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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.

Electroluminescence (EL) images with absolute photon emissions from Cu(In, Ga)Se 2 (CIGS) solar cells were obtained under different forward current injections, with the spatially distributed EL emission becoming non-uniform as the current density gradually increases. A distributed two-diode electrical three-dimensional model was established which simulated the dark current density-voltage curves and the absolute EL images of the CIGS solar cells very well. Then, the resistive effects were analyzed using this model and simulation results show that the sheet resistance of the transparent conductive oxide (TCO) layer dominates the non-uniform distribution of the EL emission in the studied CIGS thin-film solar cells. The effect of the sheet resistance of the TCO and the series resistance of the micro-diode on the EL variations is found to become obvious under high-current-injection conditions, whereas the effect of shunt resistance of the micro-diode on the EL variations becomes more obvious under low-resistance value or low-current-injection conditions.

The cover image is based on the Research Article Absolute electroluminescence imaging with distributed circuit modeling: Excellent for solar‐cell defect diagnosis by Jianyu Hong at al., https://doi.org/10.1002/pip.3236.