Light confinement in e-beam evaporated thin film polycrystalline silicon solar cells

Polycrystalline Si thin‐film (poly‐Si) solar cells need effective light‐trapping to compensate for the moderate absorption. Recent developments in the poly‐Si cell technology focus on film fabrication by e‐beam evaporation due to its manufacturing benefits, such as a very high deposition rate above 15 nm/s and inline compatible process. However, evaporated poly‐Si cells exhibit limited compatibility with textured glass. In this Letter, the coupling of the light in the absorber layer is enhanced by introducing a rough interface at the back of the solar cells. This increases the conversion efficiency from 6% to 7.1% for, respectively, planar and back textured interface with current density of 26.6 mA/cm2 for only 3.6 μm absorber thickness. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) E‐beam evaporated polycrystalline Si in thin‐film solar cells requires light trapping schemes to compensate its moderate light absorption but has limited compatibility with textured glass. The Letter on page 181 ff. shows how texturing the back of the silicon surface with an alkaline wet etching process improves the light absorption and current density up to 26.6 mA/cm2 for an absorber thickness of 3.6 micron deposited at 5 nm/s.