Photovoltaic cells on lattice-mismatched crystal substrates

A photovoltaic cell comprising a substrate composed of crystal material having a structure belonging to the cubic crystal system, said substrate having on one surface thereof an ordered plurality of curved-surface regions, at least one component photovoltaic cell which incorporates crystal material also having a structure belonging to the cubic crystal system, said crystal material which said at least one component photovoltaic cell incorporates having a lattice constant different in magnitude from the lattice constant of the crystal material of which said substrate is composed, and a layer of crystal material having a structure belonging to the cubic crystal system disposed between said one substrate surface and said at least one component photovoltaic cell, said crystal material of which said layer is composed having a lattice constant which is graded in magnitude from an initial compatible value on the side of said layer which is proximate to said one substrate surface to a final compatible value different from said initial compatible value on the side of said layer which is proximate to said at least one component photovoltaic cell.

An array of monolithic multijunction photovoltaic cells comprising a plurality of monolithic multijunction photovoltaic cells each of which has first and second faces and each of which has first and second component photovoltaic cells responsive to a respective one of first and second ranges of radiation wavelengths;

• and means for dividing incident radiation into first radiation with wavelengths in the first range of radiation wavelengths and second radiation with wavelengths in the second range of radiation wavelengths, directing the first radiation to the first faces, and directing the second radiation to the second faces.