Light-induced Degradation in Cz Silicon Solar Cells: Fundamental Understanding and Strategies for Its Avoidance

Solar cells manufactured on boron-doped Czochralski-grown silicon (Cz-Si) degrade in performance when exposed to light or minority carriers are injected in the dark until a stable efficiency is reached. This effect, which is now known for almost 30 years, is due to the activation of a specific metastable defect in the Cz-Si material. Although a conclusive explanation of the effect is still to be found, recent investigations have clearly revealed that the Cz-specific defect is correlated with the boron and the oxygen concentration in the material. The first part of this paper reviews the current status of the physical understanding of the effect and gives an overview of the defect models proposed in the literature. In the second part, an overview of different strategies for avoiding or reducing the light-induced degradation in Cz-Si solar cells is presented.