Inorganic Functionalization of CdSe x S 1– x /ZnS Core–Shell Quantum Dots and Their Photoelectric Properties

In this article, different CdSe x S 1– x quantum dots (QDs) with stearic acid as ligands are synthesized, and then the outer ZnS shell is coated with oleylamine (OLA) as ligands using a single molecular source method. The surface ligand exchange of CdSe 0.6 S 0.4 and CdSe 0.6 S 0.4 /ZnS QDs is conducted with ammonium zinc chloride ((NH 4 ) 2 ZnCl 4 ) inorganic ligands. The QDs layers are deposited on indium tin oxide (ITO) substrate using a spin coating method before and after ligand exchanges. The morphology, crystal form, and group of QDs are examined using a high‐resolution transmission electron microscope (HRTEM), X‐ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Under the condition of simulated sunlight irradiation, the photoelectrochemical properties are tested with an electrochemical workstation. The results show that the distance between QDs decreases after ligand exchange. The photocurrent density of CdSe 0.6 S 0.4 /ZnS QDs films after ligand exchange reaches 7.23 mA cm −2 , which is 11 times that of the photocurrent density before ligand exchange. The reason may be that ZnCl 4 2− has strong ligand electron donor capacity, which increases the probability of nonradiative transition.