Composite light intensifying layer of perovskite solar cell and preparation method of composite light intensifying layer

Abstract

The invention discloses a preparation method of a composite brightness enhancement layer of a perovskite solar cell, which is characterized by comprising the following steps: S1, coating the surface of a front plate of a perovskite cell body with a PDMS prepolymer mixture to form a PDMS material layer; s2, directly laying embossed gridding cloth on the surface of the PDMS material layer to serve as a light trapping template; s3, performing lamination treatment on the perovskite cell body laid with the light trapping template, so that the PDMS material layer is cured under the action of the grid structure of the embossed grid cloth and forms a PDMS light trapping structure with a grid concave-convex morphology; s4, the embossed gridding cloth is removed; and S5, depositing an anti-reflection film on the surface of the PDMS light trapping structure, wherein the PDMS light trapping structure and the anti-reflection film are combined to form a composite light enhancement layer. The invention has the advantages that: a composite optical structure of light trapping and reflection reduction is realized by a low-cost process, so that the light trapping capability and the current density of the cell are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of large-area photovoltaic solar cell technology, specifically to a composite brightness enhancement layer for perovskite solar cells and its preparation method. Background Technology

[0002] Perovskite solar cells have become an important development direction for next-generation photovoltaic technology due to their advantages such as low raw material cost, simple fabrication process, and high photoelectric conversion efficiency. After years of research, their laboratory photoelectric conversion efficiency has significantly improved from 3.8% in 2009 to 27.2%, demonstrating enormous industrialization potential.

[0003] However, perovskite solar cells still face some key technological challenges in their commercial application, among which optical loss is one of the key bottlenecks restricting further improvements in their current density and efficiency. Unlike traditional crystalline silicon solar cells, which can form a "textured" structure through surface chemical etching to effectively enhance light-trapping capabilities and extend the optical path of photons within the absorption layer, perovskite solar cells typically use flat float glass as the front panel. Lacking an effective light-trapping structure, this results in high Fresnel reflection losses at the glass-air interface, limiting photon utilization and making it difficult to further improve the short-circuit current density (Jsc).

[0004] To reduce reflection loss, existing technologies often deposit single-layer or multi-layer anti-reflection films (such as SiO2, MgF2, etc.) on the surface of the battery. However, although such simple optical anti-reflection designs can reduce reflectivity within a certain wavelength range, they cannot fundamentally achieve the "light trapping" effect, that is, they cannot significantly extend the effective propagation path of light within the perovskite chip layer, and their effect on improving current density is limited.

[0005] On the other hand, some studies have attempted to construct micro- and nanostructures within the perovskite chip layer itself to enhance light scattering (e.g., by forming periodic structures on the surface of the perovskite film through nanoimprinting). However, this method directly affects the process-sensitive and easily damaged perovskite material, resulting in complex processes, high costs, and the potential introduction of surface defects or interface states, impacting film quality and the long-term stability of the battery. Furthermore, some proposals have suggested directly imprinting light-trapping structures onto the encapsulating film, but this approach may affect the mechanical properties and encapsulation reliability of the encapsulating film itself, and since it is not combined with a high-efficiency antireflection layer system, the optical gain effect is limited.

[0006] Therefore, there is an urgent need to develop a composite optical structure that is compatible with existing perovskite battery packaging technology and can achieve light trapping and anti-reflection through low-cost processes without directly processing the perovskite sensitive functional layer. This would effectively improve the light-harvesting ability and current density of the battery and promote its industrialization. Summary of the Invention

[0007] This invention provides a composite light-enhancing layer for perovskite solar cells and its preparation method, which is mainly applied in the field of large-area photovoltaic solar cell technology and can effectively improve the light-harvesting ability and current density of the cells.

[0008] One technical solution adopted in this invention is: A method for preparing a composite brightness enhancement layer for a perovskite solar cell includes the following steps: S1, coating a PDMS prepolymer mixture onto the surface of the front plate of the perovskite solar cell body to form a PDMS material layer; S2, directly laying an embossed mesh fabric as a light-trapping template on the surface of the PDMS material layer; S3, laminating the perovskite solar cell body 1 with the light-trapping template, so that the PDMS material layer is cured under the action of the mesh structure of the embossed mesh fabric and forms a PDMS light-trapping structure with a mesh concave-convex morphology; S4, removing the embossed mesh fabric; S5, depositing an antireflection film on the surface of the PDMS light-trapping structure, wherein the PDMS light-trapping structure and the antireflection film are combined to form a composite brightness enhancement layer.

