Four-terminal perovskite-silicon laminated solar cell and preparation method thereof

Abstract

The invention relates to the technical field of solar cells, in particular to a four-terminal perovskite-silicon laminated solar cell and a preparation method thereof, and the four-terminal perovskite-silicon laminated solar cell comprises a top cell and a bottom cell which are laminated; wherein the top cell is a perovskite solar cell; the bottom cell is a silicon solar cell; a plurality of sub-cells in the perovskite solar cell are connected in series through a plurality of second grooves containing metal electrodes, and the position of each second groove corresponds to the position of a main grid line in the silicon solar cell. The second groove of the perovskite top cell is filled with the metal electrode, the interconnection resistance between neutron cells of the perovskite top cell can be effectively reduced on the premise that light absorption of the bottom cell is not affected, the resistivity of the whole transparent electrode is greatly reduced, and finally the purpose of improving the efficiency of a top cell device is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a four-terminal perovskite-silicon stacked solar cell and a preparation method thereof. Background Art

[0002] In photovoltaic technology, a stacked device is formed by stacking a top solar cell and a bottom solar cell, so that the top cell absorbs short-wave sunlight and the bottom cell absorbs long-wave sunlight. This can effectively utilize the solar spectrum and improve the photoelectric conversion efficiency of the solar cell. For current solar cell technology, stacking high-efficiency perovskite solar cells and silicon solar cells to form a stacked cell can effectively improve the photoelectric conversion efficiency of current solar cells. In stacked solar cell technology, since the four-terminal stacked device does not need to consider the current matching problem between the bottom cell and the top cell, the difficulty of preparation and the complexity of the process are much lower; at the same time, since the two cells that make up this type of device can be prepared independently, the process can be greatly simplified, which is conducive to reducing costs.

[0003] For four-terminal tandem solar cells, the key issue at present is the preparation of the transparent electrode of the top cell. In order to obtain a high-efficiency tandem device, the transparent electrode needs to have both high transmittance and high conductivity. High transmittance can effectively transmit sunlight that is not absorbed by the top cell to the surface of the bottom cell and be absorbed by the bottom cell, and high conductivity can enable the top cell to effectively collect photocurrent. For the top cell of a traditional four-terminal tandem solar cell, the transparent electrode is usually prepared by magnetron sputtering to prepare a high-transmittance ITO film, and then high-temperature annealing is performed to improve the conductivity of the ITO film. For perovskite solar cells, since the electron transport layer and the perovskite absorption layer of the perovskite solar cell are not resistant to high temperatures, the two types of materials will decompose at temperatures above 150 degrees, and therefore the conductivity of the ITO film cannot be improved by high-temperature annealing. Therefore, since the ITO film layer currently prepared at low temperature has a large resistance, the carriers of the top cell cannot be effectively collected, so the efficiency of the perovskite top cell using this transparent electrode is low. Summary of the invention

[0004] The purpose of the present invention is to provide a four-terminal perovskite-silicon tandem solar cell and a preparation method thereof. Based on the number and spacing of silicon cell main grid lines, metal electrodes are used as interconnections between perovskite top cell subcells, and the top cell dead zone is overlapped with the bottom cell main grid line. Through this structure, the purpose of reducing the resistance of the top cell transparent electrode can be achieved without affecting the light absorption of the bottom cell.

[0005] To achieve the above object, the present invention provides a four-terminal perovskite-silicon tandem solar cell, comprising: a stacked top cell and a bottom cell;

[0006] Among them, the top cell is a perovskite solar cell; the bottom cell is a silicon solar cell; the multiple sub-cells in the perovskite solar cell are connected in series through multiple second grooves containing metal electrodes, and the position of each second groove corresponds to the position of the main grid line in the silicon solar cell.

[0007] The present invention also provides a method for preparing a four-terminal perovskite-silicon tandem solar cell, comprising:

[0008] Preparation of perovskite solar cells;

[0009] Preparation of silicon solar cells;

[0010] By stacking perovskite solar cells and silicon solar cells, a four-terminal perovskite-silicon tandem solar cell is obtained;

[0011] The plurality of subcells in the perovskite solar cell are connected in series through a plurality of second grooves containing metal electrodes, and the position of each second groove is determined according to the position of the main grid line in the silicon solar cell.

[0012] Technical effects and advantages of the present invention:

[0013] The present invention utilizes a metal electrode to fill the second slot of the perovskite top cell, which can effectively reduce the series resistance between the neutron cells in the perovskite top cell without affecting the light absorption of the bottom cell, thereby greatly reducing the resistivity of the overall transparent electrode, and finally achieving the purpose of improving the efficiency of the perovskite top cell.

