Flexible conductive substrate and preparation method thereof, and flexible perovskite solar cell

Abstract

The invention provides a flexible conductive substrate, a flexible conductive substrate preparation method and a flexible perovskite solar cell comprising the flexible conductive substrate. The flexible conductive substrate comprises a flexible substrate layer, a substrate buffer layer and a transparent conductive layer which are stacked from bottom to top. The substrate buffer layer is made of transparent metal oxide, and the thickness of the substrate buffer layer is 5-80 nm; the flexible conductive substrate adopts a composite flexible substrate structure, the polymer film is used as the flexible substrate layer, and the nanoscale substrate buffer layer formed by the transparent metal oxide is inserted between the flexible substrate layer and the transparent conductive layer, so that the surface stress distribution of the flexible substrate layer is effectively released / homogenized; and meanwhile, the connection strength between the flexible substrate layer and the transparent conductive layer is increased, so that the transparent conductive layer is not easy to desorb, and the photoelectric property and the mechanical quality of the ultrathin flexible perovskite solar cell prepared based on the novel flexible conductive substrate structure are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a flexible conductive substrate and its preparation method, and a flexible perovskite solar cell. Background Technology

[0002] Perovskite solar cells, as an emerging photovoltaic technology, have become a research hotspot due to their high efficiency potential and low cost advantages. Compared with traditional rigid cells, flexible perovskite solar cells, with their lightweight, high power-to-weight ratio and bendability, show great promise in scenarios with stringent requirements for cell form adaptability, space utilization, and power density, such as aerospace energy systems, wearable electronic devices, and building-integrated photovoltaics.

[0003] However, flexible perovskite solar cells face three main problems:

[0004] 1. Imbalance between substrate flexibility and mechanical strength: To meet support requirements, the thickness of current polymer substrates is usually >150μm, which leads to a significant tendency for the substrate to become rigid, making it difficult to achieve small curvature radius bending. In addition, the tensile strength of polymer substrates is generally low, which has obvious limitations in application scenarios with high requirements for surface adhesion and flexibility.

[0005] 2. Poor performance of transparent conductive substrates for flexible cells: The fabrication process of flexible perovskite solar cells requires the preparation of a high-transmittance metal oxide conductive electrode (transparent conductive layer) on the surface of a flexible substrate using a coating technique. However, the high-transmittance electrode grown on the surface of the flexible substrate film has problems such as high sheet resistance and poor uniformity, which makes the performance of the transparent conductive substrate of flexible cells much lower than that of rigid module substrates.

[0006] 3. Insufficient structural strength between the flexible substrate and the high-transmittance electrode: Under repeated bending and twisting deformation, the high-transmittance electrode is prone to detach from the surface of the flexible substrate, causing battery failure.

[0007] Therefore, there is an urgent need to develop a novel conductive substrate structure that combines high flexibility, low sheet resistance electrodes, and strong interfacial bonding. Summary of the Invention

[0008] To address the aforementioned technical problems, the present invention aims to provide a flexible conductive substrate and its preparation method, as well as a flexible perovskite solar cell.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A first aspect of the present invention is to provide a flexible conductive substrate comprising a flexible substrate layer, a substrate buffer layer and a transparent conductive layer stacked from bottom to top; the substrate buffer layer is composed of a transparent metal oxide and has a thickness of 5 to 80 nm.

[0011] Furthermore, the transparent metal oxide is one or more of the following: tungsten-doped indium oxide, zinc-doped indium oxide, aluminum oxide, tin oxide, nickel oxide, vanadium pentoxide, and copper oxide.

[0012] Furthermore, the flexible substrate is a polymer film, and the material of the polymer film is selected from at least one of polyimide, polyethylene naphthalate, polyethylene terephthalate, polycarbonate, polydimethylsiloxane, polyetheretherketone, polystyrene, and polyurethane, and the thickness of the flexible substrate is 1 to 100 μm.

[0013] Furthermore, the thickness of the transparent conductive layer is 100-800 nm, and its material is selected from at least one of tin-doped indium oxide, fluorine-doped tin oxide, tungsten-doped indium oxide, and zinc-doped indium oxide.

[0014] A second aspect of the present invention is to provide a method for preparing the above-mentioned flexible conductive substrate, comprising the following steps:

[0015] S1. A polymer film is used as a flexible substrate layer, and a transparent metal oxide with a thickness of 5-80 nm is deposited on the upper surface of the flexible substrate layer as a substrate buffer layer;

[0016] S2. A transparent conductive layer is deposited on the upper surface of the substrate buffer layer obtained in step S1;

[0017] S3. Perform thermal annealing on the device obtained in step S2, and then cool it to room temperature to obtain a flexible conductive substrate.

[0018] Furthermore, in step S1, the thickness of the polymer film is 1 to 100 μm, and the material is selected from at least one of polyimide, polyethylene naphthalate, polyethylene terephthalate, polycarbonate, polydimethylsiloxane, polyetheretherketone, polystyrene, and polyurethane.

[0019] Furthermore, in step S1, the substrate buffer layer is made of one or more of the following materials: tungsten-doped indium oxide, zinc-doped indium oxide, aluminum oxide, tin oxide, nickel oxide, vanadium pentoxide, and copper oxide. It is deposited by a wet process or a dry process. The wet process includes spin coating, slot coating, blade coating, and screen printing. The dry process includes thermal evaporation coating, magnetron sputtering coating, reactive plasma sputtering coating, electron beam coating, and atomic layer deposition.

