Duration: 24 months
The desire to undertake long space missions to reach more distant destinations has always been an important goal in the space community, requiring solar cells with high end of life (EOL) performances and enhanced lifetime. Also, weight reduction and material-efficient cells reaching such high extended EOL performances become more and more important to decrease the need for the critical material Ge and allow for more sustainability. Today’s product for most satellites is a Ge-based 3-junction solar cell. It has been an efficient technology, but it is gradually reaching its limits and new concepts are required to reduce weight and environmental impact, and to extend the lifetime. This is the reason why ESA proposed a challenge to reach 33% EOL efficiency. To do so, it is especially necessary to increase the radiation hardness of the limiting GaAs cells, i.e., reducing its thickness without reducing its current production. Thus, the objective of this project is the realization of an innovative selective photonic rear side mirror for a GaInP/GaAs 2-junction solar cell that scatters the light within the GaAs to allow for a thinner subcell. In the case of success, the newly developed structuring process will enable revolutionary solar cells, that within EQE and reflectance measurements of example solar cells prove the feasibility of the concept. In future steps we expect a potentially ultralight and radiation hard cell with EOL efficiency above 30% for a dual-junction and 33% for a multi-junction solar cell. This solar cell can be of great interest for long-range missions, but also can compete with the standard space product (3j on Ge) due to a massively higher power-to-mass ratio not relying on a Ge substrate
