Influence of Li+ and Nd3+ co-doping on structural and optical properties of l-arginine-passivated ZnS nanoparticles

We report the effect of Li + and Nd3+ co-doping on structural and optical properties of l-arginine-passivated ZnS nanoparticles (NPs) synthesized by chemical co-precipitation method. High-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction study were used to explore the morphological and structural aspects of prepared NPs. HR-TEM analysis confirmed that the size of ZnS NPs reduces from 5 to 3 nm as the concentration of co-dopant increases from 1 to 5 wt%. Ultraviolet–visible absorption spectra show absorption peaks in the range of 295–315 nm indicating huge blue shift as compared to the bulk ZnS (340 nm, E g = 3.6 eV) due to the quantum confinement effect. The large optical band gap was estimated in the range of 3.95–4.62 eV and found increasing as the co-dopant concentration increases. Photoluminescence spectra showed that co-doped ZnS NPs emit multiple intense violet-colored (370, 375, 380, 388 and 398 nm) and blue-colored (425, 448, 455 and 465 nm) peaks with increasing intensity. Fourier transform infrared study confirmed the strong interaction between ZnS NPs and l-arginine ligands. The presence of co-dopant in the sample is confirmed by energy dispersive X-ray analysis. Based on the results, we proposed that this material is a new class of luminescent material suitable in optoelectronics devices application, especially in light-emitting devices, electroluminescent devices, display devices, etc.