飞秒激光微流道烧蚀法构建绿光硒化锌量子点的缺陷态跃迁机理研究

Zinc selenide (ZnSe) quantum dot with green fluorescence emission has no risk of heavy metal ion leakage, and is a safe and environmentally friendly wide band gap semiconductor luminescent material. Compared with the currently large-scale used cadmium selenide quantum dots, the biosafety of ZnSe quantum dots is higher. It has a promising application for forming directly contacted wearable flexible display devices. Previous studies have shown that the femtosecond laser ablation in microchannel process has a significant effect on the defect state green fluorescence emission characteristics of zinc selenide quantum dots. In view of the difficulty in explaining the problem of the defect state green-light fluorescence transition mechanism of zinc selenide quantum dots, this project focuses on two key scientific issues:（1）Establishment of multiple defect state model with deep energy level structure of green light zinc selenide quantum dots and，（2）The interaction between laser pulse and zinc selenide material during the laser ablation process in microchannel. First principles and ultrafast dynamics are the foundation theories. The exploration of influence of femtosecond laser ablation process on the formation of multiple defect states of green-light zinc selenide quantum dots is considered to be the main research line. The effect of femtosecond laser parameters during the ablation process on the new wavelength properties of green-light zinc selenide quantum dots will be revealed. The green fluorescence transition mechanism of defect state from zinc selenide quantum dots will also be improved. It will build the foundation for a safe and reliable next-generation wearable flexible display devices.

绿色荧光发射硒化锌（ZnSe）量子点没有重金属离子泄露风险，是安全环保的宽禁带半导体发光材料，较目前大规模应用的硒化镉量子点的生物安全性更高，具有构成直接接触式可穿戴柔性显示器件的应用前景。前期研究表明，飞秒激光微流道烧蚀过程对绿光硒化锌量子点的缺陷荧光发射特性有显著影响。针对目前尚无法对绿光硒化锌量子点的缺陷态荧光跃迁机理做出完善解释的这一难题，本项目以第一性原理和超快动力学为基础，以飞秒激光烧蚀过程对绿光硒化锌量子点多重缺陷态形成的影响探索为主线，利用密度泛函理论和FDTD算法为手段，着重研究2个关键科学问题：（1）绿光硒化锌量子点深能级结构的多重缺陷态模型的建立和（2）飞秒激光微流道烧蚀过程中激光与硒化锌材料的相互作用关系。揭示飞秒激光微流道烧蚀参数对绿光硒化锌量子点新波长发光特性的影响规律，完善绿光硒化锌量子点的缺陷态荧光跃迁机理。为实现安全可靠的下一代可穿戴柔性显示器件奠定基础。

绿色荧光发射硒化锌（ZnSe）量子点没有重金属离子泄露风险，是安全环保的宽禁带半导体发光材料，较目前大规模应用的硒化镉量子点的生物安全性更高，具有构成直接接触式可穿戴柔性显示器件的应用前景。前期研究表明，飞秒激光微流道烧蚀过程对绿光硒化锌量子点的缺陷荧光发射特性有显著影响。针对目前尚无法对绿光硒化锌量子点的缺陷态荧光跃迁机理做出完善解释的这一难题，本项目以第一性原理和超快动力学为基础，以飞秒激光烧蚀过程对绿光硒化锌量子点多重缺陷态形成的影响探索为主线，利用密度泛函理论和FDTD算法为手段，着重研究了2个关键科学问题：（1）建立了绿光硒化锌量子点深能级结构的多重缺陷态模型。将形成能较小的Se填隙、Se替位、Zn空位、表面不饱和悬挂键作为主要的缺陷类型，参与模型的建立，以使模型更符合实际。研究揭示出500 nm波长附近的宽带隙跃迁来自于ZnSe中硒替位缺陷到硒填隙缺陷能级的电子跃迁过程。明亮的绿色荧光可能来就自这一电子跃迁过程。（2）飞秒激光烧蚀过程中产生了绿光硒化锌量子点。飞秒超快激光产生的极端物理条件导致硒化锌量子点表面化学失配加剧，这些表面缺陷会引入缺陷能级，从而导致绿色荧光的新波段输出。. 研究表明，飞秒激光微流道烧蚀过程中的极端物理条件导致硒化锌量子点产生了绿色荧光。这使得绿光硒化锌量子点的缺陷态荧光跃迁机理得到了完善。绿光硒化锌量子点所展现的明亮荧光和良好的分散性，为实现安全可靠的下一代可穿戴柔性显示器件奠定了基础，此外其还具备一定的生物医学标记的应用潜力。