CN116364791A - Solar cell and preparation method thereof - Google Patents

Solar cell and preparation method thereof Download PDF

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CN116364791A
CN116364791A CN202111624262.1A CN202111624262A CN116364791A CN 116364791 A CN116364791 A CN 116364791A CN 202111624262 A CN202111624262 A CN 202111624262A CN 116364791 A CN116364791 A CN 116364791A
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ito film
grain
ito
solar cell
amorphous silicon
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姚铮
崔巍
吴坚
蒋方丹
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Jiaxing Canadian Solar Technology Research Institute
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Jiaxing Canadian Solar Technology Research Institute
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022466—Electrodes made of transparent conductive layers, e.g. TCO, ITO layers
    • H01L31/022475—Electrodes made of transparent conductive layers, e.g. TCO, ITO layers composed of indium tin oxide [ITO]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/20—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof such devices or parts thereof comprising amorphous semiconductor materials
    • H01L31/202—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof such devices or parts thereof comprising amorphous semiconductor materials including only elements of Group IV of the Periodic Table
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/20—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof such devices or parts thereof comprising amorphous semiconductor materials
    • H01L31/208—Particular post-treatment of the devices, e.g. annealing, short-circuit elimination
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Condensed Matter Physics & Semiconductors (AREA)
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  • Photovoltaic Devices (AREA)

Abstract

The invention provides a solar cell and a preparation method thereof, wherein the solar cell comprises a silicon substrate, an intrinsic amorphous silicon layer, a doped amorphous silicon layer, an ITO film and a metal electrode, which are sequentially positioned on one side of the silicon substrate, the ITO film comprises at least two layers of ITO films, and the grain sizes of different ITO films are different. Compared with the prior art, the ITO film comprises at least two film layers with different grain sizes, so that the IV performance of the solar cell is better, and meanwhile, the reliability of the product is further ensured.

Description

Solar cell and preparation method thereof
Technical Field
The invention relates to the field of photovoltaics, in particular to a solar cell and a preparation method thereof.
Background
The Indium Tin Oxide (ITO) film is a common transparent conductive film, has the advantages of high conductivity, good light transmittance, high mechanical hardness, good stability and the like, and is a preferable electrode material for solar cells, OLED (organic light emitting diode) display screens, liquid crystal display screens and the like.
The ITO coating at present has excellent electrical and optical properties and moderate matching degree with the adjacent film layers, but is not optimized enough, and has a certain influence on the performance of devices. Taking an ITO thin film as a transparent conductive thin film of a solar cell as an example, light transmittance, carrier mobility, contact resistance with an adjacent film layer, and the like cannot be considered, and the conversion efficiency of the cell is affected.
In view of the foregoing, there is a need for a solar cell and a method for manufacturing the same, which solve the above-mentioned problems.
Disclosure of Invention
The invention aims to provide a solar cell and a preparation method thereof.
In order to solve one of the technical problems, the invention adopts the following technical scheme:
the solar cell comprises a silicon substrate, an intrinsic amorphous silicon layer, a doped amorphous silicon layer, an ITO film and a metal electrode, wherein the intrinsic amorphous silicon layer, the doped amorphous silicon layer, the ITO film and the metal electrode are sequentially arranged on one side of the silicon substrate, the ITO film comprises at least two layers of ITO films, and the grain sizes of different ITO films are different.
Further, in the two adjacent ITO films, the grains of the film layer close to the metal electrode are large.
Further, the grain size of the ITO film in contact with the doped amorphous silicon layer is 1nm to 20nm.
Further, the grain size of the ITO film in contact with the metal electrode is 20nm to 500nm.
Further, the crystal form of the ITO film contacted with the doped amorphous silicon layer is columnar crystal, and the crystal form of the ITO film contacted with the metal electrode is equiaxed crystal.
Further, the ITO thin film comprises a small-grain ITO film in contact with the doped amorphous silicon layer and a large-grain ITO film in contact with the metal electrode, wherein the thickness of the large-grain ITO film is larger than that of the small-grain ITO film.
Further, the thickness of the ITO film is 50 nm-120 nm, and the thickness of the large-grain ITO film is 40 nm-90 nm.
