The laser-damage repairing on the front surface of the N-type TOPCon solar cells with electroplated electrodes

Abstract

Electroplating electrodes, a significant technique in the metallization of Tunnel Oxide Passivated Contact (TOPCon) solar cell, have gradually become a research issue. Although laser ablation effectively removed the insulating passivation layer for subsequent metal ion deposition, laser ablation treatment inevitably caused laser-damage to the cell surface. For N-type TOPCon solar cells, laser-damage on the front surface directly impacts the P⁺ emitter layer, significantly affecting the power conversion efficiency of the solar cells. Therefore, this study focused on novel laser repair methods to facilitate electroplated metallization, thereby enhancing the power conversion efficiency of the TOPCon solar cells. Initially, the Raman spectrum method was introduced to calculate the crystallinity of the laser ablation area and evaluate the damage to the cell surface caused by laser slotting. Subsequently, a high-temperature annealing treatment was carried out, and the optimum temperature for the annealing repair method was determined based on implied open circuit voltage (iV_oc) detection. The high-temperature annealing process was improved to assist electroplating metallization for repairing laser-damage. Also, XRD detection was introduced to clarify that the repair effect of laser-damage was limited by the generated SiAlON complex. Additionally, a pre-cleaning of HF solution before electroplating was performed to remove oxidation defects. Compared to TOPCon solar cells without laser-damage repair, the power conversion efficiency of N-type TOPCon solar cells treated with electroplating technique increased to 24.85 %, with an increase of 1.44%_abs.