A solar cell of an embodiment includes a p-electrode, an n-electrode, a p-type light-absorbing layer located between the p-electrode and the n-electrode and mainly containing a cuprous oxide, and a first n-type layer which is located between the p-type light-absorbing layer and the n-electrode, which mainly contains a compound represented by Ga.sub.x1M1.sub.x2M2.sub.x3M3.sub.x4M4.sub.x5O.sub.x6, the M1 being Hf and/or Zr, the M2 being one or more selected from the group consisting of In, Ti, and Zn, the M3 being Al and/or B, the M4 is one or more selected from the group consisting of Sn, Si, and Ge, the x1, the x2, and the x6 being more than 0, the x3, the x4, and the x5 being 0 or more, and the x6 when a sum of the x1, the x2, the x3, the x4, and the x5 is 2 being 3.0 or more and 3.8 or less.

A solar cell of an embodiment includes a p-electrode, an n-electrode, a p-type light-absorbing layer located between the p-electrode and the n-electrode and mainly containing a cuprous oxide, and an n-type layer includes a first n-type layer which is located between the p-type light-absorbing layer and the n-electrode and mainly contains a compound represented by Ga.sub.x1M1.sub.x2M2.sub.x3M3.sub.x4O.sub.x5, the M1 being Al and/or B, the M2 being one or more selected from the group consisting of In, Ti, Zn, Hf, and Zr, the M3 being one or more selected from the group consisting of Sn, Si, and Ge, the x1 and the x5 being more than 0, the x2, the x3, and the x4 being 0 or more, and the x5 when a sum of the x1, the x2, the x3, and the x4 is 2 being 3.0 or more and 3.8 or less, and a second n-type layer which is located between the first n-type layer and the n-electrode and mainly contains a compound represented by Ga.sub.y1M1.sub.y2M2.sub.y3M3.sub.y4O.sub.y5, the y1 and the y5 being more than 0, the y2, the y3, and the y4 being 0 or more, and the y5 when a sum of the y1, the y2, the y3, and the y4 is 2 being 3.0 or more and 3.8 or less, or a first n-type region which is located between the p-type light-absorbing layer and the n-electrode and mainly contains a compound represented by Ga.sub.x1M1.sub.x2M2.sub.x3M3.sub.x4O.sub.x5, the M1 being Al and/or B, the M2 being one or more selected from the group consisting of In, Ti, Zn, Hf, and Zr, the M3 being one or more selected from the group consisting of Sn, Si, and Ge, the x1 and the x5 being more than 0, the x2, the x3, and the x4 being 0 or more, and the x5 when a sum of the x1, the x2, the x3, and the x4 is 2 being 3.0 or more and 3.8 or less, and a second n-type region which is located between the first n-type region and the n-electrode and mainly contains a compound represented by Ga.sub.y1M1.sub.y2M2.sub.y3M3.sub.y4O.sub.y5, the y1 and the y5 being more than 0, the y2, the y3, and the y4 being 0 or more, and the y5 when a sum of the y1, the y2, the y3, and the y4 is 2 being 3.0 or more and 3.8 or less, wherein (x2+x3) is larger than (y2+y3).

A tandem photovoltaic cell includes a top cell having a first absorber and a bottom cell having a second absorber. The top cell and the bottom cell are electrically coupled in series. The top cell is configured to receive solar radiation through a first surface of the top cell and to transmit photons through a second surface of the top cell to the bottom cell, and the bottom cell is configured to receive the photons from the top cell through a first surface of the bottom cell and to receive solar radiation through a second surface of the bottom cell. A photovoltaic module includes a multiplicity of the tandem photovoltaic cells.

A method for manufacturing a stacked thin film of an embodiment includes forming a p-electrode on a substrate, forming a film that mainly contains a cuprous oxide and/or a complex oxide of cuprous oxides on the p-electrode, and performing an oxidation treatment on the film that mainly contains the cuprous oxide and/or the complex oxide of cuprous oxides. An ozone partial pressure in the oxidation treatment is 5 [Pa] or more and 200 [Pa] or less, a treatment temperature in the oxidation treatment is 273 [K] or more and 323 [K] or less, and a treatment time in the oxidation treatment is 1 second or more and 60 minutes or less.

