| In numerous solar cells, Cu InS2 as the absorption layer of thin film solar cell has caused extensive concern of the photovoltaic researchers due to the advantages of its high absorption coefficient, the appropriate width of band gap(1.5 eV), high theoretical photovoltaic conversion efficiency(about 25% to 30%), stable performance, less sensitive to the changes of temperature, and low toxicity, and so on. However, most of the synthetic method was used the organic solvent as the solvent, and needs high temperature and high pressure conditions, which makes the CuInS2 solar cells can’t be large-scale application. Therefore, it has an important practical significance that to seek a kind of low cost, green, environmental synthesis method. In addition, different phase structure CuInS2 has different photoelectric properties; most of the synthesis methods were used to regulating the source of coppers and indium, or the kinds of ligands, and reaction temperature to control the phase structure. Therefore to seek a simple phase control method is very important and can better promote the practical application of CuInS2.In this paper, we through a simple method successfully synthesized CuIn S2 nanomaterials with different morphology under the condition of water bath and low temperature(80℃). Fistly, we used a water-soluble TGA as the complexing agent and reducing agent and synthized CuInS2 nanoparticals with different phase structure under different pH value of solution. Secondly, due to the TAA not only can be used as complexing agent and reducing agent, but also can be used as a common sufur source, we just added CuCl2, In2(SO4)3, TAA into solution and synthesized CuInS2 microspheres with porous structure. This is a more simple synthises method.The main content of the paper summarized as follows:1. The aqueous phase synthesized chalcopyrite and wurtzite CuInS2 nanomaterialsWe used deionized water as solvent, thioglycolic acid as complexing agent and sodium sulfide as sulfur source, and synthesized CuInS2 nanoparticals with chalcopyrite and wurtzite structure. Because of the pH value of solution can influences on the complexation of TGA to metal ions, we studied the influence of synthesis conditions on the crystal phase of products by altering the pH value of react ion solution. It has been found that CuInS2 gradually transformed from chalcopyrite to wurtzite with the increase of pH value. This is the first report that controls the phase transformation of Cu InS2 from chalcopyrite to wurtzite by adjusting the pH value of solution. Simultaneously, we expand the application of this method by replaced sodium sulphide with thiourea and synthesized wurtzite structure CuInS2 in alkaline conditions.2. The aqueous phase synthesized CuIn S2 porous microspheresBased on the listed above, we look forward to found a more simple synthetic method. We found that thioacetamide(TAA) not only can be used as the complexing agent complexation with metal ions, but also as the reductant can reduce the Cu2+ to Cu+, and moreover it is an common sulfur sources in the process of reaction. We just added CuCl2, In2(SO4)3, TAA into the solution and successfully synthesized CuIn S2 porous microspheres by adjust the pH value of the solution. The surface of the porous microspheres was made up of many nanosheets. The effect of the pH value, reaction time and the amount of TAA on the phase and morphology of the product has been researched. Finally, we studied the growth process of the porous microspheres and the reaction mechanism. |
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