The effect of luminescence coupling in external quantum efficiency measurement of multi-junction solar cells

In this study, we investigated the effects of bias light on the measurement of the external quantum efficiency (EQE) in multi-junction solar cells. The enhanced bias light incident on the upper layer affected the bottom EQE of the triple-junction solar cell. The artifact EQE was minimized under the specific intensity of the bias light. The photocurrent on the lower subcell increased with the excess intensity of bias light incident on the upper layer. This behavior was confirmed in the present triple-junction solar cell and also in the newly designed cell. The EQE signal the bottom cell region for the simulated monochromatic light decreased with the LED light intensity.