【作者】 郑鑫；

【导师】 李福山；

【作者基本信息】 福州大学 ， 信息光电技术， 2021， 硕士

【摘要】 量子点(quantum dots,QDs)具有优异的光电特性、可靠的光稳定性以及普遍较高的荧光量子产率,兼具高性能和低成本的量子点在光学防伪标签领域具有广泛应用前景,是一种理想的发光防伪材料。本文根据使用的不同量子点材料的特性,采用了喷墨打印、丝网印刷和光刻工艺分别对量子点墨水、量子点粉体和原位合成的钙钛矿量子点制备的薄膜进行了图案化处理,并对图案化的薄膜的形貌结构、发光特性进行了表征,实现了不同的发光防伪标签应用。主要研究内容如下:第一,我们通过调控量子点复合墨水的浓度和随机分散的微球分布密度,采用喷墨打印技术产生微米分辨率的多圆形图案和纳米分辨率的量子点迷宫图案。通过这种方法,我们首次获得了一款具有适合肉眼、便携式显微镜和高可靠性显微镜的三级识别检测系统的防伪标签。微米分辨率的多圆图案可以通过低成本的便携式显微镜进行捕捉和验证,有助于满足更多应用场景下标签的识别需求。同时,在防伪标签领域首次引入了一种能够引导深度残差网络将注意力聚焦到包含关键信息区域的人工智能识别方法,并以此作为判断标签真实性和可追溯性的依据。第二,我们采用包覆技术获得了微米级尺寸的量子点粉体,解决了量子点的环境稳定性问题,同时我们通过丝网印刷工艺使其形成图形化发光膜。这种新的量子点粉体有着不同于量子点材料的随机尺寸分布,由于量子点粉体中各尺寸颗粒的大小和位置随机,所以每个包含量子点粉体的印刷网点的白光亮场图像和紫外暗场图像都有独特的不可重复特征,且3D显微镜测得的剖面轮廓线也具有独特的特征,我们利用这些特征实现了防伪标签的多重加密。第三,我们采用光刻工艺实现钙钛矿量子点的原位合成与图案化制备。钙钛矿作为离子晶体,有着非常独特的优势,在常温下就可以通过析出结晶的方式制备出量子点,这是其他发光量子点材料难以实现的。我们通过真空处理和热处理两种后处理工艺,研究钙钛矿量子点在聚合物和光刻胶成膜形成的分裂空间辅助下的随机结晶过程。我们利用钙钛矿原位量子点在厚度约210 nm的光刻胶膜层内的随机结晶,实现了高精度荧光图案防伪标签的制备。总之,本论文聚焦于研究与量子点材料相适应的图形化组装工艺,并针对安全标签领域存在的问题进行优化,有望为量子点的图形化组装加工提供实验指导,并为新型光学防伪标签的应用提供创新方案。更多还原

【Abstract】 Quantum dots(QDs)have excellent photoelectric properties,reliable optical stability,and generally high fluorescence quantum yield.Quantum dots with high performance and low cost have a wide application prospect in the field of optical anti-counterfeiting labels and are kinds of ideal light-emitting anti-counterfeiting materials.In this thesis,according to the characteristics of different quantum dot materials used,ink-jet printing,screen printing and lithography processes were used to pattern the quantum dot ink,quantum dot powder and perovskite quantum dot films prepared by in-situ synthesis,respectively.The pattern of the morphology of membrane structure and the luminescent properties have been characterized,and different the light-emitting anti-counterfeit label applications have been implemented.The main research contents are as follows:First and foremost,we used inkjet printing technology to generate micron resolution multi-circular patterns and nanometer resolution quantum dot maze patterns by adjusting the concentration of quantum dot composite ink and the randomly dispersed distribution density of microspheres.In this way,for the first time,we obtained an anti-counterfeiting label with a three-stage identification detection system suitable for naked eyes,portable microscopes,and high-reliability microscopes.Multi-circle patterns with micron resolution can be captured and verified by low-cost portable microscopes,helping to meet the needs of label recognition in more application scenarios.At the same time,an artificial intelligence identification method which can guide the deep residual network to focus on the region containing key information is introduced for the first time in the field of anti-counterfeit tags,and this method is used as the basis for judging the authenticity and traceability of tags.Secondly,we used the cladding technology to obtain the micron-size quantum dots powder,in order to solve the problem of environmental stability of the quantum dots,and used the screen-printing process with the quantum dots powder to form graphical luminous films.The new quantum dot powder has a random size distribution different from the quantum dot material.Due to the random size and location of the particles in the quantum dot powder,the white bright field image and the ultraviolet dark field image of each printing dot containing the quantum dot powder have unique unclonable characteristics.In addition,the profile measured by 3D microscope also has unique features,which are utilized to realize multiple encryptions of anti-counterfeit labels.Thirdly,we used lithography to synthesize perovskite quantum dots in situ and fabricate them patterned.As an ionic crystal,perovskite has a unique advantage.At room temperature,quantum dots can be prepared by precipitation and crystallization,which is difficult to be achieved by other luminescent quantum dot materials.We studied the random crystallization process of perovskite quantum dots assisted by the splitting space formed by polymer and photoresist film by vacuum treatment and heat treatment.We used the random crystallization of perovskite quantum dots in a photoresist film with a thickness of about210 nm to realize the preparation of high-precision fluorescent pattern anti-counterfeiting labels.In conclusion,this thesis focuses on the research of the graphical assembly process suitable for quantum dot materials and optimizes the existing problems in the field of security tags,which is expected to provide experimental guidance for the graphical assembly processing of quantum dots and provide innovative solutions for the application of new optical anti-counterfeiting labels.更多还原