Antireflection film and preparation method thereof, and solar cell
By employing multilayer ITO, IZO, and AZO antireflection films in solar cells, the problem that existing antireflection films cannot simultaneously achieve conductivity and antireflection has been solved, achieving low reflectivity and high-efficiency current conduction, thereby improving the photoelectric conversion efficiency of solar cells.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHONGSHAN DEHUA CHIP TECH CO LTD
- Filing Date
- 2023-02-17
- Publication Date
- 2026-05-22
AI Technical Summary
Existing antireflective films cannot simultaneously achieve good antireflection and conductivity in solar cells, resulting in low current conduction efficiency, and the metal electrodes and grid lines affect the light incident area.
A multi-layer structure consisting of a first ITO layer, an IZO layer, an AZO layer, and a second ITO layer is adopted. By precisely controlling the thickness and refractive index of each layer, broadband anti-reflection is achieved, and it is used as a conductive layer to replace traditional metal electrodes and grid wires.
Achieving an average reflectivity of less than 1% in the 400–850 nm range improves the transmittance and current conduction efficiency of solar cells, thereby enhancing current and conversion efficiency.
Smart Images
Figure CN116190463B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of solar cell technology, and in particular to an antireflective film, its preparation method, and a solar cell. Background Technology
[0002] Solar energy, as a green energy source, is gaining increasing attention due to its advantages such as being inexhaustible, pollution-free, and not limited by geographical resources. To improve the photoelectric conversion efficiency of solar cells, reduce light reflection losses on the cell surface, and increase light transmission, anti-reflection coatings in the solar cell structure play a crucial role.
[0003] Anti-reflective coatings, also known as AR films, are widely used in optoelectronic devices such as optical lenses, solar cells, and detectors, as well as related fields. Anti-reflective coatings achieve their effect by designing and matching thin film materials with different refractive indices and thicknesses to reduce reflectivity within a certain bandwidth. Generally, common materials for anti-reflective coatings are non-conductive inorganic films such as TiO2, Al2O3, SiO2, and MgF2. Therefore, anti-reflective coatings typically do not possess conductive properties, such as anti-reflective films composed of TiO2 / Al2O3. Such anti-reflective coatings require metallic materials like Ag / Au to create the metal electrodes and grid lines to provide conductivity. These metal electrodes and grid lines are often opaque, directly affecting the actual light-receiving area of the battery.
[0004] Therefore, it is necessary to develop an antireflective film that not only has an antireflective effect but also serves as a conductive layer, allowing current to be effectively conducted to the electrodes on the surface. Summary of the Invention
[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the first aspect of the present invention proposes an anti-reflective film that can effectively improve the anti-reflective effect and conductivity, thereby increasing current and conversion efficiency.
[0006] A second aspect of the present invention also provides a method for preparing an antireflective film.
[0007] A third aspect of the present invention also provides a solar cell.
[0008] An antireflective coating according to a first aspect of the present invention comprises, in sequence, a first ITO layer, an IZO layer, an AZO layer, and a second ITO layer; the thickness of the first ITO layer is 45–70 nm; the thickness of the IZO layer is 10–25 nm; the thickness of the AZO layer is 38–50 nm; and the thickness of the second ITO layer is 4–15 nm.
[0009] The antireflective film according to embodiments of the present invention has at least the following beneficial effects:
[0010] The antireflective film of this invention does not require a high-resistance blocking layer and has low internal resistance. Furthermore, by selecting a first ITO layer, an IZO layer, an AZO layer, and a second ITO layer as the antireflective film and matching their thicknesses, a good broadband antireflective effect is achieved in the range of 400–850 nm. On the other hand, the antireflective film of this application also serves as a conductive layer in solar cells, enabling current to be effectively conducted to the surface electrodes. Moreover, the metal grid lines in the solar cell can be removed, leaving only the metal electrodes for wire bonding during subsequent encapsulation, thereby increasing transmittance, current, and conversion efficiency.
[0011] According to some embodiments of the present invention, the ITO is indium tin oxide.
[0012] According to some embodiments of the present invention, the IZO is indium zinc oxide.
[0013] According to some embodiments of the present invention, the AZO is zinc aluminum oxide.
