基于卤素钙钛矿纳米晶超结构的紫外偏振增强成像研究

Due to the high luminescence quantum yield (QY), halide perovskite nanocrystals (NCs) are applied for the enhancement of UV imaging devices by converting UV light to visible light which is more sensitive to present CCDs. Additionally, by constructing anisotropic perovskite NC micro-structure, we can also detect the polarization information of the target. Then, combining these advantages, we can fabricate high performance UV imaging devices with high sensitivity and high resolution. Considering the contradiction between high quantum yield and high polarity, we are going to study the nucleation and growth mechanism of perovskite NCs and try to synthesize anisotropic nanostructure. The influence of external field and surface energy on the assembling dynamics of perovskite NCs and the final superstructure will be studied. On the basis of above results, we will try to understand the relationship between incident and output light and verify the effect of orientation of NCs, density and film thickness on absorption, transmission, and polarization emission properties. Finally, we will devote to developing image processing method based on Maxwell equation and studying the integrated scheme and optimization strategy of high performance micro UV imaging devices with low cost. This project will be able to expedite the development new types of high performance UV imaging devices.

本项目拟利用卤素钙钛矿纳米晶极高的荧光量子效率，通过构造各向异性微结构，获得具有偏振选择特性的高效光谱转换膜。在保留被探测紫外光偏振信息的同时通过光谱转换实现高响应度，从而为高灵敏、高分辨紫外偏振成像技术提供基础。针对高量子效率和高偏振特性之间的矛盾，本项目将详细研究钙钛矿纳米晶的形核生长调控机制，实现钙钛矿纳米晶形貌的均匀可控合成。研究外场力、表面能等对钙钛矿纳米晶组装的动力学过程、最终微结构形貌和取向的影响，实现钙钛矿纳米晶的定向可控组装。在此基础上，建立出射光与入射光偏振态之间的强度和偏振参数的对应关系。揭示钙钛矿纳米晶超结构对偏振紫外光选择性吸收、透射以及偏振发光特性的物理内涵，找出微结构取向、密度、厚度等参数与光学特性的内在联系。开发基于Maxwell方程的图像处理算法，研究高效、低成本微型紫外偏振增强成像模块的集成方案和优化机制。本项目的开展将推动新型高性能紫外成像器件的发展。

本项目旨在通过高偏振度和高光谱转换效率薄膜以及高性能光电探测器的制备，实现紫外偏振增强成像以及其他高能光子探测成像。本项目执行期间，在钙钛矿纳米晶合成调控、光电探测器制备等方面取得了一定的进展：（1）揭示了表面卤素空位对激子非辐射复合的重要影响，发展了原位卤素钝化策略，实现了>90%量子效率钙钛矿纳米晶的一步合成；（2）提出了等效配体的概念，实现了钙钛矿纳米晶表面的有效钝化和强结合，通过调控等效配体与钙钛矿纳米晶表面的作用方式，实现了单分散与各向异性生长，在组装的薄膜中获得了0.58的高发光偏振度；（3）发展了高质量钙钛矿薄膜的空间限域制备技术，提出了基于界面隧道效应增强钙钛矿光电探测器探测能力和稳定性的策略，实现了pW级微弱光探测成像及高达8个数量级的信噪比；（4）构筑了钙钛矿纳米线/液晶复合有序微结构薄膜以及纵向排列二维钙钛矿薄膜，分别实现了基于光谱转换的紫外偏振增强成像和直接偏振成像。将光谱转换思想和高性能光电探测器的构筑运用到了X射线探测成像领域，获得了高达54684 μC Gy−1 cm−2的探测灵敏度。在本项目的支持下，共发表SCI论文6篇，授权发明专利4项，获得江苏省高校科技奖一等奖、江苏省青年颗粒学奖等奖项，入选科睿唯安全球高被引学者，爱思唯尔中国高被引学者，江苏省333高层次人才培养工程等。