[0020] Furthermore, in step S2, the transparent conductive layer is made of at least one of tin-doped indium oxide, fluorine-doped tin oxide, tungsten-doped indium oxide, and zinc-doped indium oxide, with a thickness of 100–800 nm, and is deposited by a dry process, wherein the dry process is one or a combination of magnetron sputtering, reactive plasma sputtering, electron beam deposition, atomic layer deposition, and chemical vapor deposition.

[0021] Furthermore, in step S3, the temperature of the thermal annealing treatment is 50–400°C, and the time is 1–100 min.

[0022] A third aspect of the present invention is to provide a flexible perovskite solar cell, comprising:

[0023] A flexible conductive substrate, wherein the flexible conductive substrate is the aforementioned flexible conductive substrate or is prepared by the aforementioned preparation method;

[0024] A first carrier transport layer, a perovskite active layer, a second carrier transport layer, and a counter electrode are sequentially formed on the upper surface of the transparent conductive layer.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects:

[0026] 1. Innovative Battery Structure Design: The flexible conductive substrate of this invention is a novel flexible conductive substrate that adopts a composite flexible substrate structure of "flexible substrate layer + substrate buffer layer". A polymer film with high mechanical strength is used as the flexible substrate layer. At the same time, a nanoscale (5-80nm) substrate buffer layer composed of transparent metal oxide is inserted between the flexible substrate layer and the transparent conductive layer. This effectively releases / homogenizes the surface stress distribution of the flexible substrate layer and increases the connection strength between the flexible substrate layer and the transparent conductive layer, making the transparent conductive layer less prone to desorption. The photoelectric properties and mechanical properties of the ultrathin flexible perovskite solar cells prepared based on this novel flexible conductive substrate structure are significantly improved.

[0027] 2. Extremely Thin, Flexible, and High Power-to-Weight Ratio: The flexible conductive substrate provided by this invention, through the introduction of a substrate buffer layer, enables the overall thickness of the flexible perovskite solar cell to be reduced to the micrometer level, achieving extreme lightweighting of the battery and realizing a high power-to-weight ratio of 1000W / kg. This provides a lightweight energy solution for applications that are extremely sensitive to load (such as aerospace vehicles and wearable devices). At the same time, this innovative structure cleverly retains the extremely high flexibility of the flexible substrate layer and endows it with high mechanical strength, with tensile strength reaching the level of hundreds of megapascals. This ensures that the battery can maintain excellent mechanical integrity (high stability) even under extreme bending, rubbing, and other severe deformation conditions, greatly expanding the flexibility of application scenarios.

[0028] 3. Simultaneous achievement of high conductivity and high transmittance: The flexible conductive substrate structure of this invention fundamentally solves the core problems of excessively high sheet resistance and poor uniformity that are commonly found when depositing transparent conductive layers on the surface of traditional flexible substrates by introducing a buffer layer. Specifically, the substrate buffer layer constructs an optimized interface between the flexible substrate layer and the transparent conductive layer, which significantly improves the uniformity and adhesion of the subsequent transparent conductive layer film. This not only significantly reduces the sheet resistance of the flexible conductive substrate (improving conductivity) and improves its uniformity, but also greatly improves the total transmittance of the flexible conductive substrate in the ultraviolet-visible light band due to the optimized interface structure and material selection.

[0029] 4. Improved photoelectric conversion efficiency: Based on the significant optimization of the flexible conductive substrate of this invention in terms of high conductivity (low sheet resistance, uniformity) and high light transmittance, as well as the optical and electrical benefits brought by the micron-level structure, the novel ultrathin flexible perovskite solar cell prepared can achieve higher photoelectric conversion efficiency than similar cells using ordinary flexible conductive substrates, which significantly enhances the power generation capacity of flexible perovskite solar cells in practical applications.

[0030] 5. Enhanced Environmental Stability: The substrate buffer layer in the flexible conductive substrate of this invention not only serves as a key to enhancing mechanical properties but also provides interface protection. The substrate buffer layer has a dense physical structure and stable chemical properties, effectively blocking the penetration of water vapor (H2O) and oxygen (O2) from the flexible substrate side. This active inhibition of water and oxygen permeability, combined with its enhanced mechanical stability, significantly enhances the overall environmental stability of the ultrathin flexible perovskite solar cell, effectively delaying its performance degradation caused by environmental erosion and extending the battery's lifespan. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the flexible conductive substrate of the present invention.

[0032] Figure 2 This is a schematic diagram of the structure of the flexible perovskite solar cell of the present invention.

[0033] Figure 3 This is a schematic diagram of the block-based design of the flexible conductive substrate during the sheet resistance and sheet resistance uniformity test of the flexible conductive substrate of the present invention.

[0034] Figure 4 The images show the surface morphology of the transparent conductive layer of the flexible conductive substrate after film adhesion testing in some embodiments and comparative examples of the present invention; (a) shows the surface morphology of the transparent conductive layer of the flexible conductive substrate after film adhesion testing in Embodiment 4 of the present invention; and (b) shows the surface morphology of the transparent conductive layer of the flexible conductive substrate after film adhesion testing in Comparative Example 1 of the present invention.

