Multijunction solar cells

Patent metadata

Field	Value
Publication number	US-11569404-B2
Application number	US-202016927157-A
Country	US
Kind code	B2
Filing date	Jul 13, 2020
Priority date	Dec 11, 2017
Publication date	Jan 31, 2023
Grant date	Jan 31, 2023

Abstract

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 that lies in the path of the incoming light beam.

First claim

The invention claimed is:

1. A multijunction solar cell comprising:
a semiconductor body including (i) a first semiconductor region including a tandem vertical stack of at least an upper solar subcell, a second solar subcell, and a third solar subcell;
(ii) a second semiconductor region disposed adjacent to the first semiconductor region and including a tandem vertical stack of the second solar subcell and the third solar subcell, but not the upper solar subcell of the first semiconductor region; (iii) a highly doped lateral conduction layer disposed adjacent to and directly above the second solar subcell of each respective one of the regions; and (iv) a plurality of grid lines disposed over the upper solar subcell in the first semiconductor region, there being no grid lines disposed over the second solar subcell in the second semiconductor region, wherein the absence of the upper solar subcell in the tandem vertical stack of the second semiconductor region facilitates an increase in current collection in the second solar subcell;
wherein the second semiconductor region comprises a plurality of discrete spaced-apart regions disposed between the grid lines, the grid lines extending substantially parallel to edges of the discrete spaced-apart regions, and
wherein the thickness of the upper solar subcell is designed so that the current collection in the upper solar subcell at the beginning-of-life has greater current collection per unit area than the current collection per unit area in the second solar subcell, thereby increasing the overall power output of the multijunction solar cell at the end-of-life.

2. The multijunction solar cell as defined in claim 1 , wherein the collective surface area of the second semiconductor region constitutes between 5% and 10% of a surface of the multijunction solar cell.

3. The multijunction solar cell as defined in claim 1 , wherein the second semiconductor region forms a plurality of spaced apart irregularly shaped regions across a surface of the multijunction solar cell.

4. The multijunction solar cell as defined in claim 3 , wherein the spaced apart irregularly shaped regions comprise alphanumeric characters.

5. The multijunction solar cell as defined in claim 4 , wherein the alphanumeric characters represent a unique serial number for each multijunction solar cell.

6. The multijunction solar cell as defined in claim 3 , wherein the spaced apart irregularly shaped regions comprise a pictorial design.

7. The multijunction solar cell as defined in claim 1 , further comprising a distributed Bragg reflector (DBR) structure disposed below the second solar subcell and above the third solar subcell, wherein the DBR structure includes a first DBR layer composed of a plurality of n type or p type Al x Ga 1-x As layers, and a second DBR layer disposed over the first DBR layer and composed of a plurality of n or p type Al y Ga 1-y As layers, where 0<x<1, 0<y<1, and y is greater than x.

8. The multijunction solar cell as defined in claim 1 , wherein the lateral conduction layer is composed of gallium arsenide (GaAs) or gallium indium phosphide (GalnP).

9. The multijunction solar cell as defined in claim 1 , further comprising:
a bottom subcell disposed below the third solar subcell and is the last of the subcells to receive incident light.

10. The multijunction solar cell as defined in claim 1 , wherein a thickness of the upper solar subcell is between 600 nm and 1200 nm.

11. The multijunction solar cell as defined in claim 1 , wherein the EOL to the BOL ratio of the short circuit current of the second solar subcell is greater than 95%.

12. The multijunction solar cell as defined in claim 1 , wherein the short circuit current density in the upper solar subcell in the first semiconductor region is the same as the short circuit density of the second solar subcell in the second semiconductor region.

13. The multijunction solar cell as defined in claim 1 , wherein:
the upper solar subcell is composed of indium gallium aluminum phosphide; and
the second solar subcell includes an emitter layer composed of indium gallium phosphide or aluminum gallium arsenide, and a base layer composed of aluminum gallium arsenide.

14. The multijunction solar cell as defined in claim 13 , wherein:
the upper solar subcell has a band gap in the range of 2.0 to 2.2 eV; the second solar subcell has a band gap in the range of 1.6 to 1.8 eV;
and further comprising a fourth solar subcell disposed below the third solar subcell.

15. The multijunction solar cell as defined in claim 1 , wherein the upper solar subcell has a band gap in the range of 1.85 to 1.95 eV and a first thickness, and the second solar subcell has a band gap in the range of 1.3 to 1.42 eV and a second thickness where the second thickness is greater than the first thickness.

16. The multijunction solar cell as defined in claim 1 , wherein the current collection in the upper solar subcell is designed to match with the current collection in the second solar subcell at the end-of-life (EOL).

Assignees

• Solaero Tech Corp

Inventors

• Derkacs Daniel
• Mcglynn Daniel

Classifications

• H01L31/0725 Primary

  Electricity · mapped topic

• H01L31/0693

  Electricity · mapped topic

• H01L31/056

  Electricity · mapped topic

• H01L31/0475

  Electricity · mapped topic

• H01L31/03046

  Electricity · mapped topic