CN108511537B - Solar cell - Google Patents
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- CN108511537B CN108511537B CN201810673308.0A CN201810673308A CN108511537B CN 108511537 B CN108511537 B CN 108511537B CN 201810673308 A CN201810673308 A CN 201810673308A CN 108511537 B CN108511537 B CN 108511537B
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- 239000010410 layer Substances 0.000 claims abstract description 184
- 239000000758 substrate Substances 0.000 claims abstract description 30
- 239000002344 surface layer Substances 0.000 claims abstract description 20
- 230000008021 deposition Effects 0.000 claims description 26
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 21
- 230000031700 light absorption Effects 0.000 claims description 14
- 239000010409 thin film Substances 0.000 claims description 14
- 239000011787 zinc oxide Substances 0.000 claims description 11
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 10
- 229910052750 molybdenum Inorganic materials 0.000 claims description 10
- 239000011733 molybdenum Substances 0.000 claims description 10
- WUPHOULIZUERAE-UHFFFAOYSA-N 3-(oxolan-2-yl)propanoic acid Chemical compound OC(=O)CCC1CCCO1 WUPHOULIZUERAE-UHFFFAOYSA-N 0.000 claims description 7
- 229910052980 cadmium sulfide Inorganic materials 0.000 claims description 7
- 229910052751 metal Inorganic materials 0.000 claims description 7
- 239000002184 metal Substances 0.000 claims description 7
- 238000010248 power generation Methods 0.000 claims description 4
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- 238000006243 chemical reaction Methods 0.000 description 15
- KTSFMFGEAAANTF-UHFFFAOYSA-N [Cu].[Se].[Se].[In] Chemical compound [Cu].[Se].[Se].[In] KTSFMFGEAAANTF-UHFFFAOYSA-N 0.000 description 11
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- DVRDHUBQLOKMHZ-UHFFFAOYSA-N chalcopyrite Chemical compound [S-2].[S-2].[Fe+2].[Cu+2] DVRDHUBQLOKMHZ-UHFFFAOYSA-N 0.000 description 1
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- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
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- 238000005118 spray pyrolysis Methods 0.000 description 1
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- 239000011593 sulfur Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
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- 238000007738 vacuum evaporation Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- 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
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
- H01L31/022441—Electrode arrangements specially adapted for back-contact solar cells
-
- 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
- H01L31/0216—Coatings
- H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/02167—Coatings for devices characterised by at least one potential jump barrier or surface barrier for solar cells
-
- 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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
-
- 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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/541—CuInSe2 material PV cells
Abstract
The present invention relates to a solar cell comprising: a substrate; the back electrode layer is arranged above the substrate and comprises a first layer and a second layer, the first layer is close to one side of the substrate, and the volume density of the second layer is smaller than that of the first layer; a light absorbing layer disposed over the second layer; and a front electrode layer disposed over the second layer; and wherein there is no sharp demarcation between the first layer and the second layer. Compared with the solar cell with the smooth back electrode surface in the prior art, the solar cell with the rough surface layer with the appropriate volume density is beneficial to spontaneously forming a light limiting effect, reducing the light reflectivity of the solar cell and improving the light absorptivity.
Description
Technical Field
The invention relates to the field of solar photovoltaics, in particular to a solar cell.
Background
The rapid development of economy brings global energy crisis, environmental pollution and other problems, and the development of renewable energy and clean energy is urgent. In recent years, solar energy has gradually replaced fossil energy as a new energy source with advantages of low price, abundant content, easy availability, no pollution and the like. The utilization of solar energy as an energy source is mainly embodied in the utilization of the solar energy for power generation.
