Preparation And Properties Of Lead - Free Silver Paste On Solar Cells

Solar energy is a kind of renewable clean energy. The solar cell is an important way of using solar energy, and the silver paste is a key raw material to make solar cells, the quality of the silver paste plays a key role on the performance of the solar cell. The silver paste for the current domestic production of solar cells is mostly dependent on import, and the silver paste using for most solar cells contain lead. Therefore, in order to get rid of dependence on imported paste and relieve environment pollution, we must independently develop the lead-free silver paste that various aspects performance meet the requirements of solar cells, it is very urgent and significant.In this paper, preparation of silver paste composition raw materials was studied and analyzed, the preparation of the lead-free conductive silver paste for solar cells and related properties of the silver paste had been studied. The influence of paste composition ratio and sintering process on its performance had been discussed.The lead-free glass powders were prepared by melting water quenching mixture of Bi2O3, SiO2, B2O3, AI2O3, TiO2, NaF, ZnO and SnO2. The effects of the components of the glass powders on the transition temperature and acid and alkali resistance have been studied, and selected the glass powder composition ratio that had optimum transition temperature and chemical stability.Silver power was prepared from AgN03by chemical reduction. Effects of reaction pH and dropping speed of AgNO3solution on particle size and morphology of silver were investigated, the results show that the silver powder had better performance when pH was7and dropping speed of AgNO3solution was5ml/min. And the organic vehicle of the conductive silver paste for solar cells had been producted.Silver paste was fabricated by uniformly mixing with silver powder, glass powder and organic carrier. The effects of the glass powder content, particle size and morphology of silver, silver powder mixture of two different particle size and morphology, flake silver content in silver powder, the sintering temperature and sintering time on the properties of the silver film were studied in details. The test results show that:Considering sheet resistance and adhesion of the silver film, the silver film can obtain better performance when the glass content at5%, the silver powder content at80%(the2μm silver flake and2μm spherical silver adding by mass fraction at5:3), the sintering peak temperature at760℃and sintering holding time at 7minutes. The sheet resistance of silver film is3.7mΩ/□and the adhesion of the silver film is7.6N.