[0014] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the cross section of the top cell and the bottom cell;

[0016] Figure 2 A top view of the top cell and the bottom cell;

[0017] Figure 3 Schematic diagram of the preparation of perovskite top cell. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] In order to better understand the present invention, the present invention is briefly introduced below: For a four-terminal perovskite-silicon tandem solar cell, Figure 1 As shown, the light-incident surface of the bottom cell silicon solar cell contains a silver main grid line, and the main grid line is an opaque material. Therefore, the area covered by the main grid line cannot receive incident light and thus cannot provide photocurrent. For the top cell perovskite solar cell, it is composed of several sub-cells connected in series at groove 2 through a transparent electrode, and grooves 1, 2, and 3 are formed by laser etching. This area is called a dead zone and cannot provide photocurrent. Therefore, the present invention changes the connection method at groove 2 to a connection through a metal electrode, and at the same time aligns and overlaps this area with the main grid line of the bottom cell, as shown in FIG. Figure 2 Through this structural design, the conductivity of the transparent electrode of the top cell can be effectively improved without affecting the light absorption of the bottom cell.

[0020] Among them, slot 2 can also be recorded as the second slot. It should also be noted that the structural parameters of the top cell and the bottom cell in the above figure are only for the convenience of describing this scheme, and the actual cell parameters shall prevail. The following is a detailed introduction to the four-terminal perovskite-silicon tandem solar cell:

[0021] A four-terminal perovskite-silicon tandem solar cell, comprising: a stacked top cell and a bottom cell;

[0022] Among them, the top cell is a perovskite solar cell; the bottom cell is a silicon solar cell; the multiple sub-cells in the perovskite solar cell are connected in series through multiple second grooves (grooves 2) containing metal electrodes, and the position of each second groove corresponds to the position of the main grid line in the silicon solar cell.

[0023] Specifically, the groove 2 is filled with a metal electrode.

[0024] Specifically, the number of the grooves 2 is equal to or less than the number of the main grid lines of the silicon solar cell.

[0025] Specifically, the width of the groove 2 is equal to or smaller than the width of the main grid line of the silicon solar cell.

[0026] The present invention also provides a method for preparing a four-terminal perovskite-silicon tandem solar cell, such as Figure 3 As shown, the method includes:

[0027] 1. The first groove is etched on the FTO film layer deposited on the glass surface by laser (of course, other etching tools can also be used), and then the hole transport layer (HTL), perovskite layer, and electron transport layer (ETL) are prepared in sequence.

[0028] Among them, the processes for preparing the hole transport layer (HTL), the perovskite layer, and the electron transport layer (ETL) belong to the prior art in the present invention and will not be introduced in detail here, as long as they can be implemented.

[0029] 2. According to the position, width and number of the bottom battery main grid, the groove 2 is etched by laser.

[0030] 3. Use a mask (or other masking tools) to mask all areas except the groove 2 part, and form a layer of metal electrode in the groove 2 area by methods such as thermal evaporation and magnetron sputtering to achieve mutual connection of the sub-batteries.

[0031] The thermal evaporation process is as follows: taking copper evaporation as an example, firstly, the perovskite solar cell is placed in the evaporation chamber, and the chamber is evacuated to a vacuum degree of 4×10 -4 to 5×10 -5 The evaporation source is then heated by applying a voltage to the evaporation source, and the evaporation rate is adjusted, and then the film is evaporated to the desired thickness at an evaporation rate of 0.2 nm / s.

[0032] The process of magnetron sputtering is as follows: taking copper sputtering as an example, the perovskite solar cell is first placed in a vacuum chamber and the chamber is evacuated to a vacuum degree of 4×10 -4 to 5×10 -5 Pa. Then, by applying different sputtering powers and sputtering gas pressures to the equipment, the metal of the required thickness is sputtered at the required sputtering rate.

[0033] 4. Use a suitable method to prepare a transparent electrode. This technical solution takes the preparation of ITO by magnetron as an example. Other methods can also be used to prepare transparent electrodes, such as AZO, etc. Finally, laser etching is used to etch the groove 3 to separate the sub-cells and complete the preparation of the top cell.

[0034] 5. Mechanically stack the top cell and the bottom cell to form a four-terminal stacked device.

[0035] Specifically, the main grid line spacing of the silicon solar cell is 1-3mm, and the main grid line width is 0.1-0.3mm. Preferably, the main grid line spacing of the silicon solar cell is 3mm, and the main grid line width is 0.3mm; the second groove is located between the first groove and the third groove, and the distances between the first groove, the second groove and the third groove are all 0.02mm, and the width of the first groove is 0.04mm, the width of the second groove is 0.06mm, and the width of the third groove is 0.04mm. Figure 2 shown.

