Ultra-lightweight and flexible inverted metamorphic four junction solar cells for space applications
Malte Klitzke, Jonas Schön, Rosalinda H. van Leest, G.M.M.W. Bissels, Elias Vlieg, Michael Schachtner, Frank Dimroth, David Lackner
Abstract
In this work an inverted metamorphic four junction (IMM4J) solar cell with 30.9% conversion efficiency in beginning of life conditions under the AM0 (1367 W/m 2 ) spectrum is presented. Additionally, our newest improved IMM3J cell, consisting of Ga 0.51 In 0.49 P/GaAs/Ga 0.73 In 0.27 As subcells, with 30.6% efficiency is also shown. The IMM4J solar cells consist of Al 0.05 Ga 0.46 In 0.49 P/Al 0.14 Ga 0.86 As/Ga 0.89 In 0.11 As/Ga 0.73 In 0.27 As subcells and are epitaxially grown by metal organic vapor phase epitaxy (MOVPE) on a GaAs substrate. These IMM solar cells achieve power-to-mass ratios of 3 W/g or more, which is more than three times higher than standard germanium based triple or four junction space solar cells. The losses in comparison to the simulated near-term potential efficiency of 33.8% for the IMM4J are analyzed in detail. Furthermore, the irradiation behavior for 1 MeV electron fluences of 1 × 10 14 e − /cm 2 and 2.5 × 10 14 e − /cm 2 for the IMM4J cells was investigated. A roadmap to further develop this concept towards an IMM5J with a realistic begin of life (BOL) efficiency potential of 35.9% under AM0 is presented.