稀土掺杂下转换发光材料的光谱调制和能量传递研究

发布时间：2018-08-07 19:32

【摘要】：随着能源短缺和环境问题的日益严峻,可再生无污染的天然能源太阳能受到普遍关注。晶体硅太阳能电池占据着太阳能电池市场绝大部分份额,广泛应用于航天、工业、农业、军事、民用等领域。然而,太阳光分布(300-2500 nm, AM 1.5G)和硅太阳能电池响应曲线(Eg≈1.12 eV,λ≈1100 nm)的光谱失配导致太阳能电池的光电转换效率比较低。于是,如何通过光谱调制(Spectral Modulation)增加硅基太阳能电池的光电转换效率成为当前学术界和产业界研究的热点问题之一。鉴于此,可以通过能量传递过程将紫外-可见光(300～500 nm)转换为长波长的近红外光(900～1100 nm)或可见光,从而减小能量损失,提高硅基太阳能电池的光电转换效率。本文主要以性质稳定的铝酸盐、氯硼酸盐、硼酸盐和钒酸盐作为基质材料,稀土离子为掺杂剂,采用溶胶-凝胶法和固相法合成了硅基太阳能电池用稀土掺杂下转换发光材料。主要包括四部分的内容：(1)以Dy~(3+)离子与Dy~(3+)-Yb~(3+)、Pr~(3+)-Yb~(3+)、Tb~(3+)-Yb~(3+)双掺离子对为掺杂剂,制备了稀土掺杂Li_8Bi_2(MoO_4)_7体系荧光粉。利用X-射线衍射仪、荧光光谱仪等对样品的合成条件、结构物相、掺杂浓度、下转换发光性质等进行了研究。依据发射光谱确定了Dy~(3+)离子在Li_8Bi_2(MoO_4)_7基质中发光的黄蓝比,实现了白光发射。通过计算得到了Dy~(3+)-Yb~(3+)、Pr~(3+)-Yb~(3+)、Tb~(3+)-Yb3双掺体系的能量传递效率,并分析了下转换能量传递机理。比较了Dy~(3+)、Pr~(3+)、Tb~(3+)不同窄带吸收(f-f)敏化剂离子对Yb~(3+)离子近红外发光的影响,最终获得有效的近红外发射,并探讨了这些荧光粉在硅基太阳能电池上的潜在应用。(2)采用传统的高温固相法合成了RE~(3+)-Yb~(3+)(RE= Tb, Pr, Nd)双掺、Ce~(3+)-Tb~(3+)-Yb~(3+)三掺杂的Ba_2Y(BO_3)_2Cl下转换荧光粉。首先,对双掺体系中Tb~(3+)/Pr~(3+)/Nd~(3+)到Yb~(3+)的能量传递过程进行了研究。然后,系统地对比了Ce~(3+)-Tb~(3+)-Yb~(3+)三掺与对应的Ce~(3+)-Yb~(3+)和Tb~(3+)-Yb~(3+)双掺最佳掺杂样品的下转换发光性质。探索了Tb~(3+)-Yb~(3+)三掺杂体系中的下转换机理,详细分析了可能存在的Ce~(3+)→Tb~(3+), Ce~(3+)→Tb~(3+),Tb~(3+)→Yb~(3+)+和Ce~(3+)→Tb~(3+)→Yb~(3+)四种能量传递过程。阐明了在能量传递过程中Tb~(3+)起桥梁作用,具有f-d跃迁特征的Ce~(3+)离子是一种高效的敏化剂,可以扩大紫外-可见波段吸收截面积并增强了近红外发射强度。表明Ba_2Y(BO3)2Cl:Ce~(3+),lT~(3+),Yb~(3+)宽谱吸收近红外荧光粉是一种有潜力的硅基太阳能电池用下转换层材料。(3)合成了Ba_3Y(BO_3)_3:Ce~(3+),Nd3'硼酸盐基近红外下转换发光材料,利用Ce~(3+)到Nd~(3+)的能量传递将近紫外光转换为近红外光。在356nm激发下,不仅能产生Ce~(3+)离子的特征蓝紫光宽谱发射,还可以发射出Nd~(3+)离子的近红外光。讨论了Nd~(3+)离子掺杂浓度对近红外发光强度的影响。充分表明,Ce~(3+)-Nd~(3+)双掺Ba_3Y(BO_3)_3荧光粉可以产生位于900-1100 nm波段的近红外光,能够提高硅基太阳能电池的光电转换效率。(4)采用溶胶-凝胶法合成了以Ba_2RV_3O_(11)(R=La,Y,Gd,Bi)钒酸盐为基质的下转换发光材料。对Ba_2RV_3O_(11):Eu~(3+)荧光粉的下转换发光性质进行了分析。着重研究了基质敏化型近红外下转换发光材料Ba_2LaV_3O_(11):Yb~(3+)和Ba_2YV_3O_(11):Nd~(3+)/HO~(3+)/Yb~(3+)的近红外发光性质以及相应的下转换发光机理。证实了存在钒酸盐基质到Yb~(3+)的能量传递,探索了Ba_2LaV_3O_(11):Yb~(3+)荧光粉中的能量传递类型。钒酸盐基荧光粉是一类有潜力的硅基太阳能电池用下转换光谱调制材料。
[Abstract]:As the energy shortage and environmental problems become increasingly severe, renewable and non polluting natural energy solar energy is widely concerned. Crystal silicon solar cells occupy most of the market share of solar cells, widely used in space, industry, agriculture, military, civil and other fields. However, the solar distribution (300-2500 nm, AM 1.5G) and silicon sun The spectral mismatch of the cell response curve (Eg 1.12 eV, lambda 1100 nm) leads to the low photoelectric conversion efficiency of the solar cells. Therefore, how to increase the photoelectric conversion efficiency of the silicon based solar cells by spectral modulation (Spectral Modulation) has become one of the hot issues in the current academic and Industry research. The energy transfer process converts ultraviolet visible light (300~500 nm) to long wavelength near infrared light (900~1100 nm) or visible light, thus reducing energy loss and improving the photoelectric conversion efficiency of silicon based solar cells. This paper mainly uses aluminate, borate, borate and vanadate as matrix material, and rare earth ions as admixture. The rare earth doped conversion luminescent materials for silicon based solar cells were synthesized by sol-gel method and solid phase method. The main contents of four parts were as follows: (1) Dy~ (3+) ions and Dy~ (3+) -Yb~ (3+), Pr~ (3+) -Yb~ (3+), Tb~ (3+) doped double ions were used as dopants. The synthesis conditions, structure phase, doping concentration, and down conversion luminescence properties of the samples were studied by - ray diffractometer, fluorescence spectrometer and so on. According to the emission spectra, the yellow and blue ratio of Dy~ (3+) ions in Li_8Bi_2 (MoO_4) _7 matrix was determined, and the Dy~ (3+) -Yb~ (3+), Pr~ (3+) -Yb~ was obtained by calculation. 