ScholarWorks@성균관대학교

초록

This study investigates recovery from light- and elevated-temperature-induced degradation (LeTID) in laboratory-fabricated silicon heterojunction (HJT) solar cells using direct-current (DC) electrical bias. The HJT cells were exposed to 1 sun illumination at 85 °C for 15 h, resulting in a measurable performance loss. After stress treatment, the normalized device parameter decreased to 0.9527, the series resistance increased to approximately 0.9 Ω cm2, and the external quantum efficiency (EQE) response decreased, especially in the long-wavelength region. Electrical recovery was then performed under forward and reverse DC bias at a fixed injection current of 0.5 A and applied bias voltages of 0.76, 1.43, and 2.00 V. Forward bias produced faster and more complete recovery than reverse bias. At 2.00 V, the normalized parameter recovered to 0.9998 within 7 h, whereas reverse bias required up to 9 h to reach a comparable but slightly lower recovery level. The series resistance decreased to approximately 0.5 Ω cm2 after recovery. Dark current–voltage analysis showed reduced leakage and recombination current after electrical recovery, while EQE measurements confirmed strong spectral restoration, particularly in the 800–1100 nm region. This long-wavelength recovery suggests reduced bulk-related recombination after bias treatment. Since hydrogen redistribution was not directly measured, the proposed hydrogen-related defect mechanism is interpreted from the electrical and spectral responses. The results suggest that forward DC bias supports carrier-injection-assisted neutralization or re-passivation of recombination-active defect states. These findings show that voltage-optimized forward DC bias is an effective approach for recovering LeTID-induced performance loss in HJT solar cells and may support improved long-term stability in photovoltaic applications.

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