The ternary I-III-VI2 semiconductor of CuInSe2 nanoparticles with controllable size was synthesized via a simple solvothermal method by the reaction of elemental selenium powder and CuCl as well as InCl3 directly in the presence of anhydrous ethylenediamine as solvent. X-ray diffraction patterns and scanning electron microscopy characterization confirmed that CuInSe2 nanoparticles with high purity were obtained at different temperatures by varying solvothermal time, and the optimal temperature for preparing CuInSe2 nanoparticles was found to be between 180 and 220 °C. Indium selenide was detected as the intermediate state at the initial stage during the formation of pure ternary compound, and the formation of copper-related binary phase was completely deterred in that the more stable complex [Cu(C2H8N2)2]+ was produced by the strong N-chelation of ethylenediamine with Cu+. These CuInSe2 nanoparticles possess a band gap of 1.05 eV calculated from UV–vis spectrum, and maybe can be applicable to the solar cell devices.
Selenium nanoparticles and nanorods were successfully prepared in a mixed solvent of ethylene glycol and water at a relatively low temperature of 85°C. No other surfactant or template was employed, and glucose was used as a green and mild reducing reagent in the current synthesis. The volume ratio of ethylene glycol to water played an important role for controlling the shapes of selenium products. The obtained selenium samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectra, and UV-vis absorption spectra. The evolution process from amorphous selenium to a trigonal phase complied with a "solid-solution-solid" formation mechanism. HRTEM and SAED results indicate that the trigonal selenium nanorods grow along the [001] direction. This method might provide an environmentally-friendly and low cost route for the synthesis of other related nanomaterials with controlled morphologies.
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