U.S. patent application number 15/897718 was filed with the patent office on 2018-06-21 for array of monolithically integrated thin film photovoltaic cells and associated methods.
The applicant listed for this patent is Ascent Solar Technologies, Inc.. Invention is credited to Venugopala R. Basava, Mohan S. Misra, Prem Nath.
Application Number | 20180175234 15/897718 |
Document ID | / |
Family ID | 40135233 |
Filed Date | 2018-06-21 |
United States Patent
Application |
20180175234 |
Kind Code |
A1 |
Misra; Mohan S. ; et
al. |
June 21, 2018 |
Array Of Monolithically Integrated Thin Film Photovoltaic Cells And
Associated Methods
Abstract
A process of forming an array of monolithically integrated thin
film photovoltaic cells from a stack of thin film layers formed on
an insulating substrate includes forming at least one cell
isolation scribe in the stack of thin film layers. A second
electrical contact layer isolation scribe is formed for each cell
isolation scribe adjacent to a respective cell isolation scribe. A
via scribe is formed in the stack of thin film layers between each
cell isolation scribe and its respective second electrical contact
layer isolation scribe. Insulating ink is disposed in each cell
isolation scribe, and conductive ink is disposed in each via scribe
to form a via. Conductive ink is also disposed along the top
surface of the stack of thin film layers to form at least one
conductive grid.
Inventors: |
Misra; Mohan S.; (Golden,
CO) ; Nath; Prem; (Fort Lauderdale, FL) ;
Basava; Venugopala R.; (Highlands Ranch, CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ascent Solar Technologies, Inc. |
Thornton |
CO |
US |
|
|
Family ID: |
40135233 |
Appl. No.: |
15/897718 |
Filed: |
February 15, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14252485 |
Apr 14, 2014 |
9929306 |
|
|
15897718 |
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|
12143713 |
Jun 20, 2008 |
8716591 |
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14252485 |
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60945314 |
Jun 20, 2007 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 31/05 20130101;
H01L 31/0465 20141201; Y02E 10/50 20130101; H01L 31/1876
20130101 |
International
Class: |
H01L 31/18 20060101
H01L031/18; H01L 31/05 20140101 H01L031/05; H01L 31/0465 20140101
H01L031/0465 |
Claims
1. A process of forming an array of monolithically integrated thin
film photovoltaic cells from a stack of thin film layers formed on
an insulating substrate, the stack of thin film layers including a
first electrical contact layer formed on the substrate, a
photovoltaic stack formed on the first electrical contact layer,
and a second electrical contact layer formed on the photovoltaic
stack, the process comprising: forming at least one second
electrical contact layer isolation scribe in the stack of thin film
layers, each instance of the at least one second electrical contact
layer isolation scribe extending at least through the second
electrical contact layer of the stack of thin film layers;
extending a first portion of the at least one second electrical
contact layer isolation scribe to the substrate to form a cell
isolation scribe for each instance of the at least one second
electrical contact layer isolation scribe; disposing insulating ink
in each cell isolation scribe and in each instance of the at least
one second electrical contact layer isolation scribe; after
disposing the insulating ink, extending a via scribe from a second
portion of each second electrical contact layer isolation scribe,
each via scribe extending at least through the insulating ink of a
second portion of a respective second electrical contact layer
isolation scribe to the first electrical contact layer, the first
portion being in a different region of the second electrical
contact layer isolation scribe than the second portion; disposing
conductive ink in each via scribe to form a via; and disposing
conductive ink along the top surface of the stack of thin film
layers to form at least one conductive grid, each instance of the
at least one conductive grid connecting a respective via to the
second electrical contact layer of a photovoltaic cell adjacent
thereto.
2. The process of claim 1, the photovoltaic stack forming at least
one photovoltaic junction for converting electromagnetic energy
into electric power.
3. The process of claim 2, the photovoltaic stack including a solar
absorber layer and a window layer.
4. The process of claim 1, the step of disposing insulating ink
being executed using an ink jet printing process.
5. The process of claim 1, the steps of disposing conductive ink
being executed using an ink jet printing process.
6. The process of claim 1, at least one of the step of forming and
the steps of extending being executed using a laser scribing
process.
7. The process of claim 6, the laser scribing process including
moving the stack of thin film layers formed on the insulating
substrate on a production apparatus.
8. The process of claim 6, the laser scribing process including
moving a laser beam on a production apparatus.
9. The process of claim 1, the insulating substrate selected from
the group consisting of an insulated metal substrate, a glass
substrate, and a polymeric material substrate.
10. The process of claim 1, each of the steps being executed with a
single registration of the stack of thin film layers formed on the
insulating substrate to a production apparatus.
11. The process of claim 1, each of the steps being executed by a
single production apparatus.
12. The process of claim 1, each instance of the at least one
second electrical contact layer isolation scribe having a first
width, each cell isolation scribe having a second width, the first
width being greater than the second width.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 14/252,485 filed 14 Apr. 2014, which is a divisional of
U.S. patent application Ser. No. 12/143,713 filed 20 Jun. 2008,
which claims benefit of priority to U.S. Provisional Application
Ser. No. 60/945,314 filed 20 Jun. 2007. Each of the above-mentioned
applications is incorporated herein by reference.
BACKGROUND
[0002] A photovoltaic cell generates electric power from
electromagnetic energy (e.g., sunlight) incident thereon. Thin film
photovoltaic cells are a class of photovoltaic cells formed by
depositing a plurality of thin films onto a substrate, each of
which serves one or more specific functions. Thin film photovoltaic
cells generally include a first electrical contact layer, one or
more films that comprise the active photovoltaic device, and a
second electrical contact layer. Depending upon the orientation of
the photovoltaic cell, at least one of the first and second
electrical contact layers is transparent to allow electromagnetic
energy to reach the active device films. If the substrate is an
insulating substrate (that is, the substrate has a high electrical
resistivity interface for forming one of the first or second
electrical contacts thereon), a plurality of thin film photovoltaic
cells can be monolithically integrated onto the insulating
substrate.
