A photovoltaic solar cell comprises a nano-patterned substrate layer. A plurality of nano-windows are etched into an intermediate substrate layer to form the nano-patterned substrate layer. The nano-patterned substrate layer is positioned between an n-type semiconductor layer composed of an n-type semiconductor material and a p-type semiconductor layer composed of a p-type semiconductor material. Semiconductor material accumulates in the plurality of nano-windows, causing a plurality of heterojunctions to form between the n-type semiconductor layer and the p-type semiconductor layer.

A stacked multi-junction solar cell having a first subcell and second subcell, the second subcell having a larger band gap than the first subcell. A third subcell has a larger band gap than the second subcell, and each of the subcells include an emitter and a base. The second subcell has a layer which includes a compound formed at least the elements GaInAsP, and a thickness of the layer is greater than 100 nm, and the layer is formed as part of the emitter and/or as part of the base and/or as part of the space-charge zone situated between the emitter and the base. The third subcell has a layer including a compound formed of at least the elements GaInP, and the thickness of the layer is greater than 100 nm.

A solar cell including a sequence of layers of semiconductor material forming a solar cell; a metal contact layer over said sequence of layers; a permanent supporting substrate composed of a carbon fiber reinforced polymer utilizing a conductive polyimide binding resin disposed directly over said metal contact layer and permanently bonding thereto.

An energy conversion device comprises at least two thin film photovoltaic cells fabricated separately and joined by wafer bonding. The cells are arranged in a hierarchical stack of decreasing order of their energy bandgap from top to bottom. Each of the thin film cells has a thickness in the range from about 0.5 m to about 10 m. The photovoltaic cell stack is mounted upon a thick substrate composed of a material selected from silicon, glass, quartz, silica, alumina, ceramic, metal, graphite, and plastic. Each of the interfaces between the cells comprises a structure selected from a tunnel junction, a heterojunction, a transparent conducting oxide, and an alloying metal grid; and the top surface and/or the lower surface of the energy conversion device may contain light-trapping means.

Photovoltaic devices including direct gap III-V absorber materials and operatively associated back structures enhance efficiency by enabling photon recycling. The back structures of the photovoltaic devices include wide bandgap III-V layers, highly doped (In)GaAs layers, patterned oxide layers and metal reflectors that directly contact the highly doped (In)GaAs layers through vias formed in the back structures. Localized ohmic contacts are formed in the back structures of the devices.

Photovoltaic cells, methods for fabricating surface mount multijunction photovoltaic cells, methods for assembling solar panels, and solar panels comprising photovoltaic cells are disclosed. The surface mount multijunction photovoltaic cells include through-wafer-vias for interconnecting the front surface epitaxial layer to a contact pad on the back surface. The through-wafer-vias are formed using a wet etch process that removes semiconductor materials non-selectively without major differences in etch rates between heteroepitaxial III-V semiconductor layers.

An energy conversion device comprises at least two thin film photovoltaic cells fabricated separately and joined by wafer bonding. The cells are arranged in a hierarchical stack of decreasing order of their energy bandgap from top to bottom. Each of the thin film cells has a thickness in the range from about 0.5 m to about 10 m. The photovoltaic cell stack is mounted upon a thick substrate composed of a material selected from silicon, glass, quartz, silica, alumina, ceramic, metal, graphite, and plastic. Each of the interfaces between the cells comprises a structure selected from a tunnel junction, a heterojunction, a transparent conducting oxide, and an alloying metal grid; and the top surface and/or the lower surface of the energy conversion device may contain light-trapping means.

The disclosure describes multi-junction solar cell structures that include two or more graded interlayers.

The solar cell structure according to the present invention comprises a nanowire (205) that constitutes the light absorbing part of the solar cell structure and a passivating shell (209) that encloses at least a portion of the nanowire (205). In a first aspect of the invention, the passivating shell (209) of comprises a light guiding shell (210), which preferably has a high- and indirect bandgap to provide light guiding properties. In a second aspect of the invention, the solar cell structure comprises a plurality of nanowires which are positioned with a maximum spacing between adjacent nanowires which is shorter than the wavelength of the light which the solar cell structure is intended to absorbing order to provide an effective medium for light absorption. Thanks to the invention it is possible to provide high efficiency solar cell structures.

Disclosed are embodiments of a thin-film photovoltaic technology including a single-junction crystalline silicon solar cell with a photonic-plasmonic back-reflector structure for lightweight, flexible energy conversion applications. The back-reflector enables high absorption for long-wavelength and near-infrared photons via diffraction and light-concentration, implemented by periodic texturing of the bottom-contact layer by nanoimprint lithography. The thin-film crystalline silicon solar cell is implemented in a heterojunction design with amorphous silicon, where plasma enhanced chemical vapor deposition (PECVD) is used for all device layers, including a low-temperature crystalline silicon deposition step. Excimer laser crystallization is used to integrate crystalline and amorphous silicon within a monolithic process, where a thin layer of amorphous silicon is converted to a crystalline silicon seed layer prior to deposition of a crystalline silicon absorber layer via PECVD. The crystalline nature of the absorber layer and the back-reflector enable efficiencies higher than what is achievable in other thin-film silicon devices.