An improved electrical model for accurate and efficient simulation of TOPCon solar cells

In this work, we investigate the current–voltage characteristics of n-type TOPCon solar cells through numerical simulations, with a focus on introducing a novel discretization method, improving the numerical calculation of tunneling probabilities, and analyzing the impact of fixed positive charges within the ultrathin oxide layer on device performance. The numerical results demonstrate that the proposed improved Scharfetter–Gummel method achieves higher computational accuracy and stability in heavily doped regions, effectively reducing errors under low-current conditions. Additionally, the symmetrized transfer matrix method is extended to calculate tunneling probabilities through ultrathin oxide layers, ensuring both high accuracy and computational efficiency in the simulated current density. Furthermore, for thicker oxide layers, without increased recombination, higher fixed positive charge concentrations in the ultrathin oxide layer enhance electron tunneling, directly improving photoelectric conversion efficiency. This research provides theoretical insights and methodological guidance for the precise modeling and optimization of TOPCon solar cells and semiconductor devices, particularly those featuring a relatively high proportion of heavily doped regions and ultrathin tunneling layers.