Synthesis of Highly Luminescent CdSe/ZnCdS Quantum Dots with Deep-Red Emissions

CdSe cores with larger radius were prepared by means of two-steps injection of the Cd precursor. Efforts were made to avoid the Ostwald ripening process during the quantum dots grown up. The prepared CdSe cores showed zinc-blende structure with size exceeded over 7 nm. The emission efficiency of prepared quantum dots were 15%, while it increased drastically up to 43% after the formation of ZnCdS shells on the CdSe cores. Morphologies and structures of the quantum dots were characterized by HR-TEM and XRD diffraction. The obtained quantum dots with emission wavelengths more than 660 nm were expected to find their applications in bio-imaging and plant illuminations.