Structural and optical properties of N-acetyl-l-cysteine capped Sb2S3 quantum dots for LED applications

Abstract

Present study deals with the synthesis of N-Acetyl l-cysteine (NAC) capped Sb2S3 quantum dots via hydrothermal route. Structural properties of the synthesized material were investigated by X-ray diffraction (XRD) crystallography, photoluminescence (PL), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectroscopy, and scanning electron microscopy. XRD spectra revealed the orthorhombic structure of the as-prepared samples and assisted in the calculation of crystallite size of deposited films. The most intensive peaks for prepared samples were observed at angles 16.300, 25.150, 33.440 and 36.100 indexed as (020), (310), (211) and (231), indicating successful synthesis of Sb2S3nanoparticles. Different molar concentrations of N-acetyl-l-cysteine (NAC) were employed as capping agent and it was observed that its addition resulted in decrease in noise together with decline in peak broadness as well asits shifting toward higher angles at higher concentration, thus showing better crystallinity of Sb2S3. Fourier transform infrared spectroscopy (FTIR) was used to identify the chemical bond vibrations of the different groups present in Sb2S3nanoparticles. UV–Vis spectroscopy and photoluminescence analysis were carried out to observe the optical tuneability of the as prepared samples in correspondence of its bandgap. In case of UV–Vis, the absorption spectra demonstrated a sharp fall in absorbance spectrum near the band edge indicating that the material has a direct bandgap. It was found that the value of band gap energy changed from 2.57 to 1.97 eV for different concentration of NAC. However in case of PL, the strong emission peak shift was common for all samples between 647 nm and 712 nm that reflected the slight red shift in the prepared thin films.