Mitigating LeTID-Induced performance loss through high-frequency AC carrier injection: Architecture-dependent recovery trends in crystalline silicon solar cells

Light- and Elevated Temperature-Induced Degradation (LeTID) is a major reliability concern in crystalline silicon (c-Si) solar cells, especially those incorporating hydrogen-rich passivation layers. This study investigates and compares the degradation and recovery behavior of PERC, TOPCon, and HJT cells under 1-sun illumination at 85 °C. PERC cells showed the highest degradation, with a 16.6 % η loss due to hydrogen-induced formation of Fe–H and BO–H complexes. TOPCon cells experienced a 12.5 % decline, attributed to defect accumulation at the tunnel oxide and poly-Si interface. In contrast, HJT cells exhibited only a 6.3 % reduction, as hydrogen remained confined within the amorphous silicon layer. High-frequency AC carrier injection at 100  kHz was applied to promote electrical recovery. The regenerated efficiencies reached 93.1 % in PERC, 94.7 % in TOPCon, and 99.8 % in HJT cells. Recovery was driven by recombination-enhanced defect reactions that dissociate hydrogen-related defect complexes and enable re-passivation of recombination centers. This comparative analysis reveals that hydrogen dynamics, passivation stability, and defect activation pathways determine both degradation severity and recovery efficiency. The results validate AC carrier injection as an effective and architecture-adaptive strategy for mitigating LeTID and enhancing the long-term performance of c-Si photovoltaics.