A method of fabricating a solar cell, comprising: forming an intrinsic amorphous silicon layer, a doped amorphous silicon layer, an ITO film and a metal electrode on one side of the silicon substrate in sequence; forming the ITO film includes: at least two layers of ITO films are formed, and the grain sizes of different ITO films are different.
Further, the process for forming the small-grain ITO film in contact with the doped amorphous silicon layer comprises the following steps: the coating pressure is 0.7-1.5 Pa, and the power density is 2-8 kW/m.
Further, the process of forming the large-grain ITO film in contact with the metal electrode comprises the following steps: the coating pressure is 0.3 Pa-0.7 Pa, and the power density is 5-15 kW/m.
Further, forming the ITO film includes: forming a small-grain ITO film in contact with the doped amorphous silicon layer and forming a large-grain ITO film in contact with the metal electrode, wherein the grain size of the small-grain ITO film is 1-20 nm, and the grain size of the large-grain ITO film is 20-500 nm.
Further, the small-grain ITO film has a grain size of 1 to 20nm and a thickness of 10 to 30nm.
Further, the crystal grain of the large-crystal grain ITO film is 15-500 nm, and the thickness of the large-crystal grain ITO film is 40-90 nm.
The beneficial effects of the invention are as follows: compared with the prior art, the ITO film comprises at least two film layers with different grain sizes, so that the IV performance of the solar cell is better, and meanwhile, the reliability of the product is further ensured.
Drawings
Fig. 1 is a schematic structural view of a solar cell according to an embodiment of the present invention;
fig. 2 is a schematic structural view of a solar cell according to another embodiment of the present invention.
The solar cell comprises a 1 solar cell, a 1-silicon base, a 2-first intrinsic amorphous silicon layer, a 3-first doped amorphous silicon layer, a 4-first ITO film, a 41-small-grain ITO film, a 42-large-grain ITO film, a 5-first metal electrode, a 6-second intrinsic amorphous silicon layer, a 7-second doped amorphous silicon layer, an 8-second ITO film and a 9-second metal electrode.
Detailed Description
The present invention will be described in detail below with reference to specific embodiments shown in the drawings. These embodiments are not intended to limit the invention and structural, methodological, or functional modifications of these embodiments that may be made by one of ordinary skill in the art are included within the scope of the invention.
In the various illustrations of the invention, certain dimensions of structures or portions may be exaggerated relative to other structures or portions for convenience of illustration, and thus serve only to illustrate the basic structure of the inventive subject matter.
Referring to fig. 2, a solar cell 100 according to a preferred embodiment of the invention includes a silicon substrate 1, intrinsic amorphous silicon layers 2,6, doped amorphous silicon layers 3,7, ITO films 4,8, and metal electrodes 5,9 sequentially located on one side of the silicon substrate.
When the solar cell 100 is a double-sided heterojunction cell, it comprises a silicon substrate 1, a first intrinsic amorphous silicon layer 2, a first doped amorphous silicon layer 3, a first ITO film 4, and a first metal electrode 5 sequentially located on a first side of the silicon substrate 1, and a second intrinsic amorphous silicon layer 6, a second doped amorphous silicon layer 7, a second ITO film 8, and a second metal electrode 9 sequentially located on a second side of the silicon substrate 1.
The silicon base 1 is formed by texturing a silicon wafer. In one embodiment, an N-type silicon wafer is selected, the resistivity is 0.5 to 3 omega cm, the thickness is 150 to 200 mu m, and the size is 156.75cm. The silicon wafer is textured by the alkaline solution to form a pyramid structure, so that the sunlight capturing is improved.
The first intrinsic silicon layer 2 and the second intrinsic silicon layer 6 are collectively called as the intrinsic amorphous silicon layers 2,6, and perform passivation on the silicon substrate 1.
The first doped amorphous silicon layer 3 and the second doped amorphous silicon layer 7 are collectively called as doped amorphous silicon layers 3 and 7, and the doping types of the first doped amorphous silicon layer and the second doped amorphous silicon layer are opposite. In one embodiment, the first doped amorphous silicon layer 3 is an N-type doped amorphous silicon layer, such as a phosphorus doped amorphous silicon layer; the second doped amorphous silicon layer 5 is a P-type doped amorphous silicon layer, such as a boron doped amorphous silicon layer. Of course, the doping types of the first doped amorphous silicon layer 3 and the second doped amorphous silicon layer 5 may be interchanged.
