自恢复应力发光纳米材料的结构与功能研究

Among the Elastico-Mechanoluminescence (E-ML) smart materials, self-recoverable ML materials have many advantages not only in the realization of direct mechanical-light conversion, but also in the potential applications including and stress visualization for visual stress sensor and intelligently passive display due to their high brightness (~120cd/m2) and durability over 100000 repeated mechanical stresses (~10kP). As one ML particle can be used as single stress sensor or displays unit, the performances of sensing and visualization are mainly dependent on the instinct properties of particle such as particle size distribution, crystal orientation, composition, E-ML intensity and color. In this project, core@shell structure of self-recovery ML materials with controllable sizes and structural orientations are proposed to be well designed and prepared. The mechanical-light conversion including mechanical-color changing properties and E-ML mechanism of the different types of core@shell ML nanostructures under mechanical stimuli will be systematically researched. Base on the experimental results, the correlations between the size, orientation, composition and ML performance of the selected nano-materials will be clarified. Simultaneously, the relationships between self-recovery ML performances and the modes of the mechanical stimuli, e.g. vertical touching and horizontal sliding, are proposed to be systematically investigated. By utilization of the prepared ML materials, we propose to design a novel kind of protocol sensor and luminescent device with soft and wearable properties for visibly tactile sensing and imaging. The performances of stress visualization, mapping and sensing properties will be investigated and evaluated by recording and analyzing the photograph or video of self-recovery E-ML emission. Once refined, the project would be expected to be of vital importance on the fields of stress sensing and visualizations as well as power-free display, for example, wearable tactile sensor, advanced touch screen, and intelligent robots.

作为弹性应力发光智能材料的一个分支，自恢复应力发光材料不仅具有力-光直接转换能力，还能在数10万次以上反复动态力(~10kP压强)下保持稳定的高亮度发光(~120cd/m2)，在可视化应力传感和智能无源显示器件领域表现出极为重要的优势。单一发光颗粒作为一个独立传感和显示单元，其性能取决于材料的自身的尺寸、取向、结构、发光亮度和颜色。然而当前研究只限颗粒受力大小对发光强度对应关系的单一模式。本项目通过设计合成具有自恢复应力发光掺杂核壳结构作为传感单元，研究其自恢复发光特性(如颜色)的变化核发光机理，阐明在力作用下，核壳构成与发光特性之间的关系；研究不同纳米核壳结构作为传感单元在接触压力及滑动力下发光变化规律，设计可穿戴柔性触觉传感显示器件；通过记录并检测发光图像信息来评估可视化和传感效果。本项目预期在可视化应力传感和显示领域，如触觉传感器，新型触摸屏和智能机器人领域具有重应用。

本项目选取掺杂型自恢复应力发光体系作为研究对象，以硫化锌/硫氧锌钙基半导体化合物为备选基质材料，以金属离子掺杂结合基质元素替代的办法实现自恢复应力发光性能的调控。通过对合成工艺控制，结构优化，实现应力发光晶体尺寸和形貌的可控生长与制备，通过调控掺杂发光离子，实现在同一动态压强下应力发光光谱从紫外到红外的全稀土光谱（300nm~1550nm）灵活调控，通过灵活的异质结结构设计，利用结区的界面与压电协同效应提升应力发光亮度为单相材料的2倍以上。同时，在此基础上研究材料结构与自恢复发光应力发光特性关联。筛选所制备的优异应力发光结构，包括高亮度多光谱的异质结结构，选取合适的弹性有机体进行复合，摸索配比，制备出同时能承受稳定机械摩擦和压缩力柔性复合物，实现机械力驱动发光的新型原型器件，研究器件在按压、摩擦和拉伸触碰等条件下的自恢复应力发光特性，包括强度、颜色与重复施加应力的依赖关系。提出并验证基于自恢复应力发光复合器件在实际场景中的应用可能性。在不同场景下，通过采集发光动态视频和图像，利用数值软件分析建立起视频和图像信息与动态应力的对应关系，包括亮度、色度和响应时间等参量在动态力作用下的变化规律。研究并分析在可视化传感、智能电子签名、触摸式显示屏和电子皮肤等器件中的应用优势，提出新思路。同时拓展其应用范围，包括节能显示与照明领域的可能性，针对功能的自恢复应力发光结构，系统分类研究其在无源显示、智能传感、应力编码防伪、新型触摸式显示屏和电子皮肤等器件中实用效果。该项目为高性能应力发光新材料与潜在的应用场景提供了大量的实验数据，并为自恢复应力发光在相关领域的应用指明了方向，同时实验结合理论分析，基于晶体缺陷与能带理论，提出了与所研究材料体系自恢复发光契合的机理模型。在项目支持下，研究团队在Advanced Materials，Advanced Functional Materials，Advanced Science，Small，Nano Research，Nano Energy，Science Bulletin，Infomat 与《发光学报》等国际/国内期刊发表研究论文30余篇，申请专利10余项，研究成果有望在将来的智能传感，新型显示与成像技术，节能照明等领域具有重要应用前景。