【作者】 王祥夫；

【导师】 颜晓红；

【作者基本信息】 南京航空航天大学 ， 光学工程， 2012， 博士

【摘要】 能量转换材料广泛应用于光学、磁学、电学等科学领域。光致发光能量转换材料的研究关系着激光晶体材料、太阳能电池、生物荧光标记、荧光显示材料、长余辉发光材料等关键技术领域，其能量转换机制及晶体场调节等对发光中心的影响是制约发光特征和效率的主要因素。为了提高光致发光能量转换材料的性能，我们提出了紫外光和红外光的光子协同增强效应的物理模型，设计了相关实验，研究了该机制的可行性；为了探索内部电荷再分布对能量转换材料的合成机理和光学性质的影响，我们研究了金属离子掺杂对能量转换材料的结构相和荧光调制。本论文的具体研究内容如下：1.我们介绍了稀土掺杂能量转换材料的种类、特征、应用以及制备方法，光伏电池的发展状况以及从光学角度提高光伏效率的途径。2.我们提出了光子协同增强效应机制，并合成了Er3+掺杂的YbF3和NaGdF4磷光体。在紫外光和红外光的单模和双模激发下，研究分析了这两种磷光体的稳态和瞬态荧光光谱的变化趋势。结果发现，在369nm+980nm双模共激发下，紫外光和红外光的光子协同增强效应在Er3+掺杂的YbF3中能够实现，并获得了最大为10.43%的656nm红光的绝对增强。在370nm (或442nm)+1.54μm双模共激发下，在Er3+掺杂的NaGdF4中实现了紫外光（或蓝光）和红外光的协同效应，获得了最大为42.2%的658nm红光的绝对增强。通过分析红外光的光子数的变化和红光的荧光寿命的变化，我们证明了光子协同增强效应的存在性。该工作为解决光电转换过程中红外光的子带损失和紫外光的热损失问题提供了新的思路。3.我们提出了在蓝光激发下实现白光LED的设想，制备了Eu3+/Ho3+掺杂的TGNL玻璃，研究了该玻璃在蓝光激发下的瞬态和稳态荧光光谱。在458nm蓝光激发下，从Eu3+和Ho3+掺杂的TGNL玻璃的发射谱在1931-CIE(X, Y)色坐标上的染色点可以看出，荧光的颜色从绿光跨过黄光进入红光区，实现了颜色的宽范围调节。从能量传递角度,我们分析了Eu3+-Ho3+体系的能量转移对多色荧光发射的调节作用。该工作为解决目前商用YAG:Ce3+白光LED荧光粉的显色指数比较差的问题提供了新的方法。4.我们通过控制合成样品的形貌控制其光学性质，探索了纳米盘、微米管、纳米棒三种形貌对单一Na1.23Ca0.12Y1.28Er0.24F6磷光体的光致发光和光电性质的影响。我们用水热法合成了Na1.23Ca0.12Y1.28Er0.24F6纳米盘、微米管、纳米棒，在980nm激发下探索了不同形貌的六角相Na1.23Ca0.12Y1.28Er0.24F6的荧光发射，发现Na1.23Ca0.12Y1.28Er0.24F6纳米盘、微米管、纳米棒发射出蓝光、红黄光、红光多色荧光。同时在980nm激发下，Na1.23Ca0.12Y1.28Er0.24F6纳米盘、微米管、纳米棒也表现出新颖的内部光电效应。我们实现了通过调制Na1.23Ca0.12Y1.28Er0.24F6的形貌控制多色荧光发射和内部光电效应，并给出了相应的物理解释。5.我们从晶体内部电荷的变化调制荧光材料的结构和光谱出发，研究了电荷再分布对氟化物材料的形貌、尺寸、相结构和光学性质的调制作用。我们用水热法合成了Bi3+, Al3+, Gd3+, Yb3+掺杂的BaF2和SrF+2微纳晶体，Pr3掺杂的NaYF4:18%Yb3+/2%Er3+，Ca2+和Er3+掺杂的NaGdF4晶体，通过SEM、TEM、能谱和光谱的分析，研究了掺杂前后的形貌、尺寸、相结构和光学性质的变化情况，并利用密度泛函理论计算出了金属离子掺杂对BaF2和SrF2晶胞的电荷差分变化。理论结合实验提出了电荷再分配对氟化物形貌、相结构的调制原理。6.我们提出了在一层薄膜中同时实现减反和转光双效作用的设想，用PS小球模板法制备了Y3+2O3:Er多孔金字塔阵列，实现了孔径尺寸可控。我们研究了Y+2O3:Er3多孔金字塔阵列的透射谱和在1.538μm红外光激发下的荧光光谱，结果发现孔径对阵列的光透过率有调节作用，当孔径为420nm时样品达到87%～96%最佳的透光率。此外，Y2O3:Er3+多孔金字塔阵列还能够把1.538μm红外光转化为绿光、红光、红外光。通过Li+离子的掺杂，我们进一步调节了Y32O3:Er+多孔金字塔阵列的荧光发射，使红光增强了19倍，红外光增强了3倍。这种具有减反/转光双功能度的Y2O3:Er3+多孔金字塔阵列可能用作太阳能电池的光学层材料。最后，我们总结了本论文的研究工作并提了多频区多光子协同增强，以及协同转光/陷光双效的纳米组装体的展望。更多还原