[0014] According to some embodiments of the present invention, the thickness of the first ITO layer is 50–60 nm; the thickness of the IZO layer is 15–20 nm; the thickness of the AZO layer is 42–47 nm; and the thickness of the second ITO layer is 6–12 nm. Therefore, the antireflective film of this application has better antireflective effect within these ranges.
[0015] According to some embodiments of the present invention, the refractive index of the first ITO layer is 1.9 to 2.1; the refractive index of the IZO layer is 2.0 to 2.2; the refractive index of the IZO layer is 1.8 to 2.0; and the refractive index of the second ITO layer is 1.9 to 2.1. Thus, the combination of refractive index and thickness within the above range further enhances the broadband antireflective effect of the antireflective coating.
[0016] According to some embodiments of the present invention, the refractive index of the first ITO layer is 2.0; the refractive index of the IZO layer is 2.1; the refractive index of the IZO layer is 1.9; and the refractive index of the second ITO layer is 2.0.
[0017] According to some embodiments of the present invention, the refractive index data involved in the present invention are all measured at 500 nm.
[0018] According to some embodiments of the present invention, the antireflective film has an average reflectivity of less than 1% in the range of 400–850 nm.
[0019] The method for preparing the antireflective film according to a second aspect embodiment of the present invention includes the following steps:
[0020] A first ITO layer, an IZO layer, an AZO layer, and a second ITO layer are sequentially deposited on the surface of the substrate by electron beam evaporation.
[0021] According to some embodiments of the present invention, the electron beam evaporation rate is 1 A / s to 10 A / s.
[0022] According to some embodiments of the present invention, the coating temperature of the electron beam evaporation is 100°C to 200°C.
[0023] According to some embodiments of the present invention, the oxygen flow rate of the electron beam evaporation is 5 sccm to 30 sccm.
[0024] A third aspect of the present invention provides a solar cell comprising the antireflective film described above.
[0025] According to some embodiments of the present invention, the solar cell is at least one of a triple-junction solar cell, a quadruple-junction solar cell, a quintuple-junction solar cell, or a hexaple-junction solar cell.
[0026] According to some embodiments of the present invention, the triple-junction solar cell is a triple-junction gallium arsenide solar cell.
[0027] According to some embodiments of the present invention, the triple-junction gallium arsenide solar cell includes a Ge-based cell;
[0028] The GaInAs cell is grown on one side of the Ge substrate cell;
[0029] GaInP top cell, grown on the surface of the cell in GaInAs.
[0030] In this invention, the triple-junction gallium arsenide solar cell consists of a Ge bottom cell, a GaInAs middle cell, and a GaInP top cell stacked sequentially.
[0031] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description
[0032] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:
[0033] Figure 1 This is a schematic diagram of the antireflective film according to Embodiment 1 of the present invention;
[0034] Figure 2 This is a schematic diagram of the solar cell structure of Embodiment 3 of the present invention.
[0035] Figure label:
[0036] 100, Anti-reflective coating; 101, First ITO layer; 102, IZO layer; 103, AZO layer; 103, Second ITO layer; 200, Triple-junction gallium arsenide solar cell; 300, Indicates electrode. Detailed Implementation
[0037] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.
[0038] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.
[0039] Example 1
[0040] Example 1 provides an antireflective coating, which sequentially includes a first ITO layer 101, an IZO layer 102, an AZO layer 103, and a second ITO layer 104; the thickness of the first ITO layer 101 is 52 nm; the thickness of the IZO layer 102 is 16 nm; the thickness of the AZO layer 103 is 45 nm; the thickness of the second ITO layer 104 is 10 nm; and the refractive indices of the first ITO layer 101, the IZO layer 102, the AZO layer 103, and the second ITO layer 104 are 2.0, 2.1, 1.9, and 2.0, respectively.
[0041] Example 2
[0042] Example 2 provides an antireflective coating, which sequentially includes a first ITO layer 101, an IZO layer 102, an AZO layer 103, and a second ITO layer 104; the thickness of the first ITO layer 101 is 60 nm; the thickness of the IZO layer 102 is 20 nm; the thickness of the AZO layer 103 is 42 nm; the thickness of the second ITO layer 104 is 6 nm; and the refractive indices of the first ITO layer 101, IZO layer 102, AZO layer 103, and second ITO layer 104 are 2.0, 2.1, 1.9, and 2.0, respectively.
