Sentaurus Simulation of Monolithic Solar Cells with High Open-Circuit Voltage

The integration of multiple solar cells in series in a single wafer increases the output voltage, and reduces the output current. With this new concept we can power small appliances with a single wafer, and if these solar cells are integrated in a larger module the series resistance losses are mitigated. To isolate the individual cells, we space them apart in the wafer. The challenge is to optimize the spacing between cells to balance the short-circuit losses with leakages (narrow spacing). Increasing the surface recombination in the intercell region reduces the effect of leakage current, reducing the spacing between cell leading to higher current. Although initially simulations of monolithic solar cell only have less than 15% of efficiency, the new design can improve the efficiency to over 20%. The new design increased the leakage resistance between the parallel cells which decreased the leakage current to less than 10% of the original value and increase the FF from 58.9% to 79.8%.