[0035] In the figure: 1-flexible substrate layer; 2-substrate buffer layer; 3-transparent conductive layer; 4-first carrier transport layer; 5-perovskite active layer; 6-second carrier transport layer; 7-counter electrode. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0037] See Figure 1 The present invention first provides a flexible conductive substrate, comprising a flexible substrate layer 1, a substrate buffer layer 2 and a transparent conductive layer 3 stacked from bottom to top; the substrate buffer layer 2 is composed of a transparent metal oxide and has a thickness of 5 to 80 nm.

[0038] The novel flexible conductive substrate of this invention differs from ordinary flexible conductive substrate structures in that it uses a high-mechanical-strength polymer film as the flexible substrate layer 1, and adds a nanoscale (5-80 nm) substrate buffer layer 2 made of transparent metal oxide between the flexible substrate layer 1 and the transparent conductive layer 3. The introduction of the substrate buffer layer 2 forms a composite flexible substrate structure. The micron-sized polymer film can meet the support, material strength, and optical performance requirements of the flexible substrate in flexible perovskite solar cells. Simultaneously, this substrate structure possesses good flexibility, allowing it to withstand extreme flexibility conditions such as rolling and crumpling. The substrate buffer layer 2, composed of transparent metal oxide nanoscale (5-80 nm) substrate buffer layer 2, can effectively release / homogenize the surface stress distribution of the flexible substrate layer and reduce surface damage to the flexible substrate layer 1 during the preparation of the upper transparent conductive layer 3. The resulting flexible conductive substrate has the characteristics of low sheet resistance, high uniformity and ultra-transparency, which provides a guarantee for the preparation of high-performance ultrathin flexible perovskite solar cells. At the same time, the substrate buffer layer 2 can increase the connection strength between the flexible substrate layer 1 and the transparent conductive layer 3, making the transparent conductive layer 3 less prone to desorption, thereby improving the mechanical durability and long-term stability of the flexible perovskite solar cell.

[0039] Figure 1In the novel flexible conductive substrate, the flexible substrate layer 1 is a polymer film with a thickness of micrometers. Compared with the flexible substrates with a film thickness of at least hundreds of micrometers in ordinary flexible conductive substrates, the thickness of the flexible substrate layer 1 in this invention can be reduced to 1 / 100 of the thickness of the flexible substrate in ordinary flexible conductive substrates. This achieves a significant improvement in flexibility and weight reduction compared with ordinary flexible conductive substrates, and more fully leverages the advantages of flexible perovskite solar cells in flexible application scenarios. The substrate buffer layer 2 is composed of transparent metal oxide, forming a dense and uniform metal oxide layer on the surface of the flexible substrate layer 1. This can reduce the damage and stress residue on the surface of the underlying flexible substrate layer 1 caused by the transparent conductive layer 3 during the coating process, thereby improving the optoelectronic performance of the flexible conductive substrate. Furthermore, due to the presence of dense oxide, the water and oxygen permeability on one side of the flexible substrate layer 1 is suppressed, which can improve the environmental stability of the flexible battery.

[0040] According to the present invention, the polymer material of the flexible substrate layer 1 should possess advantages such as high transparency, flexibility, high mechanical strength, light weight, and durability, and can be one or a combination of polymers selected from polyimide, polyethylene naphthalate, polyethylene terephthalate, polycarbonate, polydimethylsiloxane, polyetheretherketone, polystyrene, and polyurethane. Specifically:

[0041] 1) Polyethylene terephthalate (PET) has the following characteristics: high light transmittance (>85%), good mechanical flexibility, low cost, easy processing, and good chemical resistance; however, its thermal stability is poor (glass transition temperature T). g (70-80℃), not suitable for high-temperature processes;

[0042] 2) Polyethylene naphthalate (PEN), characterized by high light transmittance (>80%) and superior thermal stability compared to PET (T). g It has good mechanical flexibility (<120℃); however, its cost is slightly higher than PET, making it suitable for flexible perovskite solar cells that require medium-temperature treatment.

[0043] 3) Polyimide (PI), characterized by: high light transmittance (>85%), and extremely high thermal stability (T). g It exhibits good mechanical flexibility and chemical stability (>300℃); however, the material is relatively expensive and is suitable for flexible perovskite solar cells with high-temperature processes.

[0044] 4) Polycarbonate (PC), characterized by high light transmittance (>90%), good mechanical strength and flexibility, and good chemical resistance; however, its thermal stability is generally low (T). g =150℃), suitable for flexible perovskite solar cells with low or medium temperature processes;

[0045] 5) Polydimethylsiloxane (PDMS) has the following characteristics: high light transmittance (>90%), extremely high flexibility and stretchability, and good chemical stability; however, its thin film surface energy is low, and surface treatment is required to improve the deposition of perovskite thin films. It is suitable for ultra-flexible or stretchable perovskite solar cells.

[0046] 6) Polyetheretherketone (PEEK), characterized by high thermal stability (T... g =143℃, melting point about 343℃), good mechanical strength and chemical stability, suitable for flexible perovskite solar cells with high-temperature processes;

[0047] 7) Polystyrene (PS) is characterized by high light transmittance (>90%), low cost, and ease of processing, but its thermal stability is relatively poor (T). g =100℃), suitable for flexible perovskite solar cells with low-temperature processes;

[0048] 8) Polyurethane (PU) has the following characteristics: it has extremely high flexibility and stretchability, high light transmittance, but poor thermal stability, making it suitable for ultra-flexible or stretchable perovskite solar cells.

