A composite electron transport layer, its fabrication method, and a perovskite solar cell

Abstract

This invention provides a composite electron transport layer, its fabrication method, and a perovskite solar cell. The composite electron transport layer comprises a carbon material substrate film, an IWSO thin film, an oxide-containing buffer layer, and a transparent conductive semiconductor material layer stacked together. Through its multilayer structure and material combination, the composite electron transport layer of this invention inserts an intermediate-energy-level oxide-containing buffer layer between the IWSO and transparent conductive semiconductor material layers without sacrificing efficiency. This creates a smoother energy level gradient, protects the high-performance core IWSO layer, enhances its reliability, and significantly improves the stability of the perovskite solar cell.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, and relates to a composite electron transport layer, its preparation method, and perovskite solar cells. Background Technology

[0002] In inverted perovskites, commercially available components currently primarily employ a transparent conductive semiconductor material layer between the metal electrode and the electron transport layer to improve reverse bias stability. However, most transparent conductive materials (TCOs) and metal electrodes are currently deposited using magnetron sputtering, and high-energy particle bombardment can damage both the perovskite layer and the electron transport layer.

[0003] In perovskite solar cell research, interface engineering is key to improving device performance. Existing technologies can reduce the risk of thermal damage by introducing an ALD deposition process with a wide temperature range, but the protection effect on the electron transport layer is limited, and the performance of the electron transport layer in existing technologies needs to be improved. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a composite electron transport layer, its preparation method, and a perovskite solar cell. The composite electron transport layer of the present invention, through a multi-layer structure and material combination, inserts an intermediate-level oxide buffer layer between the IWSO and transparent conductive semiconductor material layers without sacrificing efficiency. This forms a smoother energy level ladder, protecting the high-performance core layer IWSO, enhancing its reliability, and significantly improving the stability of the perovskite solar cell.

[0005] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a composite electron transport layer comprising a carbon material base film, a tungsten-doped indium oxide (IWSO) thin film, an oxide buffer layer, and a transparent conductive semiconductor material layer stacked together.

[0006] In the composite electron transport layer of this invention, the carbon material base film has a low HOMO energy level, which can help block holes from flowing back to the ETL and reduce interfacial recombination. An IWSO thin film is deposited on the surface of the carbon material base film. 6+ Doping can provide a large number of free electrons, while due to W 6+ The ionic radius of In 3+The close proximity of the indium content to the perovskite layer, its small lattice distortion, and weak carrier scattering result in extremely high electron mobility for IWSO. This ensures the highly efficient extraction and transport of photogenerated electrons, directly improving the fill factor and short-circuit current of the battery. Compared to conventional transparent conductive materials (such as IZO), IWSO exhibits higher mobility and better bias stability. However, indium in IWSO may diffuse into the perovskite layer or interdiffusion / reaction with the upper metal layer during subsequent processes (such as thermal evaporation of electrodes or exposure to air) or long-term use, leading to interface deterioration and performance degradation. This invention incorporates an oxide-containing buffer layer between the IWSO thin film and the transparent conductive semiconductor material layer to enhance reliability, buffer against high-energy particle bombardment, and reduce film damage caused during the fabrication of the conductive semiconductor material layer. Furthermore, the oxide-containing buffer layer enhances reliability without affecting the conductivity of the composite electron transport layer, significantly extending the lifespan of the perovskite module under long-term ultraviolet radiation, reducing perovskite decomposition, and decreasing power decay of the module.

[0007] Preferably, the material of the carbon-based film includes C. 60 And / or PCBM.

[0008] Preferably, the thickness of the carbon material base film is 8nm to 15nm, for example: 8nm, 9nm, 10nm, 12nm or 15nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0009] Preferably, the thickness of the IWSO film is 12nm~18nm, for example: 12nm, 13nm, 15nm, 16nm or 18nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0010] Preferably, the material of the oxide-containing buffer layer includes any one or a combination of at least two of alumina, zirconium oxide, titanium oxide, tin oxide, or a titanium oxide / graphene composite material. Typical but non-limiting combinations include combinations of alumina and zirconium oxide, combinations of alumina and tin oxide, or combinations of titanium oxide and zirconium oxide.