[0009] This method utilizes embossed mesh fabric as a template and combines it with lamination to directly replicate a light-trapping structure with optical functions on a PDMS layer, which is then integrated with an anti-reflection film. The process is simple, suitable for large-scale industrial application, and can efficiently and cost-effectively fabricate a composite light-enhancing layer that combines efficient light trapping (light-trapping structure) and low surface reflection (anti-reflection film), thereby synergistically improving the light absorption efficiency and short-circuit current density of perovskite solar cells.

[0010] In step S1, the PDMS prepolymer mixture is coated onto the front panel surface using a slot coating method. This ensures that the PDMS prepolymer mixture is coated onto the front panel surface with a uniform, continuous, and controllable thickness, which is beneficial for the subsequent formation of a PDMS material layer and light-trapping structure with consistent thickness.

[0011] The embossed mesh fabric described in step S2 comprises a periodically arranged array of protrusions or depressions, with lines having a diameter of 100-500 μm. Limiting the mesh structure to a periodic arrangement and a line diameter within the 100-500 μm range allows for precise control of the characteristic dimensions of the replicated PDMS light-trapping structure. This range of protrusions and depressions effectively scatters incident light, extending the optical path within the cell and significantly enhancing the photon-trapping capability of the perovskite active layer.

[0012] In step S3, the lamination temperature is 100℃-125℃, and the lamination time is 18min-25min. Within this temperature range, the PDMS material can be fully and uniformly cured and molded under appropriate pressure, forming a light-trapping structure with good mechanical stability and clear morphology.

[0013] The antireflective coating mentioned in step S5 is a SiO2 film or a MgF2 film. Selecting SiO2 or MgF2, which has a good refractive index match, as the antireflective coating material can form an effective refractive index gradient with the PDMS light-trapping structure and the external air, allowing more light to enter the light-trapping structure and achieving superposition optimization of the light-trapping and antireflection effects.

[0014] In step S5: Suitable and optional film formation technologies are provided for different antireflective film materials. The SiO2 film is formed by roller coating, spraying, or slot coating; the MgF2 film is formed by thermal evaporation or magnetron sputtering.

[0015] The thickness of the SiO2 film is 80nm-150nm, and the thickness of the MgF2 film is 100nm-200nm.

[0016] The mass ratio of PDMS base adhesive to curing agent in the PDMS prepolymer mixture is controlled at (5-15):1, which allows for precise adjustment of the curing speed of PDMS. This ratio range ensures that PDMS has suitable rheological properties and degree of curing during the lamination process, thereby effectively replicating the template structure and forming a light-trapping layer with suitable flexibility and durability.

[0017] In step S1, the thickness of the PDMS material layer is 2000 μm. In step S3, the thickness of the PDMS light-trapping structure is 200 μm.

[0018] This thickness design ensures that the PDMS layer has sufficient structural strength to maintain the light-trapping morphology after compression, while its overall thickness is moderate and will not have a negative impact on the photoelectric performance or mechanical packaging of the battery.

[0019] The composite brightness enhancement layer is prepared using the method for composite brightness enhancement layers in perovskite solar cells.

[0020] Compared to existing technologies, this invention offers the following advantages: 1. Significant optical gain: By forming a light-trapping structure on an independent PDMS layer using mesh imprinting and combining it with a traditional SiO2 / MgF2 antireflection film, a synergistic enhancement effect of light trapping and antireflection is achieved. This significantly reduces surface reflection loss while increasing the photon transmission path within the perovskite chip layer, thereby effectively improving the battery's short-circuit current density (Jsc) and photoelectric conversion efficiency. 2. Economical and efficient fabrication process: Employing room-temperature lamination technology and mesh fabric as a template eliminates the need for expensive equipment and high-temperature treatment. This simplifies the production process, reduces manufacturing costs, and provides excellent process compatibility, making it suitable for large-area, batch fabrication and offering significant industrialization advantages. 3. Balanced structural optimization and reliability: By independently setting the light-trapping structure on the PDMS layer, the direct processing of the perovskite chip layer or encapsulation film in traditional solutions is avoided. This effectively maintains the integrity of the battery's core functional layer and the reliability of the encapsulation, ensuring long-term device stability while achieving optical gain. This solution exhibits good process compatibility with various existing perovskite battery structures (formal / reverse, rigid / flexible). Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of the perovskite solar cell of the present invention. Figure 1 .

