U.S. patent application number 12/271704 was filed with the patent office on 2011-01-27 for multi-junction solar cell devices.
This patent application is currently assigned to STION CORPORATION. Invention is credited to HOWARD W.H. LEE.
Application Number | 20110017298 12/271704 |
Document ID | / |
Family ID | 43496240 |
Filed Date | 2011-01-27 |
United States Patent
Application |
20110017298 |
Kind Code |
A1 |
LEE; HOWARD W.H. |
January 27, 2011 |
MULTI-JUNCTION SOLAR CELL DEVICES
Abstract
A photovoltaic cell structure for manufacturing a photovoltaic
device. The photovoltaic cell structure includes a substrate
including a surface region. A first conductor layer overlies the
surface region. The photovoltaic cell structure includes a lower
cell structure. The lower cell structure includes a first P type
absorber layer using a first semiconductor metal chalcogenide
material and/or other semiconductor material overlying the first
conductor layer. The first P type absorber material is
characterized by a first bandgap ranging from about 0.5 eV to about
1.0 eV, a first optical absorption coefficient greater than about
10.sup.4 cm.sup.-1. The lower cell structure includes a first
N.sup.+ type window layer comprising at least a second metal
chalcogenide material and/or other semiconductor material overlying
the first P absorber layer. The photovoltaic cell structure
includes an upper cell structure. The upper cell structure includes
a second P type absorber layer using a third semiconductor metal
chalcogenide material. The second P type absorber layer is
characterized by a second bandgap ranging from about 1.0 eV to 2.2
eV and a second optical absorption coefficient greater than about
10.sup.4 cm.sup.-1. A second N.sup.+ type window layer comprising a
fourth metal chalcogenide material overlies the second P absorber
layer. A tunneling junction layer is provided between the upper
cell structure and the lower cell structure.
Inventors: |
LEE; HOWARD W.H.; (Saratoga,
CA) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER, EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
STION CORPORATION
San Jose
CA
|
Family ID: |
43496240 |
Appl. No.: |
12/271704 |
Filed: |
November 14, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60988414 |
Nov 15, 2007 |
|
|
|
60988099 |
Nov 14, 2007 |
|
|
|
Current U.S.
Class: |
136/261 ;
257/E21.002; 438/95 |
Current CPC
Class: |
Y02E 10/541 20130101;
H01L 31/0749 20130101; H01L 2924/0002 20130101; H01L 31/043
20141201; H01L 25/047 20130101; Y02P 70/50 20151101; Y02P 70/521
20151101; H01L 31/0725 20130101; H01L 2924/0002 20130101; H01L
2924/00 20130101 |
Class at
Publication: |
136/261 ; 438/95;
257/E21.002 |
International
Class: |
H01L 31/00 20060101
H01L031/00; H01L 21/02 20060101 H01L021/02; H01L 31/18 20060101
H01L031/18 |
Claims
1. A photovoltaic cell structure for manufacturing a photovoltaic
device, the photovoltaic cell structure comprises: a substrate
including a surface region; a first conductor layer overlying the
surface region; a lower cell structure, the lower cell structure
comprising a first P type absorber comprising at least a first
metal chalcogenide material and/or other suitable semiconductor
material overlying the first conductor layer, the first P type
absorber material being characterized by a first bandgap ranging
from 0.5 eV to 1.0 eV, a first optical absorption coefficient
greater than about 10.sup.4 cm.sup.-1, and a first thickness
ranging from 0.5 um to 2 um; a first N.sup.+ type window layer
comprising at least a second metal chalcogenide material and/or
other suitable semiconductor material overlying the first P type
absorber layer; a tunneling junction layer overlying the first
N.sup.+ type window layer of the lower cell, the tunneling junction
layer comprising at least a p.sup.++ type semiconductor material
and an n.sup.++ type semiconductor material; an upper cell
structure, the upper cell structure comprising: a second P type
absorber material comprising at least a third metal chalcogenide
material overlying the tunneling junction layer, the second P type
absorber material being characterized by a second bandgap ranging
from 1.0 eV to 2.2 eV and a second optical absorption coefficient
greater than about 10.sup.4 cm.sup.-1, a second thickness ranging
from 0.5 um to 2 um; a second N.sup.+ type window layer comprising
at least a fourth metal chalcogenide material overlying the second
absorber layer; a buffer layer overlying the second N.sup.+ type
window layer of the upper cell structure; the buffer layer being
characterized by a resistivity greater than about 10 kohm-cm; and a
second conductor layer overlying the buffer layer.
2. The structure of claim 1 wherein the substrate is a
semiconductor, for example, silicon, germanium, compound
semiconductor material such as a III-V gallium arsenide, germanium,
silicon germanium, and others.
3-5. (canceled)
6. The structure of claim 1 wherein the first metal chalcogenide
material is selected from a semiconductor metal oxide, a
semiconductor metal sulfide, a semiconductor metal selenide, or
semiconductor metal telluride.
7. The structure of claim 1 wherein the second metal chalcogenide
material is selected from a semiconductor metal oxide, a
semiconductor metal sulfide, a semiconductor metal selenide, or a
semiconductor metal telluride, or a semiconductor metal
silicide.
8. The structure of claim 1 wherein the third metal chalcogenide
material is selected from a semiconductor metal oxide, a
semiconductor metal sulfide, a semiconductor metal selenide, or
semiconductor telluride.
9. The structure of claim 1 wherein the fourth metal chalcogenide
material is selected from a semiconductor metal oxide, a
semiconductor metal sulfide, a semiconductor metal selenide, or a
semiconductor metal telluride.
10. The structure of claim 1 wherein the first P type absorber
layer comprises an iron disilicide material.
11. The structure of claim 1 wherein the first N.sup.+ type window
layer comprises a zinc sulfide material.
12. The structure of claim 1 wherein the second P type absorber
layer comprises a copper oxide material.
13. The structure of claim 1 wherein the second N.sup.+ window
layer comprises a zinc sulfide material.
14. The structure of claim 1 wherein the first bandgap is less than
the second bandgap.
15. (canceled)
16. The structure of claim 1 wherein the first conductor layer
comprises a transparent conducting oxide material selected from
ZnO:Al, SnO:F, ITO, and others.
