基于干涉/梯度曝光的聚合物分散液晶器件的制备

PREPARATION OF POLYMER DISPERSED LIQUID CRYSTAL DEVICE BASED ON INTERFERENCE / GRADIENT EXPOSURE

蒋皓东

11849142

硕士

材料科学与工程

刘言军

2020-05-25

2020-07-24

哈尔滨工业大学

深圳

液晶材料目前广泛的应用于液晶显示器(Liquid Crystal Display，LCD)，但是随着显示技术的发展，LCD显示由于其结构带来的缺点，其市场份额慢慢的被有机发光二极管(Organic Light Emitting Diode，OLED)显示技术取代。基于这一背景，本文利用聚合物分散液晶(Polymer Dispersed Liquid Crystal，PDLC)技术，尝试实现液晶材料在非LCD领域的应用。但传统的PDLC薄膜中的液晶微滴是随机分布的，因此所形成的聚合物结构不可控。为了得到结构可控的聚合物，我们利用周期性分布的紫外光来制备PDLC薄膜。这样一来，通过相分离，聚合物在光强高处聚合，液晶在光强暗处析出，就能实现周期性的聚合物/液晶结构。本文的主要研究内容如下：首先，是利用全息聚合物分散液晶(Holographic Polymer Dispersed Liquid Crystal，HPDLC)光栅的相关技术，实现了高反射率的分布式布拉格反射器(Distributed Bragg Reflector，DBR)薄膜的快速制备。这一方法相较于传统技术，简单、快速且便宜，并能通过改变干涉角度，实现特定波长选择性的高反射。之后，我们利用图案化的掩膜版，在液晶盒内实现反射全息曝光，得到了全息图案化的DBR薄膜。这种全息薄膜有望在防伪等领域实现相关应用。由于制备的DBR薄膜是中空多孔的，其比表面积大，液体可以快速进入其中导致折射率发生相应的变化，从而实现薄膜反射光谱的变化。在液体检测上，这种薄膜能够实现高灵敏度的可视化快速检测。之后，我们利用灰阶掩膜版，结合相分离复合薄膜(Phase Separated Composite Films，PSCOF)技术，十分便捷的制备了液晶微透镜阵列。对其形貌进行表征，发现液晶取向良好，结构均一、平整。通过电荷耦合元件(Charge-coupled Device，CCD)的观测，其聚焦以及成像效果良好，且均一性也良好。对微透镜阵列施加电压，在不同电压下观测其聚焦以及成像的变化，计算焦距变化。结果显示，其具有可调性。这一微透镜阵列在集成成像等领域有着广泛的应用前景。

Liquid crystal materials are widely used in LCD now. But with the development of display technology, the market share of LCD is slowly replaced by OLED technology due to the disadvantages of the LCD. Based on this background, this paper used PDLC technology to realize the application of liquid crystal materials in non-displays field.However, the liquid crystal droplets in the traditional PDLC films are randomly distributed, so the polymer structure is not controllable. In order to obtain polymer with controllable structure, we used periodically distributed ultraviolet light to prepare PDLC films. In this way, through phase separation, the polymer polymerized in the region with high light intensity, and liquid crystal precipitated in the region with low light intensity, thus realizing the periodic polymer / liquid crystal structure. The main contents of this paper are as follows:Firstly, we used the HPDLC technology to realize the high reflectivity DBR films. This method is simple, fast, and inexpensive compared to traditional techniques. At the same time, it can realize selective high reflection of specific wavelength by changing the interference angle. After that, we also used a patterned photomask to realize reflective holographic exposure in the liquid crystal cell and obtained a holographic patterned DBR film. This holographic film can be used in anti-counterfeiting and other fields. Since the prepared DBR film is hollow and nanoporous, which means its specific surface area is large. So the liquid can quickly enter into it, which causes the refractive index of the air layer to change accordingly and makes the reflection spectrum change. In liquid sensor, this kind of film can realize high-sensitivity visualization and rapid detection.Then, we used gray-scale photomask and PSCOF technology to prepare liquid crystal microlens array conveniently. After that, we characterized the morphology of microlens array. The orientation of liquid crystal was good and the structure was uniform and flat. We then sat up an optical path to detect the focusing and imaging effects of the microlens array under polarized light. Through CCD observation, the focusing and imaging effects were good, and the uniformity was also good. Finally, by applying voltage to the microlens array, we observed its focus and imaging changed at different voltages. At the same time, we calculated the focal length change to see its electrical control. The results showed that it was tunable. This kind of microlens array has wide application prospects in 3D imaging and other fields.

聚合物分散液晶 全息 DBR薄膜 灰阶曝光 微透镜阵列 焦距可调

polymer dispersed liquid crystal holographic DBR films gray scale exposure microlens array focal length tunable

中文

联合培养

南方科技大学

蒋皓东. 基于干涉/梯度曝光的聚合物分散液晶器件的制备[D]. 深圳. 哈尔滨工业大学,2020.