Thin film solar cells, also known as "solar chips" or "photovoltaic cells," are devices that utilize the conversion of light energy into electrical energy. The thin-film solar cell mainly generates electricity by forming a P-N section thin film on a substrate by a Copper Indium Gallium Selenide (CIGS) material and other materials, and has the advantages of strong light absorption capacity, high conversion efficiency, low manufacturing cost, flexibility, stable electricity generation, environmental friendliness and the like. The conversion efficiency of the thin-film solar cell is the percentage of the converted effective electric energy to the incident sunlight energy, and the current highest conversion efficiency of the laboratory solar cell exceeds 22%, but the high conversion efficiency is difficult to achieve in the actual industrial production. The production cost can be effectively saved by improving the light energy conversion efficiency of the solar cell, and the energy crisis problem is further solved.
Disclosure of Invention
In order to solve the technical problems in the prior art, the present invention provides a solar cell, including: a substrate; the back electrode layer is arranged above the substrate and comprises a first layer and a second layer, the first layer is close to one side of the substrate, and the volume density of the second layer is smaller than that of the first layer; a light absorbing layer disposed over the second layer; and a front electrode layer disposed over the second layer.
As described above, the first and second back electrode layers include metal molybdenum.
In the solar cell, the thickness of the second back electrode layer is 5-30nm.
In the solar cell, the thickness of the first back electrode layer is 300-1000nm.
The solar cell as described above, wherein the molybdenum content per unit volume of the second back electrode layer is about 6g/cm 3 。
The solar cell as described above, wherein the molybdenum content per unit volume of the first back electrode layer is about 10g/cm 3 。
In the solar cell, the second back electrode layer has a rough surface layer, and the roughness Ra is Ra < 30nm.
As described above, the first back electrode layer may further include a first deposition layer and a second deposition layer, the first deposition layer having a volume density less than that of the second deposition layer, wherein the first deposition layer is adjacent to the substrate.
A method for manufacturing a thin film solar cell comprises the following steps: preparing a first back electrode layer on a substrate; preparing a second back electrode layer on the first back electrode layer, wherein the volume density of the second back electrode layer is less than that of the first back electrode layer; preparing a light absorbing layer on the second back electrode layer; a front electrode layer is prepared on the light absorbing layer.
Compared with the solar cell with the smooth back electrode surface in the prior art, the solar cell with the back electrode surface with the rough surface layer with moderate volume density is beneficial to spontaneously forming a light limiting effect, reducing the light reflectivity of the solar cell and improving the light absorptivity.
Drawings
Preferred embodiments of the present invention will be described in further detail below with reference to the accompanying drawings, in which:
FIGS. 1A and 1B are schematic diagrams of a thin film solar cell according to one embodiment of the invention; and
fig. 2 is a flow chart of the fabrication of a thin film solar cell according to one embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
In the following detailed description, reference is made to the accompanying drawings that form a part hereof and in which is shown by way of illustration specific embodiments of the application. In the drawings, like numerals describe substantially similar components throughout the different views. Various specific embodiments of the present application are described in sufficient detail below to enable those skilled in the art to practice the teachings of the present application. It is to be understood that other embodiments may be utilized and structural, logical or electrical changes may be made to the embodiments of the present application.
The basis of the operation of the solar cell is the photovoltaic effect of a semiconductor PN junction, namely when sunlight irradiates the PN junction in the solar cell, the distribution state of charges in the solar cell changes, and electromotive force and current are generated on two sides of the PN junction.
Fig. 1A and 1B are schematic diagrams of a thin film solar cell according to one embodiment of the present invention. According to an embodiment of the present invention, a common soda-lime glass is used as the substrate 101, wherein sodium element enters CIGS crystal grains (the light absorption layer 103) in a diffusion manner, so that the growth of the CIGS crystal grains (the light absorption layer 103) is promoted, the electrical properties of the light absorption layer 103 are optimized, and particularly, the P-type characteristics of the light absorption layer 103 can be improved. As alternative embodiments, other rigid materials such as glass, ceramic, etc., or flexible materials such as metal, plastic, etc., may be used for the substrate 101. It should be noted that some glasses may need to be processed by special processes during use, such as borosilicate glass and polyimide glass; if a metal is selected as the substrate 101, an insulating barrier layer, such as silicon oxide, silicon nitride and the like, needs to be plated on the side of the upper surface of the metal, which is in contact with other components of the solar cell; if plastics are selected as the substrate, care should be taken as to the temperature limit to which the selected plastics are resistant.
