Method for recycling metal electrode of perovskite solar cell by solution intercalation method

Abstract

The application relates to the technical field of perovskite solar cells, in particular to a method for recycling metal electrodes of perovskite solar cells by a solution intercalation method, which comprises the following steps: step 1, soaking the perovskite solar cell in a perovskite precursor solvent to separate the metal electrode film from the conductive substrate; step 2, taking out the conductive substrate from the soaking solution; step 3, using a filter screen to fish out the metal electrode film from the soaking solution and transferring the metal electrode film into anhydrous ethanol solution for soaking; step 4, transferring the anhydrous ethanol solution containing the metal electrode film into a centrifugal tube, and performing centrifugal treatment to realize solid-liquid separation; and step 5, after the centrifugal treatment is completed, taking out the metal electrode film and drying the metal electrode film to complete the recycling of the metal electrode. The metal electrode film is separated and recycled from the conductive substrate by the solution intercalation effect, instead of directly dissolving the metal electrode itself, so that the main body integrity and surface quality of the metal electrode film can be maintained, and the recycling value of the metal electrode film can be improved.

Description

Technical Field

[0001] This application relates to the field of perovskite solar cell technology, specifically to a method for recovering metal electrodes of perovskite solar cells using a solution intercalation method. Background Technology

[0002] Perovskite solar cells, as a new generation of thin-film photovoltaic devices, have seen rapid development in recent years due to their advantages such as high light absorption coefficient, long carrier diffusion length, tunable bandgap, and relatively simple fabrication process. Their photoelectric conversion efficiency has continued to improve, demonstrating promising application prospects. A typical perovskite solar cell usually consists of a layered structure including a conductive substrate, an electron transport layer or hole transport layer, a perovskite absorber layer, a hole transport layer or electron transport layer, and metal electrodes. The conductive substrate is generally ITO conductive glass, FTO conductive glass, or a flexible transparent conductive substrate. The metal electrodes are usually located on the outermost side of the device and are often formed by depositing metal materials such as gold and silver through vacuum evaporation to achieve efficient collection and transport of charge carriers.

[0003] In existing technologies, precious metals such as gold and silver are often used as back electrodes for perovskite solar cells due to their high conductivity, suitable work function, and good chemical stability. On the one hand, precious metal electrodes facilitate better electrical contact with the transport layer, reducing interfacial energy loss and improving device performance. On the other hand, the dense and uniform metal electrode film formed by vacuum evaporation plays a positive role in improving device efficiency and stability. However, precious metal materials are expensive. If a large number of devices are discarded due to substandard performance, aging failure, or process screening during laboratory research and large-scale manufacturing, it will result in significant waste of metal electrode materials and further increase the manufacturing cost of perovskite solar cells.

[0004] Existing methods for recycling metal electrodes from waste perovskite solar cells mainly involve mechanical stripping, crushing followed by purification, or chemical treatment. Mechanical stripping often relies on external force, which can easily lead to breakage of the metal electrode film, resulting in poor recovery integrity. While crushing followed by purification can achieve a certain degree of metal recovery, it typically involves complex processes, difficult separation and purification, and demanding equipment, hindering its widespread application in laboratory settings or under low-cost conditions. Especially for multilayer, stacked thin-film devices like perovskite solar cells, the metal electrodes are tightly bonded to the underlying functional layers and conductive substrate. Achieving effective separation and recycling of the metal electrode film without significantly increasing process complexity remains a key technical challenge in this field. Summary of the Invention

[0005] To address the above problems, this invention provides a method for recovering metal electrodes from perovskite solar cells using a solution intercalation method, comprising the following steps: Step 1: Immerse the perovskite solar cell in the perovskite precursor solvent to separate the metal electrode film from the conductive substrate. Step 2: Remove the conductive substrate from the immersion solution; Step 3: Use a filter to remove the metal electrode film from the soaking solution and transfer it to anhydrous ethanol solution for soaking; Step 4: Transfer the anhydrous ethanol solution containing the metal electrode film to a centrifuge tube and centrifuge it to achieve solid-liquid separation. Step 5: After centrifugation, remove the metal electrode film and dry it to complete the metal electrode recovery.

