| I-III-VI2 type semiconductor material has important application value in photoelectric technology. CuInS2 is a typical I-III-VI2 semiconductor with high absorption coefficient of about 105 cm-1, and has a band gap of 1.50 eV, which is well matched with the solar spectrum. With stable performance, CuInS2 is not sensitive to temperature, and its cost is lower. This material is also environmental friendly because it does not include high toxic components in itself. At present, the main problem is that most solvothermal synthesis method use autoclave to prepare CuInS2 nanoparticles with chalcopyrite structure. It reduces the safety of the experiment and is not proper to industrial production in future. In this paper,Added the appropriate complexing agents and surfactants, CuInS2 nanocrystals was synthesized using liquid reflux method by injecting precursors of CuCl.H2O, InCl3.4H2O, H3CCSNH2, the ethylene glycol was used as the reaction medium insteading of water. In our experiment, it didn't need to adopt high pressure environment and it was easy to operate. The product was charactered by XRD, FESEM, TEM, HRTEM, EDS, XPS, FT-IR, UV-Vis to study the impacts of the copper source, sulfur source, precursor concentration, ratio, injection temperature, growth temperature, and operating procedures .We also analyzed the chemical reaction process and crystal growth mechanism in the ethylene glycol system, and ultimately determined the appropriate nucleation temperature and growth temperature. At Later stages of experiment, we used drawing film method with CuInS2 nanocrystalline colloidal solution prepared at preliminary stage to prepare film, and analyzed the impact of heat treatment on film structure and morphology.Through the experimental result, we ultimately determined CuCl and H3CCSNH2 to be copper source and sulfur source; the results showed that copper source, sulfur source, precursor ratio and feeding mode have great impacts on the structure and morphology of the products. Different injection temperatures directly affect the formation of products: when injecting the precursors at low-temperature, the CuS binary phase was formed at first, and then the binary phase changed to the CuInS2 ternary phase, eventually a single chalcopyrite structure CuInS2 nanocrystalline was formed. When injecting at higher temperature, the CuInS2 nucleus was formed directly. By controlling the nucleation temperature and the appropriate growth temperature, small CuInS2 nanocrystals with narrow size distribution can be prepared. The addition of PVP can improve the dispersion of the nanocrystals and the film formation. Dispersing CuInS2 nanocrystals in ethanol, stable suspension of CuInS2 nanocrystals can be prepared. The results showed that heat treatment has no major influence on the particle size. |