3 the energy transfer efficiency of the dual doped system and the mechanism of down conversion energy transfer were analyzed. The effects of Dy~ (3+), Pr~ (3+), Tb~ (3+) on the near infrared luminescence of Yb~ (3+) ions by different narrow band absorption (f-f) ions were compared, and the effective near infrared emission was obtained. The potential applications of these phosphors to silicon based solar cells were discussed. (2) the potential application of these phosphors to silicon based solar cells was discussed. The conversion of RE~ (3+) -Yb~ (3+) (RE= Tb, Pr, Nd) and Ce~ (3+) -Tb~ (3+) -Tb~ (3+) three dopants are synthesized by the traditional high temperature solid-phase method. The down conversion luminescence properties of the best doped Ce~ (3+) -Yb~ (3+) and Tb~ (3+) -Yb~ (3+) doped samples are investigated. The mechanism of the down conversion in the Tb~ (3+) -Yb~ (3+) three doping system is explored. The possible existing four energy transfer processes are analyzed in detail. In the process of energy transfer, Tb~ (3+) plays a bridge role, and the Ce~ (3+) ion with the characteristics of F-D transition is a highly efficient sensitizer. It can enlarge the absorption section area of the ultraviolet visible band and enhance the near infrared emission intensity. It shows that Ba_2Y (BO3) 2Cl:Ce~ (3+), lT~ (3+), and broad spectrum absorption near infrared phosphor is a potential silicon based sun. A lower conversion layer material for battery. (3) Ba_3Y (BO_3) _3:Ce~ (3+), Nd3'borate base near infrared light conversion luminescent material, using Ce~ (3+) to Nd~ (3+) energy transfer nearly ultraviolet light to near infrared light. Under 356nm excitation, not only can produce the characteristic blue violet light spectrum emission of Ce~ (3+) ions, but also can emit the ions. Near infrared light. The effect of Nd~ (3+) ion doping concentration on near infrared luminescence intensity is discussed. It is shown that Ce~ (3+) -Nd~ (3+) doped Ba_3Y (BO_3) _3 phosphor can produce near infrared light in 900-1100 nm band, and can improve the photoelectric conversion efficiency of silicon based solar cells. (4) the sol-gel method is used to synthesize Ba_2RV_3O_ (11) (R=La). The lower conversion luminescence properties of Ba_2RV_3O_ (11): Eu~ (3+) phosphor are analyzed in the down conversion luminescence properties of Ba_2RV_3O_ (11): Eu~ (3+) phosphor. The properties of the near infrared luminescence of the matrix sensitized near infrared lower conversion luminescent materials Ba_2LaV_3O_ (11), Yb~ (3+) and Ba_2YV_3O_ (11), and the corresponding down conversion are emphatically studied. Luminescence mechanism. The energy transfer of vanadate matrix to Yb~ (3+) is confirmed and the energy transfer type in Ba_2LaV_3O_ (11): Yb~ (3+) phosphor is explored. Vanadate base phosphor is a kind of potential silicon based solar cell using down conversion spectral modulation material.
【学位授予单位】：西北大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O482.31

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