[0006] This invention utilizes the strong dissolving, penetrating, and interface-weakening properties of perovskite precursor solvents on the perovskite absorber layer and its adjacent functional layers. The solvent gradually inserts itself into the interlayer interface, edge defects, and micropores of the perovskite solar cell between the metal electrode film and the underlying structure, thereby dissolving or relaxing the intermediate residual layer, reducing the adhesion between the metal electrode film and the conductive substrate, and ultimately achieving separation. Subsequently, residual precursor solvent and impurities are removed by immersion in anhydrous ethanol, and the metal electrode film is recovered by centrifugation and drying. This invention employs a solution intercalation method, where the precursor solvent penetrates into the interlayer interface, promoting interface separation through solvent action. Compared to mechanical stripping or complex purification methods, this invention offers advantages such as simple operation, mild process, low equipment requirements, low cost, minimal damage to the metal electrode film, high recovery purity, and ease of subsequent recycling, making it particularly suitable for the recovery and reuse of gold, silver, and other metal electrodes in perovskite solar cells.

[0007] Furthermore, in step 4, centrifugation is performed at room temperature for 5 minutes at a speed of 8000 rpm.

[0008] Furthermore, after step 2 and before step 3, the process includes retrieving the detached metal electrode film from the soaking solution and transferring it to a clean precursor solvent for a second soaking. This utilizes the new precursor solvent to continue dissolving and removing perovskite residues, transport layer residues, and other impurities adhering to the surface of the metal electrode film, avoiding the impact of increased concentration of dissolved components in the original soaking solution on the cleaning effect, thereby improving the cleaning efficiency of the electrode film surface. Simultaneously, the second soaking also helps to further weaken the adhesion between residual interfacial substances and the metal electrode film, resulting in a cleaner and purer surface of the recovered metal electrode film, which is more conducive to subsequent ethanol washing, centrifugation, and recycling.

[0009] Furthermore, in step 5, a vacuum drying oven is used to dry the metal electrode film. This is beneficial for removing residual anhydrous ethanol and trace solvents from the surface and interior of the metal electrode film in a low oxygen and low moisture environment, thereby improving drying efficiency and uniformity. At the same time, the vacuum environment can reduce oxidation, contamination, or changes in surface condition caused by contact between the metal electrode film and oxygen and moisture in the air during the drying process. This is especially beneficial for maintaining the surface cleanliness and recycling quality of metal electrodes such as silver and copper, and helps to achieve more stable subsequent processing and recycling results.

[0010] Furthermore, after step 5, the recovered metal electrode film is further processed into solid particles or block solids by sintering or direct melting. This transforms the recovered sheet-like or fragmented metal electrodes into reusable raw materials with more regular shapes, making storage and transportation easier. This reduces the problems of easy curling, breakage, and inconvenience in handling the film. At the same time, the processed solid particles or block solids are more conducive to subsequent use as raw materials for vapor deposition in vacuum evaporation equipment, improving the compatibility between the recovered metal electrodes and subsequent preparation processes, thereby enhancing the practicality and recycling value of the recovery method of this invention.

[0011] Furthermore, the metal electrode film is made of silver, and the perovskite precursor solvent is dimethyl sulfoxide (DMSO). As a commonly used perovskite precursor solvent, DMSO has strong dissolving and penetrating capabilities for the perovskite absorber layer and its related residual layers. It can effectively weaken the interfacial bonding between the silver electrode film and the underlying structure, thereby promoting the separation of the silver electrode film from the conductive substrate. Simultaneously, the silver electrode itself is not easily dissolved directly by DMSO. Therefore, while achieving interfacial intercalation separation, it helps maintain the integrity of the main structure of the silver electrode film, thereby improving recovery efficiency, recovery purity, and subsequent recycling value.

[0012] Furthermore, the metal electrode film is made of gold, and the perovskite precursor solvent is N,N-dimethylformamide (DMF). N,N-dimethylformamide has good dissolving and penetrating effects on the perovskite absorber layer and related interfacial residual layers. It can gradually insert along the interlayer interface and weaken the adhesion between the gold electrode film and the underlying structure, thereby promoting the separation of the gold electrode film from the conductive substrate. Simultaneously, gold itself has high chemical stability and does not readily react significantly with N,N-dimethylformamide, which helps maintain the integrity and surface quality of the gold electrode film while achieving interfacial separation, thus improving the stability of the recovery process, the recovery purity, and the subsequent recycling efficiency.

