A multi junction laminated laser photovoltaic cell includes a cell unit laminated body and upper and lower electrodes electrically connected with the bottom and top of the cell unit laminated body, respectively, wherein the cell unit laminated body includes more than 6 laminated PN-junction subcells, adjacent two subcells are connected in series via tunnel junctions, wherein each PN-junction subcell uses a semiconductor single crystal material with a specific band gap as the absorption layer, the multiple subcells at least have two different band gaps, and the band gaps of the subcells are arranged in such an order that they decrease successively from the light incidence side to other side of the photovoltaic cell.

A multi junction laminated laser photovoltaic cell includes a cell unit laminated body and upper and lower electrodes electrically connected with the bottom and top of the cell unit laminated body, respectively, wherein the cell unit laminated body includes more than 6 laminated PN-junction subcells, adjacent two subcells are connected in series via tunnel junctions, wherein each PN-junction subcell uses a semiconductor single crystal material with a specific band gap as the absorption layer, the multiple subcells at least have two different band gaps, and the band gaps of the subcells are arranged in such an order that they decrease successively from the light incidence side to other side of the photovoltaic cell.

A marking method for applying a unique identification to each individual solar cell stack of a semiconductor wafer, at least comprising the steps: Providing a semiconductor wafer having an upper side and an underside, which comprises a Ge substrate forming the underside; and generating an identification with a unique topography by means of laser ablation, using a first laser, on a surface area of the underside of each solar cell stack of the semiconductor wafer, the surface area being formed in each case by the Ge substrate or by an insulating layer covering the Ge substrate.

Tandem solar cell configurations are provided where at least one of the cells is a metal chalcogenide cell. A four-terminal tandem solar cell configuration has two electrically independent solar cells stacked on each other. A two-terminal solar cell configuration has two electrically coupled solar cells (same current through both cells) stacked on each other. Carrier selective contacts can be used to make contact to the metal chalcogenide cell (s) to alleviate the troublesome Fermi level pinning issue. Carrier-selective contacts can also remove the need to provide doping of the metal chalcogenide. Doping of the metal chalcogenide can be provided by charge transfer. These two ideas can be practiced independently or together in any combination.

There is disclosed ultrahigh-efficiency single- and multi-junction thin-film solar cells. This disclosure is also directed to a substrate-damage-free epitaxial lift-off (“ELO”) process that employs adhesive-free, reliable and lightweight cold-weld bonding to a substrate, such as bonding to plastic or metal foils shaped into compound parabolic metal foil concentrators. By combining low-cost solar cell production and ultrahigh-efficiency of solar intensity-concentrated thin-film solar cells on foil substrates shaped into an integrated collector, as described herein, both lower cost of the module as well as significant cost reductions in the infrastructure is achieved.

There is disclosed ultrahigh-efficiency single- and multi-junction thin-film solar cells. This disclosure is also directed to a substrate-damage-free epitaxial lift-off (“ELO”) process that employs adhesive-free, reliable and lightweight cold-weld bonding to a substrate, such as bonding to plastic or metal foils shaped into compound parabolic metal foil concentrators. By combining low-cost solar cell production and ultrahigh-efficiency of solar intensity-concentrated thin-film solar cells on foil substrates shaped into an integrated collector, as described herein, both lower cost of the module as well as significant cost reductions in the infrastructure is achieved.

A monolithic multi-junction solar cell comprising a first III-V subcell and a second III-V subcell and a third III-V subcell and a fourth Ge subcell, wherein the subcells are stacked on top of one another in the specified order, and the first subcell forms the top subcell and a metamorphic buffer is formed between the third subcell and the fourth subcell and all subcells each have an n-doped emitter layer and a p-doped base layer and the emitter doping in the second subcell is lower than the base doping.

A monolithic metamorphic multi-junction solar cell comprising a first III-V subcell and a second III-V subcell and a third III-V subcell and a fourth Ge subcell, wherein the subcells are stacked on top of each other in the indicated order, and the first subcell forms the topmost subcell, and a metamorphic buffer is formed between the third subcell and the fourth subcell and all subcells each have an n-doped emitter layer and a p-doped base layer, and the emitter layer of the second subcell is greater than the base layer.

A monolithic metamorphic multi-junction solar cell comprising a first III-V subcell and a second III-V subcell and a third III-V subcell and a fourth Ge subcell, wherein the subcells are stacked on top of each other in the indicated order, and the first subcell forms the topmost subcell, and a metamorphic buffer is formed between the third subcell and the fourth subcell and all subcells each have an n-doped emitter layer and a p-doped base layer, and the emitter layer of the second subcell is greater than the base layer.

A stacked monolithic multijunction solar cell, which includes a first subcell having a p-n junction with an emitter layer and a base layer, the thickness of the emitter layer being less than the thickness of the base layer at least by a factor of ten, and the first subcell comprising a substrate having a semiconductor material from the groups III and V or a substrate from the group IV, and which further includes a second subcell arranged on the first subcell and a third subcell arranged on the second subcell, the two subcells each including an emitter layer and a base layer, and a tunnel diode and a back side field layer each being formed between the subcells, the thickness of the emitter layer being greater than the thickness of the base layer in each case between the second subcell and in the third subcell.