Energy Transfer Processes in Highly Rare‐Earth–Doped Planar YAG Waveguides

We report on the concentration effects on active ion emissions in planar waveguides of YAG:RE³⁺ (RE=Nd, Yb, and Pr) obtained by liquid phase epitaxy on YAG substrates. Liquid phase epitaxy method, which in contrast to the standard Czochralski crystal growth technique, allowed high concentrations of activator, up to 10 at. %, to be obtained. We have investigated emission spectra, the dynamics of the emitting states and the transition linewidths in a wide concentration range. The cross‐relaxation and up‐conversion transfer rates dependence on concentration was determined.     

10BaF2:NaF, Na3AlF6/TiO2 composite as a novel visible-light-driven photocatalyst based on upconversion emission

A rare-earth free upconversion luminescent material, 10BaF2：NaF, Na3AIF6, is synthesized by a hydrothermal method. The study of fluorescent spectrum indicates that it can convert visible light （550 nm-610 nm） into ultraviolet light （290 nm 350 nm）, and two emission peaks at 304 nm and 324 nm are observed under the excitation of 583 nm at room temperature. Subsequently, 10BaF2：NaF, Na3AIF6/TiO2 composite photocatalyst is prepared and its catalytic activity is evaluated by the photocatalytic reduction of CO2 under visible light irradiation （λ〉 515 nm）. The results show that 10BaF2：NaF, Na3AIF6/TiO2 is a more effective photocatalyst for CO2 reduction than pure TiO2, their corresponding methanol yields are 179 and 0 μmol/g-cat under the same conditions. Additionally, the mechanism of photocatalytic reduction of CO2 on 10BaF2：NaF, Na3AIF6/TiO2 is proposed.     

10BaF₂:NaF,Na₃AlF₆/TiO₂ composite as a novel visible-light-driven photocatalyst based on upconversion emission

A rare-earth free upconversion luminescent material, 10BaF 2 :NaF, Na 3 AlF 6 , is synthesized by a hydrothermal method. The study of fluorescent spectrum indicates that it can convert visible light (550 nm–610 nm) into ultraviolet light (290 nm–350 nm), and two emission peaks at 304 nm and 324 nm are observed under the excitation of 583 nm at room temperature. Subsequently, 10BaF 2 :NaF, Na 3 AlF 6 /TiO 2 composite photocatalyst is prepared and its catalytic activity is evaluated by the photocatalytic reduction of CO 2 under visible light irradiation (λ > 515 nm). The results show that 10BaF 2 :NaF, Na 3 AlF 6 /TiO 2 is a more effective photocatalyst for CO 2 reduction than pure TiO 2 , their corresponding methanol yields are 179 and 0 μmol/g-cat under the same conditions. Additionally, the mechanism of photocatalytic reduction of CO 2 on 10BaF 2 :NaF, Na 3 AlF 6 /TiO 2 is proposed.     

Yb3+和Er3+共掺杂的CaF2纳米晶近紫外上转换发光

研究了Er³⁺和Yb³⁺共掺杂的CaF₂纳米材料的制备及其紫外上转换发光性质。在980 nm二极管激光器激发下,该材料可发出相对较强的紫外和绿色双色上转换发光。研究了敏化离子Yb³⁺以及发光中心离子Er³⁺掺杂量对该材料紫外上转换发光相对强度的影响,并进一步对该材料紫外上转换发光增强的可能机制进行了探讨。     

掺铒碲酸盐玻璃中的协作上转换能量转移

研制了组分为TeO₂-ZnO-Na₂O(TZN)和TeO₂-ZnO-La₂O₃(TZL)掺铒碲酸盐玻璃,测试了碲酸盐玻璃中Er³⁺离子⁴I_13/2能级荧光特性.结果发现,在较高的Er³⁺离子掺杂浓度下,碲酸盐玻璃的荧光强度随着Er³⁺离子掺杂浓度的提高而减小.分析表明,对于除     

