The effect of luminescent coupling on modulated photocurrent measurements in multijunction solar cells.

Luminescent coupling in multijunction solar cells has a major impact on device response, and its impact on current-voltage and quantum efficiency measurements is well established. However, the role of luminescent coupling in more advanced characterization techniques such as modulated photocurrent spectroscopy is virtually unknown. Here we present measurements of the frequency-dependent photocurrent of a triple junction solar cell with significant coupling between adjacent junctions. We develop an equivalent circuit model that includes luminescent coupling which shows good agreement with the measured frequency response. The model also shows how the system response can elucidate the type of charge carrier recombination in these III-V semiconductor materials.