Absolute electroluminescence characteristics of triple-junction solar cells with 35.5% efficiency

We report a world-class high-efficiency flexible GaInP/GaAs/InGaAs triple-junction solar cell achieving a certified AM1.5G efficiency of 35.5% with an area of1 cm2, along with its key fabrication conditions and electrical characteristics. Absolute electroluminescence (EL) characterizations were employed to visualize the variation of external radiative efficiencies and the spatial emission profiles of the sub-cells with various injection current densities, while the photovoltaic reciprocity relation was applied to extract their intrinsic electrical parameters. The open-circuit voltages of the GaInP, GaAs, and InGaAs sub-cells were determined to be 1.444, 1.004, and 0.480 V, corresponding to sub-cell efficiencies of 18.3%, 12.4%, and 5.3%, respectively. Furthermore, absolute EL imaging combined with three-dimensional distributed equivalent circuit modeling, incorporating a two-diode, was employed to elucidate how an increase in the local non-uniformity of J01 in the middle sub-cell impacts the electrical parameters, thereby providing critical guidance for future device optimization. The model further predicts that enhancing sub-cell uniformity could increase the overall conversion efficiency from 35.5% to 37.9% under ideal processing conditions.