Electrodeposition of Metal Matrix Composites and Materials Characterization for Thin-Film Solar Cells

Metal matrix composites, which consist of silver-multiwalled carbon nanotube-silver, layer-by-layer stacks, can electrically bridge the cracks (>40 μm) that appear in semiconductor substrates and the composite grid lines.

Air Force Research Laboratory, Kirtland Air Force Base, New Mexico

The current trend in both space and terrestrial photovoltaics is to implement high-efficiency, thin-film-based solar cells to reduce weight and materials cost while improving performance. For space photovoltaics, multi-junction (MJ) solar cells have been used almost exclusively due to their high efficiency and high radiation hardness. The efficiency of state-of-practice triple-junction (TJ) cells used in space today is approximately 30% under 1-sun Air Mass 0 (AM0) spectrum.

Multijunction technology involves stacking different bandgap subcells electrically and optically in series, connected by tunnel junctions, to effectively capture and utilize the solar spectrum. State-of-practice TJ cells consist of GaInP2 and (In)GaAs subcells grown lattice-matched via metal organic vapor phase epitaxy on an active Ge substrate.