Multi Junction Solar cells for Satellite

Higher efficiency solar cells are needed to reduce mass, volume, and cost of DoD space missions. However, to achieve higher efficiency and radiation hardness of the best to date multi-junction photovoltaic (PV) devices, several challenges must be addressed. This project aims to develop: 1) Quantum Well (QW)-based multi-junction cell that exhibits enhanced efficiency, and 2) Radiation-hardened PV cell design demonstrating the radiation tolerance of the QW multi-junction cell. Customized modeling tools will enable QW optimization, including: (a) geometrical ordering and variable QW size, (b) increased transport and separation of photogenerated carriers; and (c) improved electrical conductivity and enhanced collection efficiency. In Phase I, CFDRC, together with Rochester Institute of Technology, will concentrate on the design and demonstration of the middle cell in a multi-junction (InGaP/GaAs/Ge) configuration, the most sensitive to radiation effects. The design and implementation of QWs in this middle cell will be directly applicable to a state-of-the-art lattice-matched cell and a metamorphic cell. We will fabricate a prototype QW cell and perform baseline irradiation testing/evaluation. Phase II will continue development by implementing the QW response and radiation resistance within a multi-junction cell, resulting in significantly improved QW solar cell performance under AM0 spectrum and post-irradiation at the end of life.