The structure, optical absorption and luminescence properties of the Zn1-xThxSe quantum dots prepared via mercaptoethanol assisted colloidal approach

Abstract

Nanocrystalline Zn1-xThxSe quantum dots have been prepared using mercaptoethanol assisted colloidal approach. The prepared Zn1-xThxSe QDs exhibited a cubic crystalline structure. The Zn1-xThxSe quantum dots showed uniform spherical shapes with size in the range of 2 to 6 nm. The optical absorption spectra were shifted to large wavelengths with increasing the amount of Th ions in the ZnSe structures. The optical band gap decreased from 3.18 nm to 2.84 nm with increasing the Th ions from 0 to 0.07 mol. The replacement of the Zn ions by Th ions lead to an improvement of the intensity of luminescence by five times, a decrease of the peaks width by three times and 91% an increase of the quantum yield. The Stokes shift decreased with the increase of the Th ions was argued the suppression of the crystal defects and number of Zn2+ vacancies in the ZnSe crystals. The high luminescence intensity, narrow band of emission and the high quantum yield may enable the developed Zn1-xThxSe QDs to be used for manufacture of laser diodes.