Facile synthesis of thiol-stabilized CdSe_xTe_1-x nanocrystals

CdSe_xTe_1-x nanocrystals (x=0.25, 0.40, 0.50, 0.60 and 0.75) were synthesized using thioglycerol as a stabilizing agent. The composition of the CdSe_xTe_1-x nanocrystals was precisely controlled by tuning the precursor (Se/Te) ratio. The structural, morphological and optical properties of the nanocrystals were analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), diffused reflectance spectroscopy (DRS) and photoluminescence (PL) measurements. It is found that the Se/Te ratio significantly affects the properties of the resultant CdSe_xTe_1-x nanocrystals. XRD pattern of the CdSe_xTe_1-x nanocrystals revealed cubic, hexagonal and mixed phases depending on the ratio of Se:Te. Surface morphology of the CdSe_xTe_1-x nanocrystals showed nanoclusters of sizes ∼50 nm, with the adjacent cluster interlinking each other. DRS revealed the size dependence band gap energy prevailing in the CdSe _xTe_1-x nanocrystals from 1.52 to 2.66 eV due to the optical bowing effect. PL measurements exhibited band edge emission in the visible spectral region, and are red shifted with increase in Se concentration. The facile route employed in the present work to synthesis the CdSe _xTe_1-x nanocrystals in an aqueous medium is simple and controllable, and the strategy presented will be handy in preparing diverse semiconducting nanocrystals.