Effect of NAC and MPA ligands on growth process and optical properties of CdTe quantum dots

Abstract

This study explores the aqueous synthesis of cadmium telluride (CdTe) quantum dots (QDs) using 3-mercaptopropionic acid (MPA) and N-acetyl-L-cysteine (NAC) as stabilizing ligands, focusing on their combined effect on QD growth, optical properties, and stability. By systematically varying the Cd : MPA ratio and MPA : NAC combinations, we identified an optimal Cd : MPA ratio of 1 : 1.75, yielding a quantum yield (QY) of ∼44.8%, and an MPA : NAC ratio of 1 : 2, achieving a superior QY of 66% with enhanced QD monodispersity. The dual-ligand system resulted in smaller particle sizes, slower growth kinetics, and a bathochromic shift in photoluminescence (from 567 nm to 731 nm) over 5–180 minutes of synthesis time. The synthesized QDs exhibited excellent photostability, with QY variations of less than 3% under 29 hours of continuous laser irradiation. Transmission electron microscopy (TEM) confirmed spherical, crystalline nanoparticles with diameters of 3.4–3.6 nm. These findings highlight the potential of MPA and NAC in tailoring CdTe QD properties, offering insights for their application in optoelectronics and biomedicine.