宽带近红外LED用Ca3Sc2Si3O12:Cr3+组分设计和发光性能调控机理研究

近红外光谱技术在食品安全等无损检测方面具有广泛应用，便携化的发展对光源小型化、光谱宽带化提出了需求。荧光转换的近红外LED是满足该要求的最佳技术方案，因此，开发适合蓝光激发的宽带近红外荧光材料成为研究热点。前期研究表明Ca3Sc2Si3O12:Cr3+环境稳定性好、发光效率高，在近红外LED器件中具有优良的应用效果，但其发光带宽较为有限。为此，本项目拟通过Lu、Mg等元素共取代Ca、Sc进行组份设计，再选择与Cr3+激发峰匹配的Ce3+，以及具有特征红外发光的Yb3+和Nd3+共掺杂，调控获得谱带更宽、效率更好、稳定性更好的近红外荧光材料。通过理论与实验结合的方法，研究组分设计对能带结构、晶体场强度、电声耦合的作用规律；揭示多离子间的能量传递和发光动力学过程，阐明发光性能调控机理。本项目实施有助于促进宽带近红外LED光源的快速发展，并为新型高效率宽带近红外荧光材料的开发提供理论依据。

Smart NIR light sources, as an emerging field, are proposed to combine with smart phones together to achieve convenient and fast applications. Broad NIR-emitting phosphor-converted LEDs are believed to be the best solution. Thus, how to achieve broad NIR phosphors that can be excited efficiently by blue light is one of the most important challenges. .The silicate garnet, Ca3Sc2Si3O12 (CSSG), is a promising host for Ce3+ due to its excellent thermal stability and high QE. Fortunately, Cr3+ can be excited by blue light and show a broadband NIR emission in CSSG. Unfortunately, the reported luminescence and thermal stability were low because the Cr3+ luminescence suffer from impurities and oxidation of Cr4+. The electro-phono coupling (EPC) mechanism in CSSG that usually determines the Cr3+ luminescence is unknown. In this project, we propose a strategy to optimize CSSG:Cr3+ through the substituting of Lu3+-Mg2+ for Ca2+-Sc3+ and the co-doping of Ce3+/Yb3+/Nd3+. The effects of Lu3+-Mg2+ on the crystal-field environments, EPC and NIR luminescence will be studied. The dynamic processes and energy transfers among Ce3+/Yb3+/Nd3+/Cr3+ will be investigated. We believe that this project will provide a strong physical basis and an effective strategy to discover more and more Cr3+-doped NIR phosphors. Moreover, this work will advance the development and the application of the next-generation smart NIR light source.