[0043] Example 3
[0044] Example 3 provides an antireflective coating, which sequentially includes a first ITO layer 101, an IZO layer 102, an AZO layer 103, and a second ITO layer 104; the thickness of the first ITO layer 101 is 50 nm; the thickness of the IZO layer 102 is 15 nm; the thickness of the AZO layer 103 is 47 nm; the thickness of the second ITO layer 104 is 12 nm; and the refractive indices of the first ITO layer 101, the IZO layer 102, the AZO layer 103, and the second ITO layer 104 are 2.0, 2.1, 1.9, and 2.0, respectively.
[0045] Example 4
[0046] This embodiment describes the preparation method of the antireflective film in Example 1, including the following steps:
[0047] An antireflective coating was deposited on a substrate in an electron beam evaporation machine. The first layer was ITO material, with an evaporation rate of 5 A / s, a coating temperature of 150℃, an oxygen flow rate of 20 SCCM, and a coating thickness of 52 nm. The second layer was IZO material, with an evaporation rate of 5 A / s, a coating temperature of 150℃, an oxygen flow rate of 20 SCCM, and a coating thickness of 16 nm. The third layer was AZO material, with an evaporation rate of 5 A / s, a coating temperature of 150℃, an oxygen flow rate of 20 SCCM, and a coating thickness of 45 nm. The fourth layer was ITO material, with an evaporation rate of 5 A / s, a coating temperature of 150℃, an oxygen flow rate of 20 SCCM, and a coating thickness of 10 nm.
[0048] Example 5
[0049] Example 5 provides a triple-junction gallium arsenide solar cell, such as Figure 2 ;
[0050] Including triple-junction gallium arsenide solar cells 200;
[0051] Anti-reflective coating 100; applied to the surface of triple-junction gallium arsenide solar cell 200;
[0052] A gold electrode 300 is disposed on the surface of the antireflective film 100.
[0053] Among them, the triple-junction gallium arsenide solar cell 200 consists of a Ge bottom cell, a GaInAs middle cell, and a GaInP top cell.
[0054] The fabrication method of triple-junction gallium arsenide solar cells includes the following steps:
[0055] S1. Etch the triple-junction gallium arsenide solar cell in a cap etching solution for 2-4 minutes to remove the cap layer. The concentration of the etching solution is H3PO3:H2O2:H2O = 1.2:2.5:18.
[0056] S2. The solar cells are placed in an electron beam evaporation machine to deposit antireflective coatings. The first layer is ITO material, with an evaporation rate of 5 A / s, a coating temperature of 150℃, an oxygen flow rate of 20 SCCM, and a coating thickness of 52 nm; the second layer is IZO material, with an evaporation rate of 5 A / s, a coating temperature of 150℃, an oxygen flow rate of 20 SCCM, and a coating thickness of 16 nm; the third layer is AZO material, with an evaporation rate of 5 A / s, a coating temperature of 150℃, an oxygen flow rate of 20 SCCM, and a coating thickness of 45 nm; the fourth layer is ITO material, with an evaporation rate of 5 A / s, a coating temperature of 150℃, an oxygen flow rate of 20 SCCM, and a coating thickness of 10 nm. At 500 nm, the refractive index of AZO is 1.9, that of ITO is 2.0, and that of IZO is 2.1.
[0057] S3. Using SU-8 3005 negative photoresist prepared by MicroChem, the metal electrode pattern was prepared by coating the triple-junction gallium arsenide solar cell at 110°C for 11 min, exposure energy of 220 mJ, and development in developer for 5 min.
[0058] S4. Place the triple-junction gallium arsenide solar cell with the electrode pattern fabricated into an electron beam evaporation machine, front side down, and deposit Au metal. Use a quartz film thickness gauge to control the evaporation rate and thickness. The evaporation rate is 25 A / s, and the evaporation thickness is 5 μm. After the front electrode evaporation is completed, remove the photoresist by immersion in acetone.
