Nickel oxide hole transport layer, preparation method and application thereof

Abstract

The application provides a nickel oxide hole transport layer and a preparation method and application thereof, and the preparation method comprises the following steps: (1) placing a substrate in a reaction chamber and vacuumizing; (2) introducing an oxygen-containing gas, and performing sputtering by using two or three different sputtering target materials to obtain the nickel oxide hole transport layer; wherein the sputtering target material is a metal element doped nickel oxide target material, and the metal element doped in the sputtering target material independently comprises any one of Cu, Mg, Li, Ag, K or Na. The application obtains a multi-metal doped nickel oxide hole transport layer by setting two or three different sputtering target materials to perform sputtering. By this method, not only the hole transport capacity of the nickel oxide is effectively improved, but also the energy level of the nickel oxide can be better controlled, the conductive capacity of the nickel oxide is improved, the defect density of the nickel oxide film is reduced, and therefore a solar cell with excellent performance can be prepared.

Description

Technical Field

[0001] This invention belongs to the field of solar cells, specifically relating to a nickel oxide hole transport layer, its preparation method, and its application. Background Technology

[0002] Perovskite solar cells have continuously broken efficiency records in just a few decades, with the highest efficiency for a single cell currently reaching 25.5%. However, upright perovskite solar cells face numerous challenges, such as significant hysteresis and poor photothermal stability. In contrast, inverted structures can better address these issues. The hole transport layer in an inverted structure primarily consists of nickel oxide (NiO). x Several hole transport layers are available, including poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA). However, PEDOT:PSS and PTAA hole transport layers are unstable and expensive. Considering the needs of future large-scale production, only NiO is currently available. x It is quite suitable.

[0003] Existing NiO x The main fabrication processes include nanocrystalline solution spin coating, chemical bath deposition, atomic layer deposition, and chemical vapor deposition. While chemical bath deposition, atomic layer deposition, and nanocrystalline spin coating produce dense films, they struggle to deposit large-scale, uniform nickel oxide films. Currently, chemical vapor deposition is the most suitable large-area fabrication technique, with magnetron sputtering offering high repeatability and uniformity. Existing techniques often involve adding individual alkali metals or transition metals to the nickel oxide substrate to enhance the hole transport capability of the nickel oxide hole transport layer. For example, CN110797138A discloses a method for preparing a nickel oxide-titanium transparent conductive film, which mainly comprises a PET film, a nickel oxide film, and a small amount of titanium oxide doped into the nickel oxide film. The preparation method includes ion sputtering, sol-gel deposition, and chemical vapor deposition. However, the above improvements offer limited performance enhancement to the nickel oxide hole transport layer.

[0004] Therefore, how to effectively improve the hole transport capability of the nickel oxide hole transport layer, while simultaneously controlling the energy level of the nickel oxide hole transport layer and reducing the defect density, is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a nickel oxide hole transport layer, its preparation method, and its applications. This invention obtains a multi-metal-doped nickel oxide hole transport layer by sputtering with two or three different sputtering targets. This method not only effectively improves the hole transport capability of nickel oxide but also allows for better control of its energy levels, enhancing its conductivity and reducing the defect density of the nickel oxide film. Based on this, high-performance solar cells can be fabricated.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a nickel oxide hole transport layer, the method comprising the following steps:

[0008] (1) Place the substrate in the reaction chamber and evacuate it;

[0009] (2) Introduce oxygen-containing gas and sputter using two or three different sputtering targets to obtain the nickel oxide hole transport layer;

[0010] In this invention, the sputtering targets are all nickel oxide targets doped with metal elements, and the metal elements doped in the sputtering targets independently include any one of Cu, Mg, Li, Ag, K, or Na. By using two or three different sputtering targets, this invention obtains a multi-metal-doped nickel oxide hole transport layer. This method not only effectively improves the hole transport capability of nickel oxide but also allows for better control of the energy levels of nickel oxide, enhancing its conductivity and reducing the defect density of the nickel oxide film. Based on this, high-performance solar cells can be fabricated.

