Effect of solvent and environmental conditions on the structural and optical properties of CdS nanoparticles

Abstract

Changing the solvent and environmental conditions during the preparation of CdS nanoparticles have a marked effect on the crystal structure, size distribution, nanoparticle size, absorption and emission properties. X-ray investigations revealed that the CdS nanoparticles prepared with high surface tension solvent have clearly identified hexagonal structure. However, the nanoparticles prepared with high dipole moment solvent matched a cubic structure better than a hexagonal one. Optical absorption measurements proved that CdS nanoparticles prepared in aprotic solvent showed an increase in both size of nanoparticles and size polydispersity index (SPI) with a decrease of the dipole moment, viscosity and surface tension of the solvent, which are applicable to the nanoparticles prepared under argon and ambient atmospheres. Fluorescence spectroscopy showed that the CdS nanoparticles synthesized in aprotic solvent with high dipole moment revealed a high intensity band edge emission blue band with a small half width. Also, the increase of the dipole moment of the solvent leads to a decrease in the Stokes shift for CdS nanoparticles prepared under an argon atmosphere.