Higher-Efficiency TOPCon Solar Cells in Mass Production Enabled by Laser-Assisted Firing: Advanced Loss Analysis and Near-Term Efficiency Potential

The tunnel oxide passivated contact (TOPCon) solar cell is predicted to dominate the photovoltaic market from the year 2024. The TOPCon efficiency is steadily increasing both in the lab and high-volume production. A notable new manufacturing technology, laser-assisted firing, has been shown to enhance the power conversion efficiency (PCE) of TOPCon solar cells. This enhanced contact firing technique includes a traditional co-firing step, followed by a laser scanning process in conjunction with an applied reverse bias. In this work, we utilize the Jolywood Special Injected Metallization (JSIM), a laser-assisted firing process developed by Jolywood that is already used in high-volume production. The performance of cells from the JSIM process was evaluated by comparing them to the cells fabricated using the baseline (BL) single-step firing process. The JSIM solar cells exhibited a notably higher PCE, approximately 0.58%_abs greater, compared with the BL cells. Detailed characterization demonstrated that the front (~280 fA/cm²) and rear (~98 fA/cm²) contact recombination of baseline (BL) cells are higher than those of JSIM cells (~88 fA/cm² and ~21 fA/cm², respectively), which is also the main advantages of the JSIM technology. Quokka 3 simulations were utilized to quantify the impact of the various improvements on the final solar cell performance. With the utilization of JSIM technology, contact recombination is no longer the primary source of power loss across the cell. Finally, the simulated results illustrated that the PCE of industrial JSIM cells could further be enhanced by ~0.3%_abs through optimizing the front screen pattern. This work clearly demonstrates the feasibility of laser-assisted firing in high-volume production, enabling significantly higher efficiency TOPCon solar cells by significantly reducing silicon-metal recombination. Consequently, laser-assisted firing increases the practical efficiency limit of TOPCon solar cells, bringing them close to levels that were previously only envisioned for heterojunction silicon solar cells.