[0011] In this invention, if only one sputtering target is used for sputtering, the trivalent nickel content will be too high, which will lead to insufficient device voltage and low light transmittance, resulting in a decrease in current density. If three or more sputtering nickel targets are used for sputtering, the multi-element doping will be difficult to control in the structure, resulting in unstable nickel oxide film formation and significant performance degradation.

[0012] It should be noted that one sputtering target refers to a nickel oxide target doped with any one of Cu, Mg, Li, Ag, K, or Na; two sputtering targets refer to nickel oxide sputtering targets with different types of metals doped in them, where one sputtering target is doped with any one of Cu, Mg, Li, Ag, K, or Na, and the other sputtering target is doped with a different type of metal; the same applies to three sputtering targets. For example, it may include sputtering target 1: a nickel oxide target doped with Cu, sputtering target 2: a nickel oxide target doped with Mg, and sputtering target 3: a nickel oxide target doped with Li.

[0013] It should be noted that in this invention, "independently" means that the metal element doped in each sputtering target can be any one of Cu, Mg, Li, K or Na, and the various sputtering targets do not affect each other.

[0014] The present invention does not limit the equipment used in the preparation method. For example, it can be a small sputtering instrument in the laboratory or an industrial planar target sputtering device.

[0015] Preferably, based on the mass of the sputtering target, the doping amount of the metal element in the sputtering target is independently 0 to 15 wt.%, excluding 0, for example, it can be 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.%, 11 wt.%, 12 wt.%, 13 wt.%, 14 wt.%, or 15 wt.%, etc., preferably 8 to 12 wt.%.

[0016] In this invention, if the doping amount of metal elements in the sputtering target is too high, it will cause deformation of the crystal structure of the material, resulting in a significant decrease in the performance of the prepared battery.

[0017] Preferably, the sputtering target includes a first target and a second target, wherein the first target is selected from a Cu-doped nickel oxide sputtering target, and the second target is selected from a nickel oxide sputtering target doped with any one of Mg, Li, Ag, K or Na.

[0018] Preferably, the ratio of the amount of metal element doping in the first target to the amount of metal element doping in the second target is (0.5 to 2):1, for example, it can be 0.5:1, 0.7:1, 0.9:1, 1.1:1, 1.3:1, 1.5:1, 1.7:1 or 2:1, etc.

[0019] In this invention, if the ratio of the amount of metal element doping in the first target to the amount of metal element doping in the second target is too small, the device fill factor will be low and the final efficiency will be unsatisfactory; if the ratio of the amount of metal element doping in the first target to the amount of metal element doping in the second target is too large, the dual-target optimization effect will be insignificant, resulting in a low turn-on current and a significant impact on device efficiency.

[0020] Preferably, the substrate in step (1) is a rigid substrate or a flexible substrate.

[0021] In this invention, the type of rigid substrate is not limited; for example, it may be fluorine-doped tin oxide (FTO) conductive glass or texturized HJT silicon battery substrate, etc. The type of flexible substrate is also not limited; for example, it may be PET film, etc. It should be noted that PET film is a film material made from polyethylene terephthalate (PET) as raw material, produced by extrusion into thick sheets, and then biaxially stretched.

[0022] Preferably, after the vacuuming in step (1), the pressure inside the reaction chamber is less than or equal to 6 × 10⁻⁶. -4 Pa, for example, could be 6 × 10 -4 Pa, 5×10 -4 Pa, 4×10 -4 Pa, 3×10 -4 Pa, 2×10 -4 Pa, 1×10 -4 Pa or 5×10 -5 Pa, etc.

[0023] Preferably, the oxygen-containing gas in step (2) is a combination of an inert gas and oxygen.

[0024] Preferably, the inert gas includes argon.

[0025] Preferably, the volume ratio of the inert gas to the oxygen is (4-10):1, for example, it can be 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc.

[0026] Preferably, the sputtering in step (2) is synchronous sputtering or sequential sputtering.

[0027] Generally, sputtering on a laboratory scale can be performed using either simultaneous sputtering or sequential sputtering; on a production line, sequential sputtering is more commonly used.

[0028] Preferably, the sputtering time in step (2) is 5 to 40 minutes, for example, it can be 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes or 40 minutes.

