The influence of Ag-ion concentration on the performance of mc-Si silicon solar cells textured by metal assisted chemical etching (MACE) method

As diamond wire sawn (DWS) technique for multi-crystalline Si (mc-Si) becomes mainstream wafering technology in Si-based photovoltaic industry, metal assisted chemical etching (MACE) method will become a key technique to improve conversion efficiency. Due to the intrinsic characteristic of Ag nanoparticles precipitation reaction in solution in the first step of MACE, a large number of deep nanopores are produced on the surface of mc-Si wafer in the following etching step. The deep nanopores can lead to the degradation of mc-Si solar cell's performances. Thus, the influences of Ag-ion concentration in the first step of MACE on the solar cell's performances was carefully studied. It's found that with the increasing of Ag-ion concentration, the light trapping capabilities keeps improving. However, the solar cell's electric performances deteriorate dramatically when Ag-ion concentration reaches to a certain value. Optical and electrical simulation is performed to explain the influences of deep nanopores on the mc-Si solar cell's performances. It is found that there is an optimum Ag-ion concentration value to enhance the mc-Si solar cell's performances, and an efficiency of 18.94% is obtained for large size of 156.75 × 156.75 mm2 wafer. An absolute efficiency of 0.5% was improved as compared to the conventional acidic textured DWS mc-Si solar cell. It shows the necessity of controlling the Ag-ion concentration in the manufacture of black silicon. •Optimum condition of deep nanoholes for Ag MACE black silicon is realized through investigating the concentration of Ag ion.•The etching mechanism of Ag MACE is investigated and simulated by Sentaurus TCAD.•The simulation of nanostructure solar cell on Sentaurus TCAD reveals the disadvantages of deep nanopores.•An efficiency of 18.94 % was obtained on DWS mc-Si wafer.