A method for manufacturing a stacked thin film of an embodiment includes forming a p-electrode on a substrate, forming a film that mainly contains a cuprous oxide and/or a complex oxide of cuprous oxides on the p-electrode, and performing an oxidation treatment on the film that mainly contains the cuprous oxide and/or the complex oxide of cuprous oxides. An ozone partial pressure in the oxidation treatment is 5 [Pa] or more and 200 [Pa] or less, a treatment temperature in the oxidation treatment is 273 [K] or more and 323 [K] or less, and a treatment time in the oxidation treatment is 1 second or more and 60 minutes or less.

A multijunction solar cell including interconnected first and second discrete semiconductor regions disposed adjacent and parallel to each other including first top solar subcell, second (and possibly third) lattice matched middle solar subcells; a graded interlayer adjacent to the last middle solar subcell; and a bottom solar subcell adjacent to said graded interlayer being lattice mismatched with respect to the last middle solar subcell; wherein an opening is provided from the bottom side of the semiconductor body to one or more of the solar subcells so as to allow a discrete electrical connector to be made extending in free space and to electrically connect contact pads on one or more of the solar subcells.

A multijunction solar cell including interconnected first and second discrete semiconductor regions disposed adjacent and parallel to each other including first top solar subcell, second (and possibly third) lattice matched middle solar subcells; a graded interlayer adjacent to the last middle solar subcell; and a bottom solar subcell adjacent to said graded interlayer being lattice mismatched with respect to the last middle solar subcell; wherein an opening is provided from the bottom side of the semiconductor body to one or more of the solar subcells so as to allow a discrete electrical connector to be made extending in free space and to electrically connect contact pads on one or more of the solar subcells.

A perovskite-silicon tandem cell capable of absorbing solar radiation with energy lower than that of 1.12 eV, i.e., the bandgap of crystalline silicon—corresponding to the wavelength of 1100 nm. Ho.sup.3+ can absorb photons of wavelength range 1120 to 1190 nm, Tm.sup.3+, 1190 to 1260 nm, and Er.sup.3+, 1145 to 1580 nm, but up-conversion can be achieved using Ho.sup.3+, Tm.sup.3+, and Er.sup.3+-doped metal oxide, such as ZrO.sub.2, in perovskite-silicon tandem solar cells. Doped metal oxides, such as ZrO.sub.2 can also work as selective contacts. Such perovskite-silicon tandem structures can achieve over 30% solar energy conversion efficiency.

A photovoltaic cell includes a semiconductor element (20) formed from a direct semiconductor and a transparent biasing agent (28) overlying a first portion of the front face (22) of the semiconductor, the biasing agent producing a first depletion region (30) in the semiconductor element. A collector (40) directly contacts a second portion of the front face. The collector produces a second depletion region (44) in the semiconductor element. The collector (40) is out of direct conductive contact with the biasing agent (28) but in proximity to the biasing agent. A continuous region at least partially depleted of majority carriers extends between the first and second depletion regions at the front face of the semiconductor element, The continuous region may include overlapping portions of the first and second depletion regions (30,44), or may include an additional depletion region (160) formed by a charged dielectric (147).

A photovoltaic cell includes a semiconductor element (20) formed from a direct semiconductor and a transparent biasing agent (28) overlying a first portion of the front face (22) of the semiconductor, the biasing agent producing a first depletion region (30) in the semiconductor element. A collector (40) directly contacts a second portion of the front face. The collector produces a second depletion region (44) in the semiconductor element. The collector (40) is out of direct conductive contact with the biasing agent (28) but in proximity to the biasing agent. A continuous region at least partially depleted of majority carriers extends between the first and second depletion regions at the front face of the semiconductor element, The continuous region may include overlapping portions of the first and second depletion regions (30,44), or may include an additional depletion region (160) formed by a charged dielectric (147).