[0049] The thickness of the flexible substrate layer 1 is 1–100 μm.

[0050] According to the present invention, the transparent metal oxide constituting the substrate buffer layer 2 is preferably tungsten-doped indium oxide (IWO), zinc-doped indium oxide (IZO), aluminum oxide (Al2O3), or tin oxide (SnO). x Nickel oxide (NiO) x ), vanadium pentoxide (V₂O₅), copper oxide (Cu) x One or more of (O).

[0051] According to the present invention, the material of the transparent conductive layer may be selected from at least one of tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), tungsten-doped indium oxide (IWO), and zinc-doped indium oxide (IZO).

[0052] See also Figure 1 The present invention also provides a method for preparing the above-mentioned flexible conductive substrate, comprising the following steps:

[0053] S1. A polymer film is used as a flexible substrate layer 1, and a transparent metal oxide with a thickness of 5-80 nm is deposited on the upper surface of the flexible substrate layer 1 as a substrate buffer layer 2.

[0054] S2. Deposit a transparent conductive layer 3 on the upper surface of the substrate buffer layer 2;

[0055] S3. Perform thermal annealing on the device obtained in step S2, and then cool it to room temperature to obtain a flexible conductive substrate.

[0056] According to the present invention, in step S1, the thickness of the polymer film is 1 to 100 μm, and the material is selected from at least one of polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polycarbonate (PU), polydimethylsiloxane (PDMS), polyether ether ketone (PEEK), polystyrene (PS), and polyurethane (PU).

[0057] According to the present invention, in step S1, the material of the substrate buffer layer 2 is tungsten-doped indium oxide (IWO), zinc-doped indium oxide (IZO), aluminum oxide (Al2O3), or tin oxide (SnO). x Nickel oxide (NiO) x ), vanadium pentoxide (V₂O₅), copper oxide (Cu) x One or more of the following (O) are deposited by wet or dry processes, wherein the wet processes include spin coating, slot coating, blade coating, and screen printing, and the dry processes include thermal evaporation coating, magnetron sputtering coating, reactive plasma sputtering coating, electron beam coating, and atomic layer deposition.

[0058] According to the present invention, in step S2, the transparent conductive layer 3 is made of at least one of tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), tungsten-doped indium oxide (IWO), and zinc-doped indium oxide (IZO), with a thickness of 100-800 nm, and is deposited by a dry process, wherein the dry process is one or more of magnetron sputtering deposition, reactive plasma sputtering deposition, electron beam deposition, atomic layer deposition, and chemical vapor deposition.

[0059] According to the present invention, in step S3, the temperature of the heat annealing treatment is 50 to 400°C and the time is 1 to 100 min.

[0060] See Figure 2 The present invention also provides a flexible perovskite solar cell, comprising:

[0061] A flexible conductive substrate, wherein the flexible conductive substrate is the aforementioned flexible conductive substrate or is prepared by the aforementioned preparation method;

[0062] A first carrier transport layer 4, a perovskite active layer 5, a second carrier transport layer 6, and a counter electrode 7 are sequentially formed on the upper surface of the transparent conductive layer 3.

[0063] Figure 2The flexible perovskite solar cell of the present invention comprises a flexible conductive substrate, a first carrier transport layer 4, a perovskite active layer 5, a second carrier transport layer 6, and a counter electrode 7 sequentially formed on the upper surface of a transparent conductive layer 3; one of the first carrier transport layer 4 and the second carrier transport layer 6 is a hole transport layer, and the other is an electron transport layer; when the first carrier transport layer 4 is a hole transport layer and the second carrier transport layer 6 is an electron transport layer, the preparation method of each layer is as follows:

[0064] (1) Preparation of hole transport layer: A hole transport layer with a thickness of about 10 nm is deposited on the upper surface of the transparent conductive layer 3 by one or more combinations of spin coating, blade coating, slot coating, screen printing, magnetron sputtering, reactive plasma deposition, atomic layer deposition, and chemical vapor deposition. The material is nickel oxide (NiO). x One or more combinations of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), poly(3-hexylthiophene):poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (P3HT) and molybdenum disulfide (MoS2);

[0065] (2) Preparation of perovskite active layer 5: A perovskite precursor film is deposited on the surface of the hole transport layer by one or more of the following methods: spin coating, blade coating, slot coating, screen printing, and thermal evaporation coating. The film is then subjected to solvent extraction treatment (one or more of the following methods: vacuum chamber drying (VCD), air knife blowing, or anti-solvent method). Finally, it is annealed in a heating table or oven at 100-200℃ for 10-30 min to obtain a perovskite film with a thickness of about 1 μm. The perovskite film is one or more of the following: formamidinium perovskite, methylamino perovskite, and cesium perovskite.

