Absolute electroluminescence imaging with distributed circuit modeling: Excellent for solar-cell defect diagnosis

Spatially resolved absolute electroluminescence (EL) imaging demonstrates the localized EL intensity and the uniformity of solar cells. Combined with two-dimensional (2-D) distributed circuit network modeling, detailed and important information that is contained in experimental data can be extracted for in-depth understanding of solar cell performances. Herein, we measured the absolute EL images of three different solar cells (Si, GaAs, and Cu (In,Ga)Se₂ (CIGS)) and observed the different injection-current-dependent EL intensities of the defect points (dark or bright) on the solar cells. The origins of these defects were attributed to different defect types according to our established 2-D distributed equivalent circuit model. The results demonstrated that the combination of absolute EL imaging and distributed circuit modeling yielded accurate quantitative diagnoses of the electrical defects in solar cells.