Solar cell structures for improved current generation and collection

Patent metadata

Field	Value
Publication number	US-9530911-B2
Application number	US-201313831056-A
Country	US
Kind code	B2
Filing date	Mar 14, 2013
Priority date	Mar 14, 2013
Publication date	Dec 27, 2016
Grant date	Dec 27, 2016

Abstract

In one aspect, optoelectronic devices are described herein. In some implementations, an optoelectronic device comprises a photovoltaic cell. The photovoltaic cell comprises a space-charge region, a quasi-neutral region, and a low bandgap absorber region (LBAR) layer or an improved transport (IT) layer at least partially positioned in the quasi-neutral region of the cell.

First claim

That which is claimed is:

1. An optoelectronic device comprising a photovoltaic cell, the photovoltaic cell comprising:
a space-charge region;
a quasi-neutral region; and

a low bandgap absorber region (LBAR) layer or an improved transport (IT) layer at least partially positioned in the quasi-neutral region of the cell,
wherein the LBAR layer or the IT layer forms a first portion of a base layer of the cell and the cell further comprises:
a window layer;
a back-surface-field (BSF) layer;
an emitter layer;
a second portion of the base layer; and
a third portion of the base layer,

wherein the first portion of the base layer is disposed between the second portion of the base layer and the third portion of the base layer, the second portion of the base layer is adjacent the emitter layer, the third portion of the base layer is disposed between the first portion of the base layer and the BSF layer, and the first portion of the base layer is positioned entirely in the quasi-neutral region of the base layer, entirely in the space-charge region, or partly in the quasi-neutral region and partly in the space-charge region, wherein the first portion of the base layer has a lower aluminum mole percent and lower bandgap than the second and third portions of the base layer.

2. The device of claim 1 , wherein the LBAR layer has a lower bandgap than an immediately adjacent semiconductor layer of the cell.

3. The device of claim 1 , wherein the IT layer has a higher collected photogenerated current density than a replacement layer having the composition of an immediately adjacent photogeneration layer.

4. The device of claim 1 , wherein the cell comprises an LBAR layer and an IT layer at least partially positioned in the quasi-neutral region.

5. The device of claim 4 , wherein the LBAR layer and the IT layer are the same layer.

6. The device of claim 1 , wherein the LBAR layer or the IT layer is free or substantially free of aluminum and at least one semiconductor layer immediately adjacent the LBAR layer or the IT layer includes aluminum and has a higher bandgap than the LBAR layer or the IT layer.

7. The device of claim 1 , wherein the LBAR layer or the IT layer includes nitrogen and at least one semiconductor layer immediately adjacent the LBAR layer or the IT layer is free or substantially free of nitrogen and has a higher bandgap than the LBAR layer or the IT layer.

8. The device of claim 1 , wherein the LBAR layer or the IT layer comprises one or more of GaInP, AlGaInP, GaAs, AlGaAs, GaInAs, GaAsSb, AlGaInAs, AlGaAsSb, GaInPAs, and AlGaInPAs.

9. The device of claim 1 , wherein the device is an inorganic semiconductor device.

10. The device of claim 1 , wherein the device comprises a plurality of photovoltaic cells.

11. The device of claim 10 , wherein the device comprises a multi junction photovoltaic device and each photovoltaic cell forms a subcell of the photovoltaic device.

12. The device of claim 11 , wherein at least two of the cells of the device comprise:
a space-charge region;
a quasi-neutral region; and
a low bandgap absorber region (LBAR) layer or an improved transport (IT) layer at least partially positioned in the quasi-neutral region of the cell.

