Stability Enhancement of Crystalline Silicon Solar Cells Through Electrical Bias Induced Recovery of LeTID

LeTID presents a critical reliability issue in industrial c-Si PERC solar cells, especially under prolonged thermal and illumination stress. This study explores the application of DC electrical biasing as an external regeneration technique to mitigate LeTID effects in PERC cells. Cells were deliberately degraded under 1-sun illumination at three elevated temperatures: 75°C, 85°C, and 100°C for 11 hours, simulating accelerated aging conditions relevant to field operation. Temperature-dependent degradation was evident, with the most pronounced losses observed at 100°C, where normalized J _sc , V _oc , FF, and PCE values declined to 0.8933, 0.8886, 0.8851, and 0.8822, respectively. The series resistance increased significantly from 1.97 to 183 Ω·cm², indicating increased recombination activity due to bulk defect formation. Forward and reverse DC biasing were applied to the degraded cells to facilitate recovery. Forward biasing exhibited superior regeneration capability, restoring the initial efficiency up to 99.94% within 7 hours, compared to 99.64% in 9 hours for reverse biasing. EQE at 900 nm improved from ~ 72% (degraded) to ~ 89% (recovered), confirming the effective passivation of LeTID-induced defects. These results demonstrate that forward DC biasing is a promising, scalable approach for electrical recovery of LeTID-affected PERC cells, offering a potential post-process strategy to enhance long-term photovoltaic stability and performance.