[0029] Preferably, during the sputtering process described in step (2), the pressure in the reaction chamber is 0.2-0.4 Pa, for example, it can be 0.2 Pa, 0.25 Pa, 0.3 Pa, 0.35 Pa or 0.4 Pa.

[0030] Preferably, pre-sputtering is performed before the sputtering in step (2).

[0031] In this invention, the purpose of pre-sputtering is to remove aged material from the surface of the target material and to allow the sputtering rate and elemental abundance of the target material to reach stable values.

[0032] Preferably, the pre-sputtering time is 5 to 30 minutes, for example, it can be 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes or 30 minutes.

[0033] Preferably, after the sputtering in step (2) is completed, a post-processing process is also performed.

[0034] Preferably, the post-treatment includes thermal annealing or plasma purging.

[0035] As a preferred technical solution, the preparation method includes the following steps:

[0036] (1) Place the rigid substrate in a reaction chamber containing two sputtering targets, and evacuate the chamber until the pressure is less than or equal to 6 × 10⁻⁶. -4 Pa;

[0037] Among them, the two sputtering targets are nickel oxide targets doped with different metal elements, and the ratio of the doping amount of the metal elements is (0.5~2):1;

[0038] (2) A combination of inert gas and oxygen with a gas flow rate of 30-500 scm and a volume ratio of (4-10):1 is introduced for pre-sputtering for 5-30 min. After the pre-sputtering is completed, synchronous sputtering is performed for 5-40 min. After the sputtering is completed, post-processing is performed to obtain the nickel oxide hole transport layer.

[0039] In a second aspect, the present invention provides a nickel oxide hole transport layer, wherein the nickel oxide hole transport layer is prepared by the preparation method described in the first aspect, and the nickel oxide hole transport layer is nickel oxide doped with a multi-element metal, wherein the multi-element metal is derived from the sputtering target.

[0040] Preferably, the thickness of the nickel oxide hole transport layer is 15-25 nm, for example, it can be 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm or 25 nm.

[0041] Thirdly, the present invention provides a solar cell comprising a nickel oxide hole transport layer as described in the second aspect.

[0042] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] This invention obtains a multi-metal-doped nickel oxide hole transport layer by sputtering with two or three different sputtering targets. This method not only effectively improves the hole transport capability of nickel oxide but also allows for better control of the nickel oxide energy levels, enhancing its conductivity and reducing the defect density of the nickel oxide film.

[0045] (2) The nickel oxide hole transport layer prepared by the preparation method provided by the present invention can effectively improve the photoelectric performance of solar cells. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the reaction chamber in the equipment used in the preparation method provided in Embodiment 1 of the present invention.

[0047] Figure 2 This is a schematic diagram of the equipment used in the preparation method provided in Embodiment 5 of the present invention.

[0048] Figure 3 XPS comparison images of the nickel oxide hole transport layers prepared in Example 1 and Comparative Example 1 of this invention.

[0049] Figure 4 This is a comparison diagram of the UPS of the nickel oxide hole transport layer prepared in Example 1 and Comparative Example 1 of the present invention.

[0050] Among them, 1-vacuum system, 2-vacuum pipe, 3-pre-evacuation chamber, 4-process chamber, 5-glass substrate, 6-first sputtering target, 7-second sputtering target, 8-substrate track, 9-post-processing chamber, 10-sputtering substrate, 11-substrate baffle, 12-sputtering target I, 13-sputtering target II, 14-sputtering target III, 15-reaction chamber. Detailed Implementation

[0051] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0052] Example 1

[0053] This embodiment provides a method for preparing a nickel oxide hole transport layer. The preparation method is carried out in a laboratory miniature sputtering apparatus, wherein the reaction chamber 15 of the miniature sputtering apparatus is as follows: Figure 1 As shown, the preparation method includes the following steps:

[0054] (1) FTO glass was treated with UV ozone for 20 min and placed on sputtering substrate 10. Sputtering target I 12 was made of nickel oxide with a purity of 99.99% and doped with 10 wt.% Cu. Sputtering target II 13 was made of nickel oxide with a purity of 99.99% and doped with 10 wt.% Mg. The vacuum degree of reaction chamber 15 was reduced to 6 × 10⁻⁶. -4 Pa;

[0055] The ratio of the doping amounts of metal elements is 1:1.