[0066] (3) Preparation of the electron transport layer: An electron transport layer is formed on the surface of the perovskite active layer 5 by one or more combinations of spin coating, blade coating, slot coating, screen printing, magnetron sputtering, reactive plasma deposition, atomic layer deposition, and chemical vapor deposition. The material is tin oxide (SnO). x One or more combinations of fullerene (C60), titanium dioxide (TiO2), zinc oxide (ZnO), and fullerene derivatives (PCBM);

[0067] (4) Preparation of electrode 7: An electrode with a thickness of about 100 nanometers is prepared on the upper surface of the electron transport layer by one or more of the following methods: thermal evaporation coating, magnetron sputtering, plasma deposition. The material is gold, silver, copper and transparent electrode ITO, FTO, IWO, IZO or one or more of the following.

[0068] The flexible perovskite solar cell structure fabricated based on the flexible conductive substrate structure provided by this invention has the following advantages:

[0069] 1) High flexibility: Since the thickness of the flexible substrate is in the micrometer range (1 to 100 μm), the overall device thickness can be controlled within 10 μm. Furthermore, since the flexible substrate 1 is a polymer film with high mechanical strength, its tensile strength reaches the level of hundreds of megapascals, which is extremely high among polymers. This significantly improves the flexibility of the battery compared to ordinary flexible battery structures.

[0070] 2) High conductivity transparent substrate: The electrical performance of the flexible conductive substrate of this invention is evaluated by the "nine-point method" sheet resistance test. Its conductivity and uniformity are far superior to ordinary flexible substrates and can reach the level of rigid conductive substrates of the same level.

[0071] 3) High structural strength: The flexible perovskite solar cell prepared based on the flexible conductive substrate structure of the present invention has a tight and firm bond between the flexible substrate layer 1 and the transparent conductive layer 3, exhibiting the characteristic of not being easily desorbed in terms of mechanical impact and photothermal resistance.

[0072] The present invention will be described in detail below with reference to specific embodiments, but this does not limit the present invention.

[0073] The following embodiments involve the following testing methods:

[0074] The sheet resistance and sheet resistance uniformity of the flexible conductive substrate were tested using the "nine-point method," specifically: a 90*90mm... 2 The flexible substrate is uniformly divided into nine regions, C-1 to C-9, both vertically and horizontally, with each sub-region measuring 30*30mm. 2 ,like Figure 3 As shown. By testing the sheet resistance at each point in the test area C-1 to C-9, the 90*90mm diameter can be calculated. 2 Average sheet resistance and sheet resistance uniformity of flexible conductive substrates.

[0075] Average transmission test: The optical transmission characteristics of the flexible conductive substrate are measured using a UV-Vis spectrophotometer. The test wavelength range is set to 380-1000nm. The percentage of optical transmission of the flexible substrate at different wavelengths is measured, and the average transmission of the substrate is calculated by arithmetic average.

[0076] Tensile strength test: Referring to ASTM D882 for characterizing film and sheet materials, the dumbbell-shaped specimen method is used. The effective area width is 10-20 mm and the length is 40 mm. By controlling the tensile speed, the maximum load when the film breaks is recorded. At the same time, the film thickness is measured using a scanning tunneling microscope. The tensile strength can be calculated as: tensile strength = maximum load / (effective area width * film thickness).

[0077] Bending characteristics: Referring to IEC 63202 "Flexible photovoltaic modules - Mechanical strength and bending test standard", the battery photoelectric conversion efficiency is recorded after 2000 bending cycles under dynamic bending conditions and repeated bending at a specific radius of curvature (frequency = 1Hz). As the bending radius of curvature becomes smaller, the battery will begin to show performance degradation at a certain radius of curvature. The minimum radius of curvature at which the efficiency does not decrease is the minimum radius of curvature.

[0078] Film adhesion test: The adhesion of the flexible conductive substrate was tested using a cross-cut test according to ISO 2409-2020 "Paints and varnishes - Cross-cut test".

[0079] A standard solar simulator (AM 1.5G, 100mW / cm²) was used. 2 Perform IV testing on the device and record its open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and PCE; the test steps are as follows:

[0080] 1) Test equipment: A calibrated solar cell IV test system was used, including a Class AAA solar source, a standard reference cell, and a Keithley 2400 precision source meter;

[0081] 2) Test conditions: Light intensity of 100mW / cm² 2 The test environment temperature was controlled at 23℃ to avoid temperature interference with battery performance.

[0082] The weight of flexible perovskite solar cells was determined using a precision balance.

[0083] The materials and reagents used in the following examples are all commercially available products.

[0084] Example 1

[0085] The fabrication of the flexible conductive substrate in this embodiment includes the following steps:

[0086] S1. A 20μm thick polycarbonate film (1cm×1cm, 90% transmittance) is used as a flexible substrate layer 1. An aluminum oxide (Al2O3) layer with a thickness of 5nm is deposited on the upper surface of the flexible substrate layer 1 as a substrate buffer layer 2 by atomic layer deposition.

[0087] S2. A 200 nm thick ITO layer 3 is deposited on the upper surface of the substrate buffer layer 2 using a magnetron sputtering deposition process;

[0088] S3. Place the device obtained in step S2 in a vacuum drying oven and heat-anneal at 400°C for 5 minutes, then cool it to room temperature to obtain a flexible conductive substrate, denoted as A1;

[0089] The flexible perovskite solar cell was fabricated based on the flexible conductive substrate A1, and the steps are as follows:

[0090] (1) Fabrication of the hole transport layer (first carrier transport layer 4): A 10 nm thick layer of nickel oxide (NiO) was deposited on the upper surface of the flexible conductive substrate A1 using reactive plasma deposition. x ) as a hole transport layer;

[0091] (2) Preparation of perovskite active layer 5: A layer of formamidine perovskite precursor film was deposited on the upper surface of the hole transport layer by spin coating. The film was then subjected to solvent extraction treatment (using the anti-solvent method) and finally placed in an oven at 200°C for 10 min to obtain a formamidine perovskite film with a thickness of 1 μm as perovskite active layer 5.