The back electrode 102 is plated on the surface of the substrate 101, and according to an embodiment of the present invention, molybdenum (Mo) is used as the back electrode 102, which has the advantages of good stability, high reflectivity, and low resistance. As an alternative embodiment, metallic tungsten (W) or a transparent conductive layer (TCO) may also be used as the back electrode. According to one embodiment of the present invention, the back electrode 102 has a two-layer structure, wherein the first layer 1021 is adjacent to the substrate 101 and the second layer 1022 comprises a rough surface layer. According to one embodiment of the invention there is no sharp demarcation between the first layer and the second layer. According to one embodiment of the invention, the rough facing layer 1022 has a bulk density less than that of the first layer 1021 and a bulk density of about 4-8g/cm 3 The surface roughness does not exceed 30nm. A rough surface layer with a suitable roughness may improve the adhesion of the back electrode to the adhesion layer thereon. In the prior art, the volume density of the back electrode is about 9-10g/cm 3 The surface roughness is about 4nm, the surface is smooth, and when the rest film layers are continuously plated on the surface, the smooth surface is formed. In this case, the surface roughness of the light absorbing layer 103 is too low, the volume density is high, and the reflectance is high, which is not favorable for sufficient absorption of light energy. Compared with the solar cell with the smooth back electrode surface in the prior art, the solar cell with the moderate rough back electrode surface has a surface with lower volume density, so that the light limiting effect is formed spontaneously, the light reflectivity of the solar cell is reduced, and the light absorption rate is improved. According to one embodiment of the present invention, the back electrode surface bulk density is about 4-8g/cm 3 Surface roughness ofPreferably 30nm or less. The results of the examples of the present invention were collected and analyzed to obtain a surface bulk density of about 5 to 7g/cm 3 And when the roughness is between 10 nm and 20nm, the conversion efficiency of the solar cell is obviously improved. According to an embodiment of the present invention, the volume density may also be defined as a volume of a certain material in a unit volume, the volume density of the first back electrode layer is greater than the volume density of the second back electrode layer, the content of Mo in the first back electrode layer is greater than the content of Mo in the second back electrode layer in a unit volume, or the volume occupied by the first electrode-covered layer is greater than the volume occupied by the second back electrode layer in a unit volume.
According to an embodiment of the present invention, the first layer 1021 may further include a first deposition layer and a second deposition layer. Wherein the first deposition layer is adjacent to one side of the substrate and the second deposition layer is disposed between the first deposition layer and the second layer. According to an embodiment of the present invention, the first deposition layer has a smaller volume density than the second deposition layer, that is, the first deposition layer has a larger roughness than the second deposition layer, so that the adhesion of the back electrode can be increased; the second deposition layer is more compact than the first deposition layer, has large volume density, smooth surface, low roughness and better conductivity. The conversion efficiency of the solar cell is obviously improved by combining the rough surface layer of the second layer 1022 in the invention.
The surface of the back electrode rough surface layer 1022 is the light absorption layer 103. The back electrode has a smooth surface layer, and the light absorption layer thereon also has a smooth surface; the back electrode has a rough surface layer, and the light absorption layer thereon also has a rough surface layer. According to an embodiment of the present invention, the light absorbing layer may be a CIGS thin film having a uniform thickness. The CIGS thin film is a chalcopyrite crystal composed of four elements of copper (Cu), indium (In), gallium (Ga), and selenium (Se) In a ratio, and has a P-type characteristic In a solar cell. According to the difference of the ratio of gallium to indium, the band gap width is continuously adjustable within the range of 1.02eV to 1.65eV, so that the band gap can be applied to different illumination conditions. If the band gap is increased, sulfur may be used instead of selenium to lower the valence band. According to one embodiment of the invention, the light absorbing layer is plated on the surface of the back electrode with a roughness of less than 30nm, and correspondingly has a rough surface layer. When the solar cell with the light absorption layer with the rough surface layer is placed in the sunlight, the reflection of light energy by the rough surface is reduced, and the absorption rate is increased.
