Laser‐enhanced contact optimization on<i>i</i>TOPCon solar cells
Tobias Fellmeth, Hannes Höffler, Sebastian Mack, Eve Krassowski, Katrin Krieg, Bishal Kafle, Johannes Greulich
Abstract
Abstract The authors present their work on laser‐enhanced contact optimization (LECO) on i TOPCon solar cells. LECO improves the metal‐semi‐conductor contact resistivity ρ c on the boron emitter and the n‐TOPCon side from an underfired (thermal budget too low) state of 2.9 and 14.1 mΩcm 2 to an enhanced state of 1.8 and 2.9 mΩcm 2 . Therefore, it enables the reduction of the optimal peak firing temperature, which leads to a decrease of metal induced recombination mainly on the boron emitter side and to minor degree on the n‐TOPCon side, as shown in this work. Ultimately, LECO improves i TOPCon solar cells conversion efficiency by 0.6% abs compared with the optimal fired, untreated reference. Submitting those cells to 140°C and 2 suns equivalent irradiation for more than 4 h shows no impact on the conversion efficiency or any sign of light and elevated temperature‐induced degradation (LeTID). Confirmed by ISE CalLab, LECO improved i TOPCon solar cells reach 23.8% and 24.1% conversion efficiency on industrial typical wafer formats and processes.