[0023] Figure 2 This is a schematic diagram of the perovskite solar cell structure of the present invention. Figure 2 .

[0024] Figure 3 This is a schematic diagram of the light-trapping structure of the present invention, which is an embossed mesh fabric 3.

[0025] Reference numerals: 1-Perovskite cell body, 101-Front panel, 102-Perovskite chip layer, 103-Encapsulation film, 104-Back support layer, 105-Buffer layer, 2-PDMS material layer, 3-Embossed mesh cloth, 4-PDMS light trapping structure, 5-Antireflective coating. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the drawings. The embodiments of the present invention shown in and described with reference to the drawings are merely exemplary, and the present invention is not limited to these embodiments.

[0027] It should also be noted that, in order to avoid obscuring the invention with unnecessary details, only the structures and / or processing steps closely related to the solution according to the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0028] Furthermore, in the description of this invention, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0029] Example 1 like Figure 1-3 As shown, this embodiment provides a method for fabricating a perovskite solar cell, specifically including the following steps: Step 1: Coat the surface of the front plate 101 of the perovskite body 1 that has been stacked and is to be encapsulated with a PDMS prepolymer mixture; Prepare a perovskite battery body 1 with all internal functional layers (including buffer layer 105, back support layer 104, encapsulating film 103, perovskite chip layer 102, and front panel 101) already laminated and awaiting final encapsulation lamination. Clean and dry the surface of its front panel 101 (typically FTO / ITO conductive glass or a flexible substrate). Prepare the PDMS prepolymer mixture: In this embodiment, weigh the PDMS base adhesive and curing agent (e.g., tetramethyldisiloxane, tetraoxotetracyclothione disulfide, thioketone ester, methyltrichlorosilane, etc.) at a mass ratio of 10:1 (in other embodiments, the ratio of base adhesive to curing agent in the PDMS prepolymer mixture can be adjusted within the range of 5:1 to 15:1), and mix thoroughly in a container to form the PDMS prepolymer mixture.

[0030] In this embodiment, the perovskite battery body 1 structure includes, from top to bottom, a transparent conductive substrate (front plate 101), a perovskite chip layer 102, an encapsulating film 103, and a back support layer 104 made of tempered glass. A buffer layer 105, such as butyl rubber, is filled at both ends of the perovskite chip layer 102 and the encapsulating film 103 and between the front plate 101 and the back support layer 104 for interlayer bonding and buffering.

[0031] A slot coating process (suitable for large-area production) is used to uniformly coat the degassed PDMS prepolymer mixture onto the front glass surface of the perovskite solar cell module, forming a uniformly thick wet film (500-5000 μm thick, preferably greater than the thickness of the embossed mesh fabric 3). By precisely adjusting the slot coating process parameters—such as setting the coating gap to 200 micrometers, controlling the coating head movement speed to 30 mm / s, and setting the liquid injection rate to 180 μL / s—a uniformly thick wet film, i.e., PDMS material layer 2, can be obtained. Based on this parameter combination, the theoretical thickness of the wet film is approximately 2000 μm. After the curing and cross-linking reaction in the subsequent lamination step three, the solvent evaporates and a solid encapsulation layer is formed, and the final target thickness of the dry film will shrink to about 200 μm (the thickness of the PDMS light-trapping structure 4). PDMS has good light transmittance, flexibility, and curability, making it an ideal material substrate as an independent optical functional layer.

[0032] Step 2: Lay embossed mesh fabric 3 directly on the surface of PDMS material layer 2 as a light trapping template: Preparing the light-trapping template: In this embodiment, embossed mesh fabric 3 is selected as the light-trapping template. The surface of the embossed mesh fabric 3 has a regular grid-like uneven structure formed by the interlacing of warp and weft threads (see...). Figure 3 The diameter of the lines is 100-500µm. It can replicate an ideal pyramid-shaped light-trapping structure. Specifically, to achieve the maximum pyramid structure after lamination, theoretically, the ratio of warp and weft dimensions should be maximized. However, this weakens the structural strength of the mesh fabric and affects its lifespan. Furthermore, overly sharp protrusions can easily cause breakage or discontinuity in the light-trapping structure of the PDMS material layer 2 after lamination, thus reducing the light-trapping effect. Therefore, for a PDMS light-trapping structure 4 with a target thickness of 200µm, the warp and weft thickness of the embossed mesh fabric are designed to match: when matching the PDMS material layer 2, the optimal size is a mesh size with a line diameter of 100-500µm, forming a uniformly distributed pyramid-like structure. Its shape, period, and size are designed (e.g., matching the line diameter with the PDMS thickness) to achieve the optimal light-trapping effect while ensuring structural stability and template lifespan.