[0013] Furthermore, prior to step 1, spaced micropores are pre-formed in the edge region of the perovskite solar cell. This allows for the pre-construction of multiple channels at the device edge for the perovskite precursor solvent to penetrate, preventing the solvent from relying solely on natural edges or random defects to enter the interlayer interface. This shortens the path for solvent diffusion and intercalation between the metal electrode film and the underlying structure. Simultaneously, the micropores can serve as local stress release points and peeling initiation points, promoting the dissolution of residual interfacial layers, weakening the bond between the metal electrode film and the conductive substrate, and accelerating their separation. Moreover, placing the micropores in the edge region and using a spaced distribution method can improve penetration efficiency while minimizing the impact on the integrity of the metal electrode film, thereby improving recovery efficiency and quality.

[0014] Furthermore, before step 1, a pre-stress is applied to the perovskite solar cell and then released. This allows the layered structure of the perovskite solar cell to exhibit different deformation recovery during the compression and rebound process, thereby forming or expanding microcracks, micropores, and local debonding regions between the metal electrode film and the underlying functional layer and conductive substrate. In this way, the subsequent perovskite precursor solvent can more easily penetrate into the interlayer interface along the aforementioned loose areas and play an intercalation role, thereby accelerating the dissolution of the residual interfacial layer, weakening the adhesion between the metal electrode film and the conductive substrate, and promoting their separation. At the same time, this pretreatment method can also improve the efficiency of the solvent immersion process and the stability of the recovery process without significantly increasing the process complexity.

[0015] Furthermore, in step 1, an alternating magnetic field is applied to the perovskite solar cell immersed in the perovskite precursor solvent. This induces a current in the metal electrode film and generates moderate heat, thereby increasing the local temperature in the region near the electrode and enhancing the dissolution, penetration, and intercalation effects of the perovskite precursor solvent on the perovskite residual layer and interface materials. Simultaneously, the localized heating accelerates the mass transfer process at the interface and further weakens the bonding strength between different material layers due to differences in thermal response, facilitating faster separation of the metal electrode film from the conductive substrate. Therefore, this measure can improve the immersion stripping efficiency to a certain extent, shorten the recovery time, and contribute to enhancing the implementation effect of the solution intercalation recovery method of this invention.

[0016] The beneficial effects of this invention are: (1) This invention achieves the separation and recycling of metal electrode films and conductive substrates in perovskite solar cells through solution intercalation. The target of the action is mainly the perovskite layer and the interface residue layer, rather than directly dissolving the metal electrode itself. Therefore, it is beneficial to maintain the integrity and surface quality of the metal electrode film and improve the reuse value after recycling.

[0017] (2) The present invention uses perovskite precursor solvent, anhydrous ethanol, centrifugation and drying to complete the recovery of metal electrodes, avoiding the large-scale use of highly corrosive reagents or complex purification systems. The additional pollution generated during the process is small, the composition of the waste liquid is relatively clear, and the subsequent treatment is more convenient, thus having good environmental friendliness.

[0018] (3) The present invention mainly relies on the penetration, intercalation and dissolution of the perovskite layer and the interface residual layer by the solvent to achieve electrode separation. The overall reaction conditions are relatively mild, and there is no need for high temperature decomposition, strong mechanical stripping or violent chemical reaction, which helps to reduce the damage to the metal electrode film structure and improve the stability and controllability of the recycling process.

[0019] (4) The process flow of the present invention is simple and clear. The main equipment required is conventional equipment such as soaking container, filter screen, centrifuge tube and vacuum drying oven. The equipment requirements are low and the operation is convenient. It is suitable for the recycling of metal electrodes of laboratory waste perovskite solar cells and has the potential to be promoted and applied to large-size devices and large-scale recycling scenarios.

[0020] Based on the above beneficial effects, this invention has good application prospects in the field of perovskite solar cell technology. Attached Figure Description

[0021] Figure 1 Photograph of a perovskite solar cell with a rigid ITO conductive glass substrate and silver as the electrode.