17. (canceled)
18. The structure of claim 1 wherein the second conductor layer
comprises a transparent conducting oxide material selected from
ZnO:Al, SnO:F, ITO, and others.
19. (canceled)
20. The structure of claim 1 wherein the tunneling junction layer
provides a series connection between the upper cell structure and
the lower cell structure.
21. A photovoltaic cell structure for manufacturing of a
photovoltaic device, the structure comprises: a substrate including
a surface region; a first conductor structure overlying the surface
region; a lower cell structure overlying the first conductor
structure, the lower cell comprising: a first P type absorber layer
comprising a first metal chalcogenide material and/or other
semiconductor material, the first P type absorber layer being
characterized by a first bandgap ranging from about 0.5 eV to 1.0
eV, a first optical absorption coefficient greater than about
10.sup.4 cm.sup.-1 in a wavelength range comprising about 400 nm to
about 800 nm; a first N.sup.+ type window layer comprising a second
metal chalcogenide material and/or other semiconductor material
overlying the first P type absorber layer; a first buffer layer
overlying the first N.sup.+ type window layer; a second conductor
structure overlying the lower cell structure; an upper cell
structure overlying the second conductor structure, the upper cell
structure comprising: a second P type absorber layer comprising a
third metal chalcogenide material overlying the second conductor
layer, a bandgap ranging from 1.0 eV to 2.2 eV, a second optical
absorption coefficient greater than about 10.sup.4 cm in a
wavelength range comprising about 400 nm to about 800 nm
characterize the second P type absorber layer; a second N.sup.+
type window layer overlying the second P type absorber layer; a
second buffer layer overlying the second N.sup.+ type window layer
of the upper cell structure; the buffer layer being characterized
by a resistivity greater than about 10 k-ohm cm; and a third
conductor layer overlying the buffer layer.
22. The structure of claim 21 wherein the substrate is a
semiconductor, for example, silicon, germanium, compound
semiconductor material such as a III-V gallium arsenide, germanium,
silicon germanium, and others.
23-42. (canceled)
43. A photovoltaic cell structure for manufacturing a photovoltaic
device, the structure comprises: a substrate including a surface
region; a first photovoltaic cell structure overlying the surface
region; the first photovoltaic cell structure comprising: a first
conductor layer; a first P type absorber layer overlying the first
conductor layer, the first P type absorber layer comprising a first
metal chalcogenide material and/or other semiconductor material,
the first P type absorber layer being characterized by a first
bandgap ranging from about 0.5 eV to about 1.0 eV, a first optical
absorption coefficient greater than about 10.sup.4 cm.sup.-1 in a
wavelength range comprising about 400 nm to about 800 nm. a first
N.sup.+ type window layer comprising a second metal chalcogenide
material and or other semiconductor material overlying the first P
type absorber layer; a second conductor layer overlying the first
N.sup.+ type window layer; a second photovoltaic cell structure;
the second photovoltaic cell structure comprising: a third
conductor layer; a second P type absorber layer comprising a third
metal chalcogenide material, the second P type absorber layer being
characterized by a second bandgap ranging from 1.0 eV to 2.2 eV, a
second optical absorption coefficient greater than about 10.sup.4
cm in a wavelength range comprising about 400 nm to about 800 nm; a
second N.sup.+ type window layer overlying the second P type
absorber layer; a fourth conductor layer overlying the second
N.sup.+ type window layer; and a glue layer coupling the first
photovoltaic cell structure to the second photovoltaic cell
structure.
44. The structure of claim 43 wherein the substrate is a
semiconductor, for example, silicon, germanium, compound
semiconductor material such as a III-V gallium arsenide, germanium,
silicon germanium, and others.
45-48. (canceled)
49. The structure of claim 43 wherein the second metal chalcogenide
material is selected from is selected from a semiconductor metal
oxide, a semiconductor metal sulfide, a semiconductor metal
selenide, or semiconductor metal telluride.
50-54. (canceled)
55. The structure of claim 43 wherein the second N.sup.+ window
layer comprises a metal chalcogenide material selected from a
semiconductor metal oxide, a semiconductor metal sulfide, a
semiconductor metal selenide, or semiconductor metal telluride.
56-126. (canceled)
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application No. 60/988,414, filed Nov. 15, 2007 and U.S.
Provisional Patent Application No. 60/988,099, filed Nov. 14, 2007,
commonly assigned, incorporated herein by reference for all
purposes.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED
RESEARCH OR DEVELOPMENT
[0002] Not Applicable
REFERENCE TO A "SEQUENCE LISTING," A TABLE, OR A COMPUTER PROGRAM
LISTING APPENDIX SUBMITTED ON A COMPACT DISK
[0003] Not Applicable
BACKGROUND OF THE INVENTION
[0004] The present invention relates generally to photovoltaic cell
structure. More particularly, the present invention provides a
method and structure of a photovoltaic cell for manufacture of
solar module using a thin film process. Merely by way of example,
the present method and structure have been implemented using a
multijunction configuration, but it would be recognized that the
invention may have other configurations.
[0005] From the beginning of time, human beings have been
challenged to find way of harnessing energy. Energy comes in the
forms such as petrochemical, hydroelectric, nuclear, wind, biomass,
solar, and more primitive forms such as wood and coal. Over the
past century, modern civilization has relied upon petrochemical
energy as an important source. Petrochemical energy includes gas
and oil. Gas includes lighter forms such as butane and propane,
commonly used to heat homes and serve as fuel for cooking. Gas also
includes gasoline, diesel, and jet fuel, commonly used for
transportation purposes. Heavier forms of petrochemicals can also
be used to heat homes in some places. Unfortunately, petrochemical
energy is limited and essentially fixed based upon the amount
available on the planet Earth. Additionally, as more human beings
begin to drive and use petrochemicals, it is becoming a rather
scarce resource, which will eventually run out over time.
[0006] More recently, clean sources of energy have been desired. An
example of a clean source of energy is hydroelectric power.
Hydroelectric power is derived from electric generators driven by
the force of water that has been held back by large dams such as
the Hoover Dam in Nevada. The electric power generated is used to
power up a large portion of Los Angeles Calif. Other types of clean
energy include solar energy. Specific details of solar energy can
be found throughout the present background and more particularly
below.