[0056] (2) An argon-oxygen mixture (Ar:O2 = 7:1) was introduced at a flow rate of 30 sccm. A nickel oxide hole transport layer was prepared by sputtering. The pre-sputtering was performed for 5 min at a sputtering power of 90 W. Then, the substrate baffle 11 was opened to start sputtering at a sputtering power of 90 W for 20 min. The pressure monitored by the thin film gauge during the sputtering process was 0.3 Pa. The final thickness of the copper-magnesium doped nickel oxide hole transport thin film was 20 nm.

[0057] Example 2

[0058] This embodiment provides a method for preparing a nickel oxide hole transport layer. The preparation method is carried out in the same small laboratory sputtering apparatus as in Example 1, and includes the following steps:

[0059] (1) The PET film was treated with UV ozone for 20 min. Sputtering target I used 99.99% pure nickel oxide target as raw material, and 10 wt.% Cu was added to the target. Sputtering target II used 99.99% pure nickel oxide target as raw material, and 10 wt.% Mg was added to the target. The vacuum degree of the reaction chamber was reduced to 6 × 10⁻⁶. -4 Pa;

[0060] The ratio of the doping amounts of metal elements is 1:1.

[0061] (2) An argon-oxygen mixture (Ar:O2 = 4:1) was introduced at a flow rate of 30 sccm. A nickel oxide hole transport layer was prepared by sputtering. The pre-sputtering was performed for 5 min at a sputtering power of 90 W. Then, the substrate baffle was opened to start sputtering at a sputtering power of 90 W for 25 min. The pressure monitored by the thin film gauge during the sputtering process was 0.2 Pa. The final thickness of the copper-magnesium doped nickel oxide hole film was 22 nm.

[0062] Example 3

[0063] This embodiment provides a method for preparing a nickel oxide hole transport layer. The preparation method is carried out in the same small laboratory sputtering apparatus as in Example 1, and includes the following steps:

[0064] (1) The HJT silicon solar cell substrate was texturized using UV ozone treatment for 20 min. Sputtering target I used 99.99% pure nickel oxide target as raw material, with 8 wt.% Cu doped into the target. Sputtering target II used 99.99% pure nickel oxide target as raw material, with 8 wt.% Li doped into the target. The vacuum degree of the reaction chamber was reduced to 6 × 10⁻⁶. -4 Pa;

[0065] The ratio of the doping amounts of metal elements is 1:1.

[0066] (2) An argon-oxygen mixture (Ar:O2 = 10:1) was introduced at a flow rate of 30 sccm. A nickel oxide hole transport layer was prepared by sputtering. The pre-sputtering was performed for 10 min at a sputtering power of 90 W. Then, the substrate baffle was opened to start sputtering at a sputtering power of 90 W for 15 min. The pressure monitored by the thin film gauge during the sputtering process was 0.4 Pa. The final thickness of the copper-lithium doped nickel oxide hole film was 15 nm.

[0067] Example 4

[0068] This embodiment provides a method for preparing a nickel oxide hole transport layer. The preparation method is carried out in the same small laboratory sputtering apparatus as in Example 1, and includes the following steps:

[0069] (1) FTO glass was treated with UV ozone for 20 min. Sputtering target I was made of nickel oxide with a purity of 99.99% and doped with 10 wt.% Cu. Sputtering target II was made of nickel oxide with a purity of 99.99% and doped with 10 wt.% Mg. The vacuum degree of the reaction chamber was reduced to 6 × 10⁻⁶. -4 Pa;

[0070] The ratio of the doping amounts of metal elements is 1:1.

[0071] (2) An argon-oxygen mixture (Ar:O2 = 7:1) was introduced at a flow rate of 30 sccm. A nickel oxide hole transport layer was prepared by sputtering. The pre-sputtering was performed for 5 min at a sputtering power of 90 W. Then, the sputtering target I baffle was opened to start sputtering at a sputtering power of 90 W for 5 min. The sputtering target I baffle was closed and the sputtering target II baffle was opened to start sputtering at a sputtering power of 90 W for 5 min. The sputtering target II baffle was closed. Finally, the sputtering target I baffle was opened to start sputtering at a sputtering power of 90 W for 5 min. The sputtering target I baffle was closed. The pressure monitored by the thin film gauge during the sputtering process was 0.3 Pa. The thickness of the copper-magnesium doped nickel oxide hole transport thin film was 20 nm.

