Effect of the indium myristate precursor concentration on the structural, optical, chemical surface, and electronic properties of InP quantum dots passivated with ZnS

In this work, we present results on the synthesis and characterization of InP and InP@ZnS quantum dots (QDs), grown using a single-step chemical synthesis method without injection of hot precursors, varying the concentration of indium myristate in both cases. It was found a color variation of the QDs in solution due to the quantum confinement effects when the nanoparticle sizes are smaller than the exciton Bohr radius. The band-gap energy of the samples was determined from the absorption spectra. From the photoluminescence (PL) spectra, emission peaks located in the range from 2.1 to 3.0 eV were observed. Furthermore, an enhanced PL emission due to a passivation effect in the ZnS-covered InP QDs was obtained. From X-ray diffraction (XRD), it was shown the presence of crystalline phases of the InP, ZnS, and In2O3 nanoparticles, with sizes ranging from 8 to 10 nm as determined by high resolution transmission electron microscopy (HR-TEM). From X-ray photoelectron spectroscopy (XPS) analysis, it was confirmed the formation of InP, ZnS, and In2O3; moreover, by means of a valence band analysis, the electronic structure of the samples was further investigated. The effect of the indium myristate precursor concentration on the optical, structural, surface chemical, and electronic properties of InP and InP@ZnS QDs will be discussed.