[0092] (3) Fabrication of the electron transport layer (second carrier transport layer 6): A 20 nm thick tin oxide (SnO) layer was formed on the upper surface of the perovskite active layer 5 using magnetron sputtering. x ) as an electron transport layer;

[0093] (4) Preparation of counter electrode 7: A Cu layer with a thickness of 150 nm was prepared on the upper surface of the electron transport layer by thermal evaporation coating method as counter electrode 7, and a flexible perovskite solar cell was obtained, denoted as Z1.

[0094] Example 2

[0095] The fabrication of the flexible conductive substrate in this embodiment includes the following steps:

[0096] S1. A 100μm thick polyimide film (1cm×1cm, 90% transmittance) is used as the flexible substrate layer 1. A 50nm thick tin oxide (SnO) film is spin-coated onto the surface of the flexible substrate layer 1. x ) as substrate buffer layer 2;

[0097] S2. An ITO layer with a thickness of 200 nm is deposited on the upper surface of the substrate buffer layer 2 as a transparent conductive layer 3 using a reactive plasma sputtering deposition process.

[0098] S3. Place the device obtained in step S2 in a vacuum drying oven and heat-anneal at 300°C for 10 min, then cool it to room temperature to obtain a flexible conductive substrate, denoted as A2;

[0099] Flexible perovskite solar cells were fabricated based on flexible conductive substrate A2. The steps were the same as those in Example 1 (1) to (4). The resulting flexible perovskite solar cells were denoted as Z2.

[0100] Example 3

[0101] The fabrication of the flexible conductive substrate in this embodiment includes the following steps:

[0102] S1. A 9 μm thick polyetheretherketone (PEEK) film (1 cm × 1 cm, 90% transmittance) is used as the flexible substrate layer 1. A 5 nm thick tungsten-doped indium oxide (IWO) film is deposited on the surface of the flexible substrate layer 1 using a magnetron sputtering process as the substrate buffer layer 2. Specifically, a high-purity target (99%-99.999%) is used, with a base voltage ≤ 5 × 10⁻⁶. -4 Ar and O2 are introduced into the vacuum chamber of Pa, the substrate temperature is controlled at ≤80℃ (compatible with flexible devices), and ultrathin deposition is achieved by short-time sputtering (3 min) using an RF power supply. After deposition, the film is annealed at 100℃ for 10 min.

[0103] S2. A 200 nm thick ITO layer 3 is deposited on the upper surface of the substrate buffer layer 2 using a magnetron sputtering deposition process;

[0104] S3. Place the device obtained in step S2 in a vacuum drying oven and heat-anneal at 220°C for 3 minutes, then cool it to room temperature to obtain a flexible conductive substrate, denoted as A3;

[0105] Flexible perovskite solar cells were fabricated based on flexible conductive substrate A3. The steps were the same as those in Example 1 (1) to (4). The resulting flexible perovskite solar cells were denoted as Z3.

[0106] Example 4

[0107] The fabrication of the flexible conductive substrate in this embodiment includes the following steps:

[0108] S1. A 100μm thick polyethylene terephthalate (PET) film (1cm×1cm, 90% transmittance) is used as the flexible substrate layer 1. A 5nm thick zinc-doped indium oxide (IZO) layer is deposited on the surface of the flexible substrate layer 1 using a magnetron sputtering process as the substrate buffer layer 2. Specifically, a high-purity target (99%-99.999%) is used, with a base voltage ≤5×10⁻⁶. - 4 Ar and O2 are introduced into the vacuum chamber of Pa, the substrate temperature is controlled at ≤80℃ (compatible with flexible devices), and ultrathin deposition is achieved by short-time sputtering (3 min) using an RF power supply. After deposition, the film is annealed at 100℃ for 10 min.

[0109] S2. A 200 nm thick ITO layer 3 is deposited on the upper surface of the substrate buffer layer 2 using a magnetron sputtering deposition process;

[0110] S3. Place the device obtained in step S2 in a vacuum drying oven and heat-anneal at 200°C for 5 minutes, then cool it to room temperature to obtain a flexible conductive substrate, denoted as A4;

[0111] Flexible perovskite solar cells were fabricated based on flexible conductive substrate A4. The steps were the same as those in Example 1 (1) to (4). The resulting flexible perovskite solar cells were denoted as Z4.

[0112] Example 5

[0113] The fabrication of the flexible conductive substrate in this embodiment includes the following steps:

[0114] S1. A 100μm thick polyethylene terephthalate (PET) film (1cm×1cm, 90% transmittance) is used as the flexible substrate layer 1. An 8nm thick copper oxide (Cu) film is deposited on the surface of the flexible substrate layer 1 using a magnetron sputtering deposition process. x O) serves as the substrate buffer layer 2; specifically, a high-purity target (99%-99.999%) is used, with a base voltage ≤ 5×10 -4 Ar and O2 are introduced into the vacuum chamber of Pa, the substrate temperature is controlled at ≤80℃ (compatible with flexible devices), and ultrathin deposition is achieved by short-time sputtering (3 min) using an RF power supply. After deposition, the film is annealed at 100℃ for 10 min.