[0072] Example 5

[0073] This embodiment provides a method for preparing a nickel oxide hole transport layer. The preparation method is performed in an industrial-scale planar target sputtering apparatus, such as... Figure 2 As shown, the preparation method includes the following steps:

[0074] (1) Treat FTO glass with UV ozone for 30 minutes. The first sputtering target is made of nickel oxide with a purity of 99.99% as raw material and 10% Cu is added to the target. The second sputtering target is made of nickel oxide with a purity of 99.99% as raw material and 10% Ag is added to the target. Place the glass substrate with FTO glass on the track with the FTO side facing the target side and start the equipment.

[0075] The ratio of the doping amounts of metal elements is 1:1.

[0076] (2) The track system transports the FTO glass to the pre-evacuation chamber, and the vacuum system reduces the vacuum level in the chamber to 6×10⁻⁶. -4 After Pa, an argon-oxygen mixture (Ar:O2 = 9:1) is introduced at a flow rate of 500 sccm to sputter and prepare a nickel oxide hole transport layer. First, pre-sputter for 10 min at a sputtering power of 800 W. After the pre-sputtering stabilizes, the orbital system transports the FTO glass to the process chamber, which includes a first sputtering target and a second sputtering target. The orbital movement speed is 1 m / min, the process chamber is 5 m long, and the orbital moves in a reciprocating motion for 8 cycles. The pressure monitored by the thin film gauge during sputtering is 0.3 Pa. The final copper-silver doped nickel oxide film has a thickness of 20 nm.

[0077] (3) After the sputtering process is completed, the track system transports the FTO glass to the post-processing chamber for radiation annealing at 120°C for 20 minutes. After annealing, the glass is transported away from the sputtering process line by the track system.

[0078] Example 6

[0079] This embodiment provides a method for preparing a nickel oxide hole transport layer. The preparation method is carried out in the same industrial planar target sputtering equipment as in Example 5, and the preparation method includes the following steps:

[0080] (1) Treat FTO glass with UV ozone for 30 minutes. The first sputtering target is made of nickel oxide with a purity of 99.99% and 12% Cu is added to the target. The second sputtering target is made of nickel oxide with a purity of 99.99% and 12% Mg is added to the target. Place the glass substrate with FTO glass on the track with the FTO side facing the target and start the equipment.

[0081] The ratio of the doping amounts of metal elements is 1:1.

[0082] (2) The track system transports the FTO glass to the pre-evacuation chamber, and the vacuum system reduces the vacuum level in the chamber to 6×10⁻⁶. -4 After Pa, an argon-oxygen mixture (Ar:O2 = 9:1) is introduced at a flow rate of 500 sccm to sputter and prepare a nickel oxide hole transport layer. First, pre-sputter for 20 min at a sputtering power of 800 W. After the chamber stabilizes, the orbital system transports the FTO glass to the process chamber, which includes a first sputtering target and a second sputtering target. The orbital movement speed is 0.5 m / min, the process chamber is 15 m long, and the pressure monitored by the thin film gauge during sputtering is 0.3 Pa. The final copper-magnesium doped nickel oxide film has a thickness of 20 nm.

[0083] (3) After the sputtering process is completed, the orbital system transports the FTO glass to the post-processing chamber for Plsma plasma purging treatment for 10 seconds. After the treatment is completed, the glass is transported away from the sputtering process line by the orbital system.

[0084] Example 7

[0085] This embodiment provides a method for preparing a nickel oxide hole transport layer. The preparation method is carried out in the same industrial planar target sputtering equipment as in Example 5, and the preparation method includes the following steps:

[0086] (1) Treat FTO glass with UV ozone for 30 minutes. The first sputtering target is made of nickel oxide with a purity of 99.99% and 12% Cu is added to the target. The second sputtering target is made of nickel oxide with a purity of 99.99% and 12% Mg is added to the target. Place the glass substrate with FTO glass on the track with the FTO side facing the target and start the equipment.