The first ITO thin film 4 and the second ITO thin film 8 are collectively called ITO thin films 4,8, and have a great influence on the performance of the solar cell 100 in terms of conductivity, light transmittance, and stability as transparent conductive films.
The first metal electrode 5 and the second metal electrode 9 are collectively called as metal electrodes 5,9, and comprise a main grid and a fine grid for collecting and outputting electric energy.
The key point of the invention is to improve the ITO films 4,8 and the preparation process thereof, and improve the performance of the solar cell. The inventors found that: the small-grain ITO film has relatively high carrier concentration, but because the grain boundaries are more, the scattering of the grain boundaries is increased, and the carrier mobility is low, the optical absorption of the small-grain ITO film layer is serious, and the cell Isc is reduced; and migration of part of metal ions in the film layer is easier, and certain risks exist for device reliability (such as PID, DH and the like). And the large-grain ITO film has relatively low carrier concentration, high mobility and large contact loss with the amorphous silicon layer, and the cell FF is reduced.
In view of this, the ITO thin films 4,8 of the present invention include at least two layers of ITO films, and different crystal grain sizes of the ITO films can balance and consider the conductivity, light transmittance and stability of the entire ITO thin films 4,8, improve the matching degree between the ITO thin films and adjacent other thin films in terms of optics, electricity, etc., and improve the performance of the solar cell.
Preferably, the grains of the ITO film near the metal electrodes 5,9 are large in the two adjacent ITO films. The small-grain ITO film 41 with high carrier concentration and low mobility is positioned on the inner side, and the contact resistance with the doped amorphous silicon layers 3 and 7 is small, so that the FF of the battery can be improved; the large-grain ITO film 42 with few grain boundaries, high stability and high mobility is positioned on the outer side, so that the stability of the whole ITO films 4 and 8 is improved, the probability of short circuit diffusion is reduced, and the stability of the solar cell 100 is improved.
Further, when the ITO thin films 4,8 include at least three layers of ITO films, the grain sizes of the at least three layers of ITO films gradually increase along the direction from the doped amorphous silicon layers 3,7 to the metal electrodes 5,9, which can further improve the performance of the solar cell 100.
Specifically, the ITO film contacting the doped amorphous silicon layers 3,7 is a small-grain ITO film 41, and the grain size is 1 nm-20 nm, which is beneficial to the contact between the ITO films 4,8 and the doped amorphous silicon layers 3,7, has small contact resistance, and can improve the FF of the battery.
The ITO film contacted with the metal electrodes 5 and 9 is a large-grain ITO film 42, and the grain size is 20 nm-500 nm; the grain boundary is less, the stability is high, and the improvement of optical performance and the improvement of reliability are facilitated.
Preferably, the ITO films of different layers are different in crystalline form.
Preferably, the ITO film contacting the doped amorphous silicon layers 3,7 has a columnar crystal, and the columnar crystal grows longitudinally, and has a small transverse dimension, but the longitudinal length may be very long, so that the carriers of the doped amorphous silicon layers 3,7 on the inner side are advantageously transferred to the metal electrodes 5,9 on the outer side longitudinally.
The crystal forms of the ITO films contacted with the metal electrodes 5 and 9 are equiaxed crystals, and the carriers are excellent in both transverse and longitudinal transfer performance, so that the carriers can be transferred to the metal electrodes 5 and 9 from the doped amorphous silicon layers 3 and 7 and the ITO films on the inner sides in the longitudinal direction, and the carriers can be transferred to the thin grids in the transverse direction of the ITO films and collected.
In addition, the ITO thin films 4,8 include a small-grain ITO film 41 in contact with the intrinsic amorphous silicon layer, and a large-grain ITO film 42 in contact with the metal electrodes 5,9, the thickness of the large-grain ITO film 42 being larger than that of the small-grain ITO film 41, and by contacting a thin small-grain ITO film 41 with the doped amorphous silicon layers 3,7, the contact resistance is reduced, and then the thickness of the large-grain ITO film 42 is thickened as much as possible, so that the performance of the entire ITO thin films 4,8 tends to the large-grain ITO film 42, improving the stability and optical performance thereof.
