利用金属激活离子掺杂的铁电薄膜材料实现电场调控光致发光的研究

Tunable photoluminescence (PL), namely spectroscopic tuning and PL intensity enhancement in phosphors are highly desirable for the purpose of understanding the physical processes of energy transition and transfer as well as widespread applications. To date, modification of the PL in metal activator ion doped materials excited by a given excitation source can only be achieved by changing the composition of host materials and/or doping metal ions, limiting our understanding of the detailed process of luminescence and applications. By taking advantage of the unique properties of variables coupling crystal structure and polarization of ferroelectric host material in combination with the luminescence of doping metal ions affected by the crystal environment, here we propose a new concept, namely electric control of photoluminescence in ferroelectrics. In this project, in order to verify the original concept experimentally, we propose to grow various thin-films of metal ion-doped ferroelectrics by laser molecular beam epitaxy and the PL modification in metal ion-doped ferroelectrics will be realized in reversible, in-situ, real-time and dynamical way under electric-field control, which is in contrast to the above conventional chemical route. With our developed novel measurement system allowing characterization of PL and ferroelectric properties simultaneously, the synthesis process, resultant microstructure and ferroelectric properties as well as their correlations with luminescent properties of the materials, will be systemically investigated. The measured results will be compared with theoretical models to gain a more detailed understanding of the observed new phenomena. Consequently, the proposed research will give a new impulse to the investigation of both ferroelectrics and phosphors, which is expected to unlock a realm of new possibilities in the field of ferroelectric-luminescence. This also promises high impact on the multifunctional integrated device applications, such as our proposed electric controlled upconvertor.

光致发光的调控对于研究发光材料的物理机制及其广泛应用具有重要意义。目前金属离子掺杂发光材料的发光调控局限于传统的化学方法即调整材料基质和掺杂离子组分或者合成条件，这种手段限制了对具体发光动态过程的认识和应用。利用铁电基质的晶体结构和极化受外场耦合可变的性质并结合某些掺杂金属离子的发光受晶体环境影响的特征，我们在此提出了"铁电电控光致发光"新慨念。为实验证实这个原创性慨念，本研究我们用激光分子束外延法制备多种金属离子掺杂铁电薄膜，将采用与传统化学途径完全不同的电场方法，以可逆原位和实时动态方式实现对光致发光的调控。应用我们铁电-发光联合检测等实验装置，系统研究材料的合成工艺，微结构，铁电以及与发光性质的关系。实验结果将和理论模型比较，有望深入认识这种新现象。本研究将有助于推动铁电和发光材料两方面研究，尝试不同研究领域的交叉，并对研制新型多功能集成器件如提出的电控上转换发光器件带来重要影响。

金属离子掺杂的无机固体光致发光材料，在光电器件以及生物医学等领域已获得了广泛的研究和应用。遗憾的是目前实现金属离子发光材料的调控方法很有限，最常用的的办法是改变发光材料的化学组成，限制了我们对具体发光物理过程的理解。值得注意的是铁电材料是非常具有代表性的在外场作用下会发生结构变化一类体系。考虑到某些掺杂金属离子发光特性受晶体场和结构不对称程度影响，本项目研究尝试两个不同研究领域的交叉，通过将各种具有光致发光特性的合适稀土离子和过渡族离子与铁电材料结合，研究分析了铁电材料结构特对光致发光性能，包括发射波长，发射强度和荧光寿命等参数的相互影响；揭示出合成材料的微观结构，形貌，取向与铁电材料中光致发光性能之间的内在联系。本项目我们用激光沉积法精确制备出几种典型的具有光致发光特性的稀土，过渡族金属离子掺杂的铁电薄膜。研制发展了铁电-发光同时检测的实验测试装置系统，系统地研究了材料的合成工艺，铁电和掺杂金属离子发光性质的关系。观察和研究了许多金属离子在铁电体系中发光的新现象和新性能。例如，验证实现了与传统方法不同的以可逆原位实时动态方式实现电场调制发光。首次观察到Ni离子掺杂的铁电(Ba,Sr)TiO3中实现了覆盖光通讯窗口(O-L)的宽波段的发光现象，在1200 nm到超过1600 nm范围，观察到超过200 nm带宽的发光。通过对实验结果和理论进行比较，对许多新现象和机制有了深入的认识和理解，研究了发光改变现象后面的基质晶体场，温度，结构不对称性对能级跃迁和能量传递影响的具体物理过程。研究的结果可以推广到更多材料和结构体系。本研究项目的创新成果在国际同行产生了影响。标注此基金资助论文都发表在国际SCI有影响的杂志上，某些论文被ESI选为“高引论文”（Highly Cited Paper)，课题负责人应邀为国际杂志写评论，多次对此课题相关领域作特邀报告。本研究的完成将有助于推动铁电物理和发光学两方面研究，拓宽相关领域的交叉研究，对开辟新型多功能器件具有重要的意义和应用前景。