[0007] Solar energy generally converts electromagnetic radiation
from our sun to other useful forms of energy. These other forms of
energy include thermal energy and electrical power. For electrical
power applications, solar cells are often used. Although solar
energy is clean and has been successful to a point, there are still
many limitations before it becomes widely used throughout the
world. As an example, one type of solar cell uses crystalline
materials, which form from semiconductor material ingots. These
crystalline materials include photo-diode devices that convert
electromagnetic radiation into electrical current. Crystalline
materials are often costly and difficult to make on a wide scale.
Additionally, devices made from such crystalline materials have low
energy conversion efficiencies. Other types of solar cells use
"thin film" technology to form a thin film of photosensitive
material to be used to convert electromagnetic radiation into
electrical current. Similar limitations exist with the use of thin
film technology in making solar cells. That is, efficiencies are
often poor. Additionally, film reliability is often poor and cannot
be used for extensive periods of time in conventional environmental
applications. These and other limitations of these conventional
technologies can be found throughout the present specification and
more particularly below.
[0008] From the above, it is seen that improved techniques for
manufacturing photovoltaic cells and resulting devices are
desired.
BRIEF SUMMARY OF THE INVENTION
[0009] According to embodiments of the present invention,
techniques including structures for a multijunction solar device
are provided. More particularly, embodiments according to the
present invention provide a multijunction photovoltaic cell
structure and a resulting photovoltaic device using thin film metal
chalcogenide semiconductor materials and/or other suitable
semiconductor films. But it would be recognized that the present
invention has a broader range of applicability.
[0010] In a specific embodiment, a photovoltaic cell structure for
manufacturing a photovoltaic device is provided. The photovoltaic
cell structure includes a substrate member having a surface region.
The photovoltaic cell structure includes a first conductor layer
overlying the surface region of the substrate member. The
photovoltaic cell structure includes a lower cell structure
overlying the first conductor layer. In a specific embodiment, the
lower cell structure includes a first P type absorber layer. The
first P type absorber layer is characterized by a first bandgap
ranging from about 0.5 to about 1.0 eV, but can be others. The
first P type absorber layer is characterized by a first optical
absorption coefficient greater than about 10.sup.4 cm.sup.-1 in a
wavelength range comprising 400 nm to 800 nm, but can be others. In
a specific embodiment, the first P type absorber layer includes at
least a first metal chalcogenide material and/or other suitable
semiconductor material. The lower cell structure includes a first
N.sup.+ type window layer comprising at least a second metal
chalcogenide material and/or other suitable semiconductor material
overlying the first P type absorber layer. In a specific
embodiment, the photovoltaic cell structure includes an upper cell
structure. The upper cell structure includes a second P type
absorber layer. The second P type absorber layer comprises at least
a third metal chalcogenide material and/or other semiconductor
material characterized by a second bandgap ranging from about 1.0
eV to 2.2 eV, but can be others. In an alternative embodiment, the
second P absorber layer is characterized by a second bandgap
ranging from 1.0 eV to about 2.0 eV, but can be others. In a
preferred embodiment, the second P type absorber layer is
characterized by a second bandgap ranging from about 1.2 eV to
about 1.8 eV and a second optical absorption coefficient greater
than about 10.sup.4 cm.sup.-1 in a wavelength range comprising 400
nm to 800 nm. In a specific embodiment, the second bandgap is
greater than the first bandgap. The upper cell structure includes a
second N.sup.+ window layer overlying the second P absorber layer.
In a specific embodiment, the photovoltaic cell structure includes
a p.sup.++/n.sup.++ layer disposed between the upper cell structure
and the lower cell structure. In a specific embodiment, the
p.sup.++/n.sup.++ layer provides a tunneling junction for the upper
cell structure and the lower cell structure. In a specific
embodiment, the photovoltaic cell structure includes an optional
buffer layer overlying the second N.sup.+ type window layer. The
optional buffer layer is characterized by a resistivity greater
than about 10 kohm-cm according to a specific embodiment. A second
conductor structure is provided overlying the optional buffer
layer. Of course, there can be other variations, modifications, and
alternatives.
[0011] In an alternative embodiment, an alternative photovoltaic
cell structure for manufacturing of a photovoltaic device is
provided. The alternative photovoltaic cell structure includes a
substrate including a surface region. The alternative photovoltaic
cell structure includes a first conductor structure overlying the
surface region of the substrate. The alternative photovoltaic cell
structure a lower cell structure overlying the first conductor
structure. The lower cell structure includes a first P type
absorber layer. The first P type absorber layer includes a first
metal chalcogenide material and/or other suitable semiconductor
material, characterized by a first bandgap ranging from about 0.5
eV to about 1.0 eV and a first optical absorption coefficient
greater than about 10.sup.4 cm.sup.1 in the wavelength range
comprising 400 nm to 800 nm in a specific embodiment. The lower
cell structure includes a first N.sup.+ type window layer overlying
the first P type absorber layer. The first N.sup.+ type window
layer can use a second semiconductor metal chalcogenide material
and/or a suitable semiconductor material. The first P type absorber
layer and the first N.sup.+ type window layer form an interface
region characterized by a first pn.sup.+ junction. The alternative
photovoltaic cell structure includes a second conductor structure
overlying the lower cell structure. In a specific embodiment, an
upper cell structure is provided overlying the second conductor
structure. The upper cell structure includes a second P type
absorber layer. In a specific embodiment, the second P type
absorber uses a third metal chalcogenide material characterized by
a second bandgap ranging from 1.2 eV to 2.2 eV and a second optical
coefficient greater than about 10.sup.4 cm.sup.-1 for the
wavelength range comprising about 400 nm to about 800 nm. In a
specific embodiment, the second bandgap is greater than the first
bandgap. The upper cell structure includes a second N.sup.+ type
window layer overlying the second P type absorber layer. The
alternative photovoltaic cell structure includes an optional buffer
layer characterized by a resistivity greater than about 10 k-ohm cm
overlying the second N.sup.+ type window layer of the upper cell
structure. A third conductor layer overlies the buffer layer.
