Analysis of rear contacted solar cell structures for cost-effective processes and materials

The authors compare the limiting effects of high-efficiency rear contacted solar cells, screen-printed rear contacted solar cells and emitter-wrap-through solar cells for different cell thickness by means of numerical device simulation. For high diffusion lengths, the high-efficiency rear contacted cell and the emitter-wrap-through solar cell show a decreasing short circuit current density with decreasing cell thickness, whereas the screen-printed rear contact cell shows the reverse behavior due to a "pumping" effect of the floating emitter. The impact of the emitter sheet resistance in the via hole of the emitter-wrap-through cell on the illuminated IV-curve is investigated for illumination from the front and from the rear side. The presented analysis allows an optimization of rear contacted cells for application as high-efficiency and as low-cost structures.