[0036] It should be noted that this technical solution mainly takes the PIN device structure as an example, and the NIP device structure is also applicable.

[0037] In order to better explain the present invention, examples and comparative examples are provided below.

[0038] Comparative Example

[0039] This embodiment uses pin-type perovskite as the top cell as an example to prepare a four-terminal perovskite-silicon tandem solar cell, which specifically includes the following steps:

[0040] 1. Use laser to etch groove 1 on the FTO substrate. Groove 1 is located on the left side of groove 2, with a spacing of about 0.02 mm and a width of about 0.04 mm.

[0041] 2. Prepare the hole transport layer. In this example, NiOx is used as the hole transport layer. First, NiO x The nanoparticles were dispersed in deionized water (20 mg / mL) and sonicated for 24 h to obtain NiO x Nanoparticle dispersion. Then, NiO x The nanoparticle solution was spin-coated on FTO glass and then annealed at 120 °C for 30 min to obtain NiO x Hole transport layer.

[0042] 3. Prepare the perovskite layer. 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb(I 0.7 Br3)3, a certain proportion of CsI, FAI, MAI, PbI2, and PbBr2 are dissolved in a mixed solvent of DMSO and DMF to prepare a precursor solution of the perovskite absorption layer. Then the precursor solution is coated on NiO x Subsequently, the sample coated with the perovskite active layer was heat treated on a heating table at 150°C for 10 min to obtain Cs 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb(I 0.7 Br3)3 layers.

[0043] 4. Prepare the electron transport layer. The fullerene derivative [6,6]-phenyl-C is deposited on the perovskite layer by thermal evaporation. 61 -Butyric acid methyl ester (PCBM).

[0044] 5. Use laser etching to complete the preparation of groove 2. Groove 2 is located on the right side of groove 1, with a spacing of about 0.02 mm and a width of 0.06 mm.

[0045] 6. Sputter a layer of transparent electrode oxide ITO on the entire film surface by magnetron sputtering. Note that ITO is used only for this embodiment, and other types of transparent electrodes can also be used. Then, laser etching is used to complete the preparation of groove 3. Groove 3 is located on the right side of groove 2, with a spacing of about 0.02 mm and a width of 0.04 mm. The preparation of the top battery device is now completed.

[0046] 7. Mechanically stack the top battery and the bottom battery. During the stacking process, the position of slot 2 in the top battery needs to be aligned with the main grid line of the bottom battery and the efficiency test is completed. The data is shown in Table 1.

[0047] Table 1 Comparative Example Four-Terminal Perovskite-Silicon Tandem Solar Cell Test Parameters

[0048]

[0049] Example

[0050] This embodiment uses pin-type perovskite as the top cell as an example to prepare a four-terminal perovskite-silicon tandem solar cell, which specifically includes the following steps:

[0051] 1. The main grid line spacing of the silicon solar cell selected in this embodiment is 3 mm, the grid line width is about 0.3 mm, and a mask for preparing the metal electrode is designed, and the slit width in the mask is 0.06 mm.

[0052] 2. Use laser to etch groove 1 on the FTO substrate. Groove 1 is located on the left side of groove 2. The spacing is about 0.02 mm, and the width of groove 1 is about 0.04 mm.

[0053] 3. Prepare the hole transport layer. In this example, NiO x As a hole transport layer. First, NiO x The nanoparticles were dispersed in deionized water (20 mg / mL) and sonicated for 24 h to obtain NiO x Nanoparticle dispersion. Then, NiO x The nanoparticle solution was spin-coated on FTO glass and then annealed at 120 °C for 30 min to obtain NiO x Hole transport layer.

[0054] 4. Prepare the perovskite layer. 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb(I 0.7Br3)3, a certain proportion of CsI, FAI, MAI, PbI2, and PbBr2 are dissolved in a mixed solvent of DMSO and DMF to prepare a precursor solution of the perovskite absorption layer. Then the precursor solution is coated on NiO x Subsequently, the sample coated with the perovskite active layer was heat treated on a heating table at 150 degrees Celsius for 10 minutes to obtain Cs 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb(I 0.7 Br3)3 layers.

[0055] 5. Prepare the electron transport layer. The fullerene derivative [6,6]-phenyl-C is deposited on the perovskite layer by thermal evaporation. 61 -Butyric acid methyl ester (PCBM).

[0056] 6. Use laser etching to complete the preparation of groove 2. Groove 2 is located on the right side of groove 1, with a spacing of about 0.02 mm and a width of 0.06 mm.