For example, the thickness of the ITO thin films 4,8 is 50nm to 120nm, the thickness of the large-grain ITO film 42 is 40nm to 90nm, and the balance is the thickness of the small-grain ITO film 41.
In one embodiment, the ITO films 4,8 include two layers: small-grain ITO films 41 in contact with the doped amorphous silicon layers 3,7, and large-grain ITO films 42 in contact with the metal electrodes 5,9. The grain size of the small-grain ITO film 41 is 1 nm-20 nm, the crystal form is columnar crystal, and the thickness is 10 nm-30 nm; the crystal grain size of the large-crystal-grain ITO film 42 is 20-500 nm, the crystal form is equiaxed crystal, and the thickness is 40-90 nm.
Preferably, the ITO films 4 and 8 on both sides of the silicon substrate 1 are symmetrically arranged, that is, the inner film layer and the outer film layer on both sides are the same.
The invention also provides a preparation method of the solar cell, which comprises the following steps: and forming the intrinsic amorphous silicon layers 2 and 6, the doped amorphous silicon layers 3 and 7, the ITO films 4 and 8 and the metal electrodes 5 and 9 on one side of the silicon substrate 1 in sequence.
The invention improves the preparation process of the ITO films 4 and 8 to improve the performance of the solar cell, and the process of other film layers is not repeated by referring to the prior art.
Specifically, forming the ITO thin films 4,8 includes: at least two layers of ITO films are formed, the different crystal grain sizes of the ITO films are different, the conductivity, the light transmittance and the stability of the whole ITO films 4 and 8 can be balanced and considered, the matching degree of the ITO films and adjacent other film layers in the aspects of optics, electricity and the like is improved, and the performance of the solar cell is improved.
The process of forming the small-grain ITO film 41 in contact with the doped amorphous silicon layer is: the coating pressure is 0.7-1.5 Pa, and the power density is 2-8 kW/m. The ITO film with small grains is contacted with the doped amorphous silicon layer, and the contact resistance is small.
The process of forming the large-grain ITO film 42 in contact with the metal electrode is: the coating pressure is 0.3 Pa-0.7 Pa, and the power density is 5-15 kW/m. The large-grain ITO film 42 with few grain boundaries, high stability and mobility is positioned on the outer side, so that the stability of the whole ITO films 4 and 8 is improved, and the stability of the solar cell 100 is improved.
In general, the ITO thin film may include two layers of ITO films, and when the ITO thin film includes three or more layers of ITO films, the grain size of the at least three layers of ITO films may be gradually increased in the direction from the doped amorphous silicon layers 3,7 to the metal electrodes 5,9, so that the performance of the solar cell 100 may be further improved.
In one embodiment, forming the ITO films 4,8 includes: a small-grain ITO film 41 in contact with the intrinsic amorphous silicon layer is formed, and a large-grain ITO film 42 in contact with the metal electrode is formed.
The grain sizes, thicknesses, etc. of the small-grain ITO film 41 and the large-grain ITO film 42 are as described above, and will not be described again.
The preparation method of the solar cell comprises the following steps:
s1, silicon wafer: selecting an N-type silicon wafer, wherein the resistivity is 0.5-3 omega cm, the thickness is 150-200 mu m, and the size is 156.75cm;
s2, cleaning and texturing: removing a surface oxide layer by using an HF solution with the volume fraction of 5%, and forming a shallower pyramid structure on the surface of the silicon wafer by using anisotropic corrosion of monocrystalline silicon by using a method of adding alcohol to KOH, naOH or tetramethyl ammonium hydroxide (TMAH).