[0022] Figure 2 Photograph of a perovskite solar cell after being soaked in a perovskite precursor solvent.

[0023] Figure 3 Photograph of a thin film of a metal electrode immersed in anhydrous ethanol.

[0024] Figure 4 This is a photograph of the dried metal electrode film. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments. Example 1

[0026] This embodiment provides a method for recovering metal electrodes from perovskite solar cells using a solution intercalation method. In this embodiment, the perovskite solar cell uses rigid ITO conductive glass as the conductive substrate, and the metal electrode film uses a silver electrode film (e.g., Figure 1 (As shown), the perovskite precursor solvent uses DMSO. The specific steps include: Step 1: Immerse the perovskite solar cell in a perovskite precursor solvent to separate the metal electrode film from the conductive substrate. Select a discarded perovskite solar cell sample, preferably one stored in a dry, light-protected environment with no obvious corrosion on the silver electrode surface. Use a suitable-sized petri dish or beaker, add an appropriate amount of dimethyl sulfoxide (DMSO) solvent, and then use tweezers to completely immerse the perovskite solar cell in DMSO. Immerse the cell in a fume hood. As immersion proceeds, DMSO gradually penetrates along the interlayer interfaces, edges, and micro-defects, dissolving and intercalating the perovskite absorber layer and related interface residues, causing the device color to gradually fade. With continued immersion, the bond between the silver electrode film and the underlying structure is weakened, eventually separating from the ITO conductive glass substrate. To accelerate the separation process, the cell can be gently agitated with tweezers during immersion, but violent mechanical disturbance should be avoided to prevent damage to the silver electrode film. Figure 2 As shown, after immersion, the perovskite layer and related functional layers are significantly reduced, leaving only the transparent conductive substrate and the silver electrode film that has separated or is about to separate.

[0027] It should be noted that when DMSO comes into contact with perovskite materials, the primary interaction is through the lone pair electrons of the oxygen atoms in its molecules and the Pb in the perovskite materials. 2+ Coordination occurs, forming lead halide-DMSO coordination intermediates or solvation complexes. Simultaneously, DMSO exhibits strong solvation and penetration effects on the perovskite layer and its interfacial residual layers, gradually relaxing, deconstructing, and dissolving the original perovskite lattice, thereby weakening the interfacial bonding between the metal electrode film and the underlying functional layer and conductive substrate. Due to the effects of DMSO on Pb... 2+ It has a strong coordination ability, and its interaction with perovskite materials usually involves a process of coordination, intercalation, solvation and deconstruction. This is also an important basis for the present invention to use precursor solvents to achieve interfacial separation and recover metal electrode films.

[0028] Step 2: Remove the conductive substrate from the immersion solution: After the silver electrode film has fully separated from the ITO conductive glass substrate, use tweezers to remove the ITO conductive glass substrate from the immersion solution. The surface of the removed conductive substrate is essentially free of continuous silver electrode coverage, indicating separation from the silver electrode film in the immersion solution.

[0029] Step 3: Use a filter to remove the metal electrode film from the soaking solution and transfer it to anhydrous ethanol solution for further immersion: Use a filter to remove the peeled silver electrode film from the soaking solution and promptly transfer it to anhydrous ethanol solution for immersion. Preferably, the anhydrous ethanol can be replaced multiple times to remove residual DMSO and other soluble impurities from the surface of the silver electrode film. Figure 3 As shown, the silver electrode film is dispersed in anhydrous ethanol in a sheet-like state.

[0030] In some embodiments, after step 2 and before step 3, the silver electrode film peeled off from the soaking solution can be taken out and transferred to clean DMSO for a second soaking to further remove residual perovskite material and interface impurities on the electrode surface, and then transferred to anhydrous ethanol for soaking.

[0031] Step 4: Transfer the anhydrous ethanol solution containing the metal electrode film to a centrifuge tube for centrifugation to achieve solid-liquid separation: Transfer the final anhydrous ethanol solution used to soak the silver electrode film to a centrifuge tube and centrifuge at room temperature. Preferably, the centrifugation time is 5 minutes and the centrifugation speed is 8000 rpm. After centrifugation, the silver electrode film settles to the bottom of the centrifuge tube, thus achieving solid-liquid separation.