[0003] The magnitude of an electric current generated by a thin
film photovoltaic cell is proportional the area of the photovoltaic
cell. However, the magnitude of a voltage generated by the thin
film photovoltaic cell is largely a function of the materials used
to form the thin film layers. Accordingly, in order to increase an
output voltage magnitude of an array of thin film photovoltaic
cells, a plurality of cells may be electrically connected in
series.
SUMMARY
[0004] A process of forming an array of monolithically integrated
thin film photovoltaic cells from a stack of thin film layers
formed on an insulating substrate includes the following steps. At
least one cell isolation scribe is formed in the stack of thin film
layers. Each instance of the at least one cell isolation scribe
delineates the stack of thin film layers into a plurality of
photovoltaic cells, and each instance of the at least one cell
isolation scribe extends from a top surface of the stack of thin
film layers to the substrate. A second electrical contact layer
isolation scribe is formed for each instance of the at least one
cell isolation scribe. The second electrical contact layer
isolation scribe is formed in the stack of thin film layers
adjacent to a respective cell isolation scribe and extends at least
through a second electrical contact layer of the stack of thin film
layers. A via scribe is formed in the stack of thin film layers
between each cell isolation scribe and its respective second
electrical contact layer isolation scribe. Each via scribe extends
at least from the top surface of the stack of thin film layers to a
first electrical contact layer of the stack of thin film layers.
Insulating ink is disposed in each cell isolation scribe, and
conductive ink is disposed in each via scribe to form a via.
Conductive ink is also disposed along the top surface of the stack
of thin film layers to form at least one conductive grid, where
each instance of the at least one conductive grid connects a
respective via to the second electrical contact layer of an
adjacent photovoltaic cell.
[0005] A process of forming an array of monolithically integrated
thin film photovoltaic cells includes the following steps. A stack
of thin film layers is formed on an insulating substrate. The stack
of thin film layers includes a first electrical contact layer
formed on the substrate, a photovoltaic stack formed on the first
electrical contact layer, and a second electrical contact layer
formed on the photovoltaic stack. At least one cell isolation
scribe is formed in the stack of thin film layers to delineate the
stack into a plurality of photovoltaic cells. Each instance of the
at least one cell isolation scribe extends from a top surface of
the stack of thin film layers to the substrate. A second electrical
contact layer isolation scribe is formed for each instance of the
at least one cell isolation scribe. Each second electrical contact
layer isolation scribe is formed in the stack of thin film layers
adjacent to a respective cell isolation scribe, and each second
electrical contact layer isolation scribe extends at least through
the second electrical contact layer of the stack of thin film
layers. A via scribe is formed in the stack of thin film layers
between each cell isolation scribe and its respective second
electrical contact layer isolation scribe. Each via scribe extends
at least from the top surface of the stack of thin film layers to
the first electrical contact layer. Insulating ink is disposed in
each cell isolation scribe, and conductive ink is disposed in each
via scribe to form a via. Conductive ink is further disposed along
the top surface of the stack of thin film layers to form at least
one conductive grid. Each instance of the at least one conductive
grid connects a via to the second electrical contact layer of a
respective adjacent photovoltaic cell.
[0006] An array of monolithically integrated thin film photovoltaic
cells includes an insulating substrate and a plurality of
photovoltaic cells formed on the insulating substrate. Each
photovoltaic cell is separated from at least one other photovoltaic
cell by one or more cell isolation scribes filled with insulating
ink. Each photovoltaic cell includes the following: (1) a first
electrical contact layer formed on the insulating substrate; (2) a
photovoltaic stack formed on the first electrical contact layer;
(3) a second electrical contact layer formed on the photovoltaic
stack; (4) a second electrical contact layer isolation scribe
filled with insulating ink formed adjacent to a cell isolation
scribe at least partially delineating the photovoltaic cell; (5) a
via filled with conductive ink extending from the first electrical
contact layer to a top surface of the array; and (6) at least one
conductive grid disposed on the top surface of the array for
connecting two adjacent photovoltaic cells.
[0007] A process of forming an array of monolithically integrated
thin film photovoltaic cells from a stack of thin film layers
formed on an insulating substrate includes the following steps. At
least one cell isolation scribe is formed in the stack of thin film
layers to delineate the stack of thin film layers into a plurality
of photovoltaic cells. Each instance of the at least one cell
isolation scribe extends from a top surface of the stack of thin
film layers to a substrate of the stack of thin film layers. A
second electrical contact layer isolation scribe is formed for each
instance of the at least one cell isolation scribe, and each second
electrical contact layer isolation scribe is formed in the stack of
thin film layers adjacent to its respective cell isolation scribe.
Each second electrical contact layer isolation scribe extends at
least through a top contact layer of the stack of thin film layers.
A via scribe is formed in the stack of thin film layers between
each cell isolation scribe and its respective second electrical
contact layer isolation scribe. Each via scribe extends at least
from the top surface of the stack of thin film layers to a back
contact layer of the stack of thin film layers. Insulating ink is
disposed in each cell isolation scribe, and conductive ink is
disposed in each via scribe to form a via. Conductive ink is
further disposed along the top surface of the stack of thin film
layers to form at least one conductive grid, where each instance of
the at least one conductive grid connects a respective via to the
top contact layer of an adjacent photovoltaic cell.
[0008] A process of forming an array of monolithically integrated
thin film photovoltaic cells from a stack of thin film layers
formed on an insulating substrate includes the following steps. At
least one second electrical contact layer isolation scribe is
formed in a second electrical contact layer of the stack of thin
film layers. A first portion of each instance of the at least one
second electrical contact layer isolation scribe is extended to a
substrate to form a cell isolation scribe for each instance of the
at least one second electrical contact layer isolation scribe.
Insulating ink is disposed in each cell isolation scribe and in
each instance of the at least one second electrical contact layer
isolation scribe. A via scribe is formed for each instance of the
at least one second electrical contact layer isolation scribe. Each
via scribe extends at least through the insulating ink of a second
portion of a respective second electrical contact layer isolation
scribe to a first electrical contact layer. The second portion does
not overlap the first portion of each instance of the at least one
second electrical contact layer isolation scribe. Conductive ink is
disposed in each via scribe to form a via. Conductive ink is
disposed along a top surface of the stack of thin film layers to
form at least one conductive grid. Each instance of the at least
one conductive grid connects a respective via to the second
electrical contact layer of an adjacent photovoltaic cell.
