Porous silicon antireflection layer for solar cells using metal-assisted chemical etching

Porous silicon antireflection coatings were generated on fully processed screen‐printed monocrystalline silicon solar cells using metal‐assisted chemical etching in HF:H2O2:ethanol. In this method, interaction of the HF acid with the cell front grid contact results in the dissolution of silver nanoparticles which provide the catalytic sites required to initiate porous silicon formation. Control of the etching time and HF concentration was found critical to attain good antireflection proper‐ ties while avoiding front contact degradation. The optimised porous silicon layer reduced the solar cell effective reflectance from 44% to 12% in the spectral range 400–1100 nm and increased the short‐circuit current density by 46%. The solar cell efficiency was raised by 3% absolute. The simplicity of the method makes it promising for cost‐effective reduction of reflection losses in silicon solar cells. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)