U.S. patent application number 13/868871 was filed with the patent office on 2014-10-23 for solar cell with anti-reflection structure and method for fabricating the same.
This patent application is currently assigned to NATIONAL YUNLIN UNIVERSITY OF SCIENCE AND TECHNOLOGY. The applicant listed for this patent is NATIONAL YUNLIN UNIVERSITY OF SCIENCE AND TECHNOLOGY. Invention is credited to Chien-Wen Chen, Jian-Yang Lin, Wei-Jer Yang.
Application Number | 20140311568 13/868871 |
Document ID | / |
Family ID | 51728087 |
Filed Date | 2014-10-23 |
United States Patent
Application |
20140311568 |
Kind Code |
A1 |
Lin; Jian-Yang ; et
al. |
October 23, 2014 |
SOLAR CELL WITH ANTI-REFLECTION STRUCTURE AND METHOD FOR
FABRICATING THE SAME
Abstract
A solar cell with an anti-reflection structure comprises a solar
cell substrate, a meshed electric-conduction layer formed on one
surface of the solar cell substrate, a plurality of microspheres
disposed on the meshed electric-conduction layer, and a dielectric
layer. The microspheres have a diameter of 0.1-50 .mu.m. The
dielectric layer is formed between the meshed electric-conduction
layer and the microspheres, and has a thickness smaller than the
diameter of the microspheres to make the microspheres protrude from
the dielectric layer. The meshed electric-conduction layer is
formed via a screen-printing method. The present invention uses the
microspheres and the meshed electric-conduction layer to achieve an
excellent anti-reflection effect. Further, the present invention
has the advantages of a simple fabrication process and a low
fabrication cost.
Inventors: |
Lin; Jian-Yang; (Douliu
City, TW) ; Yang; Wei-Jer; (Douliu City, TW) ;
Chen; Chien-Wen; (Douliu City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OF SCIENCE AND TECHNOLOGY; NATIONAL YUNLIN UNIVERSITY |
|
|
US |
|
|
Assignee: |
NATIONAL YUNLIN UNIVERSITY OF
SCIENCE AND TECHNOLOGY
Douliu City
TW
|
Family ID: |
51728087 |
Appl. No.: |
13/868871 |
Filed: |
April 23, 2013 |
Current U.S.
Class: |
136/259 ;
438/72 |
Current CPC
Class: |
G02B 5/0226 20130101;
G02B 5/0294 20130101; H01L 31/02366 20130101; G02B 1/11 20130101;
H01L 31/18 20130101; H01L 31/02168 20130101; Y02E 10/50 20130101;
H01L 31/022425 20130101 |
Class at
Publication: |
136/259 ;
438/72 |
International
Class: |
H01L 31/052 20060101
H01L031/052; H01L 31/18 20060101 H01L031/18 |
Claims
1. A solar cell with an anti-reflection structure, comprising; a
solar cell substrate; a meshed electric-conduction layer formed on
one surface of the solar cell substrate; a plurality of
microspheres disposed on the meshed electric-conduction layer and
having a diameter of 0.1-50 .mu.m; and a dielectric layer formed
between the meshed electric-conduction layer and the microspheres,
and having a thickness smaller than the diameter of the
microspheres to make the microspheres protrude from the dielectric
layer.
2. The solar cell with the anti-reflection structure according to
claim 1, wherein the meshed electric-conduction layer includes a
plurality of accommodation spaces accommodating the
microspheres.
3. The solar cell with the anti-reflection structure according to
claim 1, wherein the solar cell substrate includes a bottom
electrode far away from the meshed electric-conduction layer, a
P-type semiconductor layer, and an N-type semiconductor layer
neighboring the meshed electric-conduction layer, which are
arranged in sequence.
4. The solar cell with the anti-reflection structure according to
claim 1, wherein the meshed electric-conduction layer is made of a
material selected from a group consisting of silver, aluminum, and
a combination thereof.
5. The solar cell with the anti-reflection structure according to
claim 1, wherein the microspheres are made of a material selected
from a group consisting of silicon dioxide, silicon nitride, and
aluminum oxide.
