Nanostructure array optoelectronic devices are disclosed. The optoelectronic device may have one or more intermediate electrical contacts that are physically and electrically connected to sidewalls of the array of nanostructures. The contacts may allow different photo-active regions of the optoelectronic device to be independently controlled. For example, one color light may be emitted or detected independently of another using the same group of one or more nanostructures. The optoelectronic device may be a pixilated device that may serve as an LED display or imaging sensor. The pixilated device may have an array of nanostructures with alternating rows and columns of sidewall electrical contacts at different layers. A pixel may be formed at the intersection of a row contact and a column contact. As one example, a single group of one or more nanostructures has a blue sub-pixel, a green sub-pixel, and a red sub-pixel.

Nanostructure array optoelectronic devices are disclosed. The optoelectronic device may have one or more intermediate electrical contacts that are physically and electrically connected to sidewalls of the array of nanostructures. The contacts may allow different photo-active regions of the optoelectronic device to be independently controlled. For example, one color light may be emitted or detected independently of another using the same group of one or more nanostructures. The optoelectronic device may be a pixilated device that may serve as an LED display or imaging sensor. The pixilated device may have an array of nanostructures with alternating rows and columns of sidewall electrical contacts at different layers. A pixel may be formed at the intersection of a row contact and a column contact. As one example, a single group of one or more nanostructures has a blue sub-pixel, a green sub-pixel, and a red sub-pixel.

Dilute nitride subcells with graded doping are disclosed. Dilute nitride subcells having graded doping display improved efficiency, short circuit current density, and open circuit voltage.

Dilute nitride subcells with graded doping are disclosed. Dilute nitride subcells having graded doping display improved efficiency, short circuit current density, and open circuit voltage.

A method of fabricating a four junction solar cell by identifying the composition and band gaps of the upper first, second and third subcells that maximizes the efficiency of the solar cell at a predetermined time after initial deployment by simulation; fabricating one or more four-junction test solar cells in accordance with the identified composition and band gaps of the upper first, second and third subcells; performing one or more optical or electrical tests on the fabricated one or more four-junction test solar cells; based on results of the tests, determining one or more properties of at least one of the upper first, second or third subcells to be modified in subsequent fabrication of four-junction solar cells, including the band gap, doping level and profile, and thickness of each of the subcell layers; and fabricating a further four-junction solar cell in accordance with the modified properties of at least one of the upper first, second or third subcells to optimize the efficiency of the solar cell at the predetermined time.

A method of fabricating a four junction solar cell by identifying the composition and band gaps of the upper first, second and third subcells that maximizes the efficiency of the solar cell at a predetermined time after initial deployment by simulation; fabricating one or more four-junction test solar cells in accordance with the identified composition and band gaps of the upper first, second and third subcells; performing one or more optical or electrical tests on the fabricated one or more four-junction test solar cells; based on results of the tests, determining one or more properties of at least one of the upper first, second or third subcells to be modified in subsequent fabrication of four-junction solar cells, including the band gap, doping level and profile, and thickness of each of the subcell layers; and fabricating a further four-junction solar cell in accordance with the modified properties of at least one of the upper first, second or third subcells to optimize the efficiency of the solar cell at the predetermined time.

A method for passing photovoltaic current between a subcell formed from a single crystal Group ll-VI semiconductor material and a subcell formed from a single crystal Group IV semiconductor material, includes the steps of forming a first subcell by an epitaxial growth process, the first subcell having a first upper surface; forming a tunnel heterojunction between the first subcell and the second subcell, and tunneling carriers formed by light incident on the first and second subcells through the tunnel heterojunction, thereby permitting a photoelectric series current to flow through the first and second subcells.

A method for passing photovoltaic current between a subcell formed from a single crystal Group ll-VI semiconductor material and a subcell formed from a single crystal Group IV semiconductor material, includes the steps of forming a first subcell by an epitaxial growth process, the first subcell having a first upper surface; forming a tunnel heterojunction between the first subcell and the second subcell, and tunneling carriers formed by light incident on the first and second subcells through the tunnel heterojunction, thereby permitting a photoelectric series current to flow through the first and second subcells.

A multijunction solar cell including interconnected first and second discrete semiconductor regions disposed adjacent and parallel to each other including first top solar subcell, second (and possibly third) lattice matched middle solar subcells; a graded interlayer adjacent to the last middle solar subcell; and a bottom solar subcell adjacent to said graded interlayer being lattice mismatched with respect to the last middle solar subcell; wherein an opening is provided from the bottom side of the semiconductor substrate to one or more of the solar subcells so as to allow a discrete electrical connector to be made extending in free space and to electrically connect contact pads on one or more of the solar subcells.

A multijunction solar cell including interconnected first and second discrete semiconductor regions disposed adjacent and parallel to each other including first top solar subcell, second (and possibly third) lattice matched middle solar subcells; a graded interlayer adjacent to the last middle solar subcell; and a bottom solar subcell adjacent to said graded interlayer being lattice mismatched with respect to the last middle solar subcell; wherein an opening is provided from the bottom side of the semiconductor substrate to one or more of the solar subcells so as to allow a discrete electrical connector to be made extending in free space and to electrically connect contact pads on one or more of the solar subcells.