[0009] A process of forming an array of monolithically integrated
thin film photovoltaic cells from a stack of thin film layers
formed on an insulating substrate includes the following steps. At
least one second electrical contact layer isolation scribe is
formed in the stack of thin film layers. Each instance of the at
least one second electrical contact layer isolation scribe extends
at least through the second electrical contact layer of the stack
of thin film layers. A first portion of each instance of the at
least one second electrical contact layer isolation scribe is
extended to a substrate to form a cell isolation scribe for each
instance of the at least one second electrical contact layer
isolation scribe. A second portion of each instance of the at least
one second electrical contact layer isolation scribe is extended to
a first electrical contact layer to form a via scribe. The second
portion does not overlap the first portion of each instance of the
at least one second electrical contact layer isolation scribe.
Insulating ink is disposed in each cell isolation scribe and in
each instance of the at least one second electrical contact layer
isolation scribe such that insulating ink does not fill the via
scribe. Conductive ink is disposed in each via scribe to form a
via. Conductive ink is disposed along a top surface of the stack of
thin film layers to form at least one conductive grid. Each
instance of the at least one conductive grid connects a respective
via to the second electrical contact layer of an adjacent
photovoltaic cell.
BRIEF DESCRIPTION OF DRAWINGS
[0010] FIG. 1 is a top perspective view of one array of
monolithically integrated photovoltaic cells, in accord with an
embodiment.
[0011] FIG. 2 shows one process of forming an array of
monolithically integrated photovoltaic cells, in accord with an
embodiment.
[0012] FIG. 3 shows one process of performing scribing and printing
processes, in accord with an embodiment.
[0013] FIG. 4 shows one process of performing scribing and printing
processes, in accord with an embodiment.
[0014] FIG. 5 is a cross-sectional view of one stack of thin-film
layers formed on an insulating substrate, in accord with an
embodiment.
[0015] FIGS. 6A-6E are cross-sectional views of an array of
monolithically integrated photovoltaic cells formed according to an
embodiment of the process of FIG. 3.
[0016] FIGS. 7A-7F are cross-sectional views of an array of
monolithically integrated photovoltaic cells formed according to an
embodiment of the process of FIG. 4.
[0017] FIG. 8 shows one process of performing scribing and printing
processes, in accord with an embodiment.
[0018] FIG. 9 shows one process of performing scribing and printing
processes, in accord with an embodiment.
[0019] FIGS. 10A-10E are cross-sectional views of an array of
monolithically integrated photovoltaic cells formed according to an
embodiment of the process of FIG. 8.
[0020] FIGS. 11A-11F are cross-sectional views of an array of
monolithically integrated photovoltaic cells formed according to an
embodiment of the process of FIG. 9.
[0021] FIG. 12 is a top plan view of one array of monolithically
integrated photovoltaic cell formed according to the processes of
FIG. 3 or 4.
[0022] FIG. 13 is a cross-sectional view of the array of
monolithically integrated photovoltaic cells of FIG. 12.
DETAILED DESCRIPTION OF DRAWINGS
[0023] It is noted that, for purposes of illustrative clarity,
certain elements in the drawings may not be drawn to scale.
Specific instances of an element may be referred to by use of a
numeral in parentheses (e.g., photovoltaic cell 102(1)) while
numerals without parentheses refer to any such item (e.g.,
photovoltaic cells 102).
[0024] FIG. 1 is a top perspective view of one array 100 of
monolithically integrated photovoltaic cells 102, which generate
electric power from electromagnetic radiation 104 (e.g., sunlight),
either incident on the photovoltaic cells, or transmitted to the
photovoltaic cells through a transparent substrate. The electric
power is accessible via electrical terminals 106(1) and 106(2).
Array 100 includes a plurality of photovoltaic cells 102
monolithically integrated onto an insulating substrate 108.
Substrate 108 may be, but need not be, at least partially
transparent. Although array 100 is illustrated as including ten
photovoltaic cells 102 (only photovoltaic cells 102(1) and 102(10)
are labeled for illustrative clarity), array 100 may include any
quantity of photovoltaic cells 102.
[0025] Photovoltaic cells 102 are, for example, electrically
connected in series. In such a case, a voltage magnitude measured
between electrical terminals 106(1) and 106(2) is approximately the
sum of the voltages generated by each photovoltaic cell 102,
neglecting losses due to impedance of interconnections between
photovoltaic cells 102.
[0026] FIG. 2 shows a process 200 of forming an array of
monolithically integrated photovoltaic cells. Process 200 may be
used, for example, to form array 100 of FIG. 1. Process 200 begins
with step 202 of forming a stack of thin film layers on an
insulating substrate. Process 200 proceeds to step 204 where
isolating and connecting processes are performed on the stack of
thin film layers formed in step 202. The isolating and connecting
processes form the plurality of monolithically integrated
photovoltaic cells from the stack of thin film layers. In an
embodiment of process 200, the isolating and connecting processes
of step 204 include scribing and printing processes, as discussed
below with respect to FIGS. 3 and 6A-6E, FIGS. 4 and 7A-7F, FIGS. 8
and 10A-10E, and FIGS. 9 and 11A-11F. It should be appreciated that
in process 200, the step of forming the stack of thin film layers
may be different from the step performing the isolating and
connecting processes. This division of steps may provide one or
more benefits, as discussed below.
[0027] Step 202 is executed using processes acceptable for forming
a stack of thin film layers on an insulating substrate. In an
embodiment of process 200, step 202 is executed using a
roll-to-roll deposition process and/or using a single deposition
line. Furthermore, in step 202, a bulk sheet of thin film layers
may be formed on an insulating substrate and subsequently cut into
two or more sections; one of these sections may then be used in
step 204. Such cutting may be performed using a production
apparatus (e.g., laser system) with means for translating a laser
beam and/or the substrate to facilitate the patterning.
[0028] FIG. 5 is a cross-sectional view of one stack 500 of thin
film layers formed on an insulating substrate. Stack 500 is an
example of a stack that may be formed in step 202 of process 200.
