The Role of Halogens in the Synthesis of Semiconductor Nanocrystals

Abstract

Abstract The presence of halogen compounds in the synthesis of semiconductor nanocrystals (NCs) produced by hot injection drastically influence their capping ligand sphere and/or chemical reactivity, allowing for the growth of hybrid systems, including composites combining NCs decorating carbon sp2 surfaces. As a result, the presence of halide anions on the surface of some NCs has proven to have a positive impact on the optical and electrical properties. In this work the effects that halogen co-solvents (including alkylchlorides, bromides, and iodides) induce in the synthesis of rod-like Wurtzite CdSe NCs generated by hot-injection will be reviewed. The proposed mechanism of the reaction as well as a detailed characterization of the capping ligand sphere by Nuclear Magnetic Resonance (NMR) and X-Ray photoelectron Spectroscopy (XPS) will be discussed. Correlated cyclic voltammetry (CV) and XPS studies have been performed to address the effect of the halide anions on the NCs surface. Finally an example of the effect of the addition of chlorine-containing co-solvents on the synthesis of PbS rock-salt NCs will be shown.