Synthesis of type-II CdSe(S)/Fe2O3 core/shell quantum dots: the effect of shell on the properties of core/shell quantum dots

CdSe(S)/Fe₂O₃ core/shell quantum dots (QDs) were prepared in an aqueous synthetic route. These were shown to be highly crystalline nanoparticles using X-ray diffraction and HRTEM, whilst optical spectroscopy showed that the particles exhibited highly photoluminescent emissions. A red shift in the emission wavelength of CdSe(S) QDs coated with Fe₂O₃ was observed, despite the crystal structure of the core remaining intact after coating with ferric oxide, indicating a direct influence of the shell on the electronic levels of the QD core. The effects of the shell on the optical properties of core/shell QDs of these type-II CdSe(S)/Fe₂O₃ QDs are rationalised by comparison to type-I CdSe(S)/ZnO QDs.