The study of the defect removal etching of black silicon for diamond wire sawn multi-crystalline silicon solar cells

We produced low-reflectivity nanostructured black silicon by metal-assisted chemical etching (MACE) technology on the 15.6 cm × 15.6 cm diamond wire sawn (DWS) multi-crystalline silicon (mc-Si) wafers. Subsequently, defect removal etching (DRE) processes were carried out for various times to form nanohills with different sizes on the wafer surface. The experimental results indicated that the DRE process could influence the size of the nanohills, reflectivity and the recombination velocities of the silicon wafers. It was found that for the black silicon wafer, with the increasing of DRE time, the reflectivity became larger and the passivation effect became better. The reflectivity and the passivation effect can be adjusted by suitable DRE processes. By this way, we successfully fabricated the DWS mc-Si solar cell (15.6 cm × 15.6 cm) with the highest conversion efficiency of 19.07%, showing an improvement in efficiency of 0.6% compared to a DWS mc-Si solar cell (15.6 cm × 15.6 cm) prepared by conventional acidic texturization.