Development of XTJ Targeted Environment (XTE) Solar Cells for Specific Space Applications

An advanced version of the XTJ family of space solar cells called XTJ Targeted Environment (XTE) is being developed at Spectrolab. The XTE cell consists of four specifically designed product variants: standard radiation fluence (SF) for GEO missions, low radiation fluence (LF) for LEO missions, high radiation fluence (HF) for orbit transfer or MEO missions, and LILT for low intensity, low temperature outer planetary environments. The XTE SF and XTE LF variants have demonstrated an average AM0 efficiencies of 32.2% and 32.6% in multiple engineering confidence cell builds. The XTE LILT cells have also achieved an average BOL efficiency of 36.6% under AM0 5.5 AU, $- 140 ^{circ}\mathrm{C}$, 4.5 mW/cm$^{2}$ Jupiter conditions in an engineering confidence cell build. Three (SF, LF, and LILT) of the four XTE cell variants completed engineering confidence tests and are underway to complete AIAA-S-111 qualification.