LeTID Mitigation by Electrical Injection Regeneration of Cz-Si and mc-Si BSF Silicon Solar Cells

Abstract

In this investigation, we provide further insight into the kinetics of light- and elevated-temperature-induced degradation (LeTID) by examining the impact of electrical injection regeneration on the development and subsequent mitigation of LeTID in boron-doped Czochralski silicon (Cz-Si) and multi-crystalline silicon (mc-Si) back-surface-field (BSF) solar cells. Electrical injection regeneration was applied to both Cz-Si and mc-Si solar cells with an injection current of 3 A at varying temperatures (180–200°C) for 20 min. The LeTID cycle was conducted at 75°C with an illumination intensity of 750 W/m2. A solar simulator was used to measure the current–voltage (I–V) characteristics of the cells. Our findings indicate that the LeTID regeneration process is influenced by both carrier injection and temperature. Notably, cells regenerated with an injection current of 3 A at 180°C for 20 min exhibited a reduction in degradation after extended light exposure under LeTID conditions. Specifically, mc-Si solar cells showed an efficiency degradation decrease of up to 3%, while Cz-Si cells displayed a similar reduction, compared to their initial values. These results highlight the enhanced anti-LeTID effects achieved through the regeneration process. Additionally, our study reveals that hydrogen and oxygen play roles in the formation and neutralization of defects associated with metallic impurities, distinct from boron-related defects. This insight contributes to understanding the complex mechanisms affecting the performance of these solar cells under various conditions.