Ultrathin Spalled Silicon Thin Films for Space Solar Power

As satellite launch costs continue to decline, affordable and lightweight solar cells will become more important than ever. This work offers such cells by mechanically exfoliating, or spalling, commercially available silicon cells. The spall process creates faceting along the surface, which can create a useful back surface which increases scattering, and therefore absorption. Spalled cells are shown, featuring faceting 20 μm wide and 5 μm tall. Lumerical simulations show an asymptotic relationship between Si thickness and Jsc. This plays an important role when choosing spall depth, finding a minimum thickness necessary for strong absorption. This work shows preliminary results of the spalled cells and simulations, and offers a pathway towards efficient space solar cells.