Effect of mercaptoethanol and Na2S dropwise addition rate on zinc sulfide semiconductor nanocrystals: synthesis and characterization

Zinc sulfide (ZnS) semiconductor nanocrystals with mercaptoethanol (ME) as a stabilizer (capping agent) were synthesized by coprecipitation method in room temperature using the solution of zinc chloride (ZnCl2) and sodium sulfide (Na2S) as starting material. The effect of ME and Na2S dropwise addition rate on the preparation of these samples was measured using UV–vis absorption and X-ray diffraction (XRD). The ultraviolet–visible (UV–vis) absorption and XRD of the prepared ZnS nanoparticles show increase of band gap and decrease of particle size with decrease in ME and Na2S dropwise addition rate to the reaction medium. This behavior is related to the size quantization effect due to the small size of the particles. The photoluminescence emission peak positions exhibit obvious blue shift from 510 to 455 nm. The particle sizes were obtained from transmission electron microscopy images.