[0012] In a yet alternative embodiment, a photovoltaic cell
structure for manufacturing a photovoltaic device is provided. The
photovoltaic cell structure includes a substrate having a surface
region. The photovoltaic cell structure includes a first
photovoltaic cell structure overlying the surface region of the
substrate. The first photovoltaic cell structure includes a first
conductor layer. The first photovoltaic cell structure includes a
first P type absorber layer overlying the first conductor layer. In
a specific embodiment, the first P type absorber layer uses a first
semiconductor metal chalcogenide material and/or other suitable
semiconductor material characterized by a first bandgap ranging
from 0.5 eV to 1.0 eV and a first optical absorption coefficient
greater than about 10.sup.4 cm.sup.-1 in the wavelength range
comprising about 400 nm to about 800 nm. The first photovoltaic
cell structure includes a first N.sup.+ type window layer overlying
the first P type absorber layer. In a specific embodiment, the
first N.sup.+ type window layer includes at least a second
semiconductor metal chalcogenide material and/or other suitable
semiconductor material. A second conductor structure overlying the
first N.sup.+ type window layer. The photovoltaic cell structure
includes a second photovoltaic cell structure. The second
photovoltaic cell structure includes a third conductor structure.
In a specific embodiment, a second P type absorber layer comprising
a third semiconductor metal chalcogenide material characterized by
a second bandgap ranging from about 1.0 eV to about 2.2 eV and a
second optical absorption greater than 10.sup.4 cm.sup.-1 in a
wavelength range comprising 400 nm to 800 nm. In a specific
embodiment, the second bandgap is greater than the first bandgap. A
second N.sup.+ type window layer overlies the second P type
absorber layer. The second N.sup.+ type window layer is formed
using a fourth metal chalcogenide material. The second photovoltaic
cell structure includes a fourth electrode structure overlying the
second N.sup.+ type window layer. In a specific embodiment, a glue
layer or a laminating layer is provided to couple the first
photovoltaic cell structure to the second photovoltaic cell.
[0013] In another specific embodiment, a method for manufacturing a
photovoltaic device is provided. The method includes providing a
first substrate including a first surface region. The method forms
a first conductor layer overlying the surface region and a first P
type absorber layer overlying the first conductor layer. In a
specific embodiment, the first P type absorber layer includes a
first metal chalcogenide material and/or other semiconductor
material. Preferably, the first P type absorber layer is
characterized by a first bandgap ranging from about 0.5 eV to about
1.0 eV, a first optical absorption coefficient greater than about
10.sup.4 cm.sup.-1 in a wavelength range comprising about 400 nm to
about 800 nm. The method includes forming a first N.sup.+ type
window layer overlying the first P type absorber layer. In a
specific embodiment, the first N.sup.+ type window layer includes a
second metal chalcogenide material and/or other semiconductor
material. A second conductor layer is formed overlying the first
N.sup.+ type window layer. In a specific embodiment, the first
conductor layer, the first P type absorber layer, the first N.sup.+
type window layer, and the second conductor layer provide for a
first photovoltaic cell structure. The method includes providing a
second substrate including a second surface region. A third
conductor layer is formed overlying the second surface region and a
second N.sup.+ type window layer is formed overlying the third
conductor layer. The method includes forming a second P type
absorber layer overlying the second N.sup.+ type window layer. In a
specific embodiment, the second N.sup.+ type window layer includes
a third metal chalcogenide material characterized by a second
bandgap ranging from 1.0 eV to 2.2 eV, a second optical absorption
coefficient greater than about 10.sup.4 cm.sup.-1 in a wavelength
range comprising about 400 nm to about 800 nm. The method forms
fourth conductor layer overlying the second P type absorber layer.
In a specific embodiment, the third conductor layer, the second P
type absorber layer, the second N.sup.+ type window layer and the
fourth conductor layer provide for a second photovoltaic cell
structure. In a specific embodiment, a glue layer is provided
between the first photovoltaic cell structure and the second
photovoltaic cell structure. The glue layer is disposed between the
second conductor layer and the forth conductor layer in a specific
embodiment.
[0014] In a yet another embodiment, a method for manufacturing of a
photovoltaic device is provided. The method includes providing a
substrate including a surface region. A first conductor structure
is formed overlying the surface region. A lower cell is formed
overlying the first conductor structure. The lower cell includes a
first P type absorber layer. In a specific embodiment, the first P
type absorber layer includes a first metal chalcogenide material
and/or other semiconductor material. The first P type absorber
layer is characterized by a first bandgap ranging from about 0.5 eV
to 1.0 eV, a first optical absorption coefficient greater than
about 10.sup.4 cm.sup.-1 in a wavelength range comprising about 400
nm to about 800 nm. The lower cell includes a first N.sup.+ type
window layer comprising a second metal chalcogenide material and/or
other semiconductor material overlying the first P type absorber
layer. The method forms a second conductor structure overlying the
lower cell structure. The method includes forming an upper cell
structure overlying the second conductor structure. The upper cell
structure includes a second P type absorber layer. The P type
absorber layer includes a third metal chalcogenide material
overlying the second conductor layer. In a specific embodiment, a
bandgap ranging from 1.0 eV to 2.2 eV, and a second optical
absorption coefficient greater than about 10.sup.4 cm.sup.-1 in a
wavelength range comprising about 400 nm to about 800 nm
characterize the second P type absorber layer. The upper cell
structure includes a second N.sup.+ type window layer overlying the
second P type absorber layer. In a specific embodiment, the method
forms a buffer layer overlying the second N.sup.+ type window layer
of the upper cell structure. The buffer layer is characterized by a
resistivity greater than about 10 k-ohm cm in a specific
embodiment. A third conductor layer is formed overlying the buffer
layer.
[0015] In a still yet another embodiment, a method for
manufacturing a photovoltaic device is provided. The method
includes providing a substrate including a surface region. A first
conductor layer is formed overlying the surface region and a lower
cell structure is formed overlying the first conductor layer. The
lower cell structure includes a first P type absorber including at
least a first metal chalcogenide material and/or other suitable
semiconductor material overlying the first conductor layer. The
first P type absorber material is characterized by a first bandgap
ranging from 0.5 eV to 1.0 eV, a first optical absorption
coefficient greater than about 10.sup.4 cm.sup.-1, and a first
thickness ranging from 0.5 um to 2 um. The lower cell structure
includes a first N.sup.+ type window layer comprising at least a
second metal chalcogenide material and/or other suitable
semiconductor material overlying the first P type absorber layer.
