Heterojunction V-groove multijunction solar cell
AssigneeInternational Business Machines Corporation
InventorsTerry I. Chappell, Jerry M. Woodall
Life of this patent
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Abstract
A solar cell is disclosed with V-grooves which are series connected, but electrically isolated, indirect bandgap solar cells which are responsive to different light frequencies on both sides of a semi-insulating optically transparent substrate. The device has a very high conversion efficiency of approximately 40% and high open-circuit voltage and low series resistance. An exemplary structure in accordance with this disclosure has a series of silicon V-groove cells on one side and another series of GaAlAs V-groove cells on the other side. The cells are of generally trapezoidal cross-section. The difference between the characteristics of the Si cell and the GaAlAs cell is matched by control of the number of V-grooves.
Claims17
A solar energy converter comprising:
- a first solar cell comprising first multiple p-n heterojunctions in association with a first type of optically active semiconductor material on one side of an insulating substrate;
- and
- a second solar cell comprising second multiple p-n heterojunctions in association with a second type of optically active semiconductor material on the opposite side of the insulating substrate;
- said first type of semiconductor material is GaAlAs, said second type of semiconductor material is Si, and said insulating substrate is semi-insulating GaP.
A solar energy converter comprising:
- a first solar cell comprising first multiple p-n heterojunctions in association with a first type of optically active semiconductor material A on one side of an insulating substrate;
- and
- a second solar cell comprising second multiple p-n heterojunctions in association with a second type of optically active semiconductor material B on the opposite side of the insulating substrate;
- wherein said material A has an indirect bandgap and carrier lifetime limited by Auger recombination,
- one side of A has a heterojunction with a material A.sub.n ' which is doped to n+ type conductivity, has a larger bandgap than A, and is lattice matched to A,
- the other side of A has a heterojunction with a material A.sub.p ' doped to p-type conductivity, and has a larger bandgap than A, and is lattice matched to A;
- wherein said insulating substrate comprises an insulation layer adjacent to A.sub.p ' whose bandgap is greater than or equal to the bandgap of said A material and whose interfaces between said first and second cells are atomically compatible;
- and wherein said material B has an indirect bandgap less than material A and carrier lifetime limited by Auger recombination,
- one side of B has a heterojunction with a material B.sub.n ' doped to n-type conductivity and lattice matched with B, and
- the other side of B has a heterojunction with a material B.sub.p ' doped to p-type conductivity and lattice matched with B.
A solar energy converter comprising:
- a region of a first semiconductor material, which is responsive to light of a first frequency, having indirect bandgap and being carrier lifetime limited by Auger recombination, and having a first quantity of p-n heterojunctions with semiconductor material which has a larger bandgap than said first material and is lattice matched thereto.
- a region of a second semiconductor material, which is responsive to light of a second frequency, having indirect bandgap and being carrier lifetime limited by Auger combination and having a second quantity of p-n heterojunctions with a semiconductor material which has a larger bandgap than said second material and is lattice matched thereto,
- said first quantity of junctions and second quantity of junctions being operable to provide comparable electrical characteristics from the p-n heterojunctions in said first and said second semiconductor materials,
- said first and second regions being conterminous with and separated by a substrate having
- electrical isolation properties and
- being optically transparent at least to light of said second frequency.
A solar energy converter having a
- first material A having indirect bandgap and carrier lifetime limited by Auger recombination,
- one side of A has a heterojunction with a material A.sub.n ' which is doped to n+ type conductivity, has a larger bandgap than A, and is lattice matched to A,
- the other side of A has a heterojunction with a material A.sub.p ' which is doped to p-type conductivity, has a larger bandgap than A, and is lattice matched to A.
A solar energy converter having
- a semiconductor material A with indirect bandgap and carrier lifetime limited by Auger recombination,
- one side of A has a heterojunction with semiconductor material A.sub.n doped to n-type conductivity and another side of A has a heterojunction with a semiconductor material A.sub.p which is doped to p-type conductivity,
- said material A.sub.n and said material A.sub.p having a larger bandgap than said material A.
Dependencies are inferred from the claim text.