[0087] The ratio of the doping amounts of metal elements is 1:1.

[0088] (2) The track system transports the FTO glass to the pre-evacuation chamber, and the vacuum system reduces the vacuum level in the chamber to 6×10⁻⁶. -4After Pa, an argon-oxygen mixture (Ar:O2 = 9:1) was introduced at a flow rate of 500 sccm for sputtering to prepare a nickel oxide hole transport layer. First, pre-sputtering was performed for 30 minutes at a sputtering power of 800 W. After the chamber stabilized, the orbital system transported the FTO glass to the process chamber, which included a first sputtering target and a second sputtering target. The orbital speed was 1 m / min, and the process chamber was 15 m long. At sputtering target 1, the orbital speed was 0.5 m / min, and the sputtering thickness was 8 nm. Subsequently, the orbital system transported the FTO glass to sputtering target 2 at a speed of 0.5 m / min, achieving a sputtering thickness of 4 nm. Finally, the orbital system transported the FTO glass to sputtering target 1 at a speed of 0.5 m / min, achieving a sputtering thickness of 8 nm, forming a sandwich structure. The pressure monitored by the thin film gauge during sputtering was 0.3 Pa. The final copper-magnesium doped nickel oxide film had a thickness of 20 nm.

[0089] (3) After the sputtering process is completed, the orbital system transports the FTO glass to the post-processing chamber for Plsma plasma purging treatment for 10 seconds. After the treatment is completed, the glass is transported away from the sputtering process line by the orbital system.

[0090] Example 8

[0091] The difference between this embodiment and Embodiment 1 is that the metal doped in sputtering target II is replaced with Na.

[0092] The remaining preparation methods and parameters are consistent with those in Example 1.

[0093] Example 9

[0094] The difference between this embodiment and Embodiment 1 is that the metal doped in the sputtering target II is replaced with Li.

[0095] The remaining preparation methods and parameters are consistent with those in Example 1.

[0096] Example 10

[0097] The difference between this embodiment and Embodiment 1 is that this embodiment also includes sputtering target III, which uses nickel oxide target with a purity of 99.99% as raw material and incorporates 10 wt.% Na into the target, so the doping ratio of the metal elements is 1:1:1.

[0098] The remaining preparation methods and parameters are consistent with those in Example 1.

[0099] Example 11

[0100] The difference between this embodiment and Embodiment 1 is that the doping amount of Mg in Target II is 5 wt.%, so the doping ratio of the metal elements is 2:1.

[0101] The remaining preparation methods and parameters are consistent with those in Example 1.

[0102] Example 12

[0103] The difference between this embodiment and Embodiment 1 is that the Cu doping amount in sputtering target I is 5 wt.%, and the Mg doping amount in sputtering target II is 5 wt.%, so the ratio of the doping amounts of the metal elements is 1:1.

[0104] The remaining preparation methods and parameters are consistent with those in Example 1.

[0105] Example 13

[0106] The difference between this embodiment and Embodiment 1 is that the Cu doping amount in sputtering target I is 15 wt.% and the Mg doping amount in sputtering target II is 15 wt.%, so the ratio of the doping amounts of the metal elements is 1:1.

[0107] The remaining preparation methods and parameters are consistent with those in Example 1.

[0108] Example 14

[0109] The difference between this embodiment and Embodiment 1 is that the Cu doping amount in sputtering target I is replaced with 18 wt.%.

[0110] Example 15

[0111] The difference between this embodiment and Embodiment 1 is that the Cu doping amount in sputtering target I and the Mg doping amount in sputtering target II are both replaced with 18 wt.%.

[0112] The remaining preparation methods and parameters are consistent with those in Example 1.

[0113] Example 16

[0114] The difference between this embodiment and Embodiment 1 is that the Cu doping amount in sputtering target I is replaced with 2.5 wt.%.

[0115] The remaining preparation methods and parameters are consistent with those in Example 1.

[0116] Example 17

[0117] The difference between this embodiment and Embodiment 1 is that the Mg doping amount in sputtering target II is replaced with 3 wt.%.

[0118] The remaining preparation methods and parameters are consistent with those in Example 1.

