Tuning optical properties of ZnS nanoparticles in micellar medium at different pH

Synthesis of sodium dodecylsulphate (SDS) capped ZnS nanopartides with relatively narrow size distribution in acidic and basic medium having average size of 11.3 and 10.7 nm respectively have been reported. The nanocrystallites were characterized by using powder X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), selected area electron diffraction (SAED), UV-vis optical absorption and photoluminescence (PL) spectroscopy. The surface charges of the nanoparticles in different mediums were studied in term of zeta potential (zeta). This study correlates the crystallinity with pH of the synthesis medium and optical property of a material. The nanoparticles synthesized in basic medium, possess higher crystallinity while those in acidic medium are microcrystalline in nature. The optical performance of the material in terms of UV absorption and photoluminescence emission at different pH has been compared and correlated with the crystallinity. The optical properties of the as-synthesized ZnS nanoparticles in both the mediums have been explained using vibrational spectroscopy. This study clearly demonstrates how to tune the optical properties of ZnS nanoparticles by changing the reaction medium to find potential applications in the field of electronics. The work reported is a step towards understanding the role of crystallinity to tune the optical properties of a material. (C) 2013 Elsevier Ltd. All rights reserved.