[0032] Step 5: After centrifugation, remove the metal electrode film and dry it to complete the metal electrode recovery. After centrifugation, use a pipette to remove the liquid from the top of the centrifuge tube, retaining the silver electrode film that has settled at the bottom. Then, dry the silver electrode film, preferably using a vacuum drying oven. Specifically, the container containing the silver electrode film can be properly sealed and placed in a vacuum drying oven at 70°C for 12 hours to thoroughly remove residual ethanol and trace amounts of solvent, obtaining the dried silver electrode film. Figure 4 As shown, the silver electrode film obtained after drying can be used as a recycling product.

[0033] In this embodiment, the recovered silver electrode film has good integrity and purity. It can be further processed into solid particles or block solids by sintering or direct melting as needed, so as to be further recycled as raw material for vapor deposition. Example 2

[0034] Based on Example 1, the material of the metal electrode film is gold, and the solvent of the perovskite precursor is DMF. In step 1, the perovskite solar cell with the gold electrode film is immersed in the DMF solution to separate the gold electrode film from the conductive substrate; then, the conductive substrate is removed, the gold electrode film is transferred to anhydrous ethanol for immersion, centrifugation, and drying are performed in the same manner as in Example 1, and finally the gold electrode film is recovered. Example 3

[0035] Based on Example 1 or Example 2, before step 1, the edge region of the perovskite solar cell is pre-drilled to pre-form spaced micropores. Specifically, the perovskite solar cell to be processed is laid flat and fixed, and multiple micropores are formed along the edge region of the cell using laser drilling. The micropores are circular, with a diameter of 50–200 μm, and the center-to-center distance between adjacent micropores is 0.5–2 mm. The distance from the center of the micropore to the edge of the perovskite solar cell is 0.2–1 mm. Preferably, the micropores are arranged in a single row with spacing along the periphery of the perovskite solar cell; for larger perovskite solar cells, double rows of staggered micropores can also be set in adjacent edge regions, with a row spacing of 0.3–1 mm between the two rows. During laser drilling, the drilling depth is controlled to penetrate the metal electrode film and the underlying local functional layer, while avoiding large-area cracking of the conductive substrate. After forming micropores, the perovskite solar cell is immersed in a perovskite precursor solvent, which allows the precursor solvent to penetrate into the interlayer interface more quickly along the micropores, thereby promoting the separation of the metal electrode film from the conductive substrate; the subsequent steps are the same as in Example 1. Example 4

[0036] Based on Examples 1-3, before step 1, a pre-pressure is applied to the perovskite solar cell and then released. Specifically, the perovskite solar cell to be treated is placed on a flat support platform, and a flat pressure head is used to apply a pre-pressure of 0.05–1 MPa in a direction perpendicular to the cell surface; the holding time is 1–60 s. After the holding time is completed, the pre-pressure is released, causing microcracks, micropores, and local debonding areas to form or expand at the interlayer interface during the rebound process of the perovskite solar cell. Subsequently, the perovskite solar cell after pre-pressure treatment is immersed in a perovskite precursor solvent to promote the penetration of the precursor solvent along the aforementioned loose interface and accelerate the separation of the metal electrode film from the conductive substrate; subsequent steps are the same as in Example 1. Example 5

[0037] Based on Example 4, in step 1, an alternating magnetic field is applied to the perovskite solar cell immersed in the perovskite precursor solvent. Specifically, a non-metallic container holding the perovskite precursor solvent and the perovskite solar cell is placed within the effective area of ​​the alternating magnetic field generator, allowing the alternating magnetic field to pass through the perovskite solar cell immersed in the perovskite precursor solvent; the magnetic induction intensity of the alternating magnetic field is 1–100 mT, the frequency of the alternating magnetic field is 50 Hz–500 kHz, and the duration of the alternating magnetic field is 10 s–30 min. Preferably, during the application of the alternating magnetic field, the temperature of the immersion system is controlled at 20–60 °C to avoid excessive temperature rise that could cause the metal electrode film to curl or break. By applying the alternating magnetic field, an induced current is generated in the metal electrode film, causing moderate heating, thereby promoting the penetration and intercalation of the perovskite precursor solvent into the interface residual layer and accelerating the separation of the metal electrode film from the conductive substrate; subsequent steps are the same as in Example 1. Example 6