[0119] Comparative Example 1

[0120] The difference between this embodiment and embodiment 1 is that sputtering target II is turned off, and only sputtering target I is used.

[0121] The remaining preparation methods and parameters are consistent with those in Example 1.

[0122] Figure 3 XPS comparison images of the nickel oxide hole transport layers prepared in Example 1 and Comparative Example 1 are shown, where (a) is the XPS characterization of Comparative Example 1 and (b) is the XPS characterization of Example 1. As can be seen from the figures, after optimization, 2p 1 / 2 In the orbital section, the content of trivalent nickel decreased significantly, while the content of divalent nickel increased. Trivalent nickel possesses catalytic properties and is unstable, leading to a reaction with the perovskite layer. Therefore, the performance of the nickel oxide hole transport layer prepared in Example 1 was significantly improved.

[0123] Figure 4 The figure shows a comparison of the HOMO energy levels of the nickel oxide hole transport layers prepared in Example 1 and Comparative Example 1. As can be seen from the figure, the HOMO energy level of Comparative Example 1 is -6.9 eV, while that of Example 1 is -6.71 eV. This indicates that the HOMO energy level of the nickel oxide film has been improved after optimization.

[0124] Comparative Example 2

[0125] The difference between this embodiment and Embodiment 1 is that sputtering target I is turned off, and only sputtering target II is used.

[0126] The remaining preparation methods and parameters are consistent with those in Example 1.

[0127] Comparative Example 3

[0128] The difference between this embodiment and Embodiment 1 is that this embodiment further includes sputtering target III and sputtering target IV. Sputtering target III uses nickel oxide target with a purity of 99.99% as raw material and incorporates 10 wt.% Na. Sputtering target IV uses nickel oxide target with a purity of 99.99% as raw material and incorporates 10 wt.% Li.

[0129] The remaining preparation methods and parameters are consistent with those in Example 1.

[0130] Performance testing

[0131] The metal-doped nickel oxide hole transport layer prepared in Examples 1-17 and Comparative Examples 1-3 is combined with an electron transport layer, a perovskite layer, and a copper electrode to obtain a solar cell. Specifically, the perovskite solar cells prepared in Examples 1, 4-17, and Comparative Examples 1-3 are perovskite solar cells, while the flexible perovskite solar cell and the silicon / perovskite tandem solar cell prepared in Examples 2 and 3 are respectively. The specific steps include:

[0132] (1) Prepare a perovskite precursor solution with the following composition: Cs 0.15 FA0.85 PbI3, concentration 1.2 mol / L, was magnetically stirred for 12 h, and filtered after complete dissolution before use;

[0133] (2) 50 μL of perovskite precursor solution was dropped onto a nickel oxide substrate and a perovskite film was obtained by scraping. The scraping speed was 15 mm / s. After the scraping was completed, the film was dried with a nitrogen gun at a nitrogen pressure of 0.6 MPa. Then, it was annealed at 125 °C for 30 min.

[0134] (3) After annealing, place it in a vacuum evaporation equipment to deposit 28nm C. 60 +8nm BCP composite electron transport layer, and finally 100nm Cu electrode is deposited by vapor deposition.

[0135] The photoelectric performance of the solar cells prepared above was tested.

[0136] The test results are shown in Table 1.

[0137] Table 1

[0138]

[0139]

[0140] analyze:

[0141] As shown in Tables 1 and 2, this invention obtains a multi-metal-doped nickel oxide hole transport layer by sputtering with a nickel oxide target doped with two or three metal elements. This method not only effectively improves the hole transport capability of nickel oxide but also allows for better control of its energy levels, enhancing its conductivity and reducing the defect density of the nickel oxide film, thereby producing a high-performance solar cell.

[0142] The data results from Examples 1, 2, and 3 show that the preparation method provided by the present invention is not only applicable to improving the performance of conventional perovskite solar cells, but also applicable to flexible perovskite solar cells and silicon / perovskite tandem cells.

[0143] A comparison of the data results from Example 1 and Examples 14-15 shows that if the metal doping amount is too high, the efficiency will decrease significantly. This is because excessive doping causes the original crystal lattice structure to deform, thereby reducing the battery performance.

