Solar cell, preparation method thereof and photovoltaic module

Abstract

The invention relates to the field of photovoltaic technology, in particular to a solar cell and a preparation method thereof and a photovoltaic module, the solar cell comprises a bottom cell and a top cell, the top cell comprises a hole transport layer, and the hole transport layer is made of a material of a NiOx layer doped with Mg and Ta; the preparation method comprises the following steps: preparing the hole transport layer through a magnetron sputtering method; wherein a target material for magnetron sputtering is a NiOx target material doped with Mg and Ta. According to the solar cell, the conductivity of the hole transport layer can be improved, the hole extraction and transmission capability can be improved, the ratio of Ni < 3 + > to Ni < 4 + > on the surface can be reduced, the interface oxidation reaction between high-valence Ni < 3 + > and Ni < 4 + > on the surface and perovskite can be reduced, the problem that the perovskite layer is damaged can be solved, the surface energy level can be improved, and the photoelectric conversion efficiency can be further improved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and more specifically, to solar cells, their fabrication methods, and photovoltaic modules. Background Technology

[0002] Heterojunction solar cells, back-contact solar cells, and perovskite / crystalline silicon tandem solar cells are all common types of solar cells. Among them, the hole transport layer of perovskite / crystalline silicon tandem solar cells plays a crucial role in photoelectric conversion efficiency.

[0003] The hole transport layer of the perovskite / crystalline silicon tandem solar cell provided by the related technology is made from NiO. x NiO x Insufficient conductivity of the hole transport layer leads to poor hole extraction and transport, and the high valence Ni on the surface... 3+ Ni 4+ It is prone to interfacial oxidation reactions with perovskite, leading to the destruction of the perovskite layer. At the same time, the energy level mismatch causes severe composite losses at the interface. Summary of the Invention

[0004] The purpose of this invention is to provide a solar cell, its fabrication method, and a photovoltaic module. The solar cell prepared by the method provided by this invention can be used in photovoltaic modules. This solar cell can improve the conductivity of the hole transport layer, enhance the extraction and transport capabilities of holes, and reduce the surface Ni content. 3+ Ni 4+ The proportion, thereby reducing the high valence Ni on the surface. 3+ Ni 4+ The interfacial oxidation reaction with perovskite improves the problem of perovskite layer damage, while also improving surface energy levels and further enhancing photoelectric conversion efficiency.

[0005] This invention is implemented as follows: In a first aspect, the present invention provides a solar cell, comprising: bottom battery; and, The top battery is stacked on top of the bottom battery; among which... The top cell includes a hole transport layer, which is made of Mg and Ta-doped NiO. x layer.

[0006] In an optional implementation, Mg 2+ Doped in the crystal lattice, Ta 5+ Doping is performed at interstitial sites in the crystal lattice to form two-site doping.

[0007] In an optional embodiment, Mg and Ta-doped NiO x Ni on the surface of the layer 3+ Ni 4+The overall proportion is 25% to 33%.

[0008] In an optional embodiment, the Mg doping amount is 0.5~5 at%; And / or, the Ta doping level is 0.1~2 at%; And / or, the thickness of the hole transport layer is 10~30nm.

[0009] In an optional implementation, the bottom cell is a crystalline silicon cell and the top cell is a perovskite cell.

[0010] Secondly, the present invention provides a method for preparing a solar cell as described in any of the foregoing embodiments, comprising: Hole transport layers were prepared by magnetron sputtering; among which... The target material for magnetron sputtering is Mg- and Ta-doped NiO. x Target material.

[0011] In an optional implementation, the magnetron sputtering voltage is 100~1100W.

[0012] In an optional implementation, the magnetron sputtering temperature is 23~100°C.

[0013] In an optional embodiment, the chamber sputtering pressure of magnetron sputtering is 0.3~1.0 Pa.

[0014] Thirdly, the present invention provides a photovoltaic module, including a solar cell of any of the foregoing embodiments, or a solar cell prepared by a method of preparing a solar cell of any of the foregoing embodiments.

[0015] The present invention has the following beneficial effects: The solar cell provided in this embodiment of the invention includes a bottom cell and a top cell stacked sequentially, wherein the hole transport layer of the top cell is made of Mg and Ta-doped NiO. x The layer can utilize the synergistic effect of Mg and Ta doping ions to optimize NiO. x Hole transport layer performance.