Stack 500 includes an insulating substrate 502, a first electrical
contact layer 504 formed on substrate 502, a photovoltaic stack 506
formed on first electrical contact layer 504, and a second
electrical contact layer 508 formed on photovoltaic stack 506. The
term "insulating substrate," in the context of stack 500, means
that substrate 502 has an interface with a high electrical
resistivity for forming a first electrical contact layer (e.g.,
layer 504) thereon.
[0029] Substrate 502 is, for example, an insulated metal substrate,
a glass substrate, or a polymeric material substrate. Photovoltaic
stack 506 includes of one or more thin film layers for converting
electromagnetic energy (e.g., sunlight) into electrical power. For
example, photovoltaic stack 506 may include thin film semiconductor
and oxide layers forming at least one junction having one of a p-n,
n-p, p-i-n, and n-i-p configuration with respect to first
electrical contact layer 504. Photovoltaic stack 506 may include
one or more sequences of the semiconductor layers. Such sequences
include, for example, a solar absorber layer and/or a window
layer.
[0030] The solar absorber layer includes, for example, a copper
group I-III-VI material or a silver based group I-III-VI material.
In each of these two cases, the solar absorber layer may further
include at least one alloy, where the alloy includes gallium,
aluminum, boron, sulfur, and/or tellurium. The solar absorber layer
may further include of a plurality of sublayers, where at least one
of the sublayers is formed of an amorphous-silicon based material
or a micro-silicon based material.
[0031] The window layer may include cadmium sulfide, zinc sulfide,
alloys of cadmium-zinc sulfide, zinc oxide, zinc hydroxide,
zinc-magnesium oxide, magnesium hydroxide, and/or indium
selenide.
[0032] Photovoltaic stack 506 may also include a buffer layer
adjacent to at least one of first electrical contact layer 504 and
second electrical contact layer 508. Examples of materials that may
be used to form the buffer layer include undoped tin oxide or
undoped zinc oxide.
[0033] First electrical contact layer 504 and second electrical
contact layer 508 are each formed of an electrically conductive
material. Electromagnetic energy must be able to at least partially
penetrate at least one of the first or second electrical contact
layers in order to reach photovoltaic stack 506. Accordingly, at
least one of first electrical contact layer 504 and second
electrical contact layer 508 must be at least partially transparent
to electromagnetic energy having a range of wavelengths that
photovoltaic stack 506 is operable to convert into electric power.
Examples of materials that may be used to form transparent
electrical contact layers include one or more of the following:
doped tin oxide, undoped tin oxide, indium-tin oxide alloys, doped
zinc oxide, and undoped zinc oxide. The following are examples of
materials that may be used to form opaque electrical contact
layers: molybdenum, alloys of molybdenum, aluminum, alloys of
aluminum, copper, and alloys of copper. The materials used to form
first electrical contact layer 504 and second electrical contact
layer 508 may be selected for compatibility with the materials
forming photovoltaic stack 506.
[0034] FIG. 3 shows one process 204(1) of performing scribing and
printing processes to form an array of monolithically integrated
thin film photovoltaic cells from a stack of thin film layers
formed on an insulating substrate. Process 204(1) is an embodiment
of step 204, and shows substeps of performing isolating and
connecting processes. FIGS. 6A-6E are cross-sectional views of an
array of monolithically integrated photovoltaic cells being formed
according to process 204(1); FIGS. 6A-6E should be referred to in
conjunction with FIG. 3.
[0035] Process 204(1) may be executed on a stack of thin film
layers formed on an insulating substrate. For example, process
204(1) may be executed on stack 600 of FIG. 6A. Stack 600, which is
an embodiment of stack 500 (see, FIG. 5), is illustrated as having
a first electrical contact layer 604 formed on an insulating
substrate 602. First electrical contact layer 604 is, for example,
a back contact layer. As another example, first electrical contact
layer 604 may be formed of a transparent conductive material if
process 204(1) is used to form an array of photovoltaic cells
having a superstrate configuration.
[0036] A photovoltaic stack 606 is formed on first electrical
contact layer 604. Photovoltaic stack 606 includes, for example, a
solar absorber layer formed on first electrical contact layer 604,
a window layer formed on the solar absorber layer, and a buffer
layer optionally formed on the window layer. As another example,
photovoltaic stack 606 may include a window layer formed on first
electrical contact layer 606 and a solar absorber layer formed on
the window layer.
[0037] A second electrical contact layer 608 is formed on
photovoltaic stack 606. Second electrical contact layer 608 is, for
example, a top contact layer or a back contact layer. Stack 600 may
have layers in addition to those illustrated in FIGS. 6A-6E.
[0038] In step 302 of process 204(1), at least one cell isolation
scribe 610 is formed in the stack of thin film layers.
Additionally, in step 302, a second electrical contact layer
isolation scribe 612 is also formed in the stack of thin film
layers for each cell isolation scribe 610. FIG. 6B shows a stack
600(1), which is an example of stack 600 after an embodiment of
step 302 is performed thereon. Cell isolation scribes 610 delineate
the stack of thin film layers into a plurality of photovoltaic
cells. The quantity and configuration of cell isolation scribes 610
determine the quantity of photovoltaic cells formed from the stack.
For example, if a stack of thin film layers is delineated with two
orthogonal cell isolation scribes 610, the stack will form four
photovoltaic cells. Each cell isolation scribe in step 302 extends
from a top surface 616 of the stack of thin film layers to
photovoltaic stack 606.
[0039] Each of the second electrical contact layer isolation
scribes 612 is adjacent to a respective cell isolation scribe 610.
Each second electrical contact layer isolation scribe 612 also
extends from top surface 616 to photovoltaic stack 606. Second
electrical contact layer isolation scribes 612 delineate the ends
of photovoltaic cells. For example, FIG. 6B shows stack 600(1)
forming two photovoltaic cells 626(1) and 626(2). A second
electrical contact layer isolation scribe 612 delineates the end of
photovoltaic cell 626(1).
[0040] In step 304, a via scribe 614 is formed in the stack of thin
film layers between each cell isolation scribe 610 and its
corresponding second electrical contact layer isolation scribe 612.
Furthermore, in step 304, each cell isolation scribe 610 is
extended to substrate 602. FIG. 6C shows a stack 600(2), which is
an example of stack 600(1) after an embodiment of step 304 is
performed thereon.
