A multijunction solar cell including an upper first solar subcell having a first band gap and positioned for receiving an incoming light beam; a second solar subcell disposed below and adjacent to and lattice matched with said upper first solar subcell, and having a second band gap smaller than said first band gap; wherein at least one of the solar subcells has a graded band gap throughout the thickness of at least a portion of the active layer.

Provided are optical devices and systems fabricated, at least in part, via printing-based assembly and integration of device components. In specific embodiments the present invention provides light emitting systems, light collecting systems, light sensing systems and photovoltaic systems comprising printable semiconductor elements, including large area, high performance macroelectronic devices. Optical systems of the present invention comprise semiconductor elements assembled, organized and/or integrated with other device components via printing techniques that exhibit performance characteristics and functionality comparable to single crystalline semiconductor based devices fabricated using conventional high temperature processing methods. Optical systems of the present invention have device geometries and configurations, such as form factors, component densities, and component positions, accessed by printing that provide a range of useful device functionalities. Optical systems of the present invention include devices and device arrays exhibiting a range of useful physical and mechanical properties including flexibility, shapeability, conformability and stretchablity.

Provided are optical devices and systems fabricated, at least in part, via printing-based assembly and integration of device components. In specific embodiments the present invention provides light emitting systems, light collecting systems, light sensing systems and photovoltaic systems comprising printable semiconductor elements, including large area, high performance macroelectronic devices. Optical systems of the present invention comprise semiconductor elements assembled, organized and/or integrated with other device components via printing techniques that exhibit performance characteristics and functionality comparable to single crystalline semiconductor based devices fabricated using conventional high temperature processing methods. Optical systems of the present invention have device geometries and configurations, such as form factors, component densities, and component positions, accessed by printing that provide a range of useful device functionalities. Optical systems of the present invention include devices and device arrays exhibiting a range of useful physical and mechanical properties including flexibility, shapeability, conformability and stretchablity.

A solar cell stack includes a first semiconductor solar cell having a p-n junction made of a first material with a first lattice constant, a second semiconductor solar cell having a p-n junction made of a second material with a second lattice constant, and the first lattice constant being at least 0.008 Å smaller than the second lattice constant, and a metamorphic buffer. The metamorphic buffer is formed between the first semiconductor solar cell and the second semiconductor solar cell. The metamorphic buffer includes a series of at least five layers. The lattice constant increases in the series in the direction of the semiconductor solar cell. The lattice constants of the layers of the metamorphic buffer are larger than the first lattice constant. Two layers of the buffer having a doping and the difference in the dopant concentration between the two layers being greater than 4E.sup.17 cm.sup.−3.

A solar cell stack includes a first semiconductor solar cell having a p-n junction made of a first material with a first lattice constant, a second semiconductor solar cell having a p-n junction made of a second material with a second lattice constant, and the first lattice constant being at least 0.008 Å smaller than the second lattice constant, and a metamorphic buffer. The metamorphic buffer is formed between the first semiconductor solar cell and the second semiconductor solar cell. The metamorphic buffer includes a series of at least five layers. The lattice constant increases in the series in the direction of the semiconductor solar cell. The lattice constants of the layers of the metamorphic buffer are larger than the first lattice constant. Two layers of the buffer having a doping and the difference in the dopant concentration between the two layers being greater than 4E.sup.17 cm.sup.−3.

An assembly for optical to electrical power conversion including a photodiode assembly having a substrate layer and an internal side, an antireflective layer, a heterojunction buffer layer adjacent the internal side; an active area positioned adjacent the heterojunction buffer layer, a plurality of n+ electrode regions and p+ electrode regions positioned adjacent the active area, and back-contacts configured to align with the n+ and p+ electrode regions. The active area converts photons from incoming light into liberated electron hole pairs. The heterojunction buffer layer prevents electrons and holes of the liberated electron hole pairs from moving toward the substrate layer. The plurality of electrode regions are configured in an alternating pattern with gaps between each n+ and p+ electrode region. The electrode regions receive and generate electrical current from migration of the electrons and the holes, provide electrical pathways for the electrical current, and provide thermal pathways to dissipate heat.

A method of coordinating wireless power transfer and data communication between a transmitter and a receiver comprising recognizing at the receiver that an energy store electrically coupled to the receiver requires an electrical charge, emitting from the receiver a beacon signal to the transmitter, the beacon signal including information about the receiver and a state of charge of the energy store, recognizing at the receiver first and second localization signals from the transmitter, establishing low-power and high-power laser beam connections between the receiver and the transmitter in response to the localization signals, and communicating further information via the low-power beam on a periodic basis while optical power is being transferred via the high-power beam. The low-power beam connection includes further information about the receiver and the state of charge of the energy store. Optical power is transferred from the transmitter to the receiver via the high-power beam.

A multijunction solar cell assembly and its method of manufacture including interconnected first and second discreate semiconductor body subassemblies disposed adjacent and parallel to each other, in the sense of the incoming illumination, each semiconductor body subassembly including first top subcell, and possibly third middle subcells and a bottom solar subcell; wherein the interconnected subassemblies form at least a Three junction solar cell by a series connection being formed between the bottom solar subcell in the first semiconductor body with its at least least two junctions and the bottom solar subcell in the second semiconductor body representing the additional junction.

A multijunction solar cell assembly and its method of manufacture including interconnected first and second discreate semiconductor body subassemblies disposed adjacent and parallel to each other, in the sense of the incoming illumination, each semiconductor body subassembly including first top subcell, and possibly third middle subcells and a bottom solar subcell; wherein the interconnected subassemblies form at least a Three junction solar cell by a series connection being formed between the bottom solar subcell in the first semiconductor body with its at least least two junctions and the bottom solar subcell in the second semiconductor body representing the additional junction.

A solar cell stack, having a first semiconductor solar cell having a p-n junction made of a first material with a first lattice constant, and a second semiconductor solar cell having a p-n junction made of a second material with a second lattice constant, and the first lattice constant being at least 0.008 Å smaller than the second lattice constant, and a metamorphic buffer, the metamorphic buffer being formed between the first semiconductor solar cell and the second semiconductor solar cell, and the metamorphic buffer including a series of three layers, and the lattice constant increasing in a series in the direction of the semiconductor solar cell, and the lattice constants of the layers of the metamorphic buffer being bigger than the first lattice constant, two layers of the buffer having a doping, and the difference in the dopant concentration between the two layers being greater than 4E17 cm.sup.−3.