Sunlight-activated yellow long persistent luminescence from Nb-doped Sr3SiO5:Eu2+ for warm-color mark applications


J. Mater. Chem. C, 2020,8, 1143-1150. https://doi.org/10.1039/C9TC05880J

Warm-color persistent luminescent materials are strongly desired for signage markings and medical imaging in comparison with green or blue counterparts. Herein we report a novel yellow long-persistent phosphor, Nb-doped Sr3SiO5:Eu2+, with a peak wavelength of ∼580 nm and persistence time of more than 14 hours at the 0.32 mcd m−2 threshold value after UV radiation. A combination of thermoluminescence (TL), thermoluminescence excitation (TLE), electron paramagnetic resonance (EPR) measurements and density functional theory (DFT) calculations reveals that the persistent luminescence enhancement is attributed to a significant Nb-induced increase of oxygen vacancies that act as electron trapping centers with appropriate trap depths. Groups of time-dependent color-change images are realized with this material, which has potential applications as anti-counterfeit and indicator marks. This investigation also expands the application of transition metal (TM) ions to the field of persistent luminescence and would motivate further exploration of TM substitutions to design and improve silicate or aluminosilicate persistent phosphors with superior performance.

Insight into the Relationship between Crystal Structure and Crystal-Field Splitting of Ce3+ Doped Garnet Compounds

J. Phys. Chem. C., 2018, 122, 6, 3567–3574. https://doi.org/10.1021/acs.jpcc.7b12826

The common understanding of the negative relationship between bond lengths and crystal-field splitting (CFS) is renewed by Ce3+ doped garnets in this work. We represent the contradictory relationship between structure data and spectroscopic crystal-field splitting in detail. A satisfactory explanation is given by expressing crystal-field splitting in terms of crystal-field parameters, on the basis of structural data. The results show that not only the bond length, but also the geometrical configuration have influence on the magnitude of crystal-field splitting. Also it is found that the ligand oxygen behaves differently with regard to multiple site substitution in garnet structure.

研究室总体介绍

光功能材料与器件研究室成员有教授2人、副教授2人， 2人获得教育部“新世纪优秀人才”称号，1人获得北京市科技新星称号。研究方向包括光功能材料与器件；材料第一性原理计算；特殊金属构件的寿命预测与控制；新型硫属半导体功能材料合成与性能表征。

光是信息、能量和美的载体。研究任务是开发可调控光的新材料。主要以化学构造—物理机制—材料应用为研究层次，应用先进方法和技术研究光功能和光电功能材料的组分－结构－性能的关系和新材料探索。目前研究对象是面向半导体照明LED用的发光材料，面向太阳能电池用的光谱转换材料，节能显示用的蓄光材料，以及新型半导体功能材料；注重提高材料性能的制备工艺、材料调控光和电的过程与机理、半导体照明封装技术和新型光电器件以及工程化应用。目的是研发并借助高性能材料和器件，充分利用光能，满足节能和环保的需求。

另外在计算材料领域，研究室以基于密度泛函理论的量子力学第一原理计算为主要手段，研究材料的结构力学、光学及输运性质。目前侧重聚变堆结构材料、锂离子电池材料、新型半导体材料和发光材料、生物医用材料钛铌合金等。基于量子力学第一原理的大规模电子结构计算随着计算机性能的飞速提高和凝聚态理论的不断发展成为理解和预测新材料结构和性质的强有力工具。理论计算与实验的密切结合，极大加快了新材料的研发进度。