This study investigates the physicochemical properties of nanocomposites based on CdSe/CdS/ZnS triplet quantum dots. Methods for their synthesis, including stepwise deposition of CdS and ZnS shells to improve optical and structural properties, are considered. The effect of the composition and size of nanoparticles on their spectral and electronic properties was analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. Particular attention is paid to the stability of quantum dots, their quantum yield, and potential applications in optoelectronics, biomedicine, and photoelectronics.