[0115] S2. An ITO layer with a thickness of 800 nm is deposited on the upper surface of the substrate buffer layer 2 as a transparent conductive layer 3 using a magnetron sputtering deposition process.

[0116] S3. Place the device obtained in step S2 in a vacuum drying oven and heat-anneal at 200°C for 5 minutes, then cool it to room temperature to obtain a flexible conductive substrate, denoted as A5;

[0117] Flexible perovskite solar cells were fabricated based on flexible conductive substrate A5. The steps were the same as those in Example 1 (1) to (4). The resulting flexible perovskite solar cells were denoted as Z5.

[0118] Example 6

[0119] The fabrication of the flexible conductive substrate in this embodiment includes the following steps:

[0120] S1. A 100 μm thick polyethylene naphthalate (PEN) film (1 cm × 1 cm, 90% transmittance) is used as the flexible substrate layer 1. Tin oxide (SnO) with a thickness of 8 nm is deposited on the surface of the flexible substrate layer 1 using a magnetron sputtering deposition process. x ) as substrate buffer layer 2; specifically: using a high-purity target (99%-99.999%), with a base voltage ≤5×10 -4Ar and O2 are introduced into the vacuum chamber of Pa, the substrate temperature is controlled at ≤80℃ (compatible with flexible devices), and ultrathin deposition is achieved by short-time sputtering (3 min) using an RF power supply. After deposition, the film is annealed at 100℃ for 10 min.

[0121] S2. A tungsten-doped indium oxide (IWO) with a thickness of 800 nm is deposited on the upper surface of the substrate buffer layer 2 as a transparent conductive layer 3 using a magnetron sputtering deposition process;

[0122] S3. Place the device obtained in step S2 in a vacuum drying oven and heat-anneal it at 50°C for 100 min, then cool it to room temperature to obtain a flexible conductive substrate, denoted as A6.

[0123] Flexible perovskite solar cells were fabricated based on flexible conductive substrate A6. The steps were the same as those in Example 1 (1) to (4). The resulting flexible perovskite solar cells were denoted as Z6.

[0124] Example 7

[0125] The fabrication of the flexible conductive substrate in this embodiment includes the following steps:

[0126] S1. A polyethylene terephthalate (PET) film with a thickness of 1 μm (1 cm × 1 cm, light transmittance 90%) is used as a flexible substrate layer 1, and vanadium pentoxide (V2O5) with a thickness of 80 nm is deposited on the upper surface of the flexible substrate layer 1 as a substrate buffer layer 2 using a slot coating process.

[0127] S2. An 800 nm thick FTO layer 3 is deposited on the upper surface of the substrate buffer layer 2 using a magnetron sputtering deposition process;

[0128] S3. Place the device obtained in step S2 in a vacuum drying oven and heat-anneal at 200°C for 5 minutes, then cool it to room temperature to obtain a flexible conductive substrate, denoted as A7;

[0129] Flexible perovskite solar cells were fabricated based on flexible conductive substrate A5, with the same steps as (1) to (4) in Example 1. The resulting flexible perovskite solar cells were denoted as Z7.

[0130] Comparative Example 1

[0131] The fabrication of the flexible conductive substrate in this comparative example includes the following steps:

[0132] 1) A polyethylene terephthalate (PET) film with a thickness of 150 μm (1 cm × 1 cm, light transmittance of 90%) was used as a flexible substrate, and an ITO layer with a thickness of 200 nm was deposited on the surface of the flexible substrate by magnetron sputtering as a transparent conductive layer.

[0133] 2) The device obtained in step S1 is placed in a vacuum drying oven and heat-annealed at 200°C for 5 minutes, and then cooled to room temperature to obtain a flexible conductive substrate, denoted as D1;

[0134] Flexible perovskite solar cells were fabricated based on flexible conductive substrate D1. The steps were the same as those in Example 1 (1) to (4). The resulting flexible perovskite solar cells were denoted as W1.

[0135] Sheet resistance and sheet resistance uniformity tests, average transmission tests, tensile strength tests, bending characteristics, and film adhesion tests were conducted on A1 to A7 and D1. The test results are shown in Table 1.

[0136] Table 1. Performance parameters of flexible conductive substrates A1-A7 and D1

[0137]

[0138] As can be seen from Table 1, compared with the flexible conductive substrate D1 in Comparative Example 1, the flexible conductive substrates A1 to A7 of the present invention have an average sheet resistance reduced by about 4 times, a maximum sheet resistance uniformity improved by about 25 times, a maximum increase of about 16% in incident light transmittance in the ultraviolet-visible band, a maximum mechanical strength improved by 9 times, and a minimum bending radius of 0.1 mm, which is 80 times lower than that of ordinary flexible conductive substrates. Through the cross-cut adhesion test, the flexible conductive substrate A4 in Example 4 of the present invention showed smooth grid edges and no film peeling during the test (see...). Figure 4 (a)) In other embodiments, the adhesion level of the transparent conductive layer 3 in the flexible conductive substrate also reaches ISO 1 level or better; while in Comparative Example 1, the flexible conductive substrate D1 has partial or large-scale peeling of the film layer along the cut edge and some grids are peeled off in whole pieces (see Figure 4 (b) The area that is peeled off accounts for 15% to 35% of the total area, and the adhesion test level is ISO 3.