S3, forming the intrinsic amorphous silicon layers 2 and 6 and the doped amorphous silicon layers 3 and 7:
silane (SiH) 4 ) A gas is introduced into the vacuum chamber and the first intrinsic amorphous silicon layer 2 is formed on the entire area of the first surface of the silicon base 1 by plasma CVD. SiH is then added to 4 Gas, H 2 Gas and PH 3 A gas is introduced into the vacuum chamber, and an N-type amorphous silicon layer 3 is formed on the first intrinsic amorphous silicon layer 2 by a plasma CVD method:
then turn over, change tray, then SiH 4 A gas is introduced into the vacuum chamber and the second intrinsic amorphous silicon layer 6 is formed on the entire area of the second surface of the silicon base 1 by plasma CVD. SiH is then added to 4 Gas, H 2 Gas and B 2 H 6 (diborane) gas is introduced into the vacuum chamber and a p-type amorphous silicon layer 7 is formed on the second intrinsic amorphous silicon layer 6 by a plasma CVD method.
S4, ITO films 4 and 8:
ITO coating is carried out on the doped amorphous silicon layers 3,7 on the front side and the back side by using a Reactive Plasma Deposition (RPD) or magnetron sputtering method; the back is shielded by the designed edge of the carrier plate, namely by a mask, the specific shielding area around is 0.8mm, and the anti-winding effect is achieved in the deposition process.
And during ITO film coating, ITO films with different grains are sequentially deposited on the first side and the second side of the substrate after the doped amorphous silicon layers 3 and 7 are deposited.
The specific method is as follows: at least 4 non-pollution film plating target positions exist in PVD mass production equipment, and different targets are arranged on the target positions; the substrate is loaded on the carrier plate and is subjected to film plating by different target positions in sequence to obtain the required film design. O at different target sites 2 Atmosphere adjustment is carried out to adjust the work function and the carrier concentration of the TCO film layer to the required concentration range.
After CVD, the silicon wafer is loaded on a carrier (carrier), the carrier is a hollowed-out flat plate design, and the edge of the hollowed-out part is provided with a convex edge of about 0.6-0.8mm so as to support the silicon wafer, and meanwhile, the front and back surface coatable areas are exposed. The physical vapor deposition mode is adopted in the specific film coating process, the phase in the target material is bombarded by certain energy, and corresponding gas is introduced at the same time, so that a certain atmosphere environment is formed, wherein the atmosphere environment is usually 90% -99% of Ar and 1% -6% of O 2 The method comprises the steps of carrying out a first treatment on the surface of the 0% -4% of H 2 . Different Ar and O are adopted for different work functions 2 、H 2 Flow ratio. The specific process selection is correspondingly described for different embodiments.
S5, printing an electrode: a layer of low-temperature conductive silver paste is respectively printed on the ITO films 4 and 8 on the front side and the back side by a screen printing method, and then the low-temperature conductive silver paste is sintered at the low temperature of 150-300 ℃ to form good ohmic contact.
Hereinafter, the present invention will be described by way of specific examples and comparative examples.
Comparative example 1: please refer to the solar cell structure shown in fig. 1.
The first ITO film 4 positioned on the front surface is a single-layer film, the ratio of indium oxide to tin oxide is 97:3, and the thickness of the film layer is 70-75 nm. The preparation process comprises the following steps: ar and O with certain gas flow rate ratio are introduced 2 、H 2 The gas is used for obtaining the ITO film with the ratio of indium oxide to tin oxide of 97:3, the plating process pressure in the process cavity is 0.7 Pa-1.0 Pa, and the grain size of the obtained first ITO film 4 is in the range of 1-10 nm.
The second ITO film 8 on the back is a single-layer film, the ratio of indium oxide to tin oxide is 90:10, and the thickness of the film layer is 70nmAbout 75nm. The preparation process comprises the following steps: ar and O with certain gas flow rate ratio are introduced 2 、H 2 The gas is used for obtaining an ITO film with the ratio of indium oxide to tin oxide of 90:10, and the plating process pressure in the process cavity is 0.7 Pa-1.0 Pa; the grain size of the obtained second ITO thin film 8 is in the range of 1 to 10 nm.
Example 1: please refer to the solar cell structure shown in fig. 1.