[0011] The titanium oxide / graphene composite material of the present invention has a double-layer structure, with graphene as the bottom layer and titanium oxide as the top layer. The ratio of the thickness of the bottom and top deposited films is 1:(6~7), for example: 1:6, 1:6.2, 1:6.5, 1:6.8 or 1:7, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0012] Preferably, the thickness of the oxide buffer layer is 4nm to 6nm, for example: 4nm, 4.5nm, 5nm, 5.5nm or 6nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0013] Preferably, the material of the transparent conductive semiconductor material layer includes ITO and / or IZO.

[0014] Preferably, the thickness of the transparent conductive semiconductor material layer is 80nm~120nm, for example: 80nm, 90nm, 100nm, 110nm or 120nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] In a second aspect, the present invention provides a method for preparing a composite electron transport layer as described in the first aspect, the method comprising the following steps: A carbon material base film is formed by vapor deposition of carbon material on the substrate surface; IWSO is deposited on the surface of a carbon material substrate to form an IWSO thin film; After depositing an oxide-containing buffer layer on the surface of an IWSO thin film, a transparent conductive semiconductor material is sputtered to obtain the composite electron transport layer.

[0016] Preferably, the substrate includes a transparent conductive glass substrate and a hole transport layer and a perovskite light-absorbing layer stacked on the surface of the transparent conductive glass substrate.

[0017] Preferably, the method of depositing IWSO includes reactive plasma deposition (RPD).

[0018] Preferably, the method of depositing the oxide-containing buffer layer includes atomic layer deposition (ALD).

[0019] Preferably, the temperature for depositing the oxide-containing buffer layer is 25°C to 150°C, for example: 25°C, 30°C, 50°C, 100°C or 150°C, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Thirdly, the present invention provides a perovskite solar cell, the perovskite solar cell comprising a transparent conductive glass substrate, a hole transport layer, a perovskite light-absorbing layer, a composite electron transport layer as described in the first aspect, and a metal electrode stacked together, wherein a carbon material base film of the composite electron transport layer is disposed on the side close to the transparent conductive glass substrate.

[0021] 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.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) The composite electron transport layer of the present invention, through multi-layer structure and material combination, inserts an intermediate energy level oxide buffer layer between IWSO and high work function transparent conductive material layer without sacrificing efficiency, which can form a smoother energy level ladder, protect the high-performance core layer IWSO, enhance its reliability, and greatly improve the stability of perovskite solar cells.

[0023] (2) The perovskite solar cell made of the composite electron transport layer described in this invention can achieve a maximum output power Pmax of 114.6W or more, a short-circuit current Isc of 1.58A, an open-circuit voltage Voc of 100.89V or more, a fill factor of 72%, a photoelectric conversion efficiency Eff of 15.92% or more, a series resistance Rs of less than 10.36Ω, a parallel resistance Rsh of less than 989Ω, a UV test attenuation of less than 14.2%, and a DH test attenuation of less than 20%. Detailed Implementation

[0024] 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.

[0025] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0026] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0027] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0028] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0029] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0030] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0031] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0032] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0033] The substrates used in the embodiments and comparative examples of this invention both include FTO glass, a nickel oxide hole transport layer with a thickness of 40 nm, and a perovskite light-absorbing layer with a thickness of 500 nm, and a composite electron transport layer is prepared on the perovskite light-absorbing layer.

[0034] Example 1 This embodiment provides a composite electron transport layer, which includes a C layer with a thickness of 11 nm. 60 The base film and the layers sequentially stacked on the C 60 The base film surface has a 15nm thick IWSO layer, a 5nm thick alumina buffer layer, and a 100nm thick ITO layer.

[0035] The composite electron transport layer is prepared by the following method: C is deposited on the substrate surface 60 , to obtain C 60 Base film; In C 60 IWSO was deposited on the base film by RPD at a deposition temperature of 60℃ to form an IWSO thin film; The composite electron transport layer was obtained by depositing an alumina buffer layer on the surface of an IWSO thin film using the ALD method with TMA and pure water as precursors at 100°C (TMA pulse time 1.2s, purge 15s, pure water pulse time 1s, purge 10s). ITO was then magnetron sputtered onto the alumina buffer layer.

