A multijunction solar cell including a substrate and a top (or light-facing) solar subcell having an emitter layer, a base layer, and a window layer adjacent to the emitter layer, the window layer composed of a material that is optically transparent, has a band gap of greater than 2.6 eV, and includes an appropriately arranged multilayer antireflection coating on the top surface thereof.

A monolithic solar cell includes a first solar cell that is a sequential stack of an electrode, a silicon substrate, and an n-type emitter layer; a recombination layer disposed on the n-type emitter layer; an interfacial layer that is a double layer constituted of PEDOT:PSS and poly-TPD or PEDOT:PSS and PCDTBT, and that is disposed on the recombination layer; and a second solar cell that includes a p-type hole selective layer and a perovskite layer disposed on the p-type hole selective layer, the a p-type hole selective layer contacting and being integrated onto the interfacial layer of the first solar cell in a heat treatment during which the interfacial layer is partially decomposed, wherein the presence of the interfacial layer prevents a reduction in photoelectric conversion efficiency that occurs if the first solar cell and the second solar cell are combined without the presence of the interfacial layer.

A monolithic solar cell includes a first solar cell that is a sequential stack of an electrode, a silicon substrate, and an n-type emitter layer; a recombination layer disposed on the n-type emitter layer; an interfacial layer that is a double layer constituted of PEDOT:PSS and poly-TPD or PEDOT:PSS and PCDTBT, and that is disposed on the recombination layer; and a second solar cell that includes a p-type hole selective layer and a perovskite layer disposed on the p-type hole selective layer, the a p-type hole selective layer contacting and being integrated onto the interfacial layer of the first solar cell in a heat treatment during which the interfacial layer is partially decomposed, wherein the presence of the interfacial layer prevents a reduction in photoelectric conversion efficiency that occurs if the first solar cell and the second solar cell are combined without the presence of the interfacial layer.

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 photovoltaic device including a photovoltaic cell and method of use is disclosed. The photovoltaic cell includes at least a first photovoltaic layer and a second photovoltaic layer arranged in a stack. The first photovoltaic layer has a first thickness and receives light at its top surface. A second photovoltaic layer has a second thickness and is disposed beneath the first photovoltaic layer and receives light passing through the first photovoltaic layer. The first thickness and the second thickness are selected so that a first light absorption at the first photovoltaic layer is equal to a second light absorption at the second photovoltaic layer. The photovoltaic cell is irradiated at its top surface with monochromatic light to generate a current.

A photovoltaic device including a photovoltaic cell and method of use is disclosed. The photovoltaic cell includes at least a first photovoltaic layer and a second photovoltaic layer arranged in a stack. The first photovoltaic layer has a first thickness and receives light at its top surface. A second photovoltaic layer has a second thickness and is disposed beneath the first photovoltaic layer and receives light passing through the first photovoltaic layer. The first thickness and the second thickness are selected so that a first light absorption at the first photovoltaic layer is equal to a second light absorption at the second photovoltaic layer. The photovoltaic cell is irradiated at its top surface with monochromatic light to generate a current.

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 the upper first solar subcell covers less than the entire upper surface of the second solar subcell, leaving an exposed portion of the second solar subcell around the periphery of the multijunction solar sell that lies in the path of the incoming light beam.

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 the upper first solar subcell covers less than the entire upper surface of the second solar subcell, leaving an exposed portion of the second solar subcell around the periphery of the multijunction solar sell that lies in the path of the incoming light beam.

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.