Synthesis, Characterization and Optical Properties of CdSe and ZnSe Quantum Dots

Abstract

In this paper, we present an organic synthesis method used for the synthesis of high quality Cadmium Selenide (CdSe) and Zinc Selenide (ZnSe) semiconductor nanocrystals. The mixture of hexadecylamine (HDA)-tetradecylphosphonic acid (TDPA), trioctylphosphine oxide (TOPO)-trioctylphosphine (TOP) has been used as stabilizing solvent for synthesis of high quality CdSe and ZnSe nanocrystals. These QDs have been characterized using various techniques like X-ray diffraction, scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) for size and morphology of samples. Fourier transform infrared spectroscopy has been used for the identification of functional groups, UV-visible absorption and Fluorescence spectroscopy for optical characteristics. These studies show that the particle size is in 2-5 nm range with cubic crystalline phase. The band gap of 3.5 and 4.5 eV has been calculated for CdSe and ZnSe nanocrystals by using Tauc relation. Effective mass approximation calculation and blue shift of photoluminescence peak also confirms the narrow size of particles. The objective of this work is to produce size controlled CdSe and ZnSe nanocrystals with organic passivated surface having high luminescence for use in different optoelectronic applications. Keywords: Semiconductor nanocrystals, organic synthesis, scanning electron microscopy, crystal structure.