Spectral properties of ultrasmall CdS nanoparticles stabilized by mercaptoacids and hydrazine

Abstract

Ultrasmall colloidal CdS quantum dots (QDs) were synthesized in water at room temperature by using a combination of two low-molecular-weight stabilizers – hydrazine and a mercaptoacid, particularly, mercaptoacetic and mercaptopropionic-2 acids. The average size of QDs was found to depend on the Cd-to-S ratio at the synthesis and be as small as 2,5 nm at 80% cadmium(II) excess. The CdS QDs emit broadband photoluminescence in the visible spectrum range with a relative quantum yield of around 5% and the radiative life time of around 100 ns.