High efficiency photovoltaic cells with self concentrating effect
Novel structures of photovoltaic cells (also called as solar cells) are provided. The Cells are based on the micro (or nano) structures which could not only increase the surface area but also have the capability of self concentrating the solar spectrum incident onto the cell. These photovoltaic cells have large power generation capability per unit physical area over the conventional cells. These cells will have enormous applications such as in space, in commercial, residential and industrial applications.
1. A photovoltaic cell comprising:
a first electrode;
an electric substrate having a top surface, overlying said first electrode, comprising a first electric material of p or n type with a three dimensional geometric pattern etched out of the said top surface of the substrate, said substrate being as single piece of material;
a second electric material of type opposite to the first electric material and of uniform thickness coating the three dimensional geometric pattern of the electric substrate, thereby providing a p-n junction along the interface between the first electric material and the second electric material that conforms to the contour of the three dimensional geometric pattern of the said top surface of said electric substrate,
whereby a top surface of the second electric material provides a three dimensional geometric pattern that follows the contour of the three dimensional geometric pattern of the said top surface of said electric substrate,
wherein the three dimensional geometric pattern of the top surface of said second electric material has an array of pyramidal, conical, truncated pyramidal, or truncated conical shaped nano-scaled protruding structures separated by gaps,
wherein each said protruding structure has tilted sides, a base, an internal angle alpha between the tilted sides and the base, and a height,
wherein the gaps separate the bases of said protruding structures,
wherein the bases of said protruding structures are oriented such that said bases of said protruding structures are coplanar,
wherein the internal angle alpha of each said protruding structure is between 4 and 90 degrees, thereby concentrating some light incident on the tilted sides of each said protruding structure onto the gaps between said protruding structures,
and wherein the height of each said protruding structure, the internal angle alpha of each said protruding structure, and the gaps between said protruding structures are oriented to reflect some light incident on the tilted sides of each said protruding structure back and forth between the tilted sides of adjacent said protruding structures;
a second electrode of uniform thickness completely covering the top surface of said second electric material, wherein said second electrode is formed from transparent material;
a passivation material, transparent to light that fills the gaps in the three dimensional geometric pattern of the surface of the second electric material and levels the top surface of the second electric material
and a radiation tolerant layer on top of the whole cell to protect the photovoltaic cell from radiation damage.
2. A photovoltaic cell according to claim 1 , wherein said first electric material is selected from the group consisting of Si, CdTe, GaAs, InP, Ge, ZnO, Si:Ge, GaSb, CdZnTe, InSb, HgCdTe, and GaN.
3. A photovoltaic cell comprising:
a first electrode;
an electric substrate having a top surface, overlying said first electrode, comprising a first electric material of p or n type with a three dimensional geometric pattern etched out of the top surface of the substrate, said substrate being a single piece of material,
wherein the three dimensional geometric pattern has an array of pyramidal, conical, truncated pyramidal, or truncated conical shaped nano-scaled protruding structures separated by gaps,
wherein each said protruding structure has tilted sides, a base, an internal angle alpha between the tilted sides and the base, and a height,
wherein the gaps separate the bases of said protruding structures,
wherein the bases of said protruding structures are oriented such that said bases of said protruding, structures are coplanar,
wherein the internal angle alpha of each said protruding structure is between 45 and 90 degrees, thereby concentrating some light incident on the tilted sides of each said protruding structure onto the gaps between said protruding structures,
and wherein the height of each said protruding, structure, the internal angle alpha of each said protruding structure, and the gaps between said protruding structures are oriented to reflect some light incident on the tilted sides of each said protruding structure hack and forth between the tilted sides of adjacent said protruding structures;
said electric substrate further comprising a second electric material of type opposite to the first electric material inside the top surface of said electric substrate, wherein the interface between the first electric material and the second electric material forms a p-n junction conforming to the three dimensional geometric pattern of the top surface of said electric substrate;
a second electrode uniform thickness completely covering the top surface of the second electric material, wherein said second electrode is formed from transparent material; and
a passivation material transparent to light that fills the gaps in the three dimensional geometric pattern of the top surface of the second electric material and levels the surface of the second electric material.
4. A photovoltaic cell according to claim 3 , wherein said p-n junction is formed by diffusing dopants into said electric substrate to create said second electric material.
5. A photovoltaic cell according to claim 3 , wherein said first electric material is selected from the group consisting of Si, CdTe, GaAs, InP, Ge, ZnO, Si:Ge, GaSb, CdZnTe, InSb, HgCdTe, and GaN.
6. A photovoltaic cell comprising:
a first electrode;
an electric substrate having a top surface, overlying said first electrode, comprising a first electric material of p or n type with a three dimensional geometric pattern etched out of the top surface of the substrate, said substrate being a single piece of material,
wherein the three dimensional geometric pattern has an array of pyramidal, conical, truncated pyramidal, or truncated conical shaped nano-scaled protruding structures separated by gaps,
wherein each said protruding structure has tilted sides, a base, an internal angle alpha between the tilted sides and the base, and a height,
wherein the gaps separate the bases of said protruding structures,
wherein the bases of said protruding structures are oriented such that said bases of said protruding structures are coplanar,
wherein the internal angle alpha of each said protruding structure is between 45 and 90 degrees, thereby concentrating some light incident on the tilted sides of each said protruding structure onto the gaps between said protruding structures,
wherein the height of each said protruding structure, the internal angle alpha of each said protruding structure, and the gaps between said protruding structures are oriented to reflect some light incident on the tilted sides of each said protruding structure back and forth between the tilted sides of adjacent said protruding structures,
wherein said height of each protruding structure is micrometer-scaled;
wherein said bases of each protruding structure have nanoscale diameter;
said electric substrate further comprising a second electric material of type opposite to the first electric material inside the top surface of said electric substrate, wherein the interface between the first electric material and the second electric material forms a p-n junction conforming to the three dimensional geometric pattern of the top surface of said electric substrate,
wherein said p-n junction is formed by diffusing dopants into said electric substrate to create said second electric material;
a second electrode of uniform thickness completely covering the top surface of the second electric material, wherein said second electrode is formed from transparent material;
a passivation material transparent to light that fills the gaps in the three dimensional geometric pattern of the top surface of the second electric material and levels the surface of the second electric material; and
a radiation tolerant layer on top of the whole cell to protect the photovoltaic cell from radiation damage.