Effect of High Monochromatic Radiation on the Electrical Performance of CIGS Solar Cell

In this article, we investigate the optically induced degradation of Cu(InGa)Se2 (CIGS) solar cells subjected to monochromatic laser irradiation. The devices under test are bifacial CIGS solar cells, fabricated on fluorine-doped SnO2 glass substrates. The electrical properties under dark and illumination conditions were characterized before laser exposure. The analysis of the current-voltage characteristics indicated that defect-assisted carrier transport dominates within the space charge region. Continuous laser exposure at constant optical power caused a decrease in open-circuit voltage (Voc). The study of the dark current-voltage curves highlights a change in the saturation current (IS) and ideality factor (n), whose increment follows a square-root dependence on time. This behavior is attributed to diffusion of Na ions toward the junction. Conversely, the Voc decay (which is correlated with the turn-on voltage decrease in dark I-V curve) is ascribed to a light-induced defect generation that enhances leakage current at the CdS/CIGS interface.