Systems and methods of three-terminal tandem solar cells are described. Three-terminal metal electrodes can be formed to contact subcells of the tandem solar cell. The three-terminal tandem cell can improve the device efficiency to at least 30%.

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.

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.

According to the present disclosure, techniques related to manufacturing and applications of power photodiode structures and devices based on group-III metal nitride and gallium-based substrates are provided. More specifically, embodiments of the disclosure include techniques for fabricating photodiode devices comprising one or more of GaN, AlN, InN, InGaN, AlGaN, and AlInGaN, structures and devices. Such structures or devices can be used for a variety of applications including optoelectronic devices, photodiodes, power-over-fiber receivers, and others.

A type-II tunnel junction is disclosed that includes a p-doped AlGaInAs tunnel layer and a n-doped InP tunnel layer. Solar cells are further disclosed that incorporate the high bandgap type-II tunnel junction between photovoltaic subcells.

A type-II tunnel junction is disclosed that includes a p-doped AlGaInAs tunnel layer and a n-doped InP tunnel layer. Solar cells are further disclosed that incorporate the high bandgap type-II tunnel junction between photovoltaic subcells.

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 photovoltaic device and a method of making the photovoltaic device are disclosed. The photovoltaic device may include a semiconductor layer epitaxially grown using a compound semiconductor material, such as a group III-V semiconductor material, wherein a surface of the semiconductor layer is textured via one or more laser pulses of a laser. The photovoltaic device may also include a dielectric layer deposited over the textured surface of the semiconductor layer, and a back metal reflector provided on the dielectric layer. The textured surface extends a path of light traveling through the photovoltaic device to increase absorption of the light within the photovoltaic device.

A solar cell comprising an epitaxial sequence of layers of semiconductor material thrilling at least a first and second solar subcells; a semiconductor contact layer disposed on the bottom surface of the second solar subcell; a reflective metal layer disposed below the semiconductor contact layer such that the reflectivity of the reflective metal layer is greater than 80% in the wavelength range 850 to 2000 nm, for reflecting light back into the second solar subcell.

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.