[0036] Example 2 This embodiment provides a composite electron transport layer, which includes a C layer with a thickness of 8 nm. 60 The base film and the laminated layers are disposed on the C 60 The base film surface has a 12nm thick IWSO layer, a 4nm thick alumina buffer layer, and an 80nm thick IZO layer.

[0037] The composite electron transport layer is prepared by the following method: C is deposited on the substrate surface 60 , to obtain C 60 Base film; In C 60 IWSO was deposited on the base film by RPD at a deposition temperature of 60℃ to form an IWSO thin film; The composite electron transport layer was obtained by depositing an alumina buffer layer on the surface of an IWSO thin film using the ALD method with TMA and pure water as precursors at 25°C (TMA pulse time 1.2s, purge 15s, pure water pulse time 1s, purge 10s). IZO was then magnetron sputtered onto the alumina buffer layer.

[0038] Example 3 This embodiment provides a composite electron transport layer, which includes a C layer with a thickness of 15 nm. 60 The base film and the laminated layers are disposed on the C 60 The base film surface has an IWSO layer with a thickness of 18 nm, an alumina buffer layer with a thickness of 6 nm, and an IZO layer with a thickness of 120 nm.

[0039] The composite electron transport layer is prepared by the following method: C is deposited on the substrate surface 60 , to obtain C 60 Base film; In C 60 IWSO was deposited on the base film by RPD at a deposition temperature of 60℃ to form an IWSO thin film; The composite electron transport layer was obtained by depositing an alumina buffer layer on the surface of an IWSO thin film using the ALD method with TMA and pure water as precursors at 150°C (TMA pulse time 1.2s, purge 15s, pure water pulse time 1s, purge 10s). IZO was then magnetron sputtered onto the alumina buffer layer.

[0040] Example 4 The only difference between this embodiment and Embodiment 1 is that the thickness of the IWSO film is 10 nm, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0041] Example 5 The only difference between this embodiment and Embodiment 1 is that the thickness of the IWSO film is 20 nm; all other conditions and parameters are exactly the same as in Embodiment 1.

[0042] Example 6 The only difference between this embodiment and Embodiment 1 is that the thickness of the alumina buffer layer is 3 nm; all other conditions and parameters are exactly the same as in Embodiment 1.

[0043] Example 7 The only difference between this embodiment and Embodiment 1 is that the thickness of the alumina buffer layer is 7 nm; all other conditions and parameters are exactly the same as in Embodiment 1.

[0044] Comparative Example 1 The only difference between this comparative example and Example 1 is that the IWSO film is replaced with an IZO film; all other conditions and parameters are exactly the same as in Example 1.

[0045] Comparative Example 2 The only difference between this comparative example and Example 1 is that the alumina buffer layer is not provided; all other conditions and parameters are exactly the same as in Example 1.

[0046] Performance testing: In the examples and comparative examples, a 100 nm thick copper electrode layer was magnetron sputtered onto the composite electron transport layer. A picosecond laser was used for P3 scribing, and after cutting the copper electrode layer, laser edge cleaning was performed to obtain a perovskite solar cell. The perovskite solar cell was then subjected to the following tests: The DH test involves subjecting the sample to a constant temperature of 85°C and relative humidity of 85% in an environmental simulation chamber for a typical duration of 1000 hours. The UV test utilizes a UV light source at 100W / m². 2 Under the specified light intensity, continuous irradiation for 60 hours.

[0047] The test results are shown in Table 1: Table 1 As shown in Table 1, based on Examples 1 to 3, the perovskite solar cell fabricated with the composite electron transport layer described in this invention can achieve a maximum output power Pmax of 114.6 W or higher, a short-circuit current Isc of 1.58 A, an open-circuit voltage Voc of 100.89 V or higher, a fill factor of 72%, a photoelectric conversion efficiency Eff of 15.92% or higher, a series resistance Rs of less than 10.36 Ω, a parallel resistance Rsh of less than 989 Ω, a UV test attenuation of less than 14.2%, and a DH test attenuation of less than 20%.

[0048] Comparing Examples 1 and 4-5, it can be seen that the thickness of the IWSO film in the composite electron transport layer of the present invention affects its performance. When the thickness of the IWSO film is controlled between 12nm and 18nm, the performance of the composite electron transport layer is better. If the thickness of the IWSO film is too large, the cell opening voltage drops significantly, affecting electron transport. If the thickness of the IWSO film is too small, its role as a buffer layer decreases, thermal damage increases, and conversion efficiency decreases.