The first ITO film 4 positioned on the front surface is a single-layer film, the ratio of indium oxide to tin oxide is 97:3, and the thickness of the film layer is 70-75 nm. The preparation process comprises the following steps: ar and O with certain gas flow rate ratio are introduced 2 、H 2 The gas is used for obtaining an ITO film with the ratio of indium oxide to tin oxide of 97:3, and the plating process pressure in the process cavity is 0.5-0.7 Pa; the grain size of the obtained first ITO thin film 4 is in the range of 20nm to 30nm.
The second ITO film 8 on the back is of a single-layer structure, the ratio of indium oxide to tin oxide is 90:10, and the thickness of the film is 70-75 nm. Ar and O with certain gas flow rate ratio are introduced 2 、H 2 The gas is used for obtaining an ITO film with the ratio of indium oxide to tin oxide of 90:10, and the plating process pressure in the process cavity is 0.5-0.7 Pa; the grain size of the obtained second ITO thin film 8 is in the range of 20-30 nm.
Example 2: please refer to the solar cell structure shown in fig. 2.
The first ITO film 4 on the front surface is a two-layer ITO film. The ITO film is contacted with the first doped amorphous silicon layer 3, the ratio of indium oxide to tin oxide is 97:3, and the thickness of the film layer is 5-10 nm; the preparation process comprises the following steps: ar and O with certain gas flow rate ratio are introduced 2 、H 2 A gas such that indium oxide: the tin oxide is 97:3, the plating process pressure in the inner ITO film process cavity is 0.7 Pa-1.0 Pa, and the grain size of the film layer is between 1nm and 10 nm. An ITO film in contact with the first metal electrode 5, wherein the ratio of indium oxide to tin oxide is 97:3, and the thickness of the film layer is 65-70 nm; the preparation process comprises the following steps: ar and O with certain gas flow rate ratio are introduced 2 、H 2 A gas such that indium oxide: tin oxide is 97:3, and the outer ITO film is manufacturedThe plating process pressure in the process cavity is 0.5 Pa-0.7 Pa; the grain size of the film layer is between 20nm and 30nm.
The second ITO thin film 8 on the back surface is a two-layer ITO film. The ITO film contacted with the second doped amorphous silicon layer 7 comprises the components of indium oxide and tin oxide in a ratio of 90:10, has a work function of 4.6-4.8 eV and has a film thickness of 5-10 nm; the preparation process comprises the following steps: ar and O with certain gas flow rate ratio are introduced 2 、H 2 A gas such that indium oxide: the tin oxide is 90:10, the plating process pressure in the inner ITO film process cavity is 0.7 Pa-1.0 Pa, and the grain size of the film layer is between 1nm and 10 nm. The ITO film contacted with the second metal electrode 9 comprises the components of indium oxide and tin oxide in a ratio of 90:10, and the thickness of the film layer is 65-70 nm. The preparation process comprises the following steps: ar and O with certain gas flow rate ratio are introduced 2 、H 2 A gas such that indium oxide: the tin oxide is 90:10, and the plating process pressure in the process cavity of the outer ITO film is 0.5 Pa-0.7 Pa; the grain size of the film layer is between 20nm and 30nm.
The performances of the solar cells 100 corresponding to comparative examples, example 1, and example 2 are shown in table 1, wherein the data of example 1 and example 2 are values of change with respect to the comparative examples.
TABLE 1
Group of Eff(％) Voc(V) Isc(A) FF(％)
Comparative example 24.51 744.9 6.416 84.92
Example 1 +0.05 +0.1 +0.028 -0.2
Example 2 +0.10 +0.1 +0.025 +0.01
The ITO films on the front and the back of the comparative example are small-grain films formed by high-voltage lines, and have the advantages of more grain boundaries, poor light transmittance, electricity and high FF. The ITO films on the front and back sides of example 1 are large grain films formed by low voltage lines, and have a new good light transmittance but slightly inferior electrical properties. The front and back ITO films of example 2 all used a combination of ITO films with different grain sizes, i.e., the inner layer was a small grain ITO film 41 formed by the high voltage route, and the outer layer was a large grain ITO film 42 formed by the low voltage route.
As can be seen from comparison of comparative example with example 1: the optical performance of the front ITO film of example 1 was improved, with a significant 28mA increase in short circuit current Isc; but the contact becomes worse, FF decreases by 0.2, the open circuit voltage Voc increases slightly by 0.1mV, and the efficiency gain is 0.05%.
