Full-Color Light-Emitting Carbon Dots with a Surface-State-Controlled Luminescence Mechanism
Full-Color Light-Emitting Carbon Dots with a Surface-State-Controlled Luminescence Mechanism
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具有表面状态控制发光机制的全色发光碳点
DOI：
10.1021/acsnano.5b05406
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发表时间：
2016-01-01
期刊：
影响因子：
17.1
通讯作者：
Xiong, Huan-Ming
中科院分区：
文献类型：
--
作者：
Ding, Hui;Yu, Shang-Bo;Xiong, Huan-Ming
采用一锅法水热合成了具有可调光致发光（PL）和量子产率高达35%的碳量子点（CD），并通过硅胶柱色谱进行分离。这些分离的CD在单波长紫外光下发出明亮而稳定的从蓝色到红色的渐变色发光。他们表现出很高的光学均匀性，也就是说，每个样品显示只有一个峰的PL激发光谱，只有一个峰的激发无关的PL发射光谱，和类似的单指数荧光寿命。虽然这些样品的颗粒大小和石墨结构在其碳芯中具有相似的分布，但样品之间的表面状态逐渐变化，特别是氧化程度。因此，所观察到的红移，在其发射峰从440至625 nm归因于逐渐减少，在其带隙的增加纳入到其表面结构的氧物种。发现这些能带取决于表面基团和结构，但不像传统的半导体量子点那样取决于颗粒尺寸。此外，由于其优异的PL特性和低细胞毒性，这些CD可用于在单波长光源下对不同颜色的细胞进行成像，而红色发射CD可用于对活体小鼠进行成像，因为它们的荧光穿透能力很强。
Carbon dots (CDs) with tunable photoluminescence (PL) and a quantum yield of up to 35% in water were hydrothermally synthesized in one pot and separated via silica column chromatography. These separated CDs emitted bright and stable luminescence in gradient colors from blue to red under a single-wavelength UV light. They exhibited high optical uniformity; that is, every sample showed only one peak in the PL excitation spectrum, only one peak in the excitation-independent PL emission spectrum, and similar monoexponential fluorescence lifetimes. Although these samples had similar distributions of particle size and graphite structure in their carbon cores, the surface state gradually varied among the samples, especially the degree of oxidation. Therefore, the observed red shift in their emission peaks from 440 to 625 nm was ascribed to a gradual reduction in their band gaps with the increasing incorporation of oxygen species into their surface structures. These energy bands were found to depend on the surface groups and structures but not on the particle size, not as in traditional semiconductor quantum dots. In addition, because of their excellent PL properties and low cytotoxicity, these CDs could be used to image cells in different colors under a single-wavelength light source, and the red-emitting CDs could be used to image live mice because of the strong penetration capability of their fluorescence.