高荧光的水溶性CdTe量子点的合成及其生长规律研究

Aqueous Synthesis of Highly Luminescent CdTe Quantum Dots and Its Growth Mechanism

以巯基乙酸(TGA)为稳定剂,通过有效引入Te源的方法,在水相中合成了高荧光的半导体CdTe量子点.其荧光发射波长在510—620nm范围内可调,最窄的半峰宽约为34nm,最高荧光量子产率可达到60%.用吸收和荧光光谱研究了其光谱特性,并用X射线粉末衍射、透射电镜、EDX谱和红外光谱对合成的CdTe纳米晶的形貌、组成和结构进行了表征.实验考察了溶液的pH值和前体组成比对合成CdTe纳米晶的影响.实验结果表明,合成溶液的pH对CdTe量子点的光谱特性和生长速率具有显著影响.随后讨论了巯基乙酸对CdTe纳米粒子在水溶液中的稳定作用,探讨了CdTe纳米晶在不同pH条件下的生长规律,提出了修正的纳米晶生长模型.

The highly fluorescent CdTe quantum dots（QDs）have been synthesized by using thioglycolic acid（TGA） as a stabilizer and a new procedure of the introduction of Te source in aqueous solution.CdTe nanocrystals（NCs） have a tunable fluorescence emission wavelength range from 510 nm to 620 nm.Their narrowest full width at half maximum（FWHM） of about 34 nm,and the maximum quantum yield（QYs） of 60%.These CdTe nanocrystals were characterized by absorption and fluorescence spectroscopy,X-ray powder diffraction,transmission electron microscopy,energy dispersive X-ray and FT-IR spectroscopy.The effects of starting pH and the molar ratio of TGA/Cd2＋ on the synthesis of CdTe QDs were investigated.The experimental results indicate that starting pH plays an important role in improving optical properties and controlling the growth rate of CdTe nanocrystals.The possible growth mechanism of CdTe nanocrystals at various pH was discussed.A new modified LSW model of particles growth was proposed.