Under CopyrightLopez, E.E.LopezHöhn, OliverOliverHöhnSchauerte, MeikeMeikeSchauerteLackner, DavidDavidLacknerSchachtner, MichaelMichaelSchachtnerReichmuth, Kasimir S.Kasimir S.ReichmuthHelmers, HenningHenningHelmers2022-03-143.8.20212021https://publica.fraunhofer.de/handle/publica/41169410.24406/publica-fhg-411694In this work the coupling process efficiency in three-junction photonic power converters based on GaAs/AlGaAs rear-heterojunction subcells is experimentally quantified. A coupling process efficiency of 32 % ± 9 % from top and middle subcells to the limiting bottom subcell is found. Furthermore, it is shown experimentally how a back reflector affects luminescence coupling in multi-junction photonic power converters by re-directing photons that are emitted by the bottom subcell towards the upper subcells.enPhotovoltaikmultijunctionphotonic powerPhotovoltaikIII-V- und Konzentrator-PhotovoltaikIII-V Epitaxie und SolarzellenPower-by-Light621697conference paper