4,研究了不同稀土離子組合共摻的上轉(zhuǎn)換發(fā)光性質(zhì)。通過(guò)對(duì)β-NaYF4以及三種不同稀土離子組合共摻β-NaYF4的第一性原理模擬計(jì)算發(fā)現(xiàn)稀土離子的引入雖然會(huì)使晶胞體積增大,但仍能保持體系的穩(wěn)定性。由于稀土離子的電子排布特性會(huì)使β-NaYF4體系的帶隙減小并變?yōu)橹苯訋?最終增強(qiáng)對(duì)紅外光的吸收。而且由于幾種稀土離子的離子半徑和電子排布都是非常相似的,所以不同稀土離子組合對(duì)β-NaYF4體系的影響也是非常一致的。采用水熱法制備NaYF4時(shí),適當(dāng)延長(zhǎng)保溫時(shí)間以及調(diào)配偏酸性的溶液環(huán)境,有利于β-NaYF4(六方相)的生成。同時(shí)提高反應(yīng)溫度,會(huì)使α-NaYF4(立方相)逐漸轉(zhuǎn)變?yōu)棣?NaYF4(六方相),但是過(guò)高的反應(yīng)溫度會(huì)使產(chǎn)物中晶體表面缺陷增多,晶粒過(guò)度生長(zhǎng),均勻性變差。在保溫時(shí)間為48h,反應(yīng)溫度為180℃,pH=3的實(shí)驗(yàn)條件下,制備的NaY(Er/Ho/Yb)F4,NaY(Er/Tm/Yb)F4及NaY(Tm/Ho/Yb)F4,均為單純的β-NaYF4(六方相)結(jié)構(gòu),并且晶粒形貌完整、尺寸均勻、分散性良好。而且在980nm和1550nm激發(fā)光源的照射下,不同稀土離子共摻的β-NaYF4都可以檢測(cè)到上轉(zhuǎn)換發(fā)光現(xiàn)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 偽-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，

本文編號(hào)：2494806