In situ synthesis of CdTe/CdSe core-shell quantum dots

In situ synthesis of CdTe/CdSe core-shell quantum dots (QD) were done by using alkyl metals such as triethyl aluminum or diethyl zinc as a reducing agent of selenium metals. The synthesis proceeds by a mechanism in which the selenide anion, which is activated by Et2Zn or Et3Al, reacts with excess cadmium cations. Elemental analysis by energy dispersive X-ray spectroscopy (EDX) showed that the CdTe core consisted of 54% of cadmium and 46% of tellurium, and the core-shell consisted of 51%of cadmium, 42% of tellurium, and 7% of selenium. High-resolution images revealed that most of the particles have a highly crystalline structure. Depth profile experiment with X-ray photoelectron spectroscopy (XPS) showed that the selenium content decreases with an increase in sputtering. The zinc blende structured core-shell QDs showed better photostability than the cores, which enabled them to be used in biomedical imaging.