Non-destructive recovery of silicon wafers from waste photovoltaic modules and investigation of their etching behavior

Abstract

The continuous increase of waste photovoltaic (PV) modules poses a great challenge to global environmental protection and human health. As the main body of waste PV modules, it is very urgent to effectively recycle the cells. In this paper, a hydrometallurgical process of “step leach-acid etch” is adopted to realize the non-destructive recovery of silicon wafers and the efficient separation of metal elements in the cells. In addition, this paper also studied the etching behavior, proved that the trivalent nitrogen-containing active substance is the key to the etching reaction, and studied the control process of the etching reaction according to the differences in surface roughness and reflectivity of silicon wafers under different reagent concentrations. Concurrently, the methodology presented in this paper employs a mere three chemical reagents, with a silicon wafer recovery rate of 96.31%. The final silicon wafers obtained have a surface roughness of less than 1.55 μm, a thickness of about 176.02 μm, a surface reflectivity of 18.82%, and a resistivity of about 1.07 Ω•cm, with excellent performance. Compared with the existing process, the process is feasible.