基于内电场实现CaZnOS体系光-力-电耦合和能量转换的原位晶体结构解析和第一性原理研究

The internal electric field exhibits an important influence on the mechanoluminescence, electroluminescence, piezoelectric properties as well as energy conversion efficiency of the electro-mechano-optical multi-functional materials. CaZnOS with layered crystal structure is an important multi-functional material candidate with electro-mechano-optical conversion ability, and it is extremely important to investigate the coupling between different external fields and the energy conversion mechanism based on the internal electric field. In the present project, several in-situ crystal structure characterization techniques and first-principle calculation will be used to investigate the following scientific issues. The correlation between the external field with the crystal structure (cell parameters, local environment of the activators and depth of the traps) and the electronic structure (band structure and density of state) of CaZnOS, as well as the creation of internal electric field will be established. The influence of internal electric field on the trap depth and carriers’ transportation, as well as the relationship between the electric field and mechanoluminescence, electroluminescence and piezoelectricity will be studied in detail. Then, the mechanisms of electro-mechano-optical coupling and energy conversion will be proposed based on the internal electric field. The regulation of the internal electric field can be achieved by the modification of crystal structure and electronic structure through selective doping in CaZnOS. It will further regulate the trap depth and carriers’ transportation, leading to the optimization and improvement of the electro-mechano-optical conversion efficiencies of CaZnOS-based multi-functional materials.

内电场对光-力-电转换多功能材料的应力发光、电致发光、压电性能和能量转换效率等方面具有重要影响。层状晶体结构的CaZnOS是具有光-力-电转换性能的多功能化合物，但对其光-力-电转换过程中涉及内电场的多场耦合效应和能量转换物理机制需要全面深入的认识。本项目拟通过多种原位晶体结构解析方法并结合第一性原理计算，研究外场(应力场、电场)作用下CaZnOS体系的晶体结构(晶胞参数、激活剂离子的配位环境、陷阱深度)和电子结构(态密度、能带结构)的变化规律，以及内电场的建立与晶体结构和电子结构的关系，分析内电场对陷阱深度、载流子输运的影响规律，及其与应力发光、电致发光和压电性能的内在联系。通过对CaZnOS基质阳离子或阴离子的选择性掺杂，调整其晶体结构和电子结构实现对内电场的调控，以进一步调控材料内部的陷阱深度和载流子输运，最终实现此类光-力-电转换多功能材料的优化设计和性能改进。

智能材料是一种基于同时呈现力、光、电、声、磁等多种物理性能之间耦合特征的多功能材料。层状晶体结构的CaZnOS是具有光-力-电转换性能的多功能化合物，但对其能量转换过程中涉及内电场的多功能耦合效应和能量转换物理机制需要全面深入的认识。本项目基于国内外相关的报道及课题组已取得的前期实验和理论结果，从宽带隙层状晶体结构的CaZnOS入手，通过选择性掺杂激活剂离子（Bi3+、Mn2+、RE3+等）来设计合成新型光-力-电转换多功能材料。从CaZnOS体系的晶体结构(晶胞参数、激活剂离子的配位环境、陷阱深度)和电子结构出发，结合实验分析和理论模拟，获得了CaZnOS体系的晶体结构和电子结构与内电场的关系，以及内电场与应力发光、压电效应和电致发光的内在联系，并在此基础上构建了内电场的多场耦合物理机制和能量转换模型，并通过对CaZnOS基质中阳离子或阴离子的选择性掺杂，实现内电场的调控进而实现材料内部陷阱深度和载流子输运的调控，最终获得高效能量转换效率的多功能材料。并且在该材料体系的基础上，开发出相应的多功能材料能量转换原型器件，实现了无损应力大小与分布的探测（应力阈值<100N）、超声分布探测、无源显示与照明、以及可以用于生物体内的应力分布探测。本项目的实施为深入理解多场耦合物理机制和能量转换模型，同时为无源显示、传感器系统、集成微光-力-电系统和信息器件智能调控系统等众多应用领域提供可利用的光-力-电转换多功能材料奠定基础。