Advanced contact grid lines on silicon solar cells
Original Publication Date: 2009-Jun-24
Included in the Prior Art Database: 2009-Jun-24
Contacting a silicon surface is still a technical challenge, especially in case of solar cell applications. The surface contact area has the high probability of recombination and other defects. Increasing the contact surface area by even etching into the contact layer reduces the know contact problems significant. Most likely the resistivity of the contact area is improved as well. The contact grid on the top side of the solar cells also causes quite some shadowing of the sun light. This again reduces the efficiency of the solar cell itself. Screen printed contact lines can’t be made ultimately thin due to process/technology restrictions. Plating technology enables much smaller contact lines, which can be even improved applying additional thinning. Also the contact etching out of a metal layer covering the silicon surface can be improved through structural thinning. An advanced line printing, with reduced line width and line embedded in the silicon surface would support better performance. There is no Ag based contact paste available which would support a line width printing in the range below 50µm. Therefore another method is discussed to achieve these line widths using other techniques. The advancement discussed below supports improved power output, due to reduced shadowing as well as improved contact resistance to the silicon surface.