【作者】 舒伟；

【导师】 肖思国；

【作者基本信息】 湘潭大学 ， 微电子学与固体电子学， 2011， 硕士

【摘要】 随着能源危机和环境污染形势日趋严峻,太阳能以其清洁、无污染、取之不尽、用之不竭的特点,已经成为人们关注的焦点。因此,将太阳光直接转换成电能的太阳能电池成为人们研究的重要方向。太阳能电池转光剂能将太阳能电池所不能利用的太阳光转换到太阳能电池能够响应波段,从而增加电池对太阳光的利用,实现电池光伏增效。由此,本文通过燃烧法合成了能够将紫外至蓝光区的光转换成红光的CaAl₁₂O₁₉:Mn⁴⁺,Ge⁴⁺红色转光材料;采用硝酸盐分解法制备了不但能够将紫外至蓝光区的光转换成红光,而且可以将绿光区的光转换成红光的CaAl₁₂O₁₉:Mn⁴⁺,Cr³⁺红色转光材料;采用化学沉淀法制备出能够将蓝光,绿光,以及红外光转换成红光的LiYF₄:Er³⁺,Ho³⁺协同转光材料。首先,鉴于大多数太阳能电池对太阳中强度最大的蓝光以及能量最高的紫外光、紫光吸收利用效率低,我们选用能够吸收紫外至蓝光区段的转光材料CaAl₁₂O₁₉:Mn⁴⁺为基质,实现其将紫外至蓝光区段光转换成发射峰值在657nm处红光,从而满足大多数太阳能电池的利用要求。为了提高了CaAl₁₂O₁₉:Mn⁴⁺转光材料的红光发射效率,我们采用掺杂Ge⁴⁺离子,后退火处理等手段,使发光效率提高了81%。我们还优化了Ge⁴⁺离子的掺杂量以及退火温度等参数,并对其发光机理进行深入的分析。在此基础上,我们还尝试将绿色转光列入研究范围内,即在CaAl₁₂O₁₉:Mn⁴⁺中掺入能够吸收绿光,并将绿光转换成红光的Cr³⁺离子,进一步扩展转光频谱范围。我们还优化了Mn⁴⁺离子与Cr³⁺离子的掺杂浓度,并讨论了两种发光中心之间的关系及其对发光的影响。红外光是太阳光中比重最大的部分,高达52%以上,而太阳能电池在此区域只能利用很少的部分。利用上转换材料可实现太阳能电池对此区域光子的利用。然而,上转换效率极低,致使转光效果不明显,达不到太阳能电池增效目的。为此,我们制备一种新型的协同转光材料LiYF₄:Er³⁺,Ho³⁺,不但可以通过斯托克斯位移将蓝绿光转换为太阳能可利用的红光,还能实现红外光的上转换,使红外光转换成太阳能电池可利用的红光,更重要的是,在高低频率光的相互作用下,两个转光过程发生的协同作用,实现其转换效率的非线性叠加。更多还原

【Abstract】 With the emergence of energy crisis and environmental pollution,solar energy has received considerable attention because it is a green, safe and inexhaustible energy. Solar cells will be widely used in many fields. Photoluminescent materials could covert the sunlight into the responding region of solar cell. Those materials could change the current situation of low efficiency of solar cells, increasing the ulitility of sunlight. In this paper, CaAl₁₂O₁₉:Mn⁴⁺,Ge⁴⁺ which can convert ultraviolet light （UV）, violet light and blue light to red light have been prepared by a combustion method. CaAl₁₂O₁₉:Mn⁴⁺,Cr³⁺ which could convert ultraviolet light （UV）, violet light, blue light and green light to red light have been prepared by solid-state reaction method accompanying thermal decomposition of nitrate assisted with wet chemical mixing route. LiYF4:Er³⁺,Ho³⁺, a new kind cooperated down and up-conversion material, which can convert blue light, green light and infrared light to red light, have been prepared by a method of co-precipitation.Since most of the solar cells couldn’t absorb the ultraviolet, violet and blue light efficiently, we choose CaAl₁₂O₁₉: Mn⁴⁺ phosphor to convert the light of high energy into 657nm red emission. With the introduction of Ge⁴⁺ and the annealing treatment, the red emission intensity in CaAl₁₂O₁₉:Mn⁴⁺ phosphor increases by 81% under 330 nm UVA excitation. The concentration of Ge⁴⁺ and annealing temperature has been optimized in our experiment. And the luminescence mechanism has been discussed.CaAl₁₂O₁₉:Mn⁴⁺,Cr³⁺ which can not only convert ultraviolet violet and blue light to red light, but also convert green light to red light, has been investigated. The concentration of Mn⁴⁺ and Cr³⁺ has optimized in our experiment. And the luminescence mechanism has been also discussed.52% sunlight is in the infrared region. Only a little of infrared light could be absorbed by most of solar cells. At present,upconversion materials can convert the infrared light to the red emission. However, the enhancement of efficiency of electroluminescent is not obvious because of low efficiency of up-conversion. Hence, LiYF4:Er³⁺,Ho³⁺, a new kind material cooperated down and up conversion has been prepared. This material not only converts blue light and green light to red light by stokes shift, but also converts infrared light to red light by up-conversion. What’s more, the efficiency of cooperated down and up-conversion is larger than the total of stokes shift and up-conversion, due to the nolinear superposition.更多还原