The buffer layer 104 on the upper surface of the light absorbing layer 103 is located between the light absorbing layer 103 and the front electrode layer, so that the band gap discontinuity between the two layers can be reduced, the problem of lattice mismatch can be solved, and the problem of mismatch of the forbidden bandwidth can be solved. According to one embodiment of the present invention, cadmium sulfide (CdS) is used as a buffer layer, which has N-type semiconductor material characteristics. Cadmium sulfide has high light transmittance and can reduce light loss of the thin-film solar cell, so that the photoelectric conversion efficiency of the solar cell is effectively increased, and the cadmium sulfide is an ideal buffer material for the solar cell.
The front electrode layer includes high-resistance zinc oxide and low-resistance zinc oxide, and constitutes the high-resistance layer 105 and the transparent electrode layer 106, respectively. According to one embodiment of the present invention, the high-resistance layer 105 is an intrinsic zinc oxide layer (i-ZnO). The transparent electrode layer 106 may serve as an upper electrode of the solar cell. In actual production, the transparent electrode layer 106 may be made of a combination material of n-doped transparent conductive substances (n-ZnO), such as AZO, GZO, IZO, ITO, or the like. According to an embodiment of the present invention, aluminum-doped zinc oxide (AZO) is used as the transparent electrode layer 106, which has high visible light transmittance and low surface resistance, and can reduce series resistance loss and improve conversion efficiency of the solar cell. The front electrode layer and the light absorbing layer 103 finally constitute a PN junction portion of the solar cell together, realizing a solar power generation function.
A gate electrode 107 is plated over the front electrode layer for collecting current. Based on the above 101 to 107, a solar cell that can realize photovoltaic power generation is finally formed.
Fig. 2 is a flow chart of the fabrication of a thin film solar cell according to one embodiment of the present invention. As shown, the method 200 of fabricating a solar cell includes the steps of: first, a substrate 201 is obtained, and a suitable material is selected as a substrate of the solar cell. According to one embodiment of the invention, the substrate selected is soda lime glass. In practice and production, the substrate may be made of other rigid materials such as glass, ceramic, etc., or flexible materials such as metal, plastic, etc. according to alternative embodiments of the present invention.
After the substrate 201 is obtained, the back electrode 202 is plated on the selected substrate. According to one embodiment of the invention, metal molybdenum is selected as a back electrode, and a molybdenum back electrode layer with the thickness of about 500nm is plated on a substrate by a magnetron sputtering method. According to one embodiment of the invention, a first deposition layer of 10-100nm is deposited on a substrate as an adhesion layer using a first sputtering gas pressure; and continuously depositing a second deposition layer of 200-1000nm on the substrate by using a second sputtering gas pressure to form a conductive layer, wherein the first sputtering gas pressure is higher than the second sputtering gas pressure. Such multiple sputtering by changing the sputtering gas pressure can improve the adhesion and conductivity of the back electrode. The back electrode layer may be formed by only one sputtering method according to the environment where the solar cell is installed and the required output power. The first sputtering gas pressure and the second sputtering gas pressure mentioned here do not refer to a specific gas pressure, but are relative concepts. In the actual production and manufacturing process, the sputtering pressure needs to be adjusted according to the actual use condition.
And (5) carrying out surface modification treatment on the back electrode 203. According to one embodiment of the invention, the surface modification treatment of the back electrode is realized by adopting an ion etching method. I.e. after the plating of the back electrode 202 is completed, it is brought into contact with Ar + Vacuum chamber of source, accelerating Ar by about 1KV voltage + And etching the surface of the back electrode for about 2-10 minutes to form a rough film surface. Experiments related to the present invention show that the roughness of the rough surface layer formed by ion etching for 2-10 minutes under the conditions is about 10-20nm. Besides the ion etching method, according to an embodiment of the present invention, the surface of the back electrode can be formed with the same roughness by using a mechanical sand blasting etching method.
