Tunable band gap energy of l-Cysteine-assisted formation of Mn-doped ZnS interconnected nanoparticles for electro-optic applications

Abstract

Interconnected pure and Mn2+-doped ZnS (ZnS: Mn) nanostructures were obtained via l-Cysteine-assisted synthetic strategy. The obtained interconnected nanostructures have been investigated systematically for their respective structural, morphological, optical and photoelectric properties. The attained XRD results reveal the cubic zinc blended structure of ZnS for all the synthesized specimens. The average grain size is found to be about ∼4.5 nm for the pure ZnS nanoparticles and ∼4.2 nm for the 3% Mn2+-doped ZnS nanoparticles which have been computed using the Debye‐Scherrer equation. The recorded TEM results indicate the interconnected nanoparticles of 4–7 nm forming the flakes which are about 200 nm in size for both the pure and Mn2+-doped ZnS NPs. Optical absorbance spectrum indicates the incorporation of Mn which induces a red shift whereby the maximum absorption of the material is witnessed. The band gap energy of the pure, 1%, 2% and 3% Mn2+-doped ZnS NPs are found to be 4.09, 3.75, 3.38 and 3.23 eV, respectively. PL peak intensity is linearly decreased with respect to the doping percentage. Enhanced electrical conductivity for ZnS nanomaterials doped with Mn2+ has been authenticated experimentally. Based on the optical and electrical properties, the Mn-doped ZnS NPs can be a potential candidate for electro-optic applications.