Study of the Structural, Optical, Electrical and Morphological Properties of Nickel Sulfide Thin Films Used in Supercapacitors

Abstract

Nickel sulfide (NiS) thin film has been deposited on glass substrates by spray-pyrolysis at 325 ± 5 °C. The precursor aqueous solution was synthetized using hexahydrated nickel nitrates and thiourea. The structural, morphological, optical and electrical properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy and four probes electrical measurements. The XRD analysis confirmed the hexagonal structure of NiS thin film, which was found to crystalize along [010] direction with an average crystallites size of 10.5 nm. The lattice parameters are a = b = 3.420 Å and c = 5.300 Å in the space group P63/mmc. The optical properties of the films were investigated through the transmittance and the reflectance measurements. The results revealed that the material exhibits a direct optical band gap of 1.03 eV. The elementary composition analysis confirmed the presence of Ni and S with a stoichiometry ratio (Ni/S) of 1.05. The morphology analysis revealed a homogenous crack-free, compact appearance and a granular surface in all scanned areas. The average roughness of the surface was 6.48 nm. On the other hand, the film exhibits a high electrical conductivity ca. 1.10 × 105 S/cm at room temperature. The above results show that the prepared NiS in this study has a good crystallization, dense morphology, good stoichiometric ratio and high conductivity; therefore, it stands as a potential candidate for application in supercapacitors as an electrode material.

Effect of annealing time on the structural, morphological, optical and electrical properties of NiS thin films

“…This shift is probably due to stresses that deform the mesh, which has led to changes in the mesh parameters that more or less shift the position of the peaks as shown in Table 3. On the other side of the coin, the data obtained in this study are also in a good agreement with the previous reports in the literature on NiS films prepared by spray-pyrolysis and other techniques [3,12,13].…”

“…We also notice on the spectra of the reflectance that the value of the reflectance is always higher than the value of the transmittance, this phenomenon can be related to a metallic behavior, which reflects the absorbent character of the nickel sulfide film [3,26].…”

“…Both phases exhibit a many applications. Different methods such as spray pyrolysis [3] the deposition of the chemical bath (CBD) [4], hydrothermal [5], adsorption and reaction of successive ionic layer (SILAR) [6], thermal evaporation [7], electro-deposition [8] and sol-gel [9] have deposited the thin films of NiS. Since thin films are very important in industrial production, an easy and inexpensive method should be sought among the methods which have proven to be effective are the spray pyrolysis method, because they do not require advanced technologies and complex devices, but they need simple devices and access to films at low cost.…”