The effect of time and Co2+ dopant on phase evolution, microstructure and optical properties of CuInS2 nanoparticles synthesized by hydrothermal method

In this research, with use of copper chloride, indium chloride, Thiourea (source of sulfur) and deionized  water as solvent, using hydrothermal method at 180 ° C and at time of 4, 6, 8, 12, 14, 16, 18 and 20 hours, the composition of CuInS2 nanoparticles was synthesized by Stoichiometric ratio of (1: 1: 2), and in the next step, this compound (CuInS2 ( with cobalt additive at 180 ° C and at time of 20 h with Stoichiometric composition of the CuIn1-xCoxS2 ​​(X = 0.1 , x=0.2)  was synthesized and the Structural changes, microstructural and Optical properties have also been studied. The use of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and Diffuse Reflection Spectroscopy (DRS) were investigated for the optical and microstructural properties. The results show that crystallite size of the synthesized single-phase nanoparticles of CIS at 16, 18 and 20 hours are 26, 29 and 32 nm, respectively. With the use of the diffraction Peaks of the planes such as (112), (220) and (312) for the sample synthesized in 20 hours, the lattice constant value a is 5.52 Å and c is 11.11 Å. FESEM micrographs showed irregular polyhedral shape for particles presence in sample synthesized in 18 hours and flaky shape for particles presence in sample synthesized in 20 hours. The band gap for a single-phase synthesized sample at 20 hours is 1. 54 eV. The band gap of (CuIn1-xCoxS2) with values (X = 0.1) was calculated to be 1.92 eV.