A comparative study of subcell optoelectronic properties and energy losses in multijunction solar cells

External luminescence quantum yields of subcells within several multijunction solar cells were measured using a calibrated hyperspectral imaging system in absolute electroluminescence mode. The measurements allowed direct comparison of subcell device parameters using the electro-optical reciprocity relationship. In particular, differences in the open circuit voltages or even the shape of the current vs voltage curves under air mass 0 illumination among similar subcells can be correlated with the variations in luminescence yields. One important finding of this work is that electroluminescence measurements can help inform solar cell electrical models such as the two-diode model in terms of better parameter selection. We compare energy losses among the different subcells and discuss how the differences in various loss terms affect the overall device performance. Some strategies to improve the overall solar cell device performance are further discussed as a result of this comparative study.

Automated summary

This study measured the external luminescence quantum yields of subcells within multijunction solar cells and utilized the measurements to optimize the electrical models of the cells. The findings showed that electroluminescence measurements can aid in parameter selection and suggested strategies for improving solar cell performance.