Increasing Transferability between Design and Epitaxial Growth of Multi-Junction Solar Cells

In this work we report on a procedure to increase the reproducibility of multi-junction solar cell growth. This is achieved by applying a systematic offset to room-temperature photoluminescence measurement to match the required band gap for obtaining current match as simulated by optical modelling. We found that the difference in band gap extracted from photoluminescence and external quantum efficiency respectively is systematic and depends on the material system under investigation. With the help of this procedure, we modelled and built a 4-junction solar cell that reaches a power conversion efficiency of 43.6 % under the AM1.5d solar spectrum that was 710-fold concentrated.