The back electrode surface modification treatment 203 is not limited to the etching manner. According to an embodiment of the present invention, the magnetron sputtering method may be further used to continuously plate the molybdenum layer on the surface of the plated back electrode by using the third sputtering gas pressure. Wherein the third sputtering gas pressure is higher than the second sputtering gas pressure. As is easily understood by those skilled in the art, the film formed by the magnetron sputtering method under high air pressure is loose and porous and has rough surface, and if the air pressure and the magnetron sputtering time are well controlled, the formation of the rough surface layer with the roughness of less than 30nm on the surface of the back electrode can be completely realized.
The modified back electrode surface is plated with a light absorbing layer 204. According to one embodiment of the present invention, a co-evaporation method is used to plate a light absorbing layer having a thickness of about 2000 to 3000nm, which is a CIGS layer in the present invention. According to another embodiment of the present invention, the CIGS layer may also be plated using a post-sputtering selenization process. It will be appreciated by those skilled in the art that there are many ways to plate a CIGS layer, in addition to the two methods listed above, three-step co-evaporation, electrochemical deposition, spray pyrolysis, screen printing, etc. The co-evaporation method and the selenization method after sputtering are the methods which are most widely researched, have mature technology and have high battery preparation efficiency. According to one embodiment of the invention, the evaporation method and the selenization after sputtering can be combined to plate the CIGC layer. Since the light absorbing layer is plated on the basis of the back electrode, and the surface of the back electrode is a rough surface layer, the CIGS layer obtained after plating also has a rough surface.
A buffer layer 205 is plated. According to one embodiment of the invention, the buffer layer is cadmium sulfide. According to one embodiment of the present invention, a buffer layer having a thickness of about 40nm is plated on the surface of the light absorbing layer using a chemical water bath method. As will be appreciated by those skilled in the art, other methods of buffer layer plating may also be used, such as vacuum evaporation, sputtering atomic layer chemical vapor deposition, electrodeposition, and the like.
The front electrode layer-the high resistance layer 206 is plated. According to one embodiment of the invention, a thin film of intrinsic zinc oxide is plated on the buffer layer to a thickness of about 50nm using magnetron sputtering. According to one embodiment of the invention, the high resistance layer may also be plated using a radio frequency sputtering method. The plating of the high-resistance layer is not limited to these two methods.
The front electrode layer-transparent electrode layer 207 is plated. According to one embodiment of the invention, the transparent electrode layer is aluminum-doped zinc oxide, and the transparent electrode layer with the thickness of about 300nm is plated on the high-resistance layer by adopting a magnetron sputtering method. In addition, radio frequency sputtering, reactive sputtering and the like can be used for plating the transparent electrode layer, and if large-scale plating is needed, a direct current radio frequency method can also be used.
Finally, the gate 208 is plated. And (4) evaporating a grid electrode on the surface of the battery to finally form the battery together with the above layers.
Using the solar cell prepared as above, the cell performance is shown in the following table:
table 1:
as shown in table 1, the surface roughness in the table is the back electrode surface roughness, reflecting the back electrode surface layer having different bulk densities. In the prior art, the volume density of the back electrode is about 10g/m 3 The roughness was about 4nm. Compared with the prior art, when the surface roughness of the back electrode is increased to 15nm, the open-circuit voltage V is increased OC Constant, short-circuit current density J SC The conversion efficiency eta of the solar cell is obviously improved; short-circuit current density J when the roughness of the back electrode surface is increased to 30nm SC Although there is an increase, its open circuit voltage V OC The fill factor FF decreases, and the solar cell conversion efficiency η decreases instead. However, as can be seen from the table, when the surface roughness of the back electrode is 15nm and 30nm, the short circuit current density is increased compared to the prior art, indicating that the improvement of the surface roughness is advantageous for increasing the light absorption rate.
