Abstract: A multijunction solar cell includes an upper first solar subcell having a first band gap, a second solar subcell having a second band gap smaller than the first band gap, and a first graded interlayer composed of (InxGa1-x)yAl1-yAs adjacent to the second solar subcell. The first graded interlayer has a third band gap greater than the second band gap subject to the constraints of having the in-plane lattice parameter greater or equal to that of the second subcell and less than or equal to that of the third subcell, wherein 0<x<1 and 0<y<1, and x and y are selected such that the band gap of the first graded interlayer remains constant throughout its thickness at 1.5 eV. A third solar subcell is adjacent to the first graded interlayer and has a fourth band gap smaller than the second band gap such that the third subcell is lattice mismatched with respect to the second subcell.

Abstract: A multijunction solar cell includes an upper first solar subcell, a second solar subcell adjacent to the first solar subcell, a third solar subcell adjacent to the second solar subcell, and a graded interlayer adjacent to the third solar subcell. The graded interlayer has a band gap that is greater than the band gap of the third solar subcell and is composed of a compositionally step-graded series of (InxGa1-x)yAl1-yAs layers with monotonically changing lattice constant, with x and y having respective values such that the band gap of the graded interlayer remains constant throughout its thickness, and wherein 0<x<1 and 0<y<1. A fourth solar subcell is adjacent to the graded interlayer and is lattice mismatched with respect to the third solar subcell. The graded interlayer provides a transition in lattice constant from the third solar subcell to the fourth solar subcell. A lower fifth solar subcell is adjacent to the fourth solar subcell.

Abstract: A multijunction solar cell includes an upper first solar subcell having a first band gap, a second solar subcell having a second band gap smaller than the first band gap, and a first graded interlayer composed of (InxGa1-x)yAl1-yAs adjacent to the second solar subcell. The first graded interlayer has a third band gap greater than the second band gap subject to the constraints of having the in-plane lattice parameter greater or equal to that of the second subcell and less than or equal to that of the third subcell, wherein 0<x<1 and 0<y<1, and x and y are selected such that the band gap of the first graded interlayer remains constant throughout its thickness at 1.5 eV. A third solar subcell is adjacent to the first graded interlayer and has a fourth band gap smaller than the second band gap such that the third subcell is lattice mismatched with respect to the second subcell.

Abstract: A multijunction solar cell includes an upper first solar subcell, a second solar subcell adjacent to the first solar subcell, a third solar subcell adjacent to the second solar subcell, and a graded interlayer adjacent to the third solar subcell. The graded interlayer has a band gap that is greater than the band gap of the third solar subcell and is composed of a compositionally step-graded series of (InxGa1-x)y Al1-yAs layers with monotonically changing lattice constant, with x and y having respective values such that the band gap of the graded interlayer remains constant throughout its thickness, and wherein 0<x<1 and 0<y<1. A fourth solar subcell is adjacent to the graded interlayer and is lattice mismatched with respect to the third solar subcell. The graded interlayer provides a transition in lattice constant from the third solar subcell to the fourth solar subcell. A lower fifth solar subcell is adjacent to the fourth solar subcell.

Abstract: A multijunction solar cell having at least four solar subcells includes a first solar subcell having a first band gap. A first graded interlayer adjacent to the first solar subcell and has a second band gap greater than the first band gap and that is constant at 1.5 eV throughout the thickness of the first graded interlayer. A second solar subcell is adjacent to the first graded interlayer and has a third band gap smaller than the first band gap of the first solar subcell. The second solar subcell is lattice mismatched with respect to the first solar subcell. A second graded interlayer is adjacent to the second solar subcell and has a fourth band gap greater than the third band gap of the second solar subcell and that is constant at 1.1 eV throughout the thickness of the second graded interlayer. A third solar subcell is adjacent to the second graded interlayer and has a fifth band gap smaller than the third band gap of the second solar subcell.