[0041] Each via scribe 614 extends from top surface 616 of the
stack of thin film layers to first electrical contact layer 604. In
the example of FIG. 6C, via scribes 614 extend from top surface 616
through second electrical contact layer 608 and photovoltaic stack
606 to first electrical contact layer 604. In step 304, each cell
isolation scribe 610 is extended such that it extends from top
surface 616 down to insulating substrate 602.
[0042] In the example FIG. 6C, cell isolation scribe 610 delineates
the beginning of photovoltaic cell 626(2). Electrical contributions
(i.e., electrical power generation) from the area between
photovoltaic cells (e.g., between photovoltaic cells 626(1) and
626(2) of) are lost as a result of patterning (i.e., forming cell
isolation scribes 610 and second electrical contact layer isolating
scribes 612). Such areas between adjacent photovoltaic cells (i.e.,
between each second electrical contact layer isolation scribe 612
and its corresponding cell isolation scribe 610) are used to
electrically connect the adjacent photovoltaic cells, as discussed
below.
[0043] Step 304 proceeds to step 306 wherein an insulating ink 618
is disposed in each cell isolation scribe 610 using a printing
process. FIG. 6D shows a stack 600(3), which is an example of stack
600(2) after an embodiment of step 306 is performed thereon.
Insulating ink 618 provides electrical isolation between adjacent
photovoltaic cells (e.g., between photovoltaic cells 626(1) and
626(2) of FIG. 6D). In a similar manner, an optional insulating ink
620 may further be disposed in step 306 (e.g., at the same time as
disposing insulating ink 618) to fill second electrical contact
layer isolation scribe 612. Both insulating inks 618 and 620 may be
applied using an ink jet printing process.
[0044] In step 308, conductive ink 622 is disposed in each via
scribe 614 using a printing process to form a via 628. Conductive
ink 622 may be further disposed on top surface 616 of the stack of
thin film layers using the printing process to form a conductive
grid 624 over a corresponding adjacent cell isolation scribe 610,
as illustrated in FIG. 6E. Conductive grid 624 electrically
connects adjacent photovoltaic cells. FIG. 6E shows a stack 600(4),
which is an example of stack 600(3) after an embodiment of step 308
is performed thereon. It should be noted that top surface 616 of
the stack of thin film layers may least partially include
insulating ink (e.g., insulating ink 618, 620) that was applied
during step 306.
[0045] In the example of FIG. 6E, via 628 electrically connects
first electrical contact layer 604 of photovoltaic cell 626(1) to
conductive grid 624. Conductive grid 624 in turn connects via 628
to second electrical contact layer 608 of photovoltaic cell 626(2).
Accordingly, first electrical contact layer 604 of photovoltaic
cell 626(1) is connected to second electrical contact layer 608 of
photovoltaic cell 626(2) by via 628 and conductive grid 624.
[0046] Conductive ink 622 may be applied using an ink jet printing
process. In process 204(1), cell isolation scribes 610, second
electrical contact layer isolation scribes 612, and/or via scribes
614 may be formed using a laser scribing process. Such laser
scribing processes may be executed using a production apparatus
(e.g., laser system) with the means for translating either the
substrate, a laser beam, or both, to achieve the desired
pattern.
[0047] FIG. 4 shows another process 204(2) of performing scribing
and printing processes to form an array of monolithically
integrated thin film photovoltaic cells from a stack of thin film
layers formed on an insulating substrate. Process 204(2) is an
embodiment of process 204 of performing isolating and connecting
processes. FIGS. 7A-7F are cross-sectional views of an array of
monolithically integrated photovoltaic cells being formed according
to process 204(2); FIGS. 7A-7F should be referred to in conjunction
with FIG. 7.
[0048] Process 204(2) is executed on a stack of thin film layers
formed on an insulating substrate. For example, process 204(2) may
be executed on stack 700) of FIG. 7A. Stack 700, which is an
embodiment of stack 500 of FIG. 5, or stack 600 of FIG. 6A,
includes an insulating substrate 702 on which a first electrical
contact layer 704 is formed. A photovoltaic stack 706 is formed on
first electrical contact layer 704, and a second electrical contact
layer 708 is formed on photovoltaic stack 706. Stack 700 may
include layers in addition to those illustrated in FIG. 7A.
[0049] In step 402 of process 204(2), at least one cell isolation
scribe 710 and a corresponding second electrical contact layer
isolation scribe 712 are formed in the stack of thin film layers.
FIG. 7B shows a stack 700(1), which is an example of stack 700
after an embodiment of step 402 is performed thereon. Cell
isolation scribes 710 delineate the stack of thin film layers into
a plurality of photovoltaic cells. The quantity and configuration
of cell isolation scribes 710 determine the quantity of
photovoltaic cells formed from the stack. For example, if a stack
of thin film layers is delineated with two orthogonal cell
isolation scribes 710, the stack will form four photovoltaic cells.
Each cell isolation scribe 710 in step 402 extends from a top
surface 716 of the stack of thin film layers to photovoltaic stack
706.
[0050] Each second electrical contact layer isolation scribe 712 is
adjacent to its respective cell isolation scribe 710. Each second
electrical contact layer isolation scribe 712 also extends from top
surface 716 to photovoltaic stack 706. Second electrical contact
layer isolation scribes 712 delineate the ends of photovoltaic
cells. For example, FIG. 7B shows stack 700(1) forming two
photovoltaic cells 726(1) and 726(2). A second electrical contact
layer isolation scribe 712 delineates the end of photovoltaic cell
726(1).
[0051] In step 404, each cell isolation scribe 710 is extended such
that it extends from top surface 716 of the stack of thin film
materials down to insulated substrate 702. FIG. 7C shows a stack
700(2), which is an example of stack 700(1) after an embodiment of
step 404 is performed thereon. In the example of FIG. 7C, cell
isolation scribe 710 delineates the beginning of photovoltaic cell
726(2).