[0016] Among them, doped Mg 2+ Ions (radius 0.072 nm) can replace Ni 2+ The site (radius 0.069 nm) can effectively reduce Ni 3+ Ni 4+ Formation, reducing Ni 3+ Ni 4+ The oxidative decomposition of perovskite films mitigates the problem of perovskite layer damage. Doped Ta 5+Ions (0.064 nm radius) occupy interstitial sites in the crystal lattice, providing additional charge carriers (increasing carrier concentration) and thus improving the conductivity of the thin film. The resulting Mg-Ta-doped NiO... x Hole transport layer, its surface Ni 3+ Ni 4+ The reduction in the proportion of the thin film, the enhanced conductivity of the thin film, and the improved charge collection and transport capabilities have led to improvements in the photoelectric conversion efficiency and other performance characteristics of solar cells.

[0017] The method for preparing the above-mentioned solar cell provided in this embodiment of the invention can not only make the surface Ni 3+ Ni 4+ The reduced ratio, enhanced conductivity of the thin film, and improved charge collection and transport capabilities have led to improvements in the photoelectric conversion efficiency of solar cells. Furthermore, it has increased the deposition rate of the hole transport layer during preparation, enabling rapid film formation and reducing production and equipment investment costs.

[0018] The photovoltaic module provided in this embodiment of the invention includes the aforementioned solar cell, which has good photoelectric conversion efficiency. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the solar cell of the present invention.

[0021] Icons: 010 - Solar cell; 110 - N-type silicon wafer; 111 - Intrinsic amorphous silicon layer; 120 - N-type doped nanocrystalline silicon layer; 130 - P-type doped nanocrystalline silicon layer; 200 - Composite layer; 310 - Hole transport layer; 330 - Hole modification layer; 400 - Perovskite light-absorbing layer; 500 - Passivation layer; 600 - Electron transport layer; 700 - Buffer layer; 800 - Transparent conductive layer; 900 - Metal grid electrode; 1000 - Optical anti-reflection layer. Detailed Implementation

[0022] To make the objectives, 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. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0023] The hole transport layer in perovskite / crystalline silicon tandem solar cells plays a crucial role in photoelectric conversion efficiency; however, NiO in related technologies... x The hole transport layer suffers from insufficient conductivity, leading to poor hole extraction and transport. Furthermore, the high valence Ni on the surface... 3+ Ni 4+ It is prone to interfacial oxidation reactions with perovskite, leading to the destruction of the perovskite layer. At the same time, the energy level mismatch causes severe composite losses at the interface.

[0024] The inventors discovered that doping with a single element can improve NiO. x The properties of the thin film; among them, Li doping can improve the conductivity of the thin film, but Li ions easily migrate to the perovskite layer and are reduced to metallic Li. This process induces the perovskite light-absorbing layer to transform into a non-photoactive phase, resulting in rapid degradation of battery performance; if NiO is used... x During film formation, adding oxygen can increase the number of Ni vacancies in the film, thereby increasing the hole carrier concentration and improving conductivity. However, this method can lead to a decrease in the Ni concentration in the film. 3+ Ni 4+ The surge in carrier mobility, coupled with the decrease in carrier mobility, exacerbates the oxidation and damage to the perovskite layer and causes carriers to accumulate due to insufficient mobility, resulting in poor device performance.

[0025] In other words, while single-element doping and increasing hole carrier concentration can improve NiO, x While some properties of the thin film can be optimized, it is difficult to simultaneously improve its electrical conductivity, rapid carrier extraction and collection, and stability at the perovskite interface.

[0026] This disclosure provides a solar cell that can be used in photovoltaic modules and a method for its fabrication, thereby improving the conductivity of the hole transport layer of the solar cell, enhancing the extraction and transport capabilities of holes, and reducing surface Ni. 3+ Ni 4+ The proportion, thereby reducing the high valence Ni on the surface. 3+ Ni 4+ The interfacial oxidation reaction with perovskite improves the problem of perovskite layer damage and improves surface energy levels, further enhancing photoelectric conversion efficiency; in other words, the solar cell disclosed herein can utilize NiO doped with Mg and Ta at dual sites. x The hole transport layer simultaneously improves the efficiency and stability of solar cells, that is, it simultaneously enhances the efficiency of NiO. x The thin film improves conductivity, enables rapid extraction and collection of charge carriers, and enhances the stability of the perovskite interface.

[0027] Please refer to Figure 1The solar cell 010 disclosed herein includes a bottom cell, a composite layer 200, and a top cell. The composite layer 200 is formed on the bottom cell, and the top cell is formed on the composite layer 200. The top cell includes a hole transport layer 310, the material of which is Mg or Ta-doped NiO. x layer.