6. A method for fabricating a solar cell with an anti-reflection
structure, comprising steps of: Step S1: preparing a solar cell
substrate; Step S2: using a screen-printing method to form a meshed
electric-conduction layer on a surface of the solar cell substrate;
Step S3: mixing a plurality of microspheres, which have a diameter
of 0.1-50 .mu.m, with a volatile solution to form a mixture
solution, and spraying the mixture solution on the meshed
electric-conduction layer to allow the microspheres to be disposed
on the meshed electric-conduction layer; and Step S4: using a
spin-coating method to coat an SOD (Spin on Dielectric) material
between the meshed electric-conduction layer and the microspheres
to form a dielectric layer, wherein the diameter of the
microspheres is greater than a sum of thicknesses of the dielectric
layer and the meshed electric-conduction layer.
7. The method for fabricating the solar cell with the
anti-reflection structure according to claim 6, wherein in the Step
S1, N-type ions are doped into a P-type semiconductor layer to form
an N-type semiconductor layer.
8. The method for fabricating the solar cell with the
anti-reflection structure according to claim 6 further comprising a
Step S3A: heating the solar cell substrate to a temperature of
80-110.degree. C. to evaporate the volatile solution, wherein the
Step S3A is interposed between the Step S3 and the Step S4.
9. The method for fabricating the solar cell with the
anti-reflection structure according to claim 6 further comprising a
Step S5: using an electron-beam evaporation method to form a bottom
electrode on one surface of the solar cell substrate, which is far
away from the meshed electric-conduction layer, wherein the Step S5
succeeds to the Step S4.
10. The method for fabricating the solar cell with the
anti-reflection structure according to claim 6, wherein the
microspheres are made of a material selected from a group
consisting of silicon dioxide, silicon nitride, and aluminum oxide.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a solar cell, particularly
to a solar cell with an anti-reflection structure and a method for
fabricating the same.
BACKGROUND OF THE INVENTION
[0002] Power shortage drives many nations to develop various
substitute energies, especially solar energy. Solar energy is easy
to access and pollution-free. Besides, solar cells are noiseless
and have a long service life. Therefore, much money has been
invested in research of solar energy. Recently, many technologies
have been developed to improve the utilization efficiency of
incident light and enhance the photoelectric conversion efficiency,
such as changing the interface material, roughening the surface or
arranging an anti-reflection layer.
[0003] In addition to promoting the photoelectric conversion
efficiency, reducing the fabrication cost to increase the economic
profit is also a focus subject of solar cell development. The cost
of solar cells can be reduced via decreasing the material cost or
improving the fabrication process. The electric-conduction layer on
the light-incident surface of a solar cell must be made of a
material featuring transparency and electric conductibility, such
as ITO (Indium Tin Oxide), which is relatively expensive. Further,
the fabrication process of solar cells requires precision CVD
(Chemical Vapor Deposition) equipment, which makes the fabrication
cost hard to reduce.
SUMMARY OF THE INVENTION
[0004] The primary objective of the present invention is to solve
the problems of high material cost and high fabrication cost in the
conventional solar cell technology.
[0005] To achieve the above-mentioned objective, the present
invention proposes a solar cell with an anti-reflection structure,
which comprises a solar cell, substrate, a meshed
electric-conduction layer formed on one surface of the solar cell
substrate, a plurality of microspheres disposed on the meshed
electric-conduction layer, and a dielectric layer. The microspheres
have a diameter of 0.1-50 .mu.m. The dielectric layer is formed
between the meshed electric-conduction layer and the microspheres,
and has a thickness smaller than the diameter of the microspheres
to make the microspheres protrude from the surface of the
dielectric layer.
