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

Abstract

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.