[0052] Step 404 proceeds to step 406, where an insulating ink 718
is disposed in each cell isolation scribe 710 using a printing
process. FIG. 7D shows a stack 700(3), which is an example of stack
700(2) after an embodiment of step 406 is performed thereon. The
insulating ink provides electrical isolation between adjacent
photovoltaic cells. In a similar manner, an optional insulating ink
720 may be disposed during step 406 (e.g., at the same time as
insulating ink is disposed in cell isolation scribes 710) to fill
second electrical contact layer isolation scribes 712. Both inks
718 and 720 may be applied using an ink jet printing process, and
may intersect in between cell isolation scribes 710 and second
electrical contact layer isolation scribes 712.
[0053] In step 408, a via scribe 714 is formed in the stack of thin
film layers between each cell isolation scribe 710 and its
respective second electrical contact layer isolation scribe 712.
FIG. 7E shows a stack 700(4), which is an example of stack 700(3)
after an embodiment of step 408 is performed thereon. Via scribe
714 extends from top surface 716 of the stack of thin film layers
to first electrical contact layer 704. In the example of FIG. 7E,
via scribe 714 extends from top surface 716 through second
electrical contact layer 708 and photovoltaic stack 706 to first
electrical contact layer 704.
[0054] In step 410, conductive ink 722 is disposed in each via
scribe 714 using a printing process to form a via 728. Conductive
ink 722 is further disposed on top surface 716 of the stack of thin
films using the printing process to form a conductive grid 724 over
a corresponding adjacent cell isolation scribe 710. Conductive grid
724 electrically connects adjacent photovoltaic cells. FIG. 7F
shows a stack 700(5), which is an example of stack 700(4) after an
embodiment of step 410 is performed thereon. It should be noted
that top surface 716 of the stack of thin film layers may least
partially include insulating ink (e.g., insulating ink 718, 720)
that was applied during step 406.
[0055] In the example of FIG. 7F, via 728 electrically connects
first electrical contact layer 704 of photovoltaic cell 726(1) to
conductive grid 724. Conductive grid 724 in turn connects via 728
to second electrical contact layer 708 of photovoltaic cell 726(2).
Accordingly, first electrical contact layer 704 of photovoltaic
cell 726(1) is connected to second electrical contact layer 708 of
photovoltaic cell 726(2). Electrical contributions (i.e.,
generation of electric power) from the area between photovoltaic
cells 726(1) and 726(2) (e.g., between each second electrical
contact layer isolation scribe 712 and its respective cell
isolation scribe 710) are lost as a result of patterning.
[0056] Conductive ink 722 may be applied using an ink jet printing
process. In process 204(2), cell isolation scribes 710, second
electrical contact layer isolation scribes 712, and/or via scribes
714 may be formed using a laser scribing process. Such a laser
scribing process may be executed using a production apparatus
(e.g., laser system) with the means for translating either the
substrate, a laser beam, or both, to achieve the desired
pattern.
[0057] FIG. 8 shows one process 204(3) of performing scribing and
printing processes to form an array of monolithically integrated
thin film photovoltaic cells from a stack of thin film layers
formed on an insulating substrate. Process 204(3) is an embodiment
of step 204, and shows substeps of performing isolating and
connecting processes. FIGS. 10A-10E are cross-sectional views of an
array of monolithically integrated photovoltaic cells being formed
according to process 204(3); FIGS. 10A-10E should be referred to in
conjunction with FIG. 8.
[0058] Process 204(3) may be executed on a stack of thin film
layers formed on an insulating substrate. For example, process
204(3) may be executed on stack 1000 of FIG. 10A. Stack 1000, which
is an embodiment of stack 500 (see, FIG. 5), stack 600 (see, FIG.
6A), or stack 700 (see, FIG. 7A), has a first electrical contact
layer 1004 formed on an insulating substrate 1002. A photovoltaic
stack 1006 is formed on first electrical contact layer 1004, and a
second electrical contact layer 1008 is formed on photovoltaic
stack 1008. Stack 1000 may have layers in addition to those
illustrated in FIGS. 10A-10E.
[0059] In step 802 of process 204(3), at least one second
electrical contact layer isolation scribe 1012 is formed in the
stack of thin film layers. FIG. 10B shows a stack 1000(1), which is
an example of stack 1000 after an embodiment of step 802 is
performed thereon. Each second electrical contact layer isolation
scribe 1012 extends from a top surface 1016 to photovoltaic stack
1006. Second electrical contact layer isolation scribes 1012
delineate the ends of photovoltaic cells 1026. For example, FIG.
10B shows stack 1000(1) forming two photovoltaic cells 1026(1) and
1026(2). A second electrical contact layer isolation scribe 1012
delineates the end of photovoltaic cell 1026(1).
[0060] In step 804, a first portion of each second electrical
contact layer isolation scribe 1012 is extended to substrate 1002
to form a cell isolation scribe 1010. Furthermore, in step 804, a
second portion of each second electrical contact layer isolation
scribe 1012 is extended to first electrical contact layer 1004 to
form a via scribe 1014. The first portion may be in a different
region of second electrical contact layer isolation scribe 1012
than the second portion. Accordingly, each cell isolation scribe
1010 and corresponding via scribe 1014 may extend from a common
respective cell isolation scribe 1012, and each cell isolation
scribe 1010 and corresponding via scribe 1014 may occupy a
different portion of stack 1000's volume. FIG. 10C shows a stack
1000(2), which is an example of stack 1000(1) after an embodiment
of step 804 is performed thereon.
[0061] Cell isolation scribes 1010 delineate the stack of thin film
layers into a plurality of photovoltaic cells 1026. The quantity
and configuration of cell isolation scribes 1010 determine the
quantity of photovoltaic cells formed from the stack. For example,
if a stack of thin film layers is delineated with two orthogonal
cell isolation scribes 1010, the stack will form four photovoltaic
cells.
[0062] In the example FIG. 10C, cell isolation scribe 1010
delineates the beginning of photovoltaic cell 1026(2). Electrical
contributions (i.e., electrical power generation) from the area
between photovoltaic cells (e.g., between photovoltaic cells
1026(1) and 1026(2)) are lost as a result of patterning. Such areas
between adjacent photovoltaic cells can be used to electrically
connect the adjacent photovoltaic cells, as discussed below.