[0028] The solar cell 010 disclosed herein can optimize NiO by utilizing the synergistic effect of two doping ions, Mg and Ta. x Hole transport layer 310 performance.

[0029] Among them, doped Mg 2+ (Radius 0.072nm) Can replace Ni 2+ Site (radius 0.069 nm), i.e., Mg 2+ Replace Ni 2+ Doping in the crystal lattice can effectively reduce Ni 3+ Ni 4+ Formation, reducing Ni 3+ Ni 4+ The oxidative decomposition of perovskite films mitigates the problem of perovskite layer damage. Doped Ta 5+ Occupying interstitial sites (with a radius of 0.064 nm), these sites can provide additional charge carriers, thereby improving the conductivity of the thin film. The resulting Mg-Ta dual-site doped NiO... x Hole transport layer 310, its surface Ni 3+ Ni 4+ The reduced ratio, enhanced conductivity of the thin film, and improved charge collection and transport capabilities have led to improvements in the photoelectric conversion efficiency and other performance characteristics of the 010 solar cell.

[0030] Optionally, the bottom cell is a crystalline silicon cell, and the top cell is a perovskite cell. The bottom cell may include at least one of monocrystalline silicon cells, polycrystalline silicon cells, PERC cells, TOPCon cells, HJT heterojunction cells, IBC cells, TBC cells, HBC cells, bifacial crystalline silicon cells, and ultrathin crystalline silicon cells. For example, the bottom cell is an HJT heterojunction cell, wherein the bottom cell includes an N-type silicon wafer 110, an intrinsic amorphous silicon layer 111 formed on the light-receiving surface and the back-lighting surface of the N-type silicon wafer 110, an N-type doped nanocrystalline silicon layer 120 formed on the intrinsic amorphous silicon layer 111 on the light-receiving surface, a P-type doped nanocrystalline silicon layer 130 formed on the intrinsic amorphous silicon layer 111 on the back-lighting surface, and a transparent conductive layer 800 formed on the P-type doped nanocrystalline silicon layer 130; a composite layer 200 is formed on the N-type doped nanocrystalline silicon layer 120; the top cell, in addition to the hole transport layer 310 formed on the composite layer 200, also includes a hole modification layer 330, a perovskite light-absorbing layer 400, a passivation layer 500, an electron transport layer 600, a buffer layer 700, and a transparent conductive layer 800 formed sequentially on the hole transport layer 310.

[0031] Optionally, metal grid electrodes 900 are formed on both the transparent conductive layer 800 of the bottom cell and the transparent conductive layer 800 of the top cell; an optical anti-reflection layer 1000 is also formed on the transparent conductive layer 800 of the top cell.

[0032] It should be understood that in other embodiments, the solar cell 010 may not include the composite layer 200. For example, a 4T structure perovskite tandem cell, where the top cell and bottom cell are fabricated independently, each with its own independent electrode and parallel current connection, without an electrical interconnect layer, and are stacked only through optical coupling (transparent adhesive / air layer), without the composite layer 200.

[0033] Optionally, NiO x The doping amount of Mg in the hole transport layer 310 is 0.5~5at%, for example: 0.5at%, 1at%, 1.5at%, 2at%, 2.5at%, 3at%, 3.5at%, 4at%, 4.5at%, 5at%, etc., which is not specifically limited here; the doping amount of Ta is 0.1~2at%, for example: 0.1at%, 0.5at%, 1.0at%, 1.2at%, 1.5at%, 2at%, etc., which is not specifically limited here.

[0034] Optionally, the thickness of the hole transport layer 310 is 10~30nm, for example: 10nm, 12nm, 15nm, 18nm, 20nm, 22nm, 25nm, 27nm, 30nm, etc., without being specifically limited here.

[0035] This disclosure also provides a method for fabricating a solar cell 010, comprising: fabricating a hole transport layer 310 by magnetron sputtering; wherein, The target material for magnetron sputtering is Mg- and Ta-doped NiO. x Target material.

[0036] This preparation method not only enables the surface Ni 3+ Ni 4+ The reduced ratio, enhanced conductivity of the thin film, and improved charge collection and transport capabilities have led to improvements in the photoelectric conversion efficiency of the solar cell 010. Furthermore, it has increased the deposition rate of the hole transport layer 310 during its fabrication, enabling rapid film formation and reducing production and equipment investment costs.