[0059] Comparative Example 1
[0060] Comparative Example 1 provides a traditional antireflective coating consisting of two layers of antireflective material. The first layer is TiO2, with a thickness of 50 nm and a refractive index of approximately 2.4, and the second layer is Al2O3, with a thickness of 70 nm and a refractive index of approximately 1.6. Since traditional antireflective coatings are non-conductive, grid lines and electrodes need to be fabricated on the battery surface before depositing the antireflective coating. The process is as follows:
[0061] S1. Using SU-8 3005 negative photoresist prepared by MicroChem, the photoresist was applied to a triple-junction gallium arsenide solar cell. The cell was baked at 110°C for 11 minutes with an exposure energy of 220 mJ and developed with developer for 5 minutes to prepare the metal electrode and grid pattern.
[0062] S2. Place the triple-junction gallium arsenide solar cell with electrode and grid pattern fabricated into an electron beam evaporation machine, front side down, and deposit Au metal. Use a quartz film thickness gauge to control the evaporation rate and thickness. The evaporation rate is 25 A / s, and the evaporation thickness is 5 μm. After the front electrode is deposited, remove the photoresist by immersion in acetone.
[0063] S3. Etch the triple-junction gallium arsenide solar cell in a cap etching solution for 2-4 minutes to remove the cap layer. The concentration of the etching solution is H3PO3:H2O2:H2O = 1.2:2.5:18.
[0064] S4. Place the battery cell into an electron beam evaporation machine to deposit an antireflective coating. The first layer is TiO2 material, with an evaporation rate of 5 A / s, a coating temperature of 150℃, an oxygen flow rate of 20 SCCM, and a coating thickness of 50 nm. The second layer is Al2O3 material, with an evaporation rate of 5 A / s, a coating temperature of 150℃, an oxygen flow rate of 20 SCCM, and a coating thickness of 70 nm. The refractive index of TiO2 at 500 nm is 2.4, and that of Al2O3 is 1.6.
[0065] S5. Apply 9260 positive photoresist produced by AZ to the triple-junction gallium arsenide solar cell, bake at 110°C for 11 minutes, expose at 1000 mJ, and develop with developer for 5 minutes to prepare the metal electrode pattern.
[0066] S6. Place the triple-junction gallium arsenide solar cell with the electrode pattern into an HF acid solution and etch for 4 minutes to remove the AR film at the electrode position to obtain the triple-junction gallium arsenide solar cell.
[0067] Due to the presence of fine grid lines, the grid ratio is relatively high, resulting in high reflectivity of triple-junction gallium arsenide solar cells made with traditional antireflective coatings.
[0068] Comparative Example 2
[0069] Comparative Example 2 provides an antireflective coating comprising, in sequence, a first ITO layer 101, an AZO layer 103, an IZO layer 102, and a second ITO layer 104; the thickness of the first ITO layer 101 is 52 nm; the thickness of the AZO layer 103 is 45 nm; the thickness of the IZO layer 102 is 16 nm; the thickness of the second ITO layer 101 is 10 nm; and the refractive indices of the first ITO layer 101, AZO layer 103, IZO layer 102, and second ITO layer 104 are 2.0, 1.9, 2.1, and 2.0, respectively.
[0070] Comparative Example 3
[0071] Comparative Example 3 provides an antireflective film comprising a first ITO layer 101, an AZO layer 103, and a second ITO layer 104. The first ITO layer 101 has a thickness of 52 nm; the AZO layer 103 has a thickness of 45 nm; the second ITO layer 104 has a thickness of 10 nm; and the refractive indices of the first ITO layer 101, the AZO layer 103, and the second ITO layer 104 are 2.0, 1.9, and 2.0, respectively.
[0072] The test methods for the average reflectance of the antireflective films corresponding to Examples 1-3 and Comparative Examples 1-3 of the present invention at 400-850nm are as follows, and the test results are shown in Table 1.
[0073] Using the solar cell fabrication method in Example 5 of this invention, antireflective films corresponding to Examples 1-3 and Comparative Examples 1-3 were used to prepare solar cell samples. The samples were then placed in a Hitachi UV spectrophotometer U-4100, with the test wavelength range set to 300nm–1800nm and a test step of 1nm. Light emitted by the spectrophotometer at various wavelengths irradiated the sample surface. After reflection, the intensity of the reflected light was measured to calculate the reflectivity of the sample at each wavelength. After testing, reflectivity values at wavelengths from 300nm to 1800nm were obtained. Using the peak area integration function of the device's built-in software, the average reflectivity value in the 400–850nm band could be obtained.