In a specific embodiment, the method forms a tunneling junction
layer overlying the first N.sup.+ type window layer of the lower
cell. The tunneling junction layer includes at least a p.sup.++
type semiconductor material and an n.sup.++ type semiconductor
material in a specific embodiment. The method includes forming an
upper cell structure. The upper cell structure includes a second P
type absorber material overlying the tunneling junction layer. In a
specific embodiment, the second P type absorber material includes
at least a third metal chalcogenide material. In a specific
embodiment, the second P type absorber material is characterized by
a second bandgap ranging from 1.0 eV to 2.2 eV, a second optical
absorption coefficient greater than about 10.sup.4 cm.sup.-1, and a
second thickness ranging from 0.5 um to 2 um. A second N.sup.+ type
window layer comprising at least a fourth metal chalcogenide
material is formed overlying the second absorber layer. The method
includes forming a buffer layer overlying the second N.sup.+ type
window layer of the upper cell structure. The buffer layer is
characterized by a resistivity greater than about 10 kohm-cm in a
specific embodiment. A second conductor layer is formed overlying
the buffer layer.
[0016] Depending on the embodiment, one or more of these features
may be included. The present invention provides a multijunction
solar cell structure using metal chalcogenides and other
semiconductor materials. The present structure can be provided
using easy to use processes using convention equipment without
further modifications. Depending upon the embodiment, each of the
metal chalcogenide semiconductor material may provided as
nanostructured or in bulk. In a specific embodiment, the present
solar cell structure provides a higher conversion efficiency in
converting sunlight into electric energy. Depending on the
embodiment, the conversion efficiency may be 15 percent to 20
percent or greater for the resulting multijunction solar cell.
Additionally, the present multifunction solar cell structure can be
provided using large scale manufacturing processes, which reduce
cost in manufacturing of the photovoltaic devices. Depending on the
embodiments, one or more of these benefits may be achieved. These
benefits will be described more fully throughout the present
specification, and particularly below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a simplified diagram illustrating a photovoltaic
cell structure according to an embodiment of the present
invention.
[0018] FIG. 2 is a simplified circuit diagram illustrating the
photovoltaic cell structure in FIG. 1.
[0019] FIG. 3 is a simplified diagram illustrating an alternative
photovoltaic cell structure according to an embodiment of the
present invention.
[0020] FIG. 4 is a simplified circuit diagram illustrating the
photovoltaic cell structure in FIG. 2.
[0021] FIG. 5 is a simplified diagram illustrating an alternative
photovoltaic cell structure according to an embodiment of the
present invention.
[0022] FIG. 6 is a simplified circuit diagram illustrating the
photovoltaic cell structure in FIG. 5.
[0023] FIG. 7 is a simplified diagram illustrating an example of a
photovoltaic cell structure according to an embodiment of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0024] According to embodiments of the present invention,
techniques directed to photovoltaic cell structure are provided.
More particularly, embodiments according to the present invention
provide a multijunction photovoltaic cell structure and a resulting
photovoltaic cell having a high conversion efficiency. But it would
be recognize that embodiments according to the present invention
have a much broader range of applicability.
[0025] FIG. 1 is a simplified diagram illustrating a photovoltaic
cell structure 100 for manufacturing a multifunction solar module
according to an embodiment of the present invention. As shown, the
photovoltaic cell structure includes a substrate member 102 having
a surface region 104. The substrate member can be made of an
insulator material, a conductor material, or a semiconductor
material, depending on the application. In a specific embodiment,
the conductor material can be nickel, molybdenum, aluminum, or a
metal alloy such as stainless steel and the likes. In a specific
embodiment, the semiconductor material may include silicon,
germanium, silicon germanium, compound semiconductor material such
as III-V materials, II-VI materials, and others. In a specific
embodiment, the insulator material can be a transparent material
such as glass, quartz, fused silica, and the like. Alternatively,
the insulator material can be a polymer material, a ceramic
material, or a layer material or a composite material depending on
the application. The polymer material may include acrylic material,
polycarbonate material, and others, depending on the embodiment. Of
course, there can be other variations modifications, and
alternatives.
[0026] As shown in FIG. 1, the photovoltaic cell structure includes
a first photovoltaic cell structure 106. In a specific embodiment,
the first photovoltaic cell structure includes a first electrode
structure 108. In a specific embodiment, the first electrode
structure uses a first conductor material characterized by a
resistivity less than about 10 ohm-cm. The first electrode
structure can be made of a suitable material or a combination of
materials. The first electrode structure can be made from a
transparent conductive electrode or materials that are light
reflecting or light blocking depending on the embodiment. Examples
of the transparent conductive electrode can include indium tin
oxide (ITO), aluminum doped zinc oxide, fluorine doped tin oxide
and others. In a specific embodiment, the transparent conductive
electrode may be provide using techniques such as sputtering,
chemical vapor deposition, electrochemical deposition, and others.
In a specific embodiment, the first electrode structure may be made
from a metal material. The metal material can include gold, silver,
nickel, platinum, aluminum, tungsten, molybdenum, a combination of
these, or an alloy, among others. In a specific embodiment, the
metal material may be deposited using techniques such as
sputtering, electroplating, electrochemical deposition and others.
Alternatively, the first electrode structure may be made of a
carbon based material such as carbon or graphite. Yet
alternatively, the first electrode structure may be made of a
conductive polymer material, depending on the application. Of
course there can be other variations, modifications, and
alternatives, modifications, and alternatives.
[0027] Referring again to FIG. 1, the first photovoltaic cell
structure includes a lower cell 110 overlying the first electrode
structure. In a specific embodiment, the lower cell includes a
first absorber layer 112 characterized by a P type impurity
characteristics. That is, the first absorber layer absorbs
electromagnetic radiation forming positively charged carriers
within the first absorber layer. In a specific embodiment, the
first absorber layer comprises a first metal chalcogenide
semiconductor material and/or other suitable semiconductor
material. The first absorber layer is characterized by a bandgap.
