Preparation of nano-patterned Si structures for hetero-junction solar cells

The 220 nm and 300 nm periodically nano-patterned Si structures with low aspect ratio were fabricated by nano-sphere lithography technique. A good anti-reflection properties in a broadband spectral range (300-1200 nm) was exhibited due to the gradually changing refractive index of the formed Si nanostructures. After deposition of the intrinsic and phosphorous-doped (P-doped) amorphous Si (a-Si) film, the weighted mean reflection of the 220 nm and 300 nm periodic nanostructures was further reduced to 3.30% and 2.96%, respectively. Due to the enhanced light absorption, both the IQE and EQE of the nano-patterned cells were improved in a wide spectral range. For the 300 nm periodically nano-patterned prototype hetero-junction solar cell, the short circuit current density was increased to 34.5 mA/cm2, which was obviously improved compared with 26.8 mA/cm2 for the flat cell.