【作者】 熊海；

【导师】 刘建军；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2011， 硕士

【摘要】 半导体量子点一般指是由Ⅱ-Ⅵ族和Ⅲ-Ⅴ族等元素组成,粒径为2～10nm的零维纳米材料。由于其具有强的量子尺寸效应,在电子,光学和表面可修饰性方面显示出优越的性质,在光电转换、半导体器件及生物标记等领域,显示出极大的研究和应用价值。量子点作为一种新型的荧光材料,与传统的有机荧光染料相比,具有宽的激发光谱,窄而对称的发射光谱、高的荧光量子产率、荧光寿命长、光稳定性好等优点。半导体量子点的制备方法主要包括有机相合成、微乳液合成和水相合成等。由于有机相和微乳液合成等方法合成量子点条件苛刻,原料成本高,毒性大,限制了该方法的实际应用。采用简单的水相合成的量子点具有很好的生物相容性,可以直接应用于生物标记。对于Ⅱ-Ⅵ族的Cd系列量子点的研究目前已经比较成熟,但由于重金属Cd的毒性,限制了其作为生物标记材料的研究和应用。在本论文中,我们通过紫外光照和相转移方法合成了水溶性的InP/ZnS复合结构量子点及系列ZnSe基荧光量子点,这些量子点低毒或无毒,作为“绿色”荧光量子点,在生物标记领域具有更广阔的应用前景。同时我们对不同量子点的制备工艺、结构和荧光性能进行了系统的研究,并考察了其对各种客体指纹显现效果的影响。实验研究结果如下：1、分别采用溶剂热法和化学法合成了InP量子点,其中溶剂热合成中,以甲苯为溶剂,十二烷胺(DDA)为包覆剂,通过改变溶剂热合成温度(150℃、165℃、180℃),可以得到颗粒尺寸为3-4nm的InP量子点,经巯基乙酸修饰后得到水溶性InP/ZnS量子点。不同温度合成InP后包覆的InP/ZnS量子点的荧光最佳发射波长分别为438nm,508nm和575nm。在紫外光照及弱碱条件下合成的水溶性InP/ZnS荧光量子点溶液可以清晰的显现出光滑客体表面的指纹细节。2、以硒粉、亚硫酸钠、硝酸锌和硝酸镉为原料,巯基乙酸为修饰剂,合成了粒径较小且分散均匀的ZnxCd1-xSe量子点水溶液,考察了反应时间、初始pH值和掺杂Cd含量的不同对ZnxCd1-xSe量子点粒径及荧光强度的影响。分析结果表明,合成量子点为球形,粒径为5nm左右,不同掺杂Cd含量的ZnxCd1-xSe量子点的荧光最佳发射波长随掺杂Cd含量增加由430nm红移到585nm。未掺杂的ZnSe量子点显现油汗指纹为蓝色,掺杂比例为Zn0.77Cd0.23Se量子点的指纹显现效果最好,ZnxCd1-xSe荧光量子点溶液可以清晰的显现出不同颜色的光滑客体表面的指纹细节,同时对血潜指纹的显现效果也较好。3、以Na2SeSO3为硒源,合成锰掺杂的水溶性Mn2+:ZnSe量子点。通过对不同修饰剂(巯基乙酸、巯基丙酸、巯基乙醇)的对比,以巯基丙酸(MPA)为修饰剂合成的Mn2+:ZnSe量子点最稳定,荧光强度最强,最佳荧光发射波长在485nm左右。XRD、TEM结果表明合成的Mn2+:ZnSe为球形颗粒,分散均匀。水溶性Mn2+:ZnSe量子点对不同客体的指纹显现效果较好,显现指纹较清晰。紫外光照合成的ZnSe/ZnS量子点荧光强度明显增强,其颗粒尺寸在4.8nm左右,显现指纹颜色为紫色或浅蓝色。更多还原

【Abstract】 The semiconductor quantum dots (QDs) are zero dimension nanocrystal composing ofⅡ-ⅥandⅢ-Ⅴelements with the particle sizes ranging from 2nm to 10nm. Due to their strong quantum size effect,QDs exhibit unique and superior electronic, optics and surface function and show great research and application value in photoelectric conversion, semiconductor devices and biomarker areas. As a new fluorescent material, the QDs have wide excitation spectrum, narrow symmetrical emission spectrum, longer fluorescence life, better light stability and high photoluminescence yield compared with traditional organic fluorescencent dyes. QDs were mainly synthesized via orgnaic phase, microemulsion and aqueous synthesis, because of harsh reaction conditions, high costs of raw material and toxicity, the method of orgnaic phase and microemulsion synthesis were limited to practical application. QDs in aqueous synthesis have the good biological compitability and are directly used as labeling material. It has been mature for synthesis and research ofⅡ-ⅥCd-containing series QDs, but the toxity of heavy metals Cd limits their research and application in biomarkers field. In this thesis, highly fluorescent water-soluble InP/ZnS QDs were prepared via phase transfer and UV-irradiation processing, a series of ZnSe based luminescent QDs were also prepared. These QDs are low-toxic or non-toxic attributing to be as green luminescent ones leading to more broad prospects in biomarkers areas. The effects of preparation routes, structure and fluorescent property of QDs on the fingerprint developing on the surface of different objects were also systematically studied and discussed. The experimental results are given as follows:1、InP QDs were synthesized via solvothermal and chemical method, respectively. Then the water-soluble InP/ZnS QDs with different particle size of 3-4nm were synthesized by changing the synthesis temperature using toluene as solvent, DDA as coating agent and mercaptoacetic acid as modifier. The best emission wavelength of InP/ZnS QDs synthesized at different temperature are 438nm,508nm and 575nm respectively. The fingerprint details on the surface of smooth objects were clearly developed with water-soluble QDs solution synthesized at weaker alkaline conditions under irradiation of UV lights.2、The aqueous solutions of ZnxCd1-xSe QDs with smaller and homogeneous particle sizes were synthesized by using Se、Na2SO3 and Cd(NO)3·2H2O as precursor and thioglycollic acid (TGA) as modifier. The effects of refluxing time, initial pH value of the reaction and the molar ratio between Zn and Cd on the particle size and fluorescence intensity of ZnxCd1-xSe QDs were studied. Through XRD、HRTEM and fluorecence spectra, it is found that the content of Cd-doped ZnxCd1-xSe QDs with crystalline size of about 5nm increases, the best fluorescent emission wavelength were changed from 430nm to 585nm. The color of mimeograph fingerprint details on the surface of smooth objects is blue. The doped Zno.77Cdo.23Se QDs has the best result for developing fingerprint. The fingerprint details on the surface of smooth objects with different background colors were clearly developed with ZnxCd1-xSe QDs solution under UV irradiation, the effect of blood latent fingerprints is also well.3、The water-soluble fluorescent Mn2+:ZnSe QDs was synthesized by using Na2SeSO3 as Se precursor. Compared with mercaptoacetic acid and mercaptoacetic ethanol as the modifiers, Mn2+:ZnSe QDs synthesized with mercaptopropionic acid as modifier are most stable and strongest fluorescence intensity around 485nm. The XRD and HRTEM were also employed to characterize the sample. It is found that Mn2+:ZnSe QDs are small crystalline size and uniform dispersion. The fingerprint details on the surface of different smooth objects were clearly developed with Mn2+:ZnSe QDs. After UV- irradiation, fluorescent intensity of ZnSe/ZnS QDs was obvious enhanced, XRD characterization showed that the particle size was about 4.8nm, the color of fingerprint was purple or shallow blue.更多还原