[0144] A comparison of the data results from Examples 1 and 16-17 shows that if the ratio of the amount of metal element doping in sputtering target I to the amount of metal element doping in sputtering target II is too large, the open-circuit voltage and short-circuit current density of the device will decrease, resulting in a decline in battery performance. If the ratio of the amount of metal element doping in sputtering target I to the amount of metal element doping in sputtering target II is too small, the fill factor of the device will be poor, resulting in a decline in battery performance.

[0145] A comparison of the data results from Example 1 and Comparative Examples 1-2 shows that doping with only a single metal makes it difficult to control trivalent nickel, resulting in insufficient device voltage and low light transmittance, which in turn reduces current density.

[0146] A comparison of the data results from Example 1 and Comparative Example 3 shows that when the number of sputtering target materials exceeds three, that is, when the number of doped metals exceeds three, the performance of the battery shows a significant decline. This is because multi-element doping is difficult to control structurally, resulting in unstable film formation.

[0147] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a nickel oxide hole transport layer, characterized in that, The preparation method includes the following steps: (1) Place the substrate in the reaction chamber and evacuate it; (2) Introduce oxygen-containing gas and sputter using two or three different sputtering targets to obtain the nickel oxide hole transport layer; The sputtering target includes a first target and a second target. The first target is selected from a Cu-doped nickel oxide sputtering target, and the second target is selected from a nickel oxide sputtering target doped with any one of the elements Mg, Li, Ag, K or Na. The ratio of the amount of metal element doping in the first target to the amount of metal element doping in the second target is (0.5~2):

1.

2. The preparation method according to claim 1, characterized in that, Based on the mass of the sputtering target, the metal element doping amount in the sputtering target is independently 0~15wt.%, excluding 0.

3. The preparation method according to claim 2, characterized in that, Based on the mass of the sputtering target, the amount of metal element doping in the sputtering target is independently 8~12 wt.%.

4. The preparation method according to claim 1, characterized in that, The oxygen-containing gas in step (2) is a combination of inert gas and oxygen gas.

5. The preparation method according to claim 4, characterized in that, The inert gas includes argon.

6. The preparation method according to claim 4, characterized in that, The volume ratio of the inert gas to the oxygen is (4~10):

1.

7. The preparation method according to claim 1, characterized in that, The sputtering in step (2) is either synchronous sputtering or sequential sputtering.

8. The preparation method according to claim 1, characterized in that, The sputtering time in step (2) is 5 to 40 minutes.

9. The preparation method according to claim 1, characterized in that, During the sputtering process described in step (2), the pressure in the reaction chamber is 0.2-0.4 Pa.

10. The preparation method according to claim 1, characterized in that, Pre-sputtering is performed before the sputtering described in step (2); The pre-sputtering time is 5 to 30 minutes.

11. The preparation method according to claim 1, characterized in that, After the sputtering process described in step (2) is completed, a post-processing process is also performed; The post-processing includes thermal annealing or plasma purging.

12. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Place the rigid substrate in a reaction chamber containing two sputtering targets, and evacuate the chamber until the pressure is less than or equal to 6 × 10⁻⁶. -4 Pa; Among them, the two sputtering targets are nickel oxide targets doped with different metal elements, and the ratio of the doping amount of the metal elements is (0.5~2):1; (2) A combination of inert gas and oxygen with a gas flow rate of 30~500scm and a volume ratio of (4~10):1 is introduced for pre-sputtering for 5~30min. After the pre-sputtering is completed, synchronous sputtering is performed for 5~40min. After the sputtering is completed, post-processing is performed to obtain the nickel oxide hole transport layer.

13. A nickel oxide hole transport layer, characterized in that, The nickel oxide hole transport layer is prepared by the preparation method according to any one of claims 1-12, and the nickel oxide hole transport layer is nickel oxide doped with a multi-metal, wherein the multi-metal comes from the sputtering target.

14. The nickel oxide hole transport layer according to claim 13, characterized in that, The thickness of the nickel oxide hole transport layer is 15~22nm.

15. A solar cell, characterized in that, The solar cell includes a nickel oxide hole transport layer as described in claim 13 or 14.

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