[0049] A comparison of Examples 1 and 6-7 shows that the thickness of the oxide buffer layer in the composite electron transport layer of the present invention affects its performance. When the thickness of the oxide buffer layer is controlled between 4nm and 6nm, the performance of the composite electron transport layer is better. If the thickness of the oxide buffer layer is too large, the cell conversion efficiency decreases and is significantly lower than the benchmark value. If the thickness of the oxide buffer layer is too small, the protective effect decreases, the cell conversion efficiency tends to be proportional, and the reliability improvement effect decreases.

[0050] A comparison of Example 1 and Comparative Example 1 shows that when an IWSO thin film is deposited on the surface of a carbon material substrate film, W 6+ Doping can provide a large number of free electrons, while due to W 6+ The ionic radius of In 3+With its close proximity, small lattice distortion, and weak carrier scattering, IWSO exhibits extremely high electron mobility, thereby ensuring that photogenerated electrons can be extracted and transported with ultra-high efficiency, directly improving the fill factor and short-circuit current of the battery. Compared with conventional IZO transparent conductive materials, IWSO has higher mobility and better bias stability.

[0051] As can be seen from the comparison between Example 1 and Comparative Example 2, the present invention provides an oxide-containing buffer layer between the IWSO thin film and the transparent conductive semiconductor material layer, which enhances its reliability, buffers high-energy particle bombardment, and reduces film damage caused during the preparation of the conductive semiconductor material layer. Moreover, the oxide-containing buffer layer can enhance its reliability without affecting the conductivity of the composite electron transport layer, thereby significantly extending the service life of the perovskite module under long-term ultraviolet irradiation, reducing the decomposition of perovskite, and reducing the power decay of the module device.

[0052] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A composite electron transport layer, characterized in that, The composite electron transport layer comprises a carbon material base film, an IWSO thin film, an oxide buffer layer, and a transparent conductive semiconductor material layer stacked together.

2. The composite electronic transport layer as described in claim 1, characterized in that, The material of the carbon-based film includes C. 60 and / or PCBM; And / or, the thickness of the carbon material base film is 8nm~15nm.

3. The composite electronic transport layer as described in claim 1 or 2, characterized in that, The thickness of the IWSO thin film is 12nm~18nm.

4. The composite electron transport layer according to any one of claims 1-3, characterized in that, The material of the oxide-containing buffer layer includes any one or a combination of at least two of alumina, zirconium oxide, titanium oxide, tin oxide, or titanium oxide / graphene composite material; And / or, the thickness of the oxide-containing buffer layer is 4nm~6nm.

5. The composite electron transport layer according to any one of claims 1-4, characterized in that, The material of the transparent conductive semiconductor material layer includes ITO and / or IZO; And / or, the thickness of the transparent conductive semiconductor material layer is 80nm~120nm.

6. A method for preparing a composite electron transport layer as described in any one of claims 1-5, characterized in that, The preparation method includes the following steps: A carbon material base film is formed by vapor deposition of carbon material on the substrate surface; IWSO is deposited on the surface of a carbon material substrate to form an IWSO thin film; After depositing an oxide-containing buffer layer on the surface of an IWSO thin film, a transparent conductive semiconductor material is sputtered to obtain the composite electron transport layer.

7. The preparation method according to claim 6, characterized in that, The substrate includes a transparent conductive glass substrate and a hole transport layer and a perovskite light-absorbing layer stacked on the surface of the transparent conductive glass substrate.

8. The preparation method according to claim 6 or 7, characterized in that, The method of depositing IWSO includes reactive plasma deposition.

9. The preparation method according to any one of claims 6-8, characterized in that, The method of depositing the oxide-containing buffer layer includes atomic layer deposition; And / or, the temperature at which the oxide-containing buffer layer is deposited is 25°C to 150°C.

10. A perovskite solar cell, characterized in that, The perovskite solar cell comprises a transparent conductive glass substrate, a hole transport layer, a perovskite light-absorbing layer, a composite electron transport layer as described in any one of claims 1-5, and a metal electrode, all stacked together. The carbon material base film of the composite electron transport layer is disposed on the side close to the transparent conductive glass substrate.

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