In a specific embodiment, the first absorber layer has a first
bandgap of ranging from about 0.7 eV to about 1.2 eV. In an
alternative embodiment, the first absorber layer can have a first
bandgap of about 0.5 eV to about 1.2 eV. In a preferred embodiment,
the first absorber layer can have a bandgap of about 0.5 eV to
about 1.0 eV. The first metal chalcogenide semiconductor material
can include a suitable metal oxide. Alternatively, the first metal
chalcogenide semiconductor material can include a suitable metal
sulfide. Yet alternatively first metal chalcogenide semiconductor
material can include a metal telluride or metal selenide depending
on the application. In certain embodiments, the first absorber
layer can be provided using a metal silicide material such as iron
disilicide material, which has a P type impurity characteristics,
and others. In a specific embodiment, the first absorber layer can
be deposited using techniques such as sputtering, spin coating,
doctor blading, powder coating, electrochemical deposition,
inkjeting, among others, depending on the application. Of course
there can be other variations, modifications, and alternatives.
[0028] In a specific embodiment, the first absorber layer has an
optical absorption coefficient greater than about 10.sup.4
cm.sup.-1 for electromagnetic radiation in a wavelength range of
about 400 nm to about 800 nm. In an alternative embodiment, the
first absorber layer can have an optical absorption coefficient
greater than about 10.sup.4 cm.sup.-1 for electromagnetic radiation
in a wavelength range of about 450 nm to about 700 nm. Of course
there can be other variations, modifications, and alternatives.
[0029] Referring to FIG. 1, the lower cell includes a first window
layer 114 overlying the first absorber layer. In a specific
embodiment, the first window layer has a N.sup.+ impurity type
characteristics. In a preferred embodiment, the first window layer
is characterized by a bandgap greater than about 2.5 eV, for
example ranging from 2.5 eV to about 5.5 eV. In a specific
embodiment, the first window layer comprises a second metal
chalcogenide semiconductor material and/or other suitable
semiconductor material. Alternatively, the second metal
chalcogenide semiconductor material can comprise a semiconductor
metal sulfide, a semiconductor metal oxide, a semiconductor metal
telluride or a semiconductor metal selenide material. In certain
embodiment, the first window layer may use an n-type zinc sulfide
material for a iron disilicide material as the first absorber
layer. In a specific embodiment, the first window layer can be
deposited using techniques such as sputtering, spin coating, doctor
blading, powder coating, electrochemical deposition, inkjeting,
among others, depending on the application. Of course there can be
other variations, modifications, and alternatives.
[0030] Again referring to FIG. 1, the first photovoltaic cell
structure includes a second electrode structure 116 overlying the
lower cell in a specific embodiment. The second electrode structure
is in electrical contact with the window layer in a specific
embodiment. In a specific embodiment, the second electrode
structure uses a conductor material characterized by a resistivity
less than about 10 ohm-cm. In a specific embodiment, the second
electrode structure can be made of a suitable material or a
combination of materials. The second electrode structure is
preferably made from a transparent conductive electrode material.
Materials that are light reflecting or light blocking may also be
used depending on the embodiment. Examples of the optically
transparent material can include indium tin oxide (ITO), aluminum
doped zinc oxide, fluorine doped tin oxide and others. In an
alternative embodiment, the second electrode structure may be made
from a metal material. The metal material can include gold, silver,
nickel, platinum, aluminum, tungsten, molybdenum, a combination of
these, or an alloy, among others. In a specific embodiment, the
metal material may be deposited using techniques such as
sputtering, electroplating, electrochemical deposition and others.
Yet alternatively, the second electrode structure may be made of a
carbon based material such as carbon or graphite. In certain
embodiments, the second electrode structure may be made of a
conductive polymer material, depending on the application. Of
course there can be other variations, modifications, and
alternatives.
[0031] As shown in FIG. 1, photovoltaic cell structure 100 includes
a second photovoltaic cell structure 118. In a specific embodiment,
the second photovoltaic cell structure includes a third electrode
structure 120. In a specific embodiment, the third electrode
structure uses a conductor material characterized by a resistivity
less than about 10 ohm-cm. In a specific embodiment, the third
electrode structure can be made of a suitable material or a
combination of materials. The third electrode structure is
preferably made from a transparent conductive electrode. Materials
that are light reflecting or light blocking may also be used
depending on the embodiment. Examples of the optically transparent
material can include indium tin oxide (ITO), aluminum doped zinc
oxide, fluorine doped tin oxide and others. In an alternative
embodiment, the second electrode structure may be made from a metal
material. The metal material can include gold, silver, nickel,
platinum, aluminum, tungsten, molybdenum, a combination of these,
or an alloy, among others. In a specific embodiment, the metal
material may be deposited using techniques such as sputtering,
electroplating, electrochemical deposition, and others. Yet
alternatively, the second electrode structure may be made of a
carbon based material such as carbon or graphite. In certain
embodiments, the second electrode structure may be made of a
conductive polymer material, depending on the application. Of
course there can be other variations, modifications, and
alternatives.
[0032] The upper photovoltaic cell includes an upper cell 122
overlying the third electrode structure. The upper cell includes a
second absorber layer 124 overlying the third electrode structure.
In a specific embodiment, the second absorber layer is
characterized by a P type impurity characteristics. That is, the
second absorber layer absorbs electromagnetic radiation forming
positively charged carriers within the second absorber layer. In a
specific embodiment, the second absorber layer comprises a third
metal chalcogenide semiconductor material. The third metal
chalcogenide semiconductor material is characterized by a second
bandgap. In a specific embodiment, the second bandgap is greater
than the first bandgap. In a specific embodiment, the second
bandgap can range from about 1.0 eV to about 2.2 eV. In an
alternative embodiment, the second bandgap can range from about 1.0
eV to about 2.5 eV. In a preferred embodiment, the third bandgap
can range from about 1.2 eV to about 1.8 eV. The third metal
chalcogenide semiconductor material can include a suitable
semiconductor metal oxide. Alternatively, the third metal
chalcogenide semiconductor material can include a suitable metal
sulfide. Yet alternatively third metal chalcogenide semiconductor
material can include a suitable semiconductor metal telluride or
metal selenide depending on the application. In a specific
embodiment, the second absorber layer is provided using a copper
oxide material, which has a p type impurity characteristics. Of
course there can be other variations, modifications, and
alternatives.