[0006] The present invention also proposes a method for fabricating
a solar cell with an anti-reflection structure, which comprises
steps of
[0007] Step S1: preparing a solar cell substrate;
[0008] Step S2: using a screen-printing method to form a meshed
electric-conduction layer on the surface of the solar cell
substrate;
[0009] Step S3: mixing a plurality of microspheres with a volatile
solution to form a mixture solution, and spraying the mixture
solution on the meshed electric-conduction layer to allow the
microspheres to be disposed on the meshed electric-conduction
layer, wherein the microspheres have a diameter of 0.1-50 .mu.m;
and
[0010] Step S4: using a spin-coating method to coat an SOD (Spin on
Dielectric) material between the meshed electric-conduction layer
and the microspheres to form a dielectric layer, wherein the
diameter of the microspheres is greater than the sum of the
thicknesses of the dielectric layer and the meshed
electric-conduction layer.
[0011] The present invention is characterized in [0012] 1. Using
microspheres and a dielectric layer to form an anti-reflection
structure having a rugged surface to increase the efficiency of
incident light utilization and the efficiency of photoelectric
conversion; [0013] 2. Using a meshed electric-conduction layer to
reduce the cost spent on the transparent electric-conduction
material; [0014] 3. Using a screen-printing method to reduce the
dependence on the CVD (Chemical Vapor Deposition) technology and
decrease the cost of fabricating solar cells.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIGS. 1A-1D schematically show the steps for fabricating a
solar cell with an anti-reflection structure according to one
embodiment of the present invention;
[0016] FIG. 2 shows a flowchart of a method for fabricating a solar
cell with an anti-reflection structure according to one embodiment
of the present invention; and
[0017] FIG. 3 shows the reflectivities of a conventional structure
and an anti-reflection structure according to one embodiment of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] The technical contents of the present invention will be
described in detail in cooperation with drawings below.
[0019] Refer to FIGS. 1A-1D. The present invention proposes a solar
cell with an anti-reflection structure, which comprises a solar
cell substrate 10, a meshed electric-conduction layer 20 formed on
one surface of the solar cell substrate 10, a plurality of
microspheres 30 disposed on the meshed electric-conduction layer
20, and a dielectric layer 40. The microspheres 30 have a diameter
of 0.1-50 .mu.m. The dielectric layer 40 is formed between the
meshed electric-conduction layer 20 and the microspheres 30 and has
a thickness smaller than the diameter of the microspheres 30 to
allow the microspheres 30 protrude from the surface of the
dielectric layer 40. The solar cell substrate 10 includes a bottom
electrode 11 far away from the meshed electric-conduction layer 20,
a P-type semiconductor layer 12, and an N-type semiconductor layer
13 neighboring the meshed electric-conduction layer 20, which are
arranged in sequence. In one embodiment, the solar cell substrate
10 also includes an intrinsic semiconductor layer (not shown in the
drawings) arranged between the P-type semiconductor layer 12 and
the N-type semiconductor layer 13 to increase the photoelectric
conversion efficiency. As the present invention is not focused on
the solar cell substrate 10, the specification will not describe
the solar cell substrate 10 in further detail. The meshed
electric-conduction layer 20 provides a plurality of accommodation
spaces 21 to accommodate the microspheres 30. In the embodiment
shown in FIGS. 1A-1D, each accommodation space 21 accommodates one
microsphere 30. In another embodiment, one accommodation space 21
can accommodate several smaller microspheres 30 if application
requires it.
[0020] In one embodiment, the meshed electric-conduction layer 20
is made of a metallic electric-conduction material, such as silver
or aluminum. The meshed electric-conduction layer 20 allows light
to pass through the accommodation spaces 21 and reach the solar
cell substrate 10 for photoelectric conversion. In one embodiment,
the microspheres 30 are made of a material selected from a group
consisting of silicon dioxide, silicon nitride, and aluminum
oxide.
[0021] Refer to FIGS. 1A-1D again, and refer to FIG. 2 also. The
present invention also proposes a method for fabricating a solar
cell with an anti-reflection structure, which comprises steps as
follows.