[0057] 7. Cover the surface of the sample in step 6 with the mask in step 1, and prepare a layer of metal electrode including but not limited to Ag, Au, Cu, etc. by thermal evaporation. In this embodiment, Cu is used as an example to fill groove 2 with metal. Then remove the mask and use magnetron sputtering to sputter a layer of transparent electrode oxide ITO on the entire film surface. After that, laser etching is used to complete the preparation of groove 3. Groove 3 is located on the right side of groove 2, with a spacing of about 0.02mm and a width of groove 3 of 0.04mm. The preparation of the top battery device is now completed.

[0058] 8. Mechanically stack the top cell and the bottom cell silicon solar cell. During the stacking process, the position of slot 2 in the top cell needs to be aligned with the main grid line of the bottom cell, and the efficiency test is completed. The data is shown in Table 2.

[0059] Table 2 Test parameters of four-terminal perovskite-silicon tandem solar cells in Example

[0060]

[0061]

[0062] Compare the short-circuit current (J) of the perovskite solar cell devices in Table 1 and Table 2. SC ) It can be seen that filling the groove 2 with a metal electrode significantly improves the J of the device. SC, indicating that the series resistance between the sub-cells in the perovskite component is significantly reduced, thereby improving the efficiency of the device. At the same time, since the position of the perovskite slot 2 coincides with the silicon solar cell, whether a metal electrode or a transparent ITO is used, it does not affect the efficiency of the underlying silicon solar cell device, indicating that the structure does not affect light absorption and transmission. Furthermore, when the same crystalline silicon bottom cell is used, the two cells are stacked, and the perovskite top cell with a metal electrode filling slot 2 achieves a higher efficiency, and thus the four-terminal perovskite-silicon stacked solar cell in the embodiment also achieves a higher efficiency.

[0063] According to the embodiments and comparative examples, in the embodiment based on the metal Cu electrode filled in slot 2, the resistance between the two sub-cells in the top cell is 21.3Ω, while in the comparative example without the metal electrode filling slot 2, the resistance between the two sub-cells in the top cell is 23.5Ω. It can be seen that the use of metal electrodes can significantly reduce the series resistance.

[0064] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A four-terminal perovskite-silicon tandem solar cell, characterized in that: include: Stacked top and bottom cells; Among them, the top cell is a perovskite solar cell; the bottom cell is a silicon solar cell; the multiple sub-cells in the perovskite solar cell are connected in series through multiple second grooves containing metal electrodes, and the position of each second groove corresponds to the position of the main grid line in the silicon solar cell.

2. The four-terminal perovskite-silicon tandem solar cell according to claim 1, characterized in that: The number of the second slots is ≤ the number of main grid lines in the silicon solar cell.

3. The four-terminal perovskite-silicon tandem solar cell according to claim 1, characterized in that: The width of the second groove is ≤ the width of the main grid line in the silicon solar cell.

4. A method for preparing a four-terminal perovskite-silicon tandem solar cell according to any one of claims 1 to 3, characterized in that: include: Preparation of perovskite solar cells; Preparation of silicon solar cells; By stacking perovskite solar cells and silicon solar cells, a four-terminal perovskite-silicon tandem solar cell is obtained; The plurality of subcells in the perovskite solar cell are connected in series through a plurality of second grooves containing metal electrodes, and the position of each second groove is determined according to the position of the main grid line in the silicon solar cell.

5. The method according to claim 4, characterized in that Preparation of perovskite solar cells, including: Etching a first groove on the FTO film layer deposited on the glass surface; After etching the first groove, a hole transport layer, a perovskite layer and an electron transport layer are sequentially prepared; After preparing the electron transport layer, etching the second groove, depositing a metal electrode in the second groove and preparing a transparent electrode; After preparing the transparent electrode, the third groove is etched to obtain a perovskite solar cell.

6. The method according to claim 5, characterized in that The metal electrodes are deposited by thermal evaporation or magnetron sputtering methods.

7. The method according to claim 4, characterized in that The main grid line spacing of silicon solar cells is 1-3mm and the main grid line width is 0.1-0.3mm.

8. The method according to claim 7, characterized in that The main grid line spacing of silicon solar cells is 3mm and the main grid line width is 0.3mm.

9. The method according to claim 8, characterized in that The second groove is located between the first groove and the third groove, and the distance between the first groove and the second groove, and between the second groove and the third groove are both 0.02 mm; Among them, the width of the first groove is 0.04 mm, the width of the second groove is 0.06 mm, and the width of the third groove is 0.04 mm.

10. The method according to claim 5, characterized in that The metal electrode includes one of the following: Ag, Au, Cu.

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