Study On Application Of Screen Print In Crystalline Silicon Solar Cells

Metallization process, as one of the most critical process in conventional crystalline silicon solar cell manufacturing, determines the final conversion efficiency of solar cells. Metallization technology mainly involves halftone, thick film paste printing and sintering. Currently high resistance grid design is one of the effective methods to improve photoelectric conversion efficiency of solar cells. Halftone directly decides the quality of grid line printing; however few researches have been conducted on screen printing domestically and internationally. This paper mainly focuses on screen parameters and thick film paste printing (double printing) in crystalline silicon solar cell application.With the development of crystalline silicon solar cells technology, screen printing is essential for the production of solar cell. The key objectives for Screen printing are:1) print electrodes on the formation of p-n junction and coated Silicon;2) export photo-carriers to achieve solar photoelectric conversion;3) deplete organic composition of paste to form a good ohmic contact between paste and wafer.The main contents n of this paper are as the following:First a new simulation model of the volume of paste was established. The original ideal model ignores the emulsion thickness of halftone, which results in a deviation between theoretical calculation and actual experiment results. This new model introduced specific mathematic expression and adhesion coefficient through experiment. The rheology paste impact is also included.Screen impacts such as screen parameters including emulsion thickness and screen thickness were studied and it’s found thinner screen has been improved. Then halftone technology on solar cells performance was studied, mainly including cell performance, relations between emulsion coating times and screen thickness. Emulsion coating times and roughness are concluded from coating experiment. Then the impact of different screen formats on cell performance was compared.Finally sintering technology was optimized based on Ag-Si contact mechanism, and research about the impact of peak sintering temperature on solar cells fill factor FF was conducted. Hardness and angle of the squeeze was optimized. It is found that double printing of the second generation has higher short circuit current and lower resistance than that of the first generation from researches on grids aspect ratio, SEM(scanning electron microscope) figure, I-V characteristics graphs, grid line resistance and contact resistance value, and PL image of the solar cells. Finally, the efficiency has evalated0.3%and the contact resistance reduced by4mΩ/cm2, meanwhile the line resistance reduced by0.11Ω/cm.In the aspect of the principles of forming contact resistance, double printing is similar to electrode plating. Differences between plated electrode and screen-printed electrode were studied in this paper, respectively comparison in the same grid line shading area;different space pf grid lines and the same shading area. Experimental results showed that the plated electrode cells enjoyed advantages in series resistance, which was similar to double printing, and further more proves the reliability of double printing.