Abstract: A multijunction solar cell having at least four solar subcells includes a first solar subcell having a first band gap, and a first graded interlayer adjacent to the first solar subcell, wherein the first graded interlayer has a second band gap greater than the first band gap and that is constant at 1.5 eV throughout the thickness of the first graded interlayer. A second solar subcell is adjacent to the first graded interlayer, wherein the second solar subcell has a third band gap smaller than the first band gap of the first solar subcell and wherein said second solar subcell is lattice mismatched with respect to the first solar subcell. A second graded interlayer is adjacent to the second solar subcell, wherein the second graded interlayer has a fourth band gap greater than the third band gap of the second solar subcell and that is constant at 1.1 eV throughout the thickness of the second graded interlayer.

Abstract: A multijunction solar cell including an upper first solar subcell, and the base-emitter junction of the upper first solar subcell being a homojunction; a second solar subcell adjacent to said first solar subcell; a third solar subcell adjacent to said second solar subcell. A first graded interlayer is provided adjacent to said third solar subcell. A fourth solar subcell is provided adjacent to said first graded interlayer, said fourth subcell is lattice mismatched with respect to said third subcell. A second graded interlayer is provided adjacent to said fourth solar subcell; and a lower fifth solar subcell is provided adjacent to said second graded interlayer, said lower fifth subcell is lattice mismatched with respect to said fourth subcell.

Abstract: A multijunction solar cell including an upper first solar subcell, and the base-emitter junction of the upper first solar subcell being a homojunction; a second solar subcell adjacent to said first solar subcell; a third solar subcell adjacent to said second solar subcell. A first graded interlayer is provided adjacent to said third solar subcell. A fourth solar subcell is provided adjacent to said first graded interlayer, said fourth subcell is lattice mismatched with respect to said third subcell. A second graded interlayer is provided adjacent to said fourth solar subcell; and a lower fifth solar subcell is provided adjacent to said second graded interlayer, said lower fifth subcell is lattice mismatched with respect to said fourth subcell.

Abstract: A multijunction solar cell including first and second solar cells on a substrate with an integral bypass diode having an intrinsic layer and operative for passing current when the multijunction solar cell is shaded. In one embodiment, a vertical sequence of solar cells are epitaxially grown on a first portion of the substrate, and the layers of the diode are epitaxially grown on a second portion of the substrate with the layers of the bypass diode being deposited subsequent to the layers of the top solar cell.

Abstract: A method of forming a multijunction solar cell includes providing a substrate, forming a first subcell by depositing a nucleation layer over the substrate and a buffer layer including gallium arsenide (GaAs) over the nucleation layer, forming a middle second subcell having a heterojunction base and emitter disposed over the first subcell and forming first and second tunnel junction layers between the first and second subcells. The first tunnel junction layer includes GaAs over the first subcell and the second tunnel junction layer includes aluminum gallium arsenide (AlGaAs) over the first tunnel junction layer. The method further includes forming a third subcell having a homojunction base and emitter disposed over the middle subcell.

Abstract: A method of making a multijunction solar cell, including first and second solar cells on a substrate with a bypass diode having an intrinsic layer and operative for passing current when the multijunction solar cell is shaded. In one embodiment, a vertical sequence of solar cells are epitaxially grown on a first portion of the substrate, and the layers of the diode are epitaxially grown on a second portion of the substrate with the layers of the bypass diode being deposited subsequent to the layers of the top solar cell.

Abstract: A concentrator photovoltaic solar cell array for terrestrial use for generating electrical power from solar radiation including a multifunction III-V compound semiconductor solar cell with material composition and bandgaps to maximize absorption in the AM1.5 spectral region, and a thickness of one micron or greater so as to be able to produce in excess of 15 watts of DC power with conversion efficiency in excess of 37%. The aggregate surface area of the grid pattern covers approximately 2 to 5% of the top cell.

Abstract: An arrangement including a concentrator lens and a photovoltaic solar cell for terrestrial use for generating electrical power from solar radiation including a multifunction III-V compound semiconductor solar cell with material composition and bandgaps to maximize absorption in the AM1.5 spectral region, and a thickness of one micron or greater so as to be able to produce in excess of 15 watts of DC power with conversion efficiency in excess of 37%. The concentration level of the lens is selected to optimize the efficiency of the solar cell.