[0033] Referring again to FIG. 1, the upper cell includes a second
window layer 126. In a specific embodiment, the second window layer
has a N.sup.+ impurity type characteristics. In a specific
embodiment, the second window layer is characterized by a bandgap
greater than about 2.5 eV, for example, ranging from about 2.5 eV
to 5.0 eV. In a specific embodiment, the second window layer
comprises a fourth metal chalcogenide semiconductor material. The
fourth metal chalcogenide semiconductor material can include a
suitable semiconductor metal sulfide, a suitable semiconductor
metal oxide, a suitable semiconductor metal telluride or a suitable
semiconductor metal selenide material. In a specific embodiment,
the second window layer may be provided using a sinc sulfide
material, which has an N type impurity characteristics. In a
specific embodiment, the second window layer may be deposited using
techniques such as sputtering, doctor blading, inkjeting,
electrochemical deposition, and others.
[0034] In a specific embodiment, the second photovoltaic cell
structure includes a fourth electrode structure 128 overlying the
upper cell. In a specific embodiment, the fourth electrode
structure uses a conductor material characterized by a resistivity
less than about 10 ohm-cm. In a specific embodiment, the fourth
electrode structure can be made of a suitable material or a
combination of materials. The fourth electrode structure is
preferably a transparent conductive electrode. Materials that are
light reflecting or light blocking may also be used depending on
the embodiment. Examples of the transparent conductive electrode
can include indium tin oxide (ITO), aluminum doped zinc oxide,
fluorine doped tin oxide and others. In an alternative embodiment,
the fourth electrode structure may be made from a metal material.
The metal material can include gold, silver, nickel, platinum,
aluminum, tungsten, molybdenum, a combination of these, or an
alloy, among others. In a specific embodiment, the metal material
may be deposited using techniques such as sputtering,
electroplating, electrochemical deposition and others. Yet
alternatively, the fourth electrode structure may be made of a
carbon based material such as carbon or graphite. In certain
embodiments, the fourth electrode structure may be made of a
conductive polymer material, depending on the application. Of
course there can be other variations, modifications, and
alternatives.
[0035] In a specific embodiment, the first photovoltaic cell
structure and the second photovoltaic cell structure are coupled
together using a glue layer 130 to form a multijunction
photovoltaic cell structure as shown in FIG. 1. As shown,
photovoltaic cell structure 100 includes a first junction region
132 caused by the first absorber layer and the first window layer.
Photovoltaic cell structure 100 includes also a second junction
region 134 caused by the second absorber layer and the second
window layer. The glue layer is a suitable material that has
desirable optical and mechanical characteristics. Such material can
be ethyl vinyl acetate or polyvinyl butyral and the like, but can
also be others. As shown in FIG. 2 a simplified circuit
representation 130 of the multijunction cell structure is depicted.
As shown, the multijunction photovoltaic cell structure has four
terminals 136, 138, 140, and 142 provided by the first electrode
structure, the second electrode structure, the third electrode
structure, and the fourth electrode structure. The multijunction
photovoltaic cell has two photodiodes 144 and 146 as provided by
the upper cell and the lower cells. Of course one skilled in the
art would recognize other variations, modifications, and
alternative.
[0036] In a specific embodiment, the photovoltaic cell structure
can have an optional buffer layer 148 disposed between the second
conductor structure and the second absorber layer of the upper cell
as shown in FIG. 1. The optional buffer layer is characterized by a
resistivity greater than about 10 kohm-cm and is preferably
optically transparent in a specific embodiment. Of course there can
be other variations, modifications, and alternatives.
[0037] FIG. 3 is a simplified diagram illustrating another
photovoltaic cell structure 300 for manufacture of a multijunction
solar cell module according to an alternative embodiment of the
present invention. Photovoltaic cell structure 300 is configured to
have two junctions and two electrode. As shown, photovoltaic cell
structure 300 includes a lower cell 302 which includes a first
pn.sup.+ junction 304. The lower cell can have a same material
composition as the lower cell as described above in connection with
the photovoltaic cell structure in FIG. 1. The lower cell is in
electrical contact with a first electrode structure 306 which
overlies a surface region 310 of a substrate member 308 also as
described above for FIG. 1.
[0038] Photovoltaic cell 300 includes an upper cell 312 which
includes a second pn.sup.+ junction 314. The upper cell also has a
same material composition as the upper cell as described above in
connection with the photovoltaic cell structure in FIG. 1. A second
electrode structure 316 overlies and in electrical contact with a
surface region 318 of the upper cell.
[0039] In a specific embodiment, a tunneling junction layer 320 is
provided between the upper cell and the lower cell as shown in FIG.
3. The tunneling junction layer comprises a p++/n++ layer and is
characterized by a thickness 322. In a specific embodiment, the
tunneling junction layer can be adjusted, either by way of
thickness, or by way of dopant characteristics, to provide an
optimized current flow between the upper cell and the lower cell.
Of course there can be other variations, modifications, and
alternatives.
[0040] Optionally, photovoltaic cell structure 300 can include a
buffer layer 324, which is optional, disposed between the second
conductor structure and the upper cell. The buffer layer prevents
diffusion of, for example, electrode materials into the
photovoltaic cell in subsequent high temperature processing steps.
Buffer layer 324 may be made from a high resistance transparent
material having a resistivity greater than 10 kOhm-cm in a specific
embodiment. Example of such high resistance transparent material
can include intrinsic semiconductor such as intrinsic zinc oxide,
intrinsic zinc sulfide and the like. Of course there can be other
variations, modifications, and alternatives.
[0041] FIG. 4 is a simplified circuit diagram for photovoltaic cell
structure 300 according to an embodiment of the present invention.
As shown, the photovoltaic cell structure includes a first
photodiode 402, a second photodiode 404, a first electrode terminal
406, and a second electrode terminal 408. Photovoltaic cell
structure 300 can be characterized by two junctions, provided by
each of the photodiodes and two electrode terminals. The first
photodiode and the second photodiode are connected in series by
means of the tunneling junction. Of course there can be other
variations, modifications, and alternatives.
