A Study of the Structural, Morphological and Luminescence Characteristics of Polyvinyl Pyrrolidone and Chitosan Capped Calcium Sulfide Nanoparticles

Semiconductor nanoparticles have gained impressive attention due to their novel optical and electronic properties. Here we report the synthesis of calcium sulfide (CaS) nanophosphors through a simple wet chemical co-precipitation method using two different capping agents polyvinyl pyrrolidone (PVP) and chitosan. The role of capping agents in determining the particle size, morphology and luminescence of CaS nanoparticles was determined using X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), room temperature Photoluminescence (PL), UV-Vis spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy. XRD studies confirmed that the nanoparticles were crystallized in cubic phase with space group 3 Fm m. PL emission spectra of the capped samples consisted of broad peaks in the range 350-500 nm with enhanced PL intensity compared to that of uncapped sample. An increase in bandgap was observed due to capping which may be attributed to size quantization effects. Capped nanoparticles showed better structural and optical properties compared to uncapped samples which can be exploited in various optoelectronic and biomedical applications.