Preparation And Application Of Monodisperse Silver Powder And Copper - Silver Composite Powder For Solar Cell

With the development of the society, Energy and environmental issues have been the major problems currently facing the world. Solar energy can be regarded as always available, an inexhaustible supply of clean energy. Solar energy is used by the solar cell. The research of silicon solar cells is focused on solar cell paste. Silver powder is the main material of the solar cell paste, and its dosage is more than 80%. The performance of silver powder directly affects the performance of solar cells, so the preparation of silver powder and its application in the solar cell paste has very important significance.In this paper, the spherical and mono-disperse silver powder was prepared by liquid phase chemical reduction, and the binary disperse system was studied. Besides, the phosphate process of Copper powder was studied. The samples were characterized by laser scattering particle analyzer, scanning electron microscope, tapping apparatus, and X-ray diffractometer, respectively.The silver powder was prepared by using ascorbic acid as reluctant. The different dispersant, binary disperse system, adding way of dispersant, feeding speed, pH, silver nitrate concentration, ascorbic acid concentration and dosage of dispersant were investigated. Based on the single factor experiments, the preparation process of silver powders was optimized by the response surface method. Two mathematical regression models of between the average particle size (apparent density) and factors were obtained, and the optimum process conditions were determined through the models. The optimum process conditions were:pH=3, [AgNO3]=0.6mol/L, [C6H8O6]=0.3mol/L, m (PVP and gum Arabica)/m (AgNO3)=2%, m (PVP)/m (gum Arabica)=1:2, reaction temperature=21 ℃, and the dispersant was added into silver nitrate and silver nitrate solution was added into ascorbic acid solution quickly. The silver powders obtained under the optimum conditions were monodisperse and spherical particles with high purity, the size distribution of 1-3um, the average particle size of 2.01 μm apparent density of 3.14g/cm and tap density of 4.96g/cm.In order to improve yield and oxidation resistance of silver coated -copper powder, the phosphatization of copper powder was studied. The phosphate liquid was compounded by using ZnO, H3PO4, HNO3 and deionized water. The different phosphate liquid, time, and temperature were investigated. The results show that the phosphatization of copper powder was helpful to improve the yield and oxidation resistance of silver coated copper.The solar cell paste was prepared by using prepared silver powder and silver coated copper powder. The conductivity, surface morphology and solar cell paste section were investigated. The result indicted that surface morphology was density, good conductivity and glass powder and silver powder were mixed well due to silver powder with high tad density. The oxygen was produced due to decomposition of organics at high temperature, and the silver coated copper powder was oxidized, so the conductivity of silver coated copper powder paste was very poor, which show silver coated copper powder was not suitable for silver paste system.