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 (V_oc). The study of the dark current–voltage curves highlights a change in the saturation current (I_S) 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 V_oc 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.