[0038] Based on Example 5, in step 1, bending stress is applied to the perovskite solar cell immersed in the perovskite precursor solvent, causing the layered structure of the perovskite solar cell to produce differences in tensile and compressive deformation during bending. This results in the formation or expansion of microcracks, micropores, and local debonding regions between the metal electrode film and the underlying functional layer and conductive substrate. This facilitates the further penetration of the perovskite precursor solvent along the aforementioned loose interface and its intercalation effect, promotes the dissolution of the interface residual layer, weakens the adhesion between the metal electrode film and the conductive substrate, and thus accelerates their separation.

[0039] In summary, this invention provides a solution intercalation method for recovering metal electrodes from perovskite solar cells. By immersing waste perovskite solar cells in a perovskite precursor solvent, the solvent's penetration, intercalation, and dissolution of the perovskite layer and interfacial residue weaken the bond between the metal electrode film and the conductive substrate, achieving separation. The metal electrode is then recovered through anhydrous ethanol immersion, centrifugation, and drying. If necessary, further improvements in recovery efficiency can be achieved through secondary immersion, vacuum drying, sintering or melting, edge pre-drilling, pre-pressure release, and alternating magnetic field assistance. This invention does not directly dissolve the metal electrodes but achieves separation and recovery while preserving the integrity of the electrode film as much as possible. It offers advantages such as a mild process, low pollution, low equipment requirements, high recovery purity, and convenient recycling. It is suitable for recovering gold, silver, and other metal electrodes from waste perovskite solar cells in laboratory settings and has the potential for application in large-area devices and large-scale recycling scenarios.

[0040] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for recovering metal electrodes from perovskite solar cells using a solution intercalation method, characterized in that, Includes the following steps: Step 1: Immerse the perovskite solar cell in the perovskite precursor solvent to separate the metal electrode film from the conductive substrate. Step 2: Remove the conductive substrate from the immersion solution; Step 3: Use a filter to remove the metal electrode film from the soaking solution and transfer it to anhydrous ethanol solution for soaking; Step 4: Transfer the anhydrous ethanol solution containing the metal electrode film to a centrifuge tube and centrifuge it to achieve solid-liquid separation. Step 5: After centrifugation, remove the metal electrode film and dry it to complete the metal electrode recovery.

2. The method for recovering perovskite solar cell metal electrodes by solution intercalation as described in claim 1, characterized in that: In step 4, centrifuge at room temperature for 5 minutes at a speed of 8000 rpm.

3. The method for recovering perovskite solar cell metal electrodes by solution intercalation as described in claim 1, characterized in that: After step 2 and before step 3, the process also includes removing the metal electrode film peeled off from the soaking solution and transferring it to a clean precursor solvent for a second soaking.

4. The method for recovering perovskite solar cell metal electrodes by solution intercalation as described in claim 1, characterized in that: In step 5, a vacuum drying oven is used to dry the metal electrode film.

5. The method for recovering perovskite solar cell metal electrodes by solution intercalation as described in claim 1, characterized in that: After step 5, the recovered metal electrode film is further processed into solid particles or block solids by sintering or direct melting.

6. The method for recovering perovskite solar cell metal electrodes by solution intercalation as described in claim 1, characterized in that: The metal electrode film is made of silver, and the perovskite precursor solvent is dimethyl sulfoxide.

7. The method for recovering perovskite solar cell metal electrodes by solution intercalation as described in claim 1, characterized in that: The metal electrode film is made of gold, and the perovskite precursor solvent is N,N-dimethylformamide.

8. The method for recovering perovskite solar cell metal electrodes by solution intercalation as described in claim 1, characterized in that: Before step 1, micropores with spacing are pre-formed in the edge region of the perovskite solar cell.

9. The method for recovering perovskite solar cell metal electrodes by solution intercalation as described in claim 1, characterized in that: Before step 1, pre-pressure is applied to the perovskite solar cell and then the pre-pressure is released.

10. The method for recovering perovskite solar cell metal electrodes by solution intercalation as described in claim 1, characterized in that: In step 1, an alternating magnetic field is applied to the perovskite solar cell immersed in the perovskite precursor solvent.

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