[0063] In step 806, insulating ink 1018 is disposed in each cell
isolation scribe 1010 and in each second electrical contact layer
isolating scribe 1012 using a printing process. FIG. 10D shows a
stack 1000(3), which is an example of stack 1000(2) after an
embodiment of step 806 is performed thereon. It should be noted
that insulating ink does not necessarily fill via scribe 1014 in
step 806. Insulating ink 1018 provides electrical isolation between
adjacent photovoltaic cells (e.g., between photovoltaic cells
1026(1) and 1026(2) of FIG. 10D). Insulating ink 1018 may be
applied using an ink jet printing process.
[0064] In step 808, conductive ink 1022 is disposed in each via
scribe 1014 using a printing process to form a via 1028. Conductive
ink 1022 may be further disposed on top surface 1016 of the stack
of thin film layers 1000(4) using the printing process to form a
conductive grid 1024 over a corresponding adjacent cell isolation
scribe 1010, as illustrated in FIG. 10E. Conductive grid 1024
electrically connects adjacent photovoltaic cells 1026. FIG. 10E
shows a stack 1000(4), which is an example of stack 1000(3) after
an embodiment of step 808 is performed thereon. It should be noted
that top surface 1016 of the stack of thin film layers 1000(4) may
least partially include insulating ink (e.g., insulating ink 1018)
that was applied during step 806.
[0065] In the example of FIG. 10E, via 1028 electrically connects
first electrical contact layer 1004 of photovoltaic cell 1026(1) to
conductive grid 1024. Conductive grid 1024 in turn connects via
1028 to second electrical contact layer 1008 of photovoltaic cell
1026(2). Accordingly, first electrical contact layer 1004 of
photovoltaic cell 1026(1) is connected to second electrical contact
layer 1008 of photovoltaic cell 1026(2) by via 1028 and conductive
grid 1024.
[0066] Conductive ink 1022 may be applied using an ink jet printing
process. In process 204(3), cell isolation scribes 1010, second
electrical contact layer isolation scribes 1012, and/or via scribes
1014 may be formed using a laser scribing process. Such laser
scribing processes may be executed using a production apparatus
(e.g., laser system) with the means for translating either the
substrate, a laser beam, or both, to achieve the desired
pattern.
[0067] FIG. 9 shows another process 204(4) of performing scribing
and printing processes to form an array of monolithically
integrated thin film photovoltaic cells from a stack of thin film
layers formed on an insulating substrate. Process 204(4) is an
embodiment of process 204 of performing isolating and connecting
processes. FIGS. 11A-1F are cross-sectional views of an array of
monolithically integrated photovoltaic cells being formed according
to process 204(4); FIGS. 11A-11F should be referred to in
conjunction with FIG. 9.
[0068] Process 204(4) is executed on a stack of thin film layers
formed on an insulating substrate. For example, process 204(4) may
be executed on stack 1100 of FIG. 11A. Stack 1100, which is an
embodiment of stack 500 of FIG. 5, stack 600 of FIG. 6A, or stack
1000 of FIG. 10A, includes an insulating substrate 1102 on which a
first electrical contact layer 1104 is formed. A photovoltaic stack
1106 is formed on first electrical contact layer 1104, and a second
electrical contact layer 1108 is formed on photovoltaic stack 1106.
Stack 1100 may include layers in addition to those illustrated in
FIG. 11A.
[0069] In step 902 of process 204(4), at least one second
electrical contact layer isolation scribe 1112 is formed in the
stack of thin film layers 1100. FIG. 11B shows a stack 1100(1),
which is an example of stack 1100 after an embodiment of step 902
is performed thereon. Second electrical contact layer isolation
scribes 1112 delineate the ends of photovoltaic cells 1126. For
example, FIG. 11B shows stack 1100(2) forming two photovoltaic
cells 1126(1) and 1126(2). A second electrical contact layer
isolation scribe 1112 delineates the end of photovoltaic cell
1126(1).
[0070] In step 904, a first portion of each second electrical
contact layer isolation scribe 1112 is extended down to substrate
1102 to form a cell isolation scribe 1110. FIG. 11C shows a stack
1100(2), which is an example of stack 1100(1) after an embodiment
of step 904 is performed thereon. Cell isolation scribes 1110
delineate the stack of thin film layers into a plurality of
photovoltaic cells 1126. The quantity and configuration of cell
isolation scribes 1110 determine the quantity of photovoltaic cells
1126 formed from the stack. For example, if a stack of thin film
layers 1100 is delineated with two orthogonal cell isolation
scribes 1110, the stack 1100(2) will form four photovoltaic cells
1126. In the example of FIG. 11C, cell isolation scribe 1110
delineates the beginning of photovoltaic cell 1126(2).
[0071] In step 906, an insulating ink 1118 is disposed in each cell
isolation scribe 1110 and in each second electrical contact layer
isolation scribe 1112 using a printing process. FIG. 11D shows a
stack 1100(3), which is an example of stack 1100(2) after an
embodiment of step 906 is performed thereon. The insulating ink
provides electrical isolation between adjacent photovoltaic cells.
Ink 1118 may be applied using an ink jet printing process.
[0072] In step 1108, a via scribe 1114 is formed in the stack of
thin film layers adjacent to each cell isolation scribe 1110. FIG.
11E shows a stack 1100(4), which is an example of stack 1100(3)
after an embodiment of step 908 is performed thereon. Via scribe
1114 extends through the insulating ink of a second portion of the
second electrical contact layer isolation scribe 1112 to first
electrical contact layer 1104. The second portion may be in a
different region of second electrical contact layer isolation
scribe 1112 than the first portion. Accordingly, each via scribe
1114 and cell isolation scribe 1110 may occupy a different portion
of stack 1100's volume.
[0073] In step 910, conductive ink 1122 is disposed in each via
scribe 1114 using a printing process to form a via 1128. Conductive
ink 1122 is further disposed on top surface 1116 of the stack of
thin films 1100(5) using the printing process to form a conductive
grid 1124 over a corresponding adjacent cell isolation scribe 1110.
Conductive grid 1124 electrically connects adjacent photovoltaic
cells 1126. FIG. 11F shows a stack 1100(5), which is an example of
stack 1100(4) after an embodiment of step 910 is performed thereon.