激光吸收铒掺杂上转换材料的光谱特性实验分析

采用湿化学法制备了铒掺杂氧化钇上转换纳米粉体材料.研究了不同掺杂浓度、掺杂元素种类对材料显微结构、物相组成和光谱特性的影响.结果表明,通过控制掺杂元素的种类、掺杂浓度可以实现对光谱性能（包括光谱反射系数和上转换光谱）的调控.实验表明,该材料对106 μm激光具有较好的吸收性能. 关键词： 铒掺杂氧化钇纳米粉体 上转换材料 激光与红外复合隐身 光谱反射系数     

光敏化铱配合物三线态材料

铱配合物由于高的激发单线态到三线态的量子转化效率和可调节的三线态寿命,近年来在三线态光敏化应用领域备受瞩目.科学家们就调控铱配合物发光波长和发光量子效率已建立起有效的分子设计策略和原则,但对如何调控铱配合物的可见光吸光响应,三线态量子产率和寿命等光敏化应用要求的重要光物理参数的相关探索并不多,相应的分子设计策略和原则远未建立.本文介绍了铱配合物与光敏化过程相关的光物理特征,改进铱配合物可见光吸收性能、调控三线态量子产率和寿命的分子设计策略,综述了铱配合物近年来应用于染料敏化太阳能电池、三线态-三线态湮灭能量上转化和光裂解水制氢的研究进展,梳理了铱配合物分子结构与光敏化性能之间的部分关联关系.     

等离子体增强上转换发光及其应用

稀土上转换纳米材料（UCNPs）是一类在近红外光激发下发出可见光的纳米材料。与有机荧光染料、量子点等发光材料相比,UCNPs具有化学稳定性高、光稳定性强、荧光寿命长、反斯托克斯位移大、发光谱带窄和光穿透深度大等诸多优点,在生物成像、传感器、激光器、光动力疗法和太阳能电池等领域有潜在的应用价值。但是由于UCNPs激活离子的吸收截面太小,导致其发光效率偏低,限制了UCNPs的进一步应用。因而如何提高上转换发光强度成为当前的研究热点。针对上述问题,本文系统阐述了金属表面等离子体共振（SPR）增强上转换发光领域的研究进展。首先介绍了SPR增强上转换发光的三种机制,随后重点介绍了化学法和物理法这两种SPR-UCNPs体系的构建方法以及其在太阳能电池、生物成像、生物检测、光热治疗和光催化等领域的应用。文章最后指出了SPR增强上转换发光领域存在的不足和未来的研究方向。     

三重态湮灭光子上转换体系聚合物基质的研究

三重态-三重态湮灭(TTA)上转换是一种通过多光子机制将低能量光波向高能量光波转换的技术,在太阳能电池、光催化、生物成像、防伪等领域具有潜在的应用前景。传统的TTA上转换一般在无氧溶液中发生,使得其应用领域严重受限。近几年固态TTA上转换发光材料的发展引起了研究者的关注,该文从TTA上转换体系聚合物基质的状态以及TTA体系在聚合物中的分散形式出发,总结了近十年TTA上转换体系在聚合物基质中的研究进展。     

Chiral self-assembly regulated photon upconversion based on triplet-triplet annihilation

Photon upconversion (UC) based on triplet-triplet annihilation (TTA) in quasi-solid or solid state has been attracting much research interest due to its great potential applications. To get effective UC, precisely controlled donor-acceptor interaction is vitally important. Chiral self-assembly provides a powerful approach for sophisticated regulation of molecular interaction. Here we report a chiral self-assembly controlled TTA-UC system composed of chiral acceptor and achiral donor. It is found that racemic mixture of acceptors could form straight fibrous nanostructures, which show strong UC emission, while chiral assemblies for homochiral acceptors emit weak upconverted light. The racemic assemblies allow efficient triplet-triplet energy transfer (TTET) and further realize efficient UC emission, while the homochiral assemblies from chiral acceptor produce twisted nanostructures, suppressing efficient triplet energy transfer and annihilation. The establishment of such chiral self-assembly controlled UC system highlights the potential applications of triplet fusion in optoelectronic materials and provides a new perspective for designing highly effective UC systems.