Effect of self-orderly textured back reflectors on light trapping in thin-film microcrystalline silicon solar cells

Light trapping is a key issue to boost the efficiency of thin-film Si solar cells including μc-Si:H. In this work, effect of textured back reflectors on light trapping in μc-Si:H cells has been investigated with self-orderly patterned Al substrates obtained by anodic oxidation. By increasing the period of the patterned substrates from 0 to 1.1 μm, the short circuit current densities of 1-μm-thick μc-Si:H cells on the patterned substrates significantly increase from 18 to over 24 mA/cm2, which is attributed to the improved light trapping in the near infrared region. The optimum period for light trapping is determined to be around 1 μm for 1-μm-thick μc-Si:H cells. In addition, it has been demonstrated that the optimized patterned substrate enhances light trapping effect in a wide range of cell thicknesses of 0.5–4 μm. It is also confirmed that natural surface texturing during μc-Si:H film growth improves light scattering for flat substrates but deteriorates the superior light scattering property of the well-designed substrates.