Synthesis and Characterization of CdS/CISe Quantum Dots with Core-Shell Structure

Quantum dots have received great interest due to their excellent optoelectronic properties. However, the surface defects of quantum dots affect the carrier transport and ultimately reduce the photovoltaic efficiency. In this paper, a core-shell quantum dot by hot-injection method is prepared to grow a narrow-band semiconductor layer (CuInSe2 (CISe) quantumdot) on the surface of a broad-band core material (cadmium sulfide (CdS) nanocrystal). The composition, structure, optical properties, and decay lifetime of CdS/CISe core-shells are investigated in more detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL), UV-vis spectrophotometry, and fluorescence spectroscopy. The CdS/CISe core-shell structure has a broadened absorption range and still shows CISe-related quantum effects. The increased size of the core-shell and the smaller specific surface area of the CISe shell layer lead to a lower carrier complexation chance, which improves the carrier lifetime.