Improved Back Surface Field with Optimized SiO ₂ /Poly‐Si Back Passivation Structure for Tunneling Oxide Passivated Contact Solar Cell

In the realm of photovoltaic technology, the performance of the SiO 2 tunneling layer and the poly‐Si contact layer in tunneling oxide passivated contact (TOPCon) solar cells is paramount to enhancing solar cell efficiency. In this article, the numerical simulation tool AFORS‐HET has been utilized to establish a model of the back contact structure for TOPCon solar cells, illuminating the impact of SiO 2 layer thickness, poly‐Si layer thickness, and doping concentration on TOPCon cell performance. The simulation results reveal optimal performance within the ranges of 0.8–1.4 nm for SiO 2 thickness, 80–120 nm for poly‐Si thickness, and 1 × 10 19 –1 × 10 21 atom cm 3 for doping concentration. The advantages of obtaining an open‐circuit voltage of ≈20 mV and a short‐circuit current density of 0.2 mA cm 2 are achieved. Based on these simulation results, the SiO 2 and poly‐Si layers are prepared at a 30 MW TOPCon cell production line. When the SiO 2 thickness, poly‐Si thickness, and doping concentration are 1.2 nm, 110 nm, and 5 × 10 20 atom cm 3 , respectively, the SiO 2 /poly‐Si back passivation structure achieves significant optimization. The recombination current density of 7.8 fA cm 2 and the contact resistivity of 3.2 mΩ cm 2 indicate excellent passivation quality and carrier transport efficiency.