[0037] It should be noted that NiO x The doping ratio of Mg and Ta in the target material is not limited; that is, any ratio within the Mg and Ta doping range is acceptable. For example, NiO doped with 0.5 at% Mg + 0.1 at% Ta is acceptable. x 0.5 at% Mg + 2 at% Ta doped NiO x 5at%Mg+2at%Ta doped NiO x 2.5 at% Mg + 1 at% Ta-doped NiO x wait.

[0038] Optionally, the magnetron sputtering voltage can be 100~1100W, for example: 100W, 200W, 300W, 400W, 500W, 600W, 700W, 800W, 900W, 100W, 1100W, etc., without specific limitation. Using a lower sputtering voltage results in lower ion energy, which can improve the bombardment damage to the composite layer 200 in the solar cell 010 with the composite layer 200.

[0039] Optionally, the magnetron sputtering temperature is 23~100℃, for example: 23℃, 27℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, etc., without being specifically limited here.

[0040] Optionally, the sputtering pressure in the magnetron sputtering chamber is 0.3~1.0 Pa, for example: 0.3 Pa, 0.5 Pa, 0.7 Pa, 1.0 Pa, etc., without being specifically limited here.

[0041] Optimizing the sputtering temperature and chamber pressure can improve the deposition rate of the hole transport layer 310.

[0042] It should be noted that the inventors also discovered that Mg and Ta-doped NiO xTarget material (Mg-Ta-NiO) x The target material has better conductivity than pure NiO. x The target material results in a higher film deposition rate (approximately 200% higher).

[0043] In the method for fabricating the solar cell 010 disclosed herein, the methods for fabricating the bottom cell, composite film, and other film layers of the top cell except for the hole transport layer 310, as well as the grid lines, are similar to those in related technologies and will not be described in detail here.

[0044] The present invention will be further described in detail below with reference to the embodiments.

[0045] Example 1 (1) An intrinsic amorphous silicon layer is prepared on the light-receiving surface and the back-lighting surface of an N-type silicon wafer, respectively; (2) An N-type doped nanocrystalline silicon layer and a P-type doped nanocrystalline silicon layer are sequentially prepared on the intrinsic amorphous silicon layer on the light-receiving side and the back-light-receiving side of an N-type silicon wafer; (3) A transparent conductive layer (ITO) is prepared on a P-type doped nanocrystalline silicon layer using magnetron sputtering. (4) A composite layer is prepared on an N-type doped nanocrystalline silicon layer; (5) Prepare a hole transport layer on the composite layer; (6) Prepare a hole-modified layer on the hole transport layer; (7) A perovskite light-absorbing layer is prepared on the front hole modification layer; (8) A passivation layer is prepared on the perovskite light-absorbing layer on the front side; (9) An electron transport layer is prepared on the front passivation layer; (10) A buffer layer is prepared on the front electron transport layer; (11) A transparent conductive layer is prepared on the buffer layer using magnetron sputtering. (12) Fabricate metal grid electrodes on the front and back transparent conductive layers; (13) An optical antireflection layer is prepared on the transparent conductive layer on the front light-receiving surface.

[0046] The hole transport layer is prepared by using Mg and Ta-doped NiO. x Using radio frequency magnetron sputtering as the target material, a hole transport layer with a thickness of 20 nm was sputtered. The sputtering pressure in the process chamber for radio frequency magnetron sputtering was 0.3 Pa, the chamber temperature was 100 °C, and the magnetron sputtering power of the target material was 100 W.

[0047] The processes of Examples 2-7 are similar to those of Example 1, with the differences shown in Table 1.

[0048] Example 8 The difference between Example 8 and Example 1 is that: when preparing the hole transport layer, the sputtering pressure in the process chamber is 1.0 Pa, the chamber temperature is 23 °C, and the magnetron sputtering power of the target is 1100 W; other processes are the same as in Example 1.

[0049] Example 9 The difference between Example 9 and Example 1 is that when preparing the hole transport layer, the sputtering pressure in the process chamber is 0.7 Pa, the chamber temperature is 55 °C, and the magnetron sputtering power of the target material is 500 W; other processes are the same as in Example 1.

[0050] Comparative Example 1 Comparative Example 1 is similar to Example 1, except that it uses NiO. x The target material is used, and other processes are described in Example 1.

[0051] Comparative Example 2 Comparative Example 2 is similar to Example 1, except that it uses Li-doped NiO. x The target material is used, and other processes are described in Example 1.

