Multiple-bandgap vertical-junction architectures for ultra-efficient concentrator solar cells

A novel multiple-bandgap multi-terminal vertical-junction (side-illumination) architecture for concentrator solar cells is proposed and simulated, wherein each stacked sub-cell operates at its own maximum power point, without the need for tunnel diodes, current matching, lattice matching, metallization grids or spectrum splitting. Practical implementation is limited to indirect bandgap semiconductors (including Si and Ge), with a dramatic reduction in series resistance such that ultra-efficient operation at irradiance levels of thousands of suns appears tenable - rivalling in principle today's best multi-junction III-V cells.