As can be seen from comparison of comparative example with example 2: the optical performance of the front ITO film is improved, the short-circuit current Isc is increased by 25mA, the contact is equivalent to that of a comparative example, FF is unchanged, the open-circuit voltage Voc is slightly increased by 0.1mV, and the efficiency gain is 0.10%.
In summary, compared with the prior art, the ITO film provided by the invention comprises at least two film layers with different grain sizes, so that the IV performance of the solar cell is better, and meanwhile, the product reliability is further ensured. The inner layer film adopts small crystal grains, has high carrier concentration and ensures contact; the outer layer film adopts a multilayer ITO film layer design with large crystal grains and high mobility and ensures light transmittance.
It should be understood that although the present disclosure describes embodiments, not every embodiment is provided with a separate embodiment, and that this description is for clarity only, and that the skilled artisan should recognize that the embodiments may be combined as appropriate to form other embodiments that will be understood by those skilled in the art.
The above list of detailed descriptions is only specific to practical embodiments of the present invention, and they are not intended to limit the scope of the present invention, and all equivalent embodiments or modifications that do not depart from the spirit of the present invention should be included in the scope of the present invention.

Claims (13)

1. The solar cell comprises a silicon substrate, and an intrinsic amorphous silicon layer, a doped amorphous silicon layer, an ITO film and a metal electrode which are sequentially arranged on one side of the silicon substrate.
2. The solar cell of claim 1, wherein: in the two adjacent ITO films, the grains of the film layer close to the metal electrode are large.
3. The solar cell of claim 1, wherein: the grain size of the ITO film contacted with the doped amorphous silicon layer is 1 nm-20 nm.
4. The solar cell of claim 1, wherein: the grain size of the ITO film in contact with the metal electrode is 20nm to 500nm.
5. The solar cell of claim 1, wherein: the crystal form of the ITO film contacted with the doped amorphous silicon layer is columnar crystal, and the crystal form of the ITO film contacted with the metal electrode is equiaxed crystal.
6. The solar cell of claim 1, wherein: the ITO film comprises a small-grain ITO film in contact with the doped amorphous silicon layer and a large-grain ITO film in contact with the metal electrode, wherein the thickness of the large-grain ITO film is larger than that of the small-grain ITO film.
7. The solar cell of claim 6, wherein: the thickness of the ITO film is 50-120 nm, and the thickness of the large-grain ITO film is 40-90 nm.
8. A method of fabricating a solar cell, comprising: forming an intrinsic amorphous silicon layer, a doped amorphous silicon layer, an ITO film and a metal electrode on one side of the silicon substrate in sequence; the method is characterized in that: forming the ITO film includes: at least two layers of ITO films are formed, and the grain sizes of different ITO films are different.
9. The method of manufacturing a solar cell according to claim 8, wherein: the process for forming the small-grain ITO film contacted with the doped amorphous silicon layer comprises the following steps: the coating pressure is 0.7-1.5 Pa, and the power density is 2-8 kW/m.
10. The method of manufacturing a solar cell according to claim 8, wherein: the process for forming the large-grain ITO film in contact with the metal electrode comprises the following steps: the coating pressure is 0.3 Pa-0.7 Pa, and the power density is 5-15 kW/m.
11. The method of manufacturing a solar cell according to claim 8, wherein: forming the ITO film includes: forming a small-grain ITO film in contact with the doped amorphous silicon layer and forming a large-grain ITO film in contact with the metal electrode, wherein the grain size of the small-grain ITO film is 1-20 nm, and the grain size of the large-grain ITO film is 20-500 nm.
12. The method of manufacturing a solar cell according to claim 9 or 11, characterized in that: the grain size of the small-grain ITO film is 1-20 nm, and the thickness of the small-grain ITO film is 10-30 nm.
13. The method of manufacturing a solar cell according to claim 10 or 11, characterized in that: the crystal grain of the large-crystal grain ITO film is 15-500 nm, and the thickness of the large-crystal grain ITO film is 40-90 nm.
CN202111624262.1A 2021-12-28 2021-12-28 Solar cell and preparation method thereof Pending CN116364791A (en)

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