Improving the Surface Passivation and Cleaning Quality of c-Si Wafers for the Application of TOPCon Solar Cells

The new generation of photovoltaic devices require high quality silicon wafer for solar cell fabrication. Minority carrier lifetime is a basic parameter to be considered for the fabrication of silicon-based energy devices. temporarily passivating the surface of solar-grade silicon wafers using an iodine-ethanol solution after a novel cleaning process involving acetone and ethanol in an ultrasonic bath and saw damage removal (SDR). After cleaning process and the saw damage removal, the 0.2 mol/L Iodine-Ethanol (I-E) solution was used for temporary chemical surface passivation to measure the bulk lifetime of the two types of wafers, which was measured to be 802 μs for phosphorus doped n-type wafer and 226 μs for gallium doped p-type wafer. We explored that with these passivation parameters, a Quokka 3 simulation study validates the use of these wafers in TOPCon solar cells, achieving 22.3% efficiency on p-type wafers and 23.3% on n-type c-Si wafers. Our research showcases the potential of cleaning methods and chemical passivation for solar-grade wafers in the production of high-efficiency solar cells.