Annealing‐Induced Interface Passivation in n‐TOPCon Silicon Solar Cells for High‐Efficiency 4T Perovskite/Si Tandems

This study investigates annealing‐induced interface passivation in n‐type tunnel oxide passivated contact (n‐TOPCon) silicon solar cells to improve the efficiency and short‐term operational stability of albedo‐driven four‐terminal (4T) perovskite/Si tandem devices. Interfacial recombination and contact degradation in the TOPCon rear subcell limit device reliability and performance. To address this issue, a controlled dark annealing strategy is applied to recover and stabilize the rear junction while reducing recombination losses. A systematic temperature–time matrix (200°C–300°C, 5–30 min) is implemented, followed by dark current–voltage ( I – V ), external quantum efficiency (EQE), and tandem performance characterization under albedo illumination. Optimized annealing at 300°C enhances device metrics, increasing the open‐circuit voltage from 664 to 669 mV, short‐circuit current density from 39.82 to 40.78 mA cm −2 , fill factor from 71.56% to 74.16%, and power conversion efficiency from 18.92% to 20.23%. Two‐diode model analysis confirms reduced defect‐assisted recombination through a significant decrease in the recombination current component. The EQE remains above 90% in the long‐wavelength region, indicating improved carrier collection. In the 4T configuration, the tandem achieves 26.75% efficiency under 1.3‐sun illumination. Short‐term testing over 96 h demonstrates improved stability after annealing.