Alkyl thiols as a sulfur precursor for the preparation of monodisperse metal sulfide nanostructures

We demonstrate a new method for preparing metal sulfide nanocrystals using alkyl thiols as a sulfur precursor. Alkyl thiols have many advantages for practical synthesis because they are miscible with most organic solvents and very stable under an air atmosphere. CdS nanocrystals were made with CdO and thiols with different alkyl chains such as n-octanethiol and octadecanethiol. They exhibited uniform size, highly crystalline structure and a sharp photoluminescence spectrum. Also, CdSe/CdS core/shell nanocrystals can be prepared by single injection of a mixture consisting of alkyl thiol and Se in trioctylphosphine to a Cd precursor. A reaction scheme is proposed as alkyl thiols react with the metal precursor to form stable metal thiolate intermediates during the initial period of reaction, and the thiolate decomposes slowly to form homogeneous nuclei