碳量子点（CQDs）是近年来发展出的一种新型零维碳纳米材料，其最显著的特点是具有可调的带隙和荧光性质，因而在光电器件领域有着广阔的应用前景。与有机小分子、聚合物、稀土化合物、无机半导体量子点等发光材料相比，CQDs在光热稳定性，生理和环境毒性，生物相容性，原料来源，制备工艺，合成成本等方面具有优势。目前，研究者们已经将CQDs作为活性发光层材料应用于电致发光二极管（LEDs），用以发展新一代的显示和固态照明技术。然而，CQDs自身还存在着红光量子产率不高，载流子传输不理想，小尺寸CQDs的合成不可控等问题，不利于发展基于CQDs的暖白光及蓝光电致LEDs。针对这些问题，本论文合成了高量子产率红光CQDs，并将其应用于暖白光电致LEDs；合成了具有良好载流子传输能力的荧光CQDs，并实现了高性能的白光电致LEDs；发展了一种可控合成小尺寸蓝光CQDs的方法，并将其应用于蓝光电致LEDs。具体工作如下：

1. 选择N,N-二甲基对苯二胺，N,N-二乙基对苯二胺和N,N-二丙基对苯二胺作为前驱体，使用溶剂热法，合成了三种红光CQDs，发射峰位于637，642和645 nm，量子产率最高为86.0%。红光CQDs具有良好的溶液可加工性。采用主客体发光层结构制备了基于红光CQDs的暖白光电致LEDs，器件表现出稳定的暖白光光谱，最大亮度为5248~5909 cd m^-2，电流效率为3.65~3.85 cd A^-1。

2. 选择2,7-二羟基萘为前驱体，磷酸为溶剂，合成了从蓝光到红光的三种CQDs，最高量子产率为75.5%。球差电镜表明其具有高结晶性的平行四边形结构。平行四边形CQDs的电子和空穴迁移率分别达到4.5×10^-2和 2.5×10^-2 cm² V^-1 s^-1，表现出高且匹配的载流子传输性能。制备了基于平行四边形CQDs的白光电致LEDs，器件的最大亮度与外量子效率分别超过了12000 cd m^-2和3.00 %。

3. 选择2,7-二羟基萘和葡萄糖为前驱体，通过热解的方法制备了蓝光CQDs，发射峰位于452 nm，量子产率为70.7%。高温下形成了葡萄糖的互穿交联网络结构，对CQDs的生长起到了限制作用，控制其尺寸为1.5 nm。通过优化旋涂工艺制备了量子产率为45.3%的蓝光CQDs发光层，并基于此制备了蓝光电致LEDs，启亮电压为3.5 V，最大亮度为1100 cd m^-2，最大电流效率为1.8 cd A^-1。

Carbon quantum dots (CQDs) are emerging zero-dimensional carbon nanomaterials that have been developed in the recent years. CQDs have shown broad application prospects in the field of photoelectric devices owing to the merits of efficient fluorescence and adjustable bandgaps. Compared to organic small molecules, polymers, rare earth compounds, inorganic semiconductor quantum dots and other luminescent materials, CQDs have advantages in photo- and thermal-stability, physiological and environmental toxicity, biocompatibility, source of raw materials, preparation process, cost, etc. Currently, researchers have utilized CQDs as active emissive layer (EML) in the application of electroluminescent light emitting diodes (LEDs), to develop a new generation of display and solid state lighting technology. However, CQDs still suffer from some problems. For instance, low red fluorescence quantum yields (QY), poor carrier transport properties, uncontrollable synthesis of small sized CQDs, which impede the development of CQDs based warm white and blue electroluminescent LEDs, respectively. To target with the above problems, in this dissertation, red emissive CQDs with high QYs were synthesized and then applied to warm white electroluminescent LEDs; CQDs with good carrier transport properties were synthesized and applied to high performance white electroluminescent LEDs; A controllable method was developed for preparing small sized blue emissive CQDs, which was applied to blue electroluminescent LEDs. The specific works are as follows:

1. Three red emissive CQDs were synthesized through the solvothermal treatment of N,N-dimethyl-, N,N-diethyl-, and N,N-dipropyl-p-PD as precursors, displaying bright red bandgap emission at 637, 642, and 645 nm, respectively, with the highest QY up to 86.0% in ethanol. Red emissive CQDs also have good solution processibility. Warm white electroluminescent LEDs based on red emissive CQDs were prepared by adopting host/guest EML, displaying voltage-stable warm white spectra and high-performance with maximum luminance (L_max) of 5248-5909 cd m^-2 and maximum current effciency (η_c,max) of 3.65-3.85 cd A^-1.

2. Blue, yellow and red emissive CQDs were prepared by selecting 2,7-Naphthelendiol as precursor and phosphoric acid as solvent, showing the highest QY up to 75.5%. Spherical aberration corrected transmission electron microscope (AC-TEM) revealed the highly crystallized parallelogram structure of CQDs. The electron and hole mobility of parallelogram CQDs were 4.5×10^-2 and 2.5×10^-2 cm² v^-1 s^-1, respectively, indicating both electrons and holes with high mobilities. High performance white electroluminescent LEDs based on parallelogram CQDs were prepared, displaying L_max and external quantum efficiency (EQE) exceeding 12000 cd m^-2 and 3.00 %, respectively.