[0139] A standard solar simulator (AM 1.5G, 100mW / cm²) was used. 2 IV tests were performed on devices Z1 to Z7 and W1. The weight of the flexible perovskite solar cells was measured using a precision balance. The open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), PCE, and mass were recorded as shown in Table 2. The power-to-quality ratio was calculated by integrating the PCE and mass data as shown in Table 2.

[0140] Table 2. Performance Comparison of Devices Z1-Z7 and W1

[0141] Devices Voc(V) Jsc(mA·cm -2 )]]> FF (%) PCE (%) Mass (mg) Work-to-weight ratio (W / kg) Z1 7.96 3.22 69.00 17.68 308 603 Z2 8.02 3.19 73.30 18.76 758 260 Z3 8.04 3.31 63.72 16.95 177 1006 Z4 8.13 3.34 81.84 22.22 1311 178 Z5 8.18 3.35 83.01 22.74 1291 185 Z6 8.11 3.32 80.85 21.77 1256 182 Z7 7.99 3.26 70.61 18.39 171 1128 W1 8.16 3.23 79.26 20.90 1292 170

[0142] As can be seen from Table 2, compared with the flexible perovskite solar cell W1 in Comparative Example 1, the flexible perovskite solar cells Z1 to Z7 of the present invention (including the flexible conductive substrate of the present invention) have higher photoelectric conversion efficiency, while the cell weight is reduced by about 7.5 times, and the power-to-weight ratio reaches 1128 W / kg, which is 6.6 times that of ordinary flexible perovskite solar cells.

[0143] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A flexible conductive substrate, characterized in that, It includes a flexible substrate layer, a substrate buffer layer and a transparent conductive layer stacked from bottom to top; the substrate buffer layer is made of transparent metal oxide and has a thickness of 5 to 80 nm.

2. The flexible conductive substrate according to claim 1, characterized in that, The transparent metal oxide is one or more of the following: tungsten-doped indium oxide, zinc-doped indium oxide, aluminum oxide, tin oxide, nickel oxide, vanadium pentoxide, and copper oxide.

3. The flexible conductive substrate according to claim 1, characterized in that, The flexible substrate is a polymer film, and the material of the polymer film is selected from at least one of polyimide, polyethylene naphthalate, polyethylene terephthalate, polycarbonate, polydimethylsiloxane, polyetheretherketone, polystyrene, and polyurethane. The thickness of the flexible substrate is 1 to 100 μm.

4. The flexible conductive substrate according to claim 1, characterized in that, The thickness of the transparent conductive layer is 100-800 nm, and its material is selected from at least one of tin-doped indium oxide, fluorine-doped tin oxide, tungsten-doped indium oxide, and zinc-doped indium oxide.

5. The method for preparing the flexible conductive substrate according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. A polymer film is used as a flexible substrate layer, and a transparent metal oxide with a thickness of 5-80 nm is deposited on the upper surface of the flexible substrate layer as a substrate buffer layer; S2. A transparent conductive layer is deposited on the upper surface of the substrate buffer layer obtained in step S1; S3. Perform thermal annealing on the device obtained in step S2, and then cool it to room temperature to obtain a flexible conductive substrate.

6. The preparation method according to claim 5, characterized in that, In step S1, the thickness of the polymer film is 1 to 100 μm, and the material is selected from at least one of polyimide, polyethylene naphthalate, polyethylene terephthalate, polycarbonate, polydimethylsiloxane, polyetheretherketone, polystyrene, and polyurethane.

7. The preparation method according to claim 5, characterized in that, In step S1, the substrate buffer layer is made of one or more of the following materials: tungsten-doped indium oxide, zinc-doped indium oxide, aluminum oxide, tin oxide, nickel oxide, vanadium pentoxide, and copper oxide. It is deposited by a wet process or a dry process. The wet process includes spin coating, slot coating, blade coating, and screen printing. The dry process includes thermal evaporation coating, magnetron sputtering coating, reactive plasma sputtering coating, electron beam coating, and atomic layer deposition.

8. The preparation method according to claim 5, characterized in that, In step S2, the transparent conductive layer is made of at least one of tin-doped indium oxide, fluorine-doped tin oxide, tungsten-doped indium oxide, and zinc-doped indium oxide, with a thickness of 100-800 nm. It is deposited by a dry process, which is one or a combination of magnetron sputtering, reactive plasma sputtering, electron beam deposition, atomic layer deposition, and chemical vapor deposition.

9. The preparation method according to claim 5, characterized in that, In step S3, the temperature of the heat annealing treatment is 50-400℃, and the time is 1-100 min.

10. A flexible perovskite solar cell, characterized in that, include: A flexible conductive substrate, wherein the flexible conductive substrate is any one of claims 1 to 4 or is prepared by any one of claims 5 to 9; A first carrier transport layer, a perovskite active layer, a second carrier transport layer, and a counter electrode are sequentially formed on the upper surface of the transparent conductive layer.

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