【Abstract】 Energy-converted materials are used widely in optics, magnetics, and electricity fields. The studyof photoluminescence energy-converted materials involves several key fields, such as laser materials,solar cells, biological fluorescence label, display materials, and long afterglow phosphor and so on.The energy transfer mechanism in the photoluminescence process, and the influence of crystal fieldon luminescent centers, are the main factors to suppress high fluorescence quantum yield. To enhanceluminescent efficiency, we proposed a physical model of the synergistic effect of the ultraviolet andinfrared photons, and designed relevant experiments to explore the possibility of the proposedphysical model. To explore the influence of redistribution of internal charges on the synthesismechanism and optical properties, we studied the phase structure and fluorescence modifications ofmetal ions doped energy-converted materials. The thesis is organized as follows:1. The species, application feature, and preparation methods of the Rare-earth ions dopedenergy-converted materials were introduced. We introduced the development status of solar cells, andpropose some methods to increase photovoltaic effect through optical means.2. We proposed the synergistic effect of ultraviolet and infrared photons. We synthesized Er3+dopedYbF3and NaGdF4phosphors to check the possibility of synergistic effect. The change trend of thetransient and steady-state spectra was studied by employing single-mode and dual-mode excitationsources. The synergistic effect of ultraviolet and infrared photons was realized in the Er3+doped YbF3phosphors under369nm and980nm dual-mode excitation. The maximal absolute enhancement rateof658nm red emission was10.43%. The synergistic effect of ultraviolet and infrared photons wasrealized in the Er3+doped NaGdF4phosphors under370nm (or442nm) and1.54μm dual-modeexcitation. The maximal absolute enhancement rate of658nm red emission was42.2%. Thepossibility of synergistic effect was proved through analyzing the number of infrared photons andlifetimes of the red emission. The photon synergistic effect is a novel method to reduce thesub-bandgap and thermalization losses caused by ultraviolet and infrared photons in photovoltaicconversion.3. We offered an idea to obtain white light LED with blue excition source. We synthesizedEu3+/Ho3+doped TGNL glass, and analyzed the transient and steady-state spectra of the glass. Theemission spectra of the glass can be converted to the Commission International de I’Eclairage (CIE)1931chromaticity diagram. The luminescent color changes from green, through yellow, and finally to red. As a result, some color-tunable luminescence emissions were obtained. We thought thatcolor-tunable luminescence emissions were modified by an energy transfer from Eu3+to Ho3+ions.This work offeres a new method to resolve the poor color rendering index of YAG:Ce3+phosphors.4. We realized to control optical properties by controlling shapes of some phosphors, and exploredthe influence of specific morphological shapes of nanodisks, nanorods and microtubes on thephotoluminescence and inner photoelectric effect of single Na1.23Ca0.12Y1.28Er0.24F6phosphor. Wesynthesized hydrothermally hexagonal Na1.23Ca0.12Y1.28Er0.24F6nanodisks, microtubes, and nanorods,and obtained luminescence emissions by exciting nanodisks, microtubes, and nanorods with a980nmlaser. As a result, the nanodisks, microtubes, and nanorods emited blue, orange, and red luminescence,respectively. Additionaly, the Na1.23Ca0.12Y1.28Er0.24F6nanodisks, microtubes, and nanorods alsoshowed inner photoelectric effect behaviors under980nm excitation. Simultaneous control ofhomochromatic luminescence and inner photoelectric effect were achieved by modifyingmorphological shapes of single Na1.23Ca0.12Y1.28Er0.24F6phosphor.5. We explored the modification of redistribution of internal charges on the shape, phase, structure,and optical properties. We synthesized hydrothermally Bi3+, Al3+, Gd3+, or Yb3+doped BaF2and SrF2,Pr3+doped NaYF4:18%Yb3+/2%Er3+, and Ca2+or Er3+doped NaGdF4. The change trend of shape,phase, structure, and optical properties of above phosphors was obtained by analyzing the images ofSEM, TEM, EDS, and spectra. The electron density difference of metal ions doped BaF2and SrF2wascalculated according to the density functional theory. We proposed a modulation principle of shape,phase, and structure of the BaF2and SrF2crystals induced by the redistribution of internal charges.6. We offered an idea to realize simultaneously anti-reflection and light-conversion in single thinfilm. We synthesized Y2O3: Er3+porous pyramid arrays by different templates of the polystyrenecollidal microsphere, in which the micropore sizes can be controlled. The transmittance spectra ofY2O3:5%Er3+porous pyramid arrays showed that the transmission ratio could be controlled byadjusting micropore diameter sizes. The fluorescence spectra of porous pyramid arrays showed that1.538μm infrared light was upconverted to green, red and infrared luminescence. The intensity of redemission band of Y+2O3:5%Er3,5%Li+pyramid arrays was about19times greater than that of thesample without Li+. The intensity of infrared emission band is about3times greater than that of thesample without Li+. The Y2O3:5%Er3+porous pyramid arrays with the roles of anti-reflection andlight-conversion could be used as optical coating of the solar cells.At last, we gave a summary of the thesis and prospect of future works of multi-photons synergisticeffect and bifunctional nanoparticle with the anti-reflection and light-conversion functions.更多还原