Preparation and characterization of CuInSe2 nanoparticles elaborated by novel solvothermal protocol using DMF as a solvent

Abstract

In this study, high purity and near stoichiometric CuInSe2 (CIS) nanoparticles have been successfully synthesized using solvothermal route. The goal of this paper is to improve the crystal quality while reducing production cost and limiting the toxicity of solvothermal reaction, as compared to processes including selenization step. Therefore, the starting solution solvothermal is constituted by the following precursors (CuSO4.5H2O, InCl3.xH2O and Se powder) which were dissolved in N, N Dimethylformamide (DMF) as solvent. A reasonable possible mechanism for the growth of CIS nanoparticles is proposed. The effect of process parameters on the synthesis and characterization of CIS nanoparticles were examined including reaction temperature (165–240 °C), process time (12–24 h) and the drying route. The as-obtained CIS nanoparticles are analyzed using diverse techniques such as x-ray diffraction (XRD), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), Raman spectroscopy and UV–vis-IR spectrophotometer. All results demonstrate that the optimal conditions for preparing a single-phase CIS obtained at 220 °C for 24 h and followed by annealing at 400 °C for 30 min under a nitrogen atmosphere. In addition, XRD results showed that the CIS nanoparticles crystallize in the chalcopyrite structure, with grain size in the order of 25 nm, which is also confirmed by TEM images. Raman spectra show the intense peak at 171 cm−1, which correspond to the chalcopyrite structure, no signature of secondary phases. Optical measurements revealed strong absorption in the entire visible light to near-infrared region and band gap (≈1.04 eV) is very close to those of absorbent materials in thin film solar cells.