[0052] Comparative Example 3 Comparative Example 3 is similar to Example 1, except that it uses Mg-doped NiO. x The target material is used, and other processes are described in Example 1.

[0053] Comparative Example 4 Comparative Example 4 is similar to Example 1, except that it uses Ta-doped NiO. x The target material is used, and other processes are described in Example 1.

[0054] The Mg and Ta doping levels of the solar cells 010 in Examples 1-9 and Comparative Examples 1-4 were measured (the detection method refers to GB / T 17359-2012), the hole transport layer 310 film thickness was measured (the detection method refers to GB / T 11378-2005), and the surface Ni content was measured. 3+ Ni 4+ The proportions (testing method refers to GB / T 19500-2004), resistivity, carrier concentration, and carrier mobility (refer to Hall effect test); the results are shown in Table 1.

[0055] The PCE (photovoltaic conversion efficiency), Voc (open-circuit voltage), Jsc (short-circuit current density), and FF (fill factor) of the solar cells 010 in Examples 1-9 and Comparative Examples 1-4 were tested; the results are shown in Table 2, and the test methods refer to GB / T 6495.1-2022.

[0056] Table 1

[0057] Table 2

[0058] According to the results in Tables 1 and 2, Mg-Ta-NiO can be prepared using the method disclosed herein. x Examples 1-9 of the hole transport layer can significantly improve carrier mobility (0.35–0.99 cm⁻¹). 2 / vs), and is favorable for carrier concentration (carrier concentration 3.15E+19~1.12E+20 / cm). 3 This enhances the conductivity of the thin film, thereby improving the transport, extraction, and collection of charge carriers; and Mg-Ta-NiO x The surface of the hole transport layer has lower Ni 3+ Ni 4+ (Mg, Ta-doped NiO) x Ni on the surface of the layer 3+ Ni 4+ The total proportion is 25% to 33%, which reduces the oxidative decomposition of the perovskite layer and achieves a more stable battery.

[0059] Meanwhile, as shown in Table 2, the PCE of the solar cell prepared by the method of this disclosure is improved, and it is also beneficial to the improvement of Voc and FF.

[0060] In summary, the solar cell 010 prepared by the method provided by this invention can be used in photovoltaic modules. This solar cell 010 can improve the conductivity of the hole transport layer 310, enhance the extraction and transport capabilities of holes, and reduce the surface Ni content. 3+ Ni 4+ The proportion, thereby reducing the high valence Ni on the surface. 3+ Ni 4+ The interfacial oxidation reaction with perovskite improves the problem of perovskite layer damage, while also improving surface energy levels and further enhancing photoelectric conversion efficiency.

[0061] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A solar cell, characterized in that, include: Bottom battery; as well as, A top battery, which is stacked on top of the bottom battery; wherein... The top-mounted solar cell includes a hole transport layer, the material of which is Mg- and Ta-doped NiO. x layer.

2. The solar cell according to claim 1, characterized in that, Mg 2+ Doped in the crystal lattice, Ta 5+ Doping is performed at interstitial sites in the crystal lattice to form two-site doping.

3. The solar cell according to claim 1, characterized in that, The Mg and Ta-doped NiO x Ni on the surface of the layer 3+ Ni 4+ The overall proportion is 25% to 33%.

4. The solar cell according to claim 1, characterized in that, The Mg doping concentration is 0.5~5 at%; And / or, the doping amount of Ta is 0.1~2 at%; And / or, the thickness of the hole transport layer is 10~30nm.

5. The solar cell according to any one of claims 1-4, characterized in that, The bottom cell is a crystalline silicon cell, and the top cell is a perovskite cell.

6. The method for preparing a solar cell according to any one of claims 1-5, characterized in that, include: Hole transport layers were prepared by magnetron sputtering; among which... The target material for magnetron sputtering is Mg- and Ta-doped NiO. x Target material.

7. The method for preparing a solar cell according to claim 6, characterized in that, The voltage for magnetron sputtering is 100~1100W.

8. The method for preparing a solar cell according to claim 6, characterized in that, The magnetron sputtering temperature is 23~100℃.

9. The method for preparing a solar cell according to claim 6, characterized in that, The chamber sputtering pressure of the magnetron sputtering is 0.3~1.0 Pa.

10. A photovoltaic module, characterized in that, This includes solar cells according to any one of claims 1-5, or solar cells prepared by any one of claims 5-9.

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