Multiple experiments show that the roughness of the back electrode after surface modification treatment is within the range of 10-20nm, which is beneficial to improving the conversion efficiency of the solar cell. Too rough a back electrode surface can affect CIGS grain growth, which in turn affects the open circuit voltage V of the solar cell OC Further, the conversion efficiency of the solar cell is affected, and the conversion efficiency is reduced.
The above embodiments are provided only for illustrating the present invention and not for limiting the present invention, and those skilled in the art can make various changes and modifications without departing from the scope of the present invention, and therefore, all equivalent technical solutions should fall within the scope of the present invention.
Claims (1)
1. A solar cell, comprising:
a substrate;
the back electrode layer is arranged above the substrate and comprises a first back electrode layer and a second back electrode layer, the first back electrode layer is close to the substrate, and the volume density of the second back electrode layer is smaller than that of the first back electrode layer;
a light absorbing layer disposed over the second back electrode layer;
and
a front electrode layer disposed over the light absorbing layer;
the first back electrode layer and the second back electrode layer comprise metal molybdenum;
the thickness of the second back electrode layer is 5-30nm;
the molybdenum content in the unit volume of the second back electrode layer is 6g/cm 3 ；
The molybdenum content in the unit volume of the first back electrode layer is 10g/cm 3 ；
The second back electrode layer is provided with a rough surface layer, and the roughness Ra is 10-20nm;
wherein the first back electrode layer is adjacent to the substrate, the second back electrode layer comprises a rough surface layer, no obvious boundary exists between the first layer and the second layer, and the volume density of the rough surface layer is less than that of the first back electrode layer; the volume density of the first back electrode layer is larger than that of the second back electrode layer, namely in a unit volume, the content of Mo in the first back electrode layer is larger than that of the second back electrode layer, or in the unit volume, the volume occupied by the first back electrode layer is larger than that of the second back electrode layer;
the first back electrode layer comprises a first deposition layer and a second deposition layer, wherein the first deposition layer is close to one side of the substrate, the second deposition layer is arranged between the first deposition layer and the second deposition layer, and the volume density of the first deposition layer is smaller than that of the second deposition layer;
the surface of the rough surface layer of the back electrode is provided with a light absorption layer; the light absorption layer is a CIGS thin film with uniform thickness, and is plated on the surface of the back electrode with the roughness of 10-20nm;
a buffer layer on the upper surface of the light absorbing layer between the light absorbing layer and the front electrode layer, and cadmium sulfide (CdS) as the buffer layer;
the front electrode layer comprises high-resistance zinc oxide and low-resistance zinc oxide which respectively form a high-resistance layer and a transparent electrode layer, and the high-resistance layer is an intrinsic zinc oxide layer (i-ZnO); the transparent electrode layer is an upper electrode of the solar cell, and aluminum-doped zinc oxide (AZO) is used as the transparent electrode layer;
the grid is plated on the front electrode layer and used for collecting current; finally forming a solar cell capable of realizing photovoltaic power generation; the thickness of the first back electrode layer is 300-1000nm.
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| JP2006165386A (en) * | 2004-12-09 | 2006-06-22 | Showa Shell Sekiyu Kk | Cis system thin film solar cell and method for manufacturing the same |
| KR101306529B1 (en) * | 2011-11-21 | 2013-09-09 | 엘지이노텍 주식회사 | Solar cell and method of fabricating the same |
| WO2014072833A2 (en) * | 2012-11-09 | 2014-05-15 | Nanoco Technologies, Ltd. | Molybdenum substrates for cigs photovoltaic devices |
| CN103354246A (en) * | 2013-07-10 | 2013-10-16 | 尚越光电科技有限公司 | CIGS (Copper Indium Gallium Selenium) solar cell back-electrode Mo film and preparation technology thereof |
| CN105355676B (en) * | 2015-11-18 | 2017-11-03 | 北京四方创能光电科技有限公司 | A kind of back electrode structure of flexible CIGS thin film solar cell |
| CN107887456A (en) * | 2017-10-30 | 2018-04-06 | 周燕红 | A kind of preparation method of back electrode molybdenum (Mo) film |
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