24.18% efficiency TOPCon solar cells enabled by super hydrophilic carbon-doped polysilicon films combined with plated metal fingers

Electroplating technology which has the potential of reducing silver consumption and lowering fabrication costs has been widely used in the photovoltaic (PV) devices. However, the poor wettability of the polysilicon film limits the application of the electroplating technology on tunnel oxide passivated contact (TOPCon) solar cells (SCs). In this work, we propose a carbon (C)-doped polysilicon with highly polar C–Si bonds to improve the surface wettability of polysilicon film. By reducing the hydrogen bubble retention during plating, a uniform, dense, and void-free Ni seed layer can be obtained. To maintain the good conductivity of polysilicon, a double-layer polysilicon structure consisting of a C-doped and a C-free polysilicon films was constructed for TOPCon device fabrication. The new design shows an excellent passivation quality with an implied open-circuit voltage (iVoc) of 745 mV for the lifetime sample and a good contact performance with a low contact resistivity (ρc) of 2–3 mΩ cm2 between plated grids and polysilicon films. Finally, the proof-of-concept TOPCon devices with the double-layer polysilicon structure and plated metal electrodes deliver a remarkable power conversion efficiency (PCE) of 24.18%. Therefore, the C-doped polysilicon combined with the electroplating technology demonstrated in this work shows great potential to obtain high-efficiency and low-cost TOPCon SCs in the PV industry.