It should be noted that top surface 1116 of the stack of thin film
layers 1100(5) may least partially include insulating ink (e.g.,
insulating ink 1118) that was applied during step 906.
[0074] In the example of FIG. 11F, via 1128 electrically connects
first electrical contact layer 1104 of photovoltaic cell 1126(1) to
conductive grid 1124. Conductive grid 1124 in turn connects via
1128 to second electrical contact layer 1108 of photovoltaic cell
1126(2). Accordingly, first electrical contact layer 1104 of
photovoltaic cell 1126(1) is connected to second electrical contact
layer 1108 of photovoltaic cell 1126(2). Electrical contributions
(i.e., generation of electric power) from the area between
photovoltaic cells 1126(1) and 1126(2) are lost as a result of
patterning.
[0075] Conductive ink 1122 may be applied using an ink jet printing
process. In process 204(4), cell isolation scribes 1110, second
electrical contact layer isolation scribes 1112, and/or via scribes
1114 may be formed using a laser scribing process. Such a laser
scribing processes may be executed using a production apparatus
(e.g., laser system) with the means for translating either the
substrate, a laser beam, or both, to achieve the desired
pattern.
[0076] In other embodiments of processes 204(1), 204(2). 204(3),
and 204(4), the order of steps may be varied. For example, second
electrical contact layer isolation scribes 612 and 712 need not be
formed in step 302 and 402 respectively; second electrical contact
layer isolation scribes 612 and 712 may be formed after step 308
and 410, respectively, for example. As another example, cell
isolation scribes 610 and 710 may be cut to their final depth (to
substrates 602 and 702, respectively) in steps 302 and 402,
respectively, thereby eliminating the need to extend cell isolation
scribes 610 and 710 in steps 304 and 404, respectively.
Additionally, it should be understood that processes described in
FIGS. 3, 4, 8, and 9 represent only some of the possible
embodiments of step 204 of FIG. 2.
[0077] FIG. 12 is a top plan view of array 1200 of monolithically
integrated photovoltaic cells 1202, and FIG. 13 is a
cross-sectional view of array 1200, as seen from side 1204 of array
1200. Array 1200 is formed according to an embodiment of process
204(1) or 204(2) of FIG. 3 and FIG. 4, respectively. Array 120X) is
illustrated as having four photovoltaic cells 1202(1)-1202(4),
which are shown as rectangular columns in FIG. 12. However, array
1200 may have any quantity of photovoltaic cells 1202. Photovoltaic
cells 1202(1)-1202(4) are electrically connected in series between
electrical terminals 1230 and 1232. Terminal 1230 is electrically
connected to the back contact layer 1212 of photovoltaic cell
1202(1) by via 1220(5). Terminal 1232 is electrically connected to
the top contact layer 1206 of photovoltaic cell 1202(4) by
conductive grid 1222(4).
[0078] FIG. 13 shows array 120X) formed of thin film layers,
including back contact layer 1212, solar absorber layer 1210,
window layer 1208, and top contact layer 1206. An insulating
substrate is disposed below a bottom surface 1234 of back contact
layer 1212. However, a substrate is not shown in FIG. 13 for
illustrative clarity. Array 1200 may include additional thin film
layers besides those illustrated in FIG. 12. For example, array
1200 may include a buffer layer disposed between window layer 1208
and top contact layer 1206.
[0079] Photovoltaic cells 1202 of array 1200 are delineated by cell
isolation scribes 1214, as can be seen in FIGS. 12 and 13. Cell
isolation scribes 1214 may extend completely through the stack of
thin film layers, as shown in FIG. 13. Each photovoltaic cell 1202
includes a second electrical contact layer isolation scribe 1216
disposed adjacent to each cell isolation scribe 1214. Each second
electrical contact layer isolation scribe 1216 extends through a
top contact layer 1206 of its respective photovoltaic cell 1202.
Array 1200 is partially bounded by isolation scribes 1218, which
also extend through second electrical contact layers 1206. Vias
1220, which are scribes filled with a conductive ink, each extend
from the back contact layer of respective photovoltaic cells to a
respective conductive grid 1222 formed on a top surface 1224 of top
contact layers 1206. Each conductive grid 1222 includes a plurality
of conducting elements 1236 electrically connected in parallel.
Each conducting element 1236 of a conductive grid 1222 is
electrically connected to the via 1220 electrically connected to
the conductive grid. Each conductive grid 1222 and via 1220 provide
electrical connection between adjacent PV cells 1202. In an
embodiment, a separation distance 1226 can range from 300 to 700
.mu.m, and a separation distance 1228 can range from 4 mm to 10
mm.
[0080] As discussed above with respect to FIG. 2, the step of
forming the stack of thin film layers and the step performing the
isolating and connecting processes may be separate respective steps
202 and 204 in process 200. This separation of steps may permit the
use of one or more of the following processes, which may be
advantageous in certain applications. First, a roll-to-roll
deposition process may be used in a single deposition line for
forming the stack of thin film layers on the insulating substrate.
Second, a stack of thin film layers formed on an insulating
substrate may be cut into requisite module sizes using a laser
system capable of moving either the substrate or laser beam, or
both, before performing the isolating and connecting processes.
Third, the steps of forming scribes during the isolating process
may be performed using a laser system capable of moving either the
substrate or laser beam, or both. Fourth, scribing and printing
processes of the isolating and connecting step may be performed
with a single registration of the stack of thin film layers formed
on an insulating substrate with a production apparatus. Fifth, the
isolating and connecting processes may be performed using one
integrated system. Sixth, the insulating ink may be protected from
high vacuum and/or high temperatures required when forming the
stack of thin film layers on an insulating substrate. Seventh,
control methods employed when producing an array of monolithically
integrated photovoltaic cells may be simplified. In particular,
inspection and process control may be separated into two stages:
one stage for forming the stack of thin film layers; and another
stage for performing the isolating and connecting processes.
[0081] Changes may be made in the above methods and systems without
departing from the scope hereof. It should thus be noted that the
matter contained in the above description and shown in the
accompanying drawings should be interpreted as illustrative, and
not in a limiting sense. The following claims are intended to cover
generic and specific features described herein, as well as all
statements of the scope of the present method and system, which, as
a matter of language, might be said to fall therebetween.
* * * * *