High-speed quantum efficiency determination of multijunction solar cells

This paper introduces an innovative and fast method to determine the external quantum efficiency (EQE). The setup was specifically designed to measure monolithic multijunction solar cells. Multijunction solar cells consist of two or more subcells exhibiting different spectral characteristics. Their spectral selective sensitivity, however, is challenging for a calibration process. The bias illumination has to be adjusted in order to achieve current limitation by the subcell under test. Therefore, an arbitrary fast tunable bias light source was integrated into the setup. This allows for the characterization of multijunction solar cells in the order of seconds compared with minutes to hours with the state-of-the-art measurement equipment. First high-speed measurement results of multijunction solar cells are directly compared with measurements using the state-of-the-art technique. The standard deviation between the both measurements is less than 1.9%, thus in the range of the general uncertainty of an EQE measurement.