13. The device of claim 1 , wherein the device comprises a photodiode.

14. An optoelectronic device comprising a photovoltaic cell, the photovoltaic cell comprising:
a space-charge region;
a quasi-neutral region; and

a low bandgap absorber region (LBAR) layer or an improved transport (IT) layer at least partially positioned in the quasi-neutral region of the cell,
wherein the LBAR layer or the IT layer forms a first portion of a base layer of the cell and the cell further comprises:
a window layer;
a back-surface-field (BSF) layer;
an emitter layer;
a second portion of the base layer; and
a third portion of the base layer,

wherein the first portion of the base layer is disposed between the second portion of the base layer and the third portion of the base layer, the second portion of the base layer is adjacent the emitter layer, the third portion of the base layer is disposed between the first portion of the base layer and the BSF layer, and wherein the first portion of the base layer has a greater degree of group-III sublattice ordering and a lower bandgap than the second and third portions of the base layer.

15. The device of claim 14 , wherein the LBAR layer has a lower bandgap than two immediately adjacent semiconductor layers of the cell.

16. The device of claim 14 , wherein the IT layer has a higher collected photogenerated current density than a replacement layer having the composition of either of the two immediately adjacent photogeneration layers.

17. The device of claim 14 , wherein the LBAR layer or the IT layer comprises no more than about 15 mole percent aluminum relative to the total amount of group III elements present in the layer and wherein at least one semiconductor layer immediately adjacent the LBAR layer or the IT layer includes a higher mole percent of aluminum than the LBAR layer or the IT layer and has a higher bandgap than the LBAR layer or the IT layer.

18. The device of claim 14 , wherein the LBAR layer or the IT layer includes nitrogen and at least one semiconductor layer immediately adjacent the LBAR layer or the IT layer includes a non-zero amount of nitrogen, the immediately adjacent semiconductor layer having a higher bandgap than the LBAR layer or the IT layer and a lower mole percent of nitrogen than the LBAR layer or the IT layer.

19. The device of claim 14 , wherein the LBAR layer or the IT layer comprises one or more of GaNAs, GaInNAs, GaNAsSb, and GaInNAsSb.

20. An optoelectronic device comprising a photovoltaic cell, the photovoltaic cell comprising:
a space-charge region;
a quasi-neutral region; and

a low bandgap absorber region (LBAR) layer or an improved transport (IT) layer at least partially positioned in the quasi-neutral region of the cell,
wherein the LBAR layer or the IT layer comprises one or more layers of a first layer type having a first bandgap and a first amount of strain with respect to the average lattice constant of the photovoltaic cell, and further comprises one or more layers of a second layer type having a second bandgap that is greater than the first bandgap, and a second amount of strain such that the layers of the second layer type are in tensile strain with respect to the layers of the first layer type, and wherein the strain of the layers of the first layer type is balanced with the strain of the layers of the second layer type such that both types of layers remain pseudomorphic and retain a coherent lattice structure with a crystal defect areal density lower than 10 6 cm −2 .

21. The device of claim 20 , wherein the LBAR layer or the IT layer is positioned entirely in the quasi-neutral region of the cell.

22. The device of claim 20 , wherein the LBAR layer or the IT layer is positioned partly in the quasi-neutral region of the cell and partly in the space-charge region of the cell.

23. The device of claim 20 , wherein the cell further comprises an emitter layer and the LBAR layer or the IT layer is positioned at least partially in the quasi-neutral region of the emitter layer.

24. The device of claim 20 , wherein the cell further comprises a base layer and the LBAR layer or the IT layer is positioned at least partially in the quasi-neutral regi

Assignees

• Boeing Co

Inventors

• King Richard R
• Fetzer Christopher M
• Law Daniel C
• Liu Xing-Quan
• Hong William D
• Edmondson Kenneth M
• Krut Dimitri D
• Boisvert Joseph C
• Karam Nasser H

Classifications

• Y02E10/544

  Solar cells from Group III-V materials · CPC title

• H01L31/0352

  Electricity · mapped topic

• H01L31/035209

  Electricity · mapped topic

• H01L31/035272 Primary

  Electricity · mapped topic

• H01L31/0687

  Electricity · mapped topic