Preparation And Characterization Of Glass Frit In Silver Paste For Solar Cell

As an important component of silver paste,glass frit make an effect on the electrical properties and photoelectric conversion efficiency of solar cells by adjusting the performance of silver.Most of the glass frit used in the current photovoltaic industry is lead glass frit,but lead's hazards to human body and environmental making the glass frit lead-free become a general trend.In this paper,TeO₂-Bi₂O₃-ZnO ternary glass samples were prepared by melt-water quenching method.By analyzing the samples with the methods of XRD,IR and DSC,the formation regions of TeO₂-Bi₂O₃-ZnO ternary glasses and the impact of the compositions on the glass network structure and thermal properties were investigated.Two kinds of TeO₂-Bi₂O₃-ZnO ternary base glasses with good properties were selected,doped with different contents of B₂O₃,the effect of B₂O₃ on the structure and properties of glasses was investigated by XRD,IR,Raman spectroscopy and DSC.Two kinds of Te-Bi-Zn-B quaternary glass frit with B₂O₃ content of 6 mol% were selected to prepare silver paste for solar cells and the properties of the silver paste were characterized.The main results are as follows:The TeO₂-Bi₂O₃-ZnO ternary system has a glass forming region ranging from 50 to 90% of TeO₂,0 to 20% of Bi₂O₃,and 0 to 50% of ZnO.The network structure of the glasses in the forming region is composed by [TeO₄] and [TeO₃] as mainly composition;Bi₂O₃ as network intermediates in the form of [Bi O3] tetrahedron and [BiO₆] octahedron,involved in the composition of the glass network;ZnO as a network modifier in the form of [ZnO6] octahedron,filled in the gap of the glass network structure,and as the role of complemented the glass network in the form of [ZnO3] tetrahedron.When the content of ZnO is low,the characteristic temperature of the glasses increases with the increase of the content of ZnO,which is the effect of [ZnO3]tetrahedral complemented the glass network plays a dominant role.When the content of ZnO is high,the characteristic temperature of glasses decreases with the increase of ZnO content,which is the disconnection of Zn2+ dominates.The characteristic temperature of the glasses decreaseswith the increase of Bi₂O₃ content,The glass-forming properties of the glasses were not changed as the B₂O₃ doped with different content in TeO₂-Bi₂O₃-ZnO ternary based glass,the network structure of the glass was still mainly composed by the form of [TeO₄] triangular pyramid and [TeO₃] triangular pyramid structure.With the increase of B₂O₃ incorporation,[TeO₃] triangular pyramid gradually transformed into [TeO₄] triangular bipyramid,and B3+ involved in the construction of glass network as the main structure of [BO3] triangular structure,improved the connectivity of the glass network,the glass transition temperature and crystallization temperature of the glasses were increased while the melting temperature was decreased.The organic solvent in the organic vehicle evaporated in the range of 50²20?,resulted in a quickly loss of the quality in silver paste;the residual solvent and the organic additives in the organic vehicle evaporated slowly in the range of 220⁵00?,slowed down the speed of quality loss in silver paste.Compared with the comparison sample,the series resistance of the solar cell prepared by the silver paste is obviously larger,the fill factor and the photoelectric conversion efficiency are obviously smaller,the electroluminescence diagram of the solar cell showed an obvious flower slice defect,which proved that the glass frit can not etch the Si Nx antireflective film completely during the sintering process,resulted in the ohmic contact between the silver electrode and the silicon wafer is not complete.