Analysis of the radiation hardness of triple- and quintuple- junction space solar cells

The Fraunhofer ISE has developed a characterization tool called spectrometric characterization. In this paper we discuss that this tool is extremely powerful to characterize triple-junction (3J) EOL cells. The current-mismatch of the subcells can be determined and the performance for current-matched subcells can be predicted. Additionally, lattice-matched AlGaInP/GaInP/AlGaInAs/GaInAs/Ge quintuple-junction (5J) cells are being developed at Fraunhofer ISE as a possible next-generation of space solar cells. This material combination aims at the same BOL efficiency as state-of-the-art 3J cells but higher EOL efficiency. Based on spectral response measurements it will be demonstrated that the 5J cells do in fact show a higher radiation hardness compared to the 3J cell.