[0033] The embossed mesh fabric 3 is carefully laid on the PDMS material layer 2 in step two, ensuring that the uneven surface of the mesh fabric is in full contact with the PDMS film and that it is laid flat without large wrinkles or air bubbles. Using the embossed mesh fabric 3 as a template is cost-effective and efficient.

[0034] Step 3: The perovskite solar cell body 1 with the light-trapping template is laminated, so that the PDMS material layer 2 is cured under the action of the grid structure of the embossed mesh cloth 3 and forms a PDMS light-trapping structure 4 with a grid concave-convex morphology. During the aforementioned PDMS coating process using a slot coating technique, the perovskite solar cell with the embossed mesh fabric 3 laid on it is fed into a laminator for lamination and encapsulation. The lamination temperature and time control parameters for the encapsulant film are the same as the curing parameters for PMDS.

[0035] In this embodiment, when the thickness of the cured PDMS (i.e., the PDMS light-trapping structure 4) is 200µm, the thickness of the embossed mesh 3 is directly between 100-500µm. When the thickness of the embossed mesh is lower than the thickness of the PDMS light-trapping structure 4, the depth of imprinting into the PDMS light-trapping structure 4 is the thickness of the embossed mesh 3. When the thickness of the embossed mesh is higher than the thickness of the PDMS light-trapping structure 4, the excess PDMS will be pressed out during the imprinting process in the aforementioned steps, and the depth of imprinting into the PDMS light-trapping structure 4 is 200µm.

[0036] The lamination process parameters are set as follows: heating plate temperature 100-125°C, lamination time 18-25 minutes (including preheating, pressure reduction, and other auxiliary parts). The specific process involves first preheating at 100-125°C for 400-600 seconds to ensure uniform heating of the PDMS prepolymer mixture and enhance its fluidity; then reducing the chamber pressure to 80 kPa and maintaining it for 20-100 seconds to fully eliminate air bubbles between the PDMS layer and the template; next, adjusting the pressure to -60 kPa (evacuating air from the chamber until the internal pressure is 60 kPa lower than the external (atmospheric) pressure) and maintaining it for 20- For 100 seconds, while continuing to vent, the PDMS is initially bonded to the template. Finally, the pressure is adjusted to -20 kPa (air is drawn from the chamber until the pressure inside is 20 kPa lower than the pressure outside (atmosphere)) and maintained for 500-1000 seconds. During this stage, the main lamination pressure is applied to allow the PDMS to fully cure while maintaining its structural shape. At the same time, the embossed mesh fabric 3 is imprinted and transferred to the surface of the cured PDMS material layer 2 under the action of heat and pressure, thereby forming a PDMS light-trapping structure 4 with a mesh-like convex and concave morphology that complements the mesh fabric structure.

[0037] This embodiment utilizes embossed mesh fabric as a template and combines it with lamination to directly replicate a light-trapping structure with optical functions on a PDMS material layer, which is then integrated with an anti-reflection film. The process is simple, suitable for large-scale industrial application, and can efficiently and cost-effectively prepare a composite light-enhancing layer that combines high-efficiency light trapping (light-trapping structure) and low surface reflection (anti-reflection film), thereby synergistically improving the light absorption efficiency and short-circuit current density of perovskite solar cells.

[0038] Step 4: Remove the embossed mesh fabric 3; After lamination, once the component temperature has dropped to a safe range (typically below 50°C), the upper embossed mesh fabric 3 (made of fluoroplastic coated fiberglass cloth, non-adhesive) is carefully peeled off and removed from the surface of the cured PDMS material layer 2. At this point, the PDMS material layer 2 is firmly bonded to the surface of the front panel 101 of the battery, exhibiting a clear mesh-like light-trapping structure.