[0074] Table 1. Data from Examples 1-3 and Comparative Examples 1-3
[0075] Reflectivity % of 400-850nm Example 1 0.7％ Example 2 0.8％ Example 3 0.9％ Comparative Example 1 5.2％ Comparative Example 2 5.8％ Comparative Example 3 6.4％
[0076] As can be seen from Table 1 above, using the antireflection film structure provided by this patent, the average reflectivity of the sample in the 400-850nm band is kept below 1%. However, using the traditional antireflection film material in Comparative Example 1, the TCO transparent conductive film material with a different coating sequence in Comparative Example 2, and the TCO transparent conductive film with a reduced number of layers in Comparative Example 3, the antireflection effect cannot be obtained well, and the average reflectivity in the 400-850nm band is above 5%.
[0077] Furthermore, the current and conversion efficiency of the solar cell in Example 5 were tested. The antireflective films in Examples 1-3 in Table 2 were prepared according to the preparation method of the solar cell in Example 5, and their photocurrent and conversion efficiency were tested.
[0078] The solar cell current density and photoelectric conversion efficiency were tested using a solar simulator according to the requirements of "GBT 6494-2017 Test Method for Electrical Performance of Solar Cells for Aerospace Use". In Example 1, compared with the solar cell chip using a conventional anti-reflective film structure in Comparative Example 1, the short-circuit current increased from 17.6 to 18.6, and the conversion efficiency increased from 31.2% to 32.8%.
[0079] Table 2 Data from Examples 1-3 and Comparative Examples 1-3
[0080] <![CDATA[Short-circuit current (mA / cm 2 )]]> Conversion efficiency (%) Example 1 18.6 32.8 Example 2 18.3 32.5 Example 3 18.4 32.6 Comparative Example 1 17.6 31.2 Comparative Example 2 17.3 30.7 Comparative Example 3 17.1 30.5
[0081] The present invention has been described in detail above with reference to the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.
Claims
1. An antireflective film, characterized in that, It comprises, in sequence, a first ITO layer, an IZO layer, an AZO layer, and a second ITO layer; the thickness of the first ITO layer is 45~70nm; the thickness of the IZO layer is 10~25nm; the thickness of the AZO layer is 38~50nm; and the thickness of the second ITO layer is 4~15nm. The refractive index of the first ITO layer is 1.9~2.1; the refractive index of the IZO layer is 2.0~2.2; the refractive index of the IZO layer is 1.8~2.0; and the refractive index of the second ITO layer is 1.9~2.
1.
2. The antireflective film according to claim 1, characterized in that, The thickness of the first ITO layer is 50~60nm; the thickness of the IZO layer is 15~20nm; the thickness of the AZO layer is 42~47nm; and the thickness of the second ITO layer is 6~12nm.
3. The antireflective film according to claim 1, characterized in that, The antireflective coating has an average reflectivity of less than 1% in the range of 400-850 nm.
4. The method for preparing the antireflective film according to any one of claims 1 to 3, characterized in that, Includes the following steps: A first ITO layer, an IZO layer, an AZO layer, and a second ITO layer are sequentially deposited on the surface of the substrate by electron beam evaporation.
5. The method for preparing the antireflective film according to claim 4, characterized in that, The electron beam evaporation rate is 1 A / s to 10 A / s.
6. The method for preparing the antireflective film according to claim 4, characterized in that, The electron beam evaporation deposition temperature is 100℃~200℃.
7. The method for preparing the antireflective film according to claim 4, characterized in that, The oxygen flow rate for electron beam evaporation is 5 sccm to 30 sccm.
8. A solar cell, characterized in that, Includes the antireflective coating as described in any one of claims 1 to 3.
9. The solar cell according to claim 8, characterized in that, The solar cell is at least one of a triple-junction solar cell, a quadruple-junction solar cell, a quintuple-junction solar cell, or a hexagonal solar cell.