Study On Sintering Process And Microscopic Mechanism Of Polycrystalline Solar Cell

With the production process of silicon solar cell reachs the bottleneck,how to further improve the efficiency of silicon solar cell while reducing production costs has become the primary problem of manufacturers.The main factors that affect the photoelectric conversion efficiency of silicon solar cells are the contact characteristics of front and back metal electrodes,the loss of incident light shielding caused by the front electrode grid and the shortwave response loss of silicon material.At present,reducing the resistance loss and shading loss caused by the pre-electrode grid lines prepared by the conductive silver paste is the focus and hotspot to improve the performance of silicon solar cells.The sintering process of the former electrode mainly affects the silver electrode density,Ag/Si contact characteristics and current transmission performance.Therefore,it is the key way to improve the performance of silicon solar cells by exploring the matched sintering process with the positive silver paste.Therefore,this study chooses the polysilicon solar cells(only without the former electrode)as the basis and the front silver paste made by our own laboratory to explore the influence on the performance of the polycrystalline silicon solar cell of the sintering process including furnace drying interval temperature,organic combustion temperature,peak temperature and sintering furnace belt speed.And in order to provide some theoretical support for the industrial production of polysilicon solar cells,this study explores the sintering microcosmic mechanism and the Ag/Si contact process by measuring microstructures at different peak temperatures such as the thickness of the interfacial glass layer,the size of the silver grain,the size of the silver particles and surface hole rate of grid line.The main contents and results of this paper are as follows:(1)The changes of the IV characteristic parameters and the resistivity of the electrode grid line were investigated under different drying interval.It was found that the difference in the drying temperature of the sintering process mainly affected the electrode grid line resistance and the battery series Resistance,thus affecting the filling and efficiency of polysilicon solar cells.(2)The changes of the IV characteristic parameters and the aspect ratio of the electrode grid were investigated under the combustion temperature of different organic materials.It was found that the temperature of the combustion zone of the organic process mainly affected the aspect ratio of the electrode grid Affect the electrode grid wire conductivity and gate line shading rate,resulting in changes in battery efficiency.(3)The change of the characteristic parameters of the battery IV,the resistance of the gate line and the contact resistivity were investigated.The results show that the sintering of the frontal electrode from the low temperature to the high temperature is good The Ag/Si contact interface glass layer thickness and the size of the silver grain were investigated by SEM.The effects of Ag/Si contact on the surface of the electrode were investigated by SEM.Process and mechanism,and from the micro perspective of the battery electrical properties of the inherent mechanism of micro-analysis.According to the SEM measurement of silver particles on the surface of the gate line and the results of the surface hole analysis of the gate line of the Image J software,the wireline sintering process is as follows:With the increase of the sintering peak temperature,the silver particles of the gate line are aggregated into each other,At the same time,the intergranular pores become larger and the conductivity is reduced.The two factors affect the density of the gate lines.It also explains that the resistivity of the gate lines does not decrease or decrease at 780? and 850?.(4)Explore the effect of different sintering furnace belt speed on the IV characteristic parameters of the battery.If the sintering furnace is too slow,the electrode grid is over-sintered,the filling of the battery is reduced and the efficiency is decreased.If the speed is too fast,,Is not conducive to the formation of Ag/Si ohmic contact,the efficiency will decline.The optimum sintering process of the self-made silver paste was determined as above.The temperature of the drying zone,the burning temperature of the organic material,the belt speed and the peak temperature of the sintering furnace were 200?,400?,7m/min,830?,then the silver electrode line resistivity reached a minimum of 3.54m ?/cm,contact resistivity is small,the battery photoelectric conversion efficiency,filling factor reached the maximum,respectively 11.444%,66.874.