结合超材料滤色片的高性能单晶钙钛矿纳米线光电探测器的研制

Single crystalline perovskites are promising for realizing high performance optoelectronic devices because of their advantages of direct bandgap, high absorption coefficients, long carrier lifetimes as well as low trapped state density produced by reduced crystal boundaries. Compared to their inorganic counterparts, single crystalline perovskite nanowire based photodetectors offer higher detectivity. Besides, perovskite nanowires show optical anisotropic property along the axial and radial directions, which can be used to detect the polarization of the incident light. And polarization measurement is crucial in the applications of communication, storage, biology, etc. Moreover, perovskite nanowires show excellent mechanical property, therefore they can be used to fabricate flexible devices. However, the reported perovskite nanowire photodetectors, which respond to broad optical spectra, cannot identify colors. ..In this project, we propose to integrate the metal grating/metamaterial/metal grating color filter together with single crystalline perovskite nanowires and let the former play the role of narrow band and polarization-sensitive color filter and the later play the role of high detectivity, aiming for realizing a high performance photodetector device. We will research the physical mechanism of the metamaterial based color filter. The influences of the geometrical and material parameters of both the gratings and metamaterials on the color filter properties will be explored. Besides, during the preparation of perovskite nanowires, the effects of deposition, passivation and transfer processes on the trapped state density, carrier mobility, and carrier lifetime of the crystal will be explored. The experimental and theoretical outcomes of this project would contribute to the realization of low-cost and high-performance photodetectors.

单晶钙钛矿材料除了具有理想的直接带隙、高的光吸收系数、高的载流子迁移率等性能外，还大幅度减少了晶界、降低了陷阱态密度，能实现性能优越的光电子器件。相比于传统无机半导体材料，基于单晶钙钛矿纳米线的光电探测器有更高的探测率。并且，它沿着轴向与径向呈现光学各向异性，可检测光的偏振度，在通信、存储、生物等领域有重要研究价值。还可利用其优异的机械性能制成柔性器件。然而，已报道的钙钛矿纳米线光电探测器对宽谱光响应，不能识别颜色。.本项目提出将金属光栅/超材料/金属光栅复合的滤色片与单晶钙钛矿纳米线相结合，同时发挥前者的窄带滤光、偏振敏感优势及后者的高探测率优势，实现一种高性能光电探测器。将阐明滤色片的物理机制，探究光栅及超材料的结构/材料等参数对滤色性能的调控规律，探究沉积、钝化及转移工艺对单晶钙钛矿纳米线的陷阱态密度、载流子迁移率/寿命等的调控规律。为开发低成本、高性能光电探测器提供实验与理论依据。

在诸多钙钛矿纳米结构中，纳米线结构具有光学各向异性，光生载流子沿其轴向高效传输，可改善光电探测器的电荷提取效率等优点，是制备高性能钙钛矿光电探测器的首要选择。但目前报道的钙钛矿纳米线光电探测器对宽谱光响应，不能识别颜色。金属光栅/超材料/金属光栅复合的滤色片具有窄带滤光及偏振敏感特性，可以实现窄带、偏振敏感、高探测率等优良性能的钙钛矿纳米线光电探测器。.本项目所开展的主要研究内容包括：设计了金属介质交替的周期性超材料狭缝阵列，获得了具有较高透射效率且中心波长可调的窄带滤色片；利用不同生长纳米线的方法，制备具有高结晶质量且低缺陷态密度的钙钛矿纳米线，并基于此制备了高性能钙钛矿纳米线光电探测器；制备了基于钙钛矿材料其他类型的光电探测器，并对其光学和电学性能进行研究。.基于本项目发表了20余篇学术论文，申请国家发明专利3项。本项目揭示了超材料狭缝宽度、狭缝周期等结构、材料参数对超材料滤色片透射性能的调控规律；通过改变前驱体溶液质量分数，研究了前驱体溶液质量分数对阵列钙钛矿纳米线直径的影响；结合干法转移技术、热蒸发法等制备了性能优异的钙钛矿纳米线、纳米片及薄膜等不同类型的光电探测器，从光电性能、光谱性能及微观形貌等方面对其性能进行了具体的研究。以此项目为依托，我们还进行了其他相关研究，包括钙钛矿激光器及光源、太阳电池、有机光电探测器等。本项目的研究对开发高性能的光电子器件具有重要的战略意义。