| In recent years, thin film solar cells has attracted widespread attention because its advantages of high performance and low cost. CIS (including CuInSe2and CuInS2, etc.) is a I-III-VI ternary compounds semiconductor materials with direct band gap, the width of the band gap can have a good match with the solar spectrum. Due to its high absorption coefficient, the width of band gap can be regulated by doping, high conversion efficiency, stable performance, and it has excellent anti-interference, radiation resistance, CIS has become one of the most promising materials in solar cells materials.In this paper, we studied the influence of different reaction conditions on the CIS phase and morphology, and its growth mechanism are analyzed, the main research results are as follows.(1) CuInSe2powders were prepared by solvothermal route involving CuCl2·2H2O as the copper source, InCl3·4H2O as the indium source, Se powders as the selenium source and ethanediamine as the reaction medium respectively. Microstructures and morphology of the samples were characterized by field emission scan electron microscopy, transmission electron microscopy, X-ray diffractometry. Optical absorption performance of the samples was tested by ultraviolet-visible spectroscopy. The results shows that the samples prepared at160℃for18h had flower-like morphology composed of large numbers of nanoplates and the thickness of CuInSe2nanoplates was about100nm. The average diameter of the flower-like microcrystals was about10μm. Further research shows these nanoplates were made up of smaller size of nanoparticles in about10nm. It shows a good absorbency in the visible light range.(2) Studied the influence of different the reaction time and reaction temperature on the CuInSe2products. Results showed that the reaction temperature and reaction time has a great influence on the product of the phase and morphology. When reaction time was too short or too long, the product was made up of messy sheets; at lower reaction temperature, the shape of product was consist of flower-like microsphere and a small amount of sheets, when reaction temperature increased to180℃, the morphology of samples become sheets. According to the change of the morphology and the phase, its formation mechanism was discussed in this paper.(3) Using solvothermal method to synthesize CuInS2nanocrystals, crude materials for synthesis were CuCh·2H2O, InCb·4H2O, CH4N2S, the solvents were ethylene glycol, ethanol, ethylenediamine, N, N-dimethylformamide (DMF). It was studied the effect of solvents, sulfur source, temperature and time on the morphology and structure of CuInS2nanocrystal. The results show that at180℃with ethylene glycol as solvent reacted for18hours could obtain single chalcopyrite-crystal CuInS2nanocrystals, morphology and structure of the products obtained under different reaction conditions are quite different. The intermediate products were appeared at lower reaction temperature or shorter reaction time, with the increase of reaction temperature or reaction time, these intermediate products disappeared and obtained single chalcopyrite-crystal CuInS2products. The reaction time was too long would destroy the crystal structure of the products. The solvent was also an important factor affecting the morphology and structure. Due to different release speeds of S2-in solvent, when used different materials as the sulfur source, the product exhibits different morphology. In addition, surface active agents could effectively improve the surface morphology of the samples. |
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