[0022] Step S1--preparing a solar cell substrate 10: Firstly, wash
a P-type semiconductor layer 12 via an RCA (Radio Corporation of
America) clean method. Next, dope N-type ions into the P-type
semiconductor layer 12 to form an N-type semiconductor layer 13, as
shown in FIG. 1A. In one embodiment, an intrinsic semiconductor
material is formed between the P-type semiconductor layer 12 and
the N-type semiconductor layer 13 to increase the photoelectric
conversion efficiency. In one embodiment, boron ion is diffused
into the bottom of the P-type semiconductor layer 12 to form a back
surface field. In one embodiment, P-type ion is doped into an
N-type semiconductor material to form the P-type semiconductor
layer 12. The fabrication of the solar cell substrate 10 can be
undertaken in different ways, depending on the requirements. The
embodiments described above are only to exemplify the methods for
fabricating the solar cell substrate 10. The present invention does
not constrain the material, structure and fabrication method of the
solar cell substrate 10. As the present invention is not focused on
the solar cell substrate 10, the specification will not describe
the method for fabricating the solar cell substrate 10 in further
detail.
[0023] Step S2--screen-printing: Use a screen-printing method to
form a meshed electric-conduction layer 20 on the surface of the
solar cell substrate 10, as shown in FIG. 1B. In one embodiment,
the meshed electric-conduction layer 20 is made of a metallic
electric-conduction material, such as silver or aluminum. The
meshed electric-conduction layer 20 provides a plurality of
accommodation spaces 21 to accommodate the microspheres 30.
[0024] Step S3--disposing a plurality of microspheres 30: Mix a
plurality of microspheres 30 with a volatile solution to form a
mixture solution, and spraying the mixture solution on the meshed
electric-conduction layer 20 to allow the microspheres 30 to be
disposed on the meshed electric-conduction layer 20, as shown in
FIG. 1C. The microspheres 30 have a diameter of 0.1-50 .mu.m. In
one embodiment, the volatile solution is a solution containing over
0.2 wt % methanol. In one embodiment, the mixture solution is
filled into an ultrasonic nebulizer, and the ultrasonic nebulizer
sprays the mixture solution on the surface of the meshed
electric-conduction layer 20. In this embodiment, each
accommodation space 21 accommodates one microsphere 30. In the
present invention, the microsphere 30 may be greater or smaller
than the accommodation space 21. While the microsphere 30 is
smaller than the accommodation space 21, one accommodation space 21
can accommodate several microspheres 30. In any way, the thickness
of the meshed electric-conduction layer 20 must be smaller than the
diameter of the microspheres 30 so that the microspheres 30 can
protrude from the meshed electric-conduction layer 20.
[0025] Step S3A--heating and evaporating: Heat the solar cell
substrate 10 to a temperature of 80-110.degree. C. to make the
volatile solution evaporate faster with only the microspheres 30
left on the surface of the meshed electric-conduction layer 20.
[0026] Step S4--forming a dielectric layer 40: Use a spin-coating
method to coat an SOD (Spin on Dielectric) material between the
meshed electric-conduction layer 20 and the microspheres 30 to form
a dielectric layer 40, as shown in FIG. 1D. The diameter of the
microspheres 30 is greater than the sum of the thicknesses of the
dielectric layer 40 and the meshed electric-conduction layer 20.
The SOD material would also be filled into the accommodation spaces
21 (shown in FIG. 1B).
[0027] Step S5--forming a bottom electrode 11 on one surface of the
solar cell substrate 10, which is far away from the meshed
electric-conduction layer 20, via an electron-beam evaporation
method.
[0028] Refer to FIG. 3. The reflectivity of the anti-reflection
structure of the present invention is expressed by Curve 51. The
reflectivity of the conventional structure is expressed by Curve
52. FIG. 3 proves that the anti-reflection structure of the present
invention has much lower reflectivity than the conventional
structure.
[0029] In conclusion, the present invention has the following
advantages: [0030] 1. The present invention uses the microspheres
and the dielectric layer to form an anti-reflection structure
having a rugged surface to increase the efficiency of utilizing the
incident light and the efficiency of photoelectric conversion;
[0031] 2. The present invention adopts a meshed electric-conduction
layer to reduce the cost spent on the transparent
electric-conduction material; [0032] 3. The present invention uses
a screen-printing method to reduce the dependence on the CVD
(Chemical Vapor Deposition) technology and decrease the cost of
fabricating solar cells.
* * * * *