Low temperature growth of metastable cubic CdSe nanocrystals and their photoluminescence properties

Metastable cubic CdSe nanocrystals have been synthesized via solution growth technique along the temperature range 55–95°C. The as-synthesized nanocrystals have been characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX). The results indicated that metastable cubic CdSe with the lattice constant a=0.609nm is formed. This cubic structure was found preserved at all temperatures growth. HRTEM measurement confirmed the good crystallinity cubic phase of the CdSe NCs with lattice constant a=0.61nm. The EDX measurement indicated the presence of Cd and Se only with atomic ratio of Cd Se is 0.56:0.44. The optical absorption as a function of the wavelength for the prepared CdSe nanocrystals at different temperatures is investigated. The results indicated the formation of CdSe nanocrystals and their size corresponding to the regime of spatial exciton confinement. The photoluminescence emission intensity for as-synthesized CdSe nanocrystals at different reaction temperatures depicted that at low temperature (55°C) the emission peak intensity of the CdSe QDs was much larger than the absorption edge, indicating the presence of surface trap-state emissions. These surface crystal defects reduced with the increase in the reaction temperature. ► Metastable cubic CdSe nanocrystals have been synthesized via water based route along the temperature range 55–95°C. ► This cubic structure was found preserved at all temperature growths. ► Formation of CdSe nanocrystals and their size are corresponding to the regime of spatial exciton confinement. ► Surface crystal defects are reduced with the increase in the reaction temperature.