Improved ac square wave-based mitigation technique for III-V/Si Bi-facial tandem solar cells under stress caused by light and elevated temperature induced degradation

This study explores Light and Elevated Temperature-Induced Degradation (LeTID) and tandem degradation in III-V/Si tandem solar cells under low-intensity illumination (0.1, 0.3, 0.5 suns) and high-temperature (85°C) conditions, emphasizing the role of ac recovery techniques. We analyzed a two-terminal III-V/Si tandem configuration, where low-intensity exposure resulted in significant degradation on bottom c-Si solar cells, reducing the current density (J_sc) by up to 8 %–5 % after 660 min. A 100 kHz square ac waveform was applied to counter this degradation, which improved activation energy from 0.43 eV during degradation to 0.60 eV after treatment. The regeneration process enhanced carrier passivation, improving J_sc, Open circuit voltage (V_oc), and Fill Factor (FF) with efficiency (Eff), recovering up to 97 % within 120 min. Initially, activation energy was 0.83 eV, which decreased to 0.43 eV during degradation and partially recovered with ac treatment. This work highlights the effectiveness of ac recovery in mitigating degradation and enhancing the performance of III-V/Si tandem solar cells.