Quasi-Omnidirectional Ultrathin Silicon Solar Cells Realized by Industrially Compatible Processes

Ultrathin crystalline silicon (c-Si) solar cells provide advantages in reducing the use of c-Si material and being flexible, but there are several challenges that need to be conquered, such as limited optical absorption, high sensitivity to surface recombination, and complicated fabrication issues. Here, all-solution-processed Si nanopyramids (SiNPs) are proposed as the surface texture for ultrathin c-Si solar cells to solve the light absorption issue, whose preparation process is simple, low-cost, and industrially compatible. Combining the SiNPs texture with good passivation technique, an efficiency of 15.1% with an open circuit voltage approaching 700 mV is realized on a 37 mu m thick c-Si solar cell. Moreover, both experimental and simulation investigation reveal that the SiNP-textured ultrathin solar cells have quasi-omnidirectional light absorption characteristic, showing a potential to produce higher all-day output power compared with the Si micropyramids textured counterpart. To further reduce the cost of ultrathin c-Si solar cells, a direct copper metallization is also investigated in replacement of silver metallization, which can result in a comparable efficiency. The present work demonstrates the conventional industrial processes for achieving low-cost ultrathin c-Si solar cells.