Facile synthesis of highly luminescent CdSe/CdxZn1 − xS quantum dots with widely tunable emission spectra

Highly luminescent CdSe/CdxZn1 − xS core/shell quantum dots (QDs) have been fabricated by a facile environmentally friendly organic route. The spherical cores and core/shell QDs were created by using Cd(AC)2·2H2O, Zn(AC)2, oleic acid, trioctylphosphine (TOP), Se, S, and trioctylamine. The preparative condition such as reaction time (2–6 min), temperature (from 290 to 310 °C), and feed rate of TOPSe (0.3–2 mL/min) creates various sizes of the cores with photoluminescence (PL) wavelengths between 570 and 618 nm. Spherical CdSe cores were coated with a CdxZn1 − xS shell via a single coating step by using different growth kinetics of CdS and ZnS at 300 °C. The CdSe/CdxZn1 − xS core/shell QDs exhibited a significant red shift of PL peaks (up to 646 nm) from the initial PL of CdSe cores with much improved PL efficiency above 40% when the shell growth. By changing the size of the core and the thickness of the shell, the emission colors of the obtained core/shell QDs can be tuned between green and red.