Production And Quality Analysis Of Ohmic Contact For Metallurgical Silicon Solar Cells

The conventional screen printing technique was used to develop and produce the metallurgical polycrystalline silicon solar cells (156x156mm2). The parameters, which will affect the conversion efficiency and whole performances of the metallurgical polycrystalline silicon solar cells, were studied i.e. screen printing front and back silver electrode, BSF, sintering temperature, screen printing plates and etc. Ellipse laser polarization, scanning electron microscope, classification of test system were utilized to test the thickness of antireflection film, refractive index, the microstructure of metal grid lines and the electrical properties of cells. Test results show that the thickness of silicon nitride thin films is around84.6-93.2nm, refractive index is2.0942～2.2627. Main grid metal was using paragraphing and hollow out shape, height and width is0.56mm and1.71mm, with aspect ratio about3.3times. The height and width of fine grid metal is15.9μm and81.4μm (the width design80μm), with aspect ratio about2times. For5200pieces of metallurgical silicon solar cells in quantify production, the majority of the cells are used phosphorus gettering of hybrid technology. The result is given as:the maximum efficiency of monolithic is17.42%; average transfer efficiency of the metallurgical silicon solar cells after optimized diffusion technology with phosphorus gettering is16.6%; the average transfer efficiency about the metallurgical silicon solar cells without optimized diffusion technology with phosphorus gettering is16.43%; the average transfer efficiency of the metallurgical silicon solar cells without optimized diffusion technology with phosphorus gettering is15.98%. The leakage pieces accounted for12.99%. The series resistance of a small part of solar cells is high in the production, taking full analysis discover that the key reason is due to some phosphorus silicon glass on the surface of solar cells being not cleared away. The printing electrodes cann’t penetrate the silicon on behind of them in the regular sintering temperature, and cann’t form a better ohmic contact.