Optical Characteristics of ZnS Passivated CdSe/CdS Quantum Dots for High Photostability and Lasing

Nanocrystal quantum dots (QDs) have great potential for optoelectronic applications such as light emitting diodes and lasers due to their superior optical properties. The core-shell CdSe/CdS QDs can suppress Auger recombination effectively and enhance the emission efficiency. However, it will lead to poor photostability due to the small conduction band offset between CdSe core and CdS shell. For effective electron confinement, a thin shell of wide band gap ZnS semiconductor was grown on the CdSe/CdS core-shell QDs. The influence of ZnS shell has been investigated by comprehensive spectroscopic characterization. It is demonstrated that the CdSe/CdS/ZnS QDs show high photostable and temperature-insensitive emission. Moreover, room temperature lasing based on CdSe/CdS/ZnS QDs coated on a fiber was achieved. The lasing action can maintain under higher temperature up to 312.6 K. The experimental result is important for high performance optoelectronic device application based on colloidal QDs.