碳量子点基发光薄膜的合成及其光致和电致发光性质

发布时间：2018-04-22 05:12

本文选题：碳量子点 + 光致发光　；参考：《太原理工大学》2017年硕士论文

【摘要】：碳量子点(Carbon quantum dots,CQDs)是一类主要由碳、氢、氧组成、粒径小于10 nm、表面富含官能团、具有荧光性能的准零维碳纳米粒子。CQDs具有易修饰、荧光范围可调、绿色环保、制备成本低等优异特性,目前已在生物成像、光学传感器、光催化、化学传感器及光电领域获得应用。本论文开展CQDs制备及CQDs在发光器件应用领域的研究,即利用其光致发光和电致发光性质作为荧光粉材料和发光层材料分别应用于光致发光二极管(Light-emitting diode,LED)和量子点基电致发光二极管(Quantum dots-based LED,QLED)。目前,基于CQDs的LED和QLED器件仍存在一些问题:一方面,CQDs作为LED的荧光粉材料主要存在荧光量子产率低、红绿蓝光谱比重低、粘接剂中分散性差的问题,会导致LED器件的发光性能较差;另一方面,CQDs作为QLED的发光层材料是量子点电致发光应用的一种新的尝试,主要存在荧光量子产率低、电荷传输性能差、器件制备工艺复杂的问题。因此,本论文旨在制备荧光量子产率高、红绿蓝光谱比重高、可直接成膜的单一基质CQDs荧光粉以及良好电荷传输性能的CQDs发光层材料,并分别将其应用于白光LED和QLED。具体研究内容和结果包括以下两方面:1、以一水合柠檬酸为碳源、硅烷偶联剂KH-792为添加剂,采用一步水热法制备了荧光量子产率为57.3%、红绿蓝光谱比重为60.1%、粒径为2.5-3.5 nm且具有激发独立性的有机硅烷功能化CQDs。该CQDs水溶液在简单的热处理条件下表现出可直接成膜的能力。将该单一基质CQDs荧光膜结合紫外LED芯片制作了白光LED器件。此白光LED器件发冷白光,色坐标为(0.31,0.36),相关色温为6282 K,显色指数为84。另外,该器件在不同的工作电压及不同的工作时间间隔下都表现出良好的光稳定性。因此,选择多羧基、羟基的有机酸为碳源,同时引入氮原子的反应体系能够制得高QY和RGB光谱比重的CQDs。选择可起粘接剂作用的添加剂,能够制得可溶液直接成膜的CQDs体系,从而应用于LED器件。2、以邻苯二甲酸为碳源、乙二胺为添加剂,采用一步水热法制备了荧光量子产率为29.3%且具有激发依赖性的CQDs。该CQDs颗粒分散性良好,粒径大小在4-7 nm之间,具有一定的晶体结构,晶面间距为0.22 nm。将其作为发光层材料结合有机功能层材料PEDOT:PSS空穴传输层、TPBI电子传输层制作了QLED器件,考察了不同的CQDs旋涂用量、旋涂转速及旋涂时间对器件性能的影响。结果表明:当CQDs旋涂用量为360μL、旋涂转速为1000 rpm、旋涂时间为30 s时,器件发蓝光,其亮度达到4.9 cd/m2,启亮电压为5.5 V。因此,选择含芳环结构的碳源可制得具有一定结晶程度的CQDs。QLED器件的性能不仅受CQDs发光层材料自身性质的影响,还受器件结构、发光层厚度等的影响。
[Abstract]:Carbon quantum Dots (C QDs) is a class of quasi zero dimensional carbon nanoparticles. CQDs are mainly composed of carbon, hydrogen and oxygen, with particle size less than 10 nm, and the surface is rich in functional groups. CQDs have the advantages of easy modification, adjustable fluorescence range and green environmental protection. At present, it has been applied in the fields of biological imaging, optical sensor, photocatalysis, chemical sensor and photoelectricity. In this thesis, the preparation of CQDs and the application of CQDs in luminescent devices are studied. That is to say, the photoluminescence and electroluminescent properties are used as phosphors and photoluminescence layer materials for Light-emitter diodes (LEDs) and Quantum dots-based LEDs (QLEDs), respectively. At present, there are still some problems in LED and QLED devices based on CQDs: on the one hand, as phosphors of LED, there are many problems such as low fluorescence quantum yield, low spectral proportion of red, green and blue, and poor dispersion in adhesives. On the other hand, it is a new attempt in the application of quantum dot electroluminescence that the photoluminescence properties of LED devices are low, and the charge transport performance is poor. Complex process of device preparation. Therefore, the aim of this thesis is to prepare single substrate CQDs phosphor with high fluorescence quantum yield, red green blue spectral specific gravity, direct film formation and CQDs luminescent layer with good charge transport performance, and to apply them to white LED and QLED respectively. The specific research contents and results include the following two aspects: 1. Using citric acid monohydrate as carbon source and silane coupling agent KH-792 as additive. Organic silane functionalized CQDswere prepared by one-step hydrothermal method with fluorescence quantum yield of 57.3%, red, green and blue spectral specific gravity of 60.1 and particle size of 2.5-3.5 nm. The CQDs aqueous solution shows the ability to form films directly under simple heat treatment conditions. The white light LED device was fabricated by combining the single substrate CQDs fluorescent film with UV LED chip. The white LED device has a cool white light with a color coordinate of 0.31 ~ 0.36 ~ 0.36, a relative color temperature of 6282 K and a color-rendering index of 84. In addition, the device exhibits good optical stability under different operating voltages and time intervals. Therefore, the organic acids with multiple carboxyl groups and hydroxyl groups were selected as carbon source, and nitrogen atoms were introduced into the reaction system to produce CQDs with high spectral specific gravity of QY and RGB. The CQDs system, which can be directly film formed by solution, can be prepared by selecting the additive which can act as binder. The system can be used in LED device. 2. Phthalic acid is used as carbon source and ethylene diamine is used as additive. CQDs with a fluorescence quantum yield of 29.3% and excitation dependence were prepared by one-step hydrothermal method. The CQDs particles have good dispersibility, the particle size is between 4-7 nm and has a certain crystal structure, and the crystal plane spacing is 0.22 nm. QLED devices were fabricated by the combination of PEDOT:PSS hole transport layer and organic functional layer material. The effects of different CQDs spin-coating dosage, spin-coating speed and spin-coating time on the performance of the device were investigated. The results show that when the amount of CQDs spin coating is 360 渭 L, the spin coating speed is 1000 rpm, and the spin coating time is 30 s, the luminance of the device is 4.9 CD / m ~ (2) and the starting voltage is 5.5 V. Therefore, the properties of CQDs.QLED devices with a certain degree of crystallization can be obtained by selecting the carbon source with aromatic ring structure, which is influenced not only by the properties of the CQDs luminescent layer, but also by the structure of the device and the thickness of the luminescent layer.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN312.8;O613.71

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