EFFECT OF OXYGEN ON SIZE-CONTROLLED SYNTHESIS OF CdSe QDs

Abstract

Unique properties of quantum dots (QDs) are controlled by their customizable particle sizes which can be engineered to suit local need. One-pot organometallic injection synthesis of cadmium selenide (CdSe) QDs is reported. The operation started with the injection of a week old selenium (Se) precursor into a boiling non-coordinating octadecene (ODE) at 195oC resulting in the formation of monodispersed size tunable CdSe QDs with discrete homogeneous nucleation. Differences in the injection and withdrawal time of the sample resulted to the dissimilarity in the shape, size and the opto-electronic properties of the QDs. The effect of oxygen on the synthesized CdSe QDs was studied by exposing freshly prepared sample to atmospheric oxygen for 206 days. The samples were characterized using optical absorption spectroscopy (UV-vis), optical photoluminescence (PL), X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM), electron dispersive X-ray (EDX) X-ray diffraction spectroscopy (XRD), and X-ray photoelectron spectroscopy (XPS). Noticeable deformation on the size, shape and the crystalline orientation of the CdSe QDs were observed on the oxygen-interacted sample.Although the synthesis method is safe and produced good quality CdSe QDs, the interaction of the sample with oxygen degrades their opto-electronic quality.