Abstract: A method and a multijunction solar device having a high band gap heterojunction middle solar cell are disclosed. In one embodiment, a triple-junction solar device includes bottom, middle, and top cells. The bottom cell has a germanium (Ge) substrate and a buffer layer, wherein the buffer layer is disposed over the Ge substrate. The middle cell contains a heterojunction structure, which further includes an emitter layer and a base layer that are disposed over the bottom cell. The top cell contains an emitter layer and a base layer disposed over the middle cell.

Abstract: A concentrator photovoltaic solar cell array for terrestrial use for generating electrical power from solar radiation including a central support which is rotatable about its central longitudinal axis, a support frame carried by, and rotatable with respect to, the central support about an axis orthogonal to said central longitudinal axis, and a solar array mounted on the support frame. The solar cell array includes a plurality of Fresnel concentrator lenses and multijunction III-V compound semiconductor solar cells each producing in excess of 10 watts of DC power. An actuator is provided for rotating the central support and the support frame so that the solar cell array is maintained substantially orthogonal to the rays of the sun as the sun traverses the sky.

Abstract: A concentrator photovoltaic solar cell array for terrestrial use for generating electrical power from solar radiation including a central support which is rotatable about its central longitudinal axis, a support frame carried by, and rotatable with respect to, the central support about an axis orthogonal to said central longitudinal axis, and a solar array mounted on the support frame. The solar cell array includes a plurality of Fresnel concentrator lenses and multijunction III-V compound semiconductor solar cells each producing in excess of 10 watts of DC power. An actuator is provided for rotating the central support and the support frame so that the solar cell array is maintained substantially orthogonal to the rays of the sun as the sun traverses the sky.

Abstract: A method and a multijunction solar device having a high band gap heterojunction middle solar cell are disclosed. In one embodiment, a triple-junction solar device includes bottom, middle, and top cells. The bottom cell has a germanium (Ge) substrate and a buffer layer, wherein the buffer layer is disposed over the Ge substrate. The middle cell contains a heterojunction structure, which further includes an emitter layer and a base layer that are disposed over the bottom cell. The top cell contains an emitter layer and a base layer disposed over the middle cell.

Abstract: A solar cell having a multijunction solar cell structure with a bypass diode is disclosed. The bypass diode provides a reverse bias protection for the multijunction solar cell structure. In one embodiment, the multifunction solar cell structure includes a substrate, a bottom cell, a middle cell, a top cell, a bypass diode, a lateral conduction layer, and a shunt. The lateral conduction layer is deposited over the top cell. The bypass diode is deposited over the lateral conduction layer. One side of the shunt is connected to the substrate and another side of the shunt is connected to the lateral conduction layer. In another embodiment, the bypass diode contains an i-layer to enhance the diode performance.

Abstract: A solar cell having a multifunction solar cell structure with a bypass diode is disclosed. The bypass diode provides a reverse bias protection for the multijunction solar cell structure. In one embodiment, the multifunction solar cell structure includes a substrate, a bottom cell, a middle cell, a top cell, a bypass diode, a lateral conduction layer, and a shunt. The lateral conduction layer is deposited over the top cell. The bypass diode is deposited over the lateral conduction layer. One side of the shunt is connected to the substrate and another side of the shunt is connected to the lateral conduction layer. In another embodiment, the bypass diode contains an i-layer to enhance the diode performance.

Abstract: A method and a multijunction solar device having a high band gap heterojunction middle solar cell are disclosed. In one embodiment, a triple-junction solar device includes bottom, middle, and top cells. The bottom cell has a germanium (Ge) substrate and a buffer layer, wherein the buffer layer is disposed over the Ge substrate. The middle cell contains a heterojunction structure, which further includes an emitter layer and a base layer that are disposed over the bottom cell. The top cell contains an emitter layer and a base layer disposed over the middle cell.