[0039] Step 5: Deposit an antireflection film 5 on the surface of the PDMS light-trapping structure 4 to form a composite light-enhancing layer combining the PDMS light-trapping structure 4 and the antireflection film 5. An antireflective film 5 is further deposited on the surface of the formed PDMS light-trapping structure 4. In this embodiment, SiO2 can be used as the antireflective film 5 material. This embodiment employs a roll coating process; in other embodiments, spraying or slot coating can also be used to uniformly coat the SiO2 sol onto the surface of the PDMS light-trapping structure 4. Subsequently, heat treatment is performed at 100-125°C to solidify the sol and form a dense SiO2 film. By controlling the sol concentration and coating parameters, the thickness of the SiO2 film is controlled to approximately 80-150 nm, which provides good antireflective performance in the visible light range. Alternatively, MgF2 can be used as the antireflective film 5 material. In this embodiment, a thermal evaporation process is used (in other embodiments, the MgF2 film can also be obtained using magnetron sputtering). In a high vacuum environment, the MgF2 raw material is heated and evaporated, causing its vapor to deposit onto the surface of the PDMS light-trapping structure 4, forming a uniform MgF2 film. By controlling the evaporation time, the thickness of the MgF2 film is controlled to approximately 100-200 nm.

[0040] Thus, a composite light-enhancing layer consisting of a "PDMS light-trapping structure 4" and a "SiO2 film" or a "MgF2 film" has been successfully prepared on the surface of the front plate 101 of the perovskite solar cell body 1.

[0041] This article uses specific examples to illustrate the structure and working principle of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a composite brightness enhancement layer for a perovskite solar cell, characterized in that, Includes the following steps: S1. A PDMS prepolymer mixture is coated on the surface of the front plate (101) of the perovskite cell body (1) to form a PDMS material layer (2). S2. Embossed mesh fabric (3) is directly laid on the surface of the PDMS material layer (2) as a light trapping template; S3. The perovskite battery body (1) on which the light-trapping template is laid is laminated, so that the PDMS material layer (2) is cured under the action of the grid structure of the embossed mesh (3) and forms a PDMS light-trapping structure (4) with a grid concave-convex morphology. S4. Remove the embossed mesh fabric (3); S5. An antireflection film (5) is deposited on the surface of the PDMS light-trapping structure (4), and the PDMS light-trapping structure (4) and the antireflection film (5) are combined to form a composite light-enhancing layer.

2. The method for preparing the composite brightness enhancement layer of the perovskite solar cell according to claim 1, characterized in that, In step S1, the PDMS prepolymer mixture is coated onto the surface of the front panel (101) using a slot coating method.

3. The method for preparing the composite brightness enhancement layer of the perovskite solar cell according to claim 1, characterized in that, The embossed mesh fabric (3) in step S2 has a mesh structure including periodically arranged raised or recessed structures, and the diameter of the warp and / or weft of the embossed mesh fabric (3) is 100-500 μm.

4. The method for preparing the composite brightness enhancement layer of the perovskite solar cell according to claim 1, characterized in that, In step S3, the lamination temperature is 100℃-125℃ and the lamination time is 18min-25min.

5. The method for preparing the composite brightness enhancement layer of the perovskite solar cell according to claim 1, characterized in that, The antireflection film (5) mentioned in step S5 is a SiO2 film or a MgF2 film.

6. The method for preparing the composite brightness enhancement layer of the perovskite solar cell according to claim 5, characterized in that, In step S5: the SiO2 film is formed by roller coating, spraying or slot coating; the MgF2 film is formed by thermal evaporation or magnetron sputtering.

7. The method for preparing the composite brightness enhancement layer of the perovskite solar cell according to claim 5, characterized in that, The thickness of the SiO2 film is 80nm-150nm; the thickness of the MgF2 film is 100nm-200nm.

8. The method for preparing the composite brightness enhancement layer of the perovskite solar cell according to claim 1, characterized in that, The mass ratio of PDMS base adhesive to curing agent in the PDMS prepolymer mixture is (5-15):

1.

9. The method for preparing the composite brightness enhancement layer of the perovskite solar cell according to claim 1, characterized in that, In S1, the thickness of the PDMS material layer (2) is 2000 μm, and in S3, the thickness of the PDMS light-trapping structure (4) is 200 μm.

10. A composite brightness enhancement layer for a perovskite solar cell, characterized in that, The composite brightening layer is prepared using the method described in any one of claims 1-9.

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