The progress of large area GaInP2/GaAs/Ge triple junction cell development at Spectrolab

In this paper we report the successful fabrication of large area, monolithic triple junction, n on p, GaInP2/GaAs/Ge cells. The highest open circuit voltage and cell efficiency (cell area: 4.078 sq cm) were measured at 2.573 V and 23.3%, respectively, under 1 sun, AMO illumination. To our knowledge, this is the highest single crystal, monolithic, two terminal triple junction cell efficiency demonstrated. In addition, excellent uniformity across a 3 inch diameter Ge substrates has also been achieved. An average cell efficiency of 22.8% across the 3 inch diameter wafer has been measured. We have also successfully fabricated welded cell-interconnect-cover (CIC) assemblies using these triple junction devices. The highest CIC efficiency was 23.2% (bare cell efficiency was 23.3%). The average efficiency for 25 CICs was 21.8%, which is very comparable to the 22.0% average bare cell efficiency before they were fabricated into the CICs. Finally, we have measured temperature coefficient and 1 MeV electron irradiation data. These will be presented in the paper.