Enabling savings in silver consumption and poly-Si thickness by integration of plated Ni/Cu/Ag contacts for bifacial TOPCon solar cells

Plated Ni/Cu/Ag contacts offer the possibility to significantly reduce silver consumption for tunnel oxide passivated contact (TOPCon) solar cells. This work demonstrates industrial bifacial TOPCon solar cells with plated Ni/Cu/Ag metallization achieving champion solar cell efficiencies of up to 24.0%. The influence of reduced poly-Si thickness down to 60 nm of the TOPCon rear side on the open circuit voltage (Voc) is analysed and the impact of laser-induced damage during laser contact opening (LCO) is characterized. Furthermore, mitigation strategies to systematic fill factor losses are developed including laser-induced nano-roughness within the LCO to increase contact adhesion and current-annealing to improve contact resistance.