[0042] FIG. 5 is a simplified diagram illustrating a photovoltaic
cell structure 500 for manufacturing of a multijunction solar
module according to another alternative embodiment of the present
invention. Photovoltaic cell structure 500 is configured to have
two junctions and three electrode terminals. As shown, photovoltaic
cell structure 500 includes a lower cell 502 which includes a first
pn.sup.+ junction 504. The lower cell can have a same material
composition as the lower cell as described above in connection with
the photovoltaic cell structure in FIG. 1. The lower cell is in
electrical contact with a first electrode structure 506 which
overlies a surface region 510 of a substrate member 508 also as
described above for FIG. 1.
[0043] Photovoltaic cell structure 500 includes an upper cell 512
which includes a second pn.sup.+ junction 514. The upper cell can
have a same material composition as the upper cell as described
above in connection with the photovoltaic cell structure in FIG. 1.
A second electrode structure 516 overlies and in electrical contact
with the upper cell.
[0044] In a specific embodiment, a third conductor structure 520 is
provided between the upper cell and the lower cell as shown in FIG.
5. The third conductor structure connects the upper cell and the
lower cell in series in a specific embodiment. In a specific
embodiment, the third conductor structure is characterized by a
resistivity less than about 10 ohm-cm. The third electrode
structure can be made of a suitable material or a combination of
materials. The third electrode structure is preferably made from a
transparent conductive electrode or materials. Examples of the
transparent conductive material can include indium tin oxide (ITO),
aluminum doped zinc oxide, fluorine doped tin oxide and others. In
an alternative embodiment, the third electrode structure may be
made from a metal material. The metal material can include gold,
silver, nickel, platinum, aluminum, tungsten, molybdenum, a
combination of these, or an alloy, among others. In a specific
embodiment, the metal material may be deposited using techniques
such as sputtering, electroplating, electrochemical deposition and
others. Yet alternatively, the third electrode structure may be
made of a carbon based material such as carbon or graphite. In
certain embodiments, the third electrode structure may be made of a
conductive polymer material, depending on the application. Of
course there can be other variations, modifications, and
alternatives.
[0045] In certain embodiments, the photovoltaic cell structure 500
can include an optional first buffer layer 524 disposed between the
second conductor structure and the upper cell as shown in FIG. 5.
Photovoltaic cell structure 500 can also include an optional second
buffer layer 526 provided between the third electrode structure and
the lower cell. These buffer layers prevent diffusion of, for
example, electrode materials into the respective photovoltaic cells
in subsequent high temperature processing steps. In a specific
embodiment, the buffer layers are characterized by a resistivity
greater than about 10 kohm-cm and can be provided using a suitable
metal oxide. Of course there can be other variations,
modifications, and alternatives.
[0046] FIG. 6 is a simplified circuit representation 600 of the
photovoltaic cell structure in FIG. 5. As shown in FIG. 6, the
photovoltaic cell structure has 3 terminals 602, 604, and 606
provided by the first electrode structure, the second electrode
structure, and the third electrode structure The photovoltaic cell
has two photodiodes 608 and 610 as provided by the upper cell and
the lower cell. Of course one skilled in the art would recognize
other variations, modifications, and alternative.
[0047] FIG. 7 is a simplified cross-sectional view of an example of
a hetero-junction cell 700 according to an embodiment of the
present invention. As shown, the cell has a substrate 701 including
a surface region. In a specific embodiment, the substrate can be a
glass material, although other materials can be used. In a specific
embodiment, the cell has a first conductor layer 703, which is a
back contact, overlying the surface region. As an example, the back
contact is a metal material. To define the lower cell structure, a
first P type absorber (e.g., P-) comprising an iron disilicide
material 705 is included. Further details of forming iron
disilicide material have been described in U.S. patent application
Ser. Nos. 12/209,801 (Attorney Docket No. 026335-001410US) filed
Sep. 12, 2008, which claims priority to US Provisional Application
No. 60/976,239, filed Sep. 28, 2007 and 12/210,173 (Attorney Docket
No. 026335-001510US) filed Sep. 12, 2008, which claims priority to
U.S. Provisional Application 60/976,317, filed Sep. 28, 2007), and
hereby incorporate by reference for all purpose. In a specific
embodiment, a first N.sup.+ type window layer is included. In a
specific embodiment, the first N.sup.+ type window layer is
provided by a N--ZnS material. In a specific embodiment, a high
resistance transparent layer 709, which is optional, overlies the
first N.sup.+ type window layer. As an example, the high resistance
layer can be intrinsic ZnS, intrinsic ZnO or other suitable
materials.
[0048] Overlying the lower cell is a transparent conductive oxide
711, which can be ZnO (doped with aluminum), SnO.sub.3 (doped with
fluorine), or other suitable materials. Disposed between the lower
and upper cells is a lamination layer and can be a glue layer,
which is optically transparent. The lamination layer may be
provided using an EVA material or a PVB material in a specific
embodiment. To form an upper cell structure, a third transparent
conductive oxide 712 is provided according to a specific
embodiment. A second P type absorber layer 713 comprising a copper
oxide material or other suitable material is formed overlying
transparent conductive oxide 712. A second N.sup.+ type window
layer 715 comprising an n-ZnS material is overlying the second P
type absorber layer. In a specific embodiment, a second high
resistance transparent layer 717 is overlying the second N.sup.+
type window layer. As an example, the second high resistance
transparent layer 717 can be intrinsic ZnS, intrinsic ZnO, or other
suitable materials. A transparent conductive oxide 719 is formed
overlying high resistance transparent layer 717 according to a
specific embodiment. Of course, depending upon the embodiment, the
materials and/layers specified can be applied to other cell
configurations such as three electrode, two electrode, and
others.
[0049] It is also understood that the examples and embodiments
described herein are for illustrative purposes only and that
various modifications or changes in light thereof will be suggested
to persons skilled in the art. For example, embodiments according
to the present invention have been described using a two cell
configuration. It is understood that the present invention can be
extended to include N cells (N.gtoreq.2). Various modifications and
changes are to be included within the spirit and purview of this
application and scope of the appended claims.
* * * * *