Method for recovering lead salt and substrate in waste perovskite device based on oxidation pickling method

Abstract

The invention relates to a method for recovering lead salt and a substrate in a waste perovskite device based on an oxidation pickling method. The method comprises the following steps: putting the waste perovskite device into a vacuum plasma cleaning machine for oxidation; preparing an organic weak acid solution with a set concentration; immersing the oxidized waste perovskite device in the organic weak acid solution for ultrasonic treatment; evaporating the obtained lead salt solution to obtain lead salt powder, adding a proper amount of formamidine salt and haloid acid, stirring for a period of time to obtain perovskite powder, and adding isopropanol and diethyl ether to wash and dry perovskite powder crystals to obtain perovskite powder crystals; cleaning the recovered substrate; and the recycled substrate and the perovskite powder are used for preparing the perovskite photovoltaic device again, so that safe, green and low-cost recycling is realized.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology, and in particular relates to a method for recovering lead salts and substrates from discarded perovskite devices based on an oxidative pickling method. Background Art

[0002] Perovskite solar cells are photovoltaic devices based on organic-inorganic hybrid metal halide semiconductor materials, representing a new third-generation solar cell technology. Since their initial application in the photovoltaic field in 2009, these cells have garnered significant attention from both academia and industry for their superior performance and economic advantages. After more than a decade of development, the laboratory-certified efficiency of single-junction perovskite solar cells has reached 25.7%, approaching the performance level of traditional crystalline silicon cells. More notably, their simple fabrication process and low equipment requirements give them enormous potential for industrialization.

[0003] In the context of sustainable development, the recycling of photovoltaic materials is of great significance. Through recycling and reuse, not only can production costs and environmental loads be reduced, but the energy recovery cycle (that is, the time required for the energy generated by the operation of the battery to offset its manufacturing energy consumption) can also be significantly shortened, which is of great strategic value for achieving the goal of carbon neutrality. A typical perovskite solar cell module is mainly composed of the following parts: a transparent conductive substrate (such as ITO, FTO or AZO, etc.), a charge transport layer (including an electron transport layer and a hole transport layer), a perovskite light absorption layer, and a metal electrode (commonly used Ag, Au, Cu, Al or carbon materials, etc.). From the perspective of cost structure, the transparent conductive substrate accounts for 50-70% of the total cost of the module, so its recycling is crucial to reducing the overall cost. In addition, the lead component in the perovskite material has potential environmental risks. Although there are currently a variety of packaging technologies that can effectively prevent lead leakage, the development of economical and environmentally friendly recycling and treatment solutions is still the fundamental way to solve the problem of lead pollution.

[0004] Current perovskite module recycling technologies face numerous challenges. The primary challenge lies in the solubility limitations of perovskite materials. Currently, only a few organic solvents, such as DMF, DMSO, NMP, and GBL, as well as some ionic liquids, can effectively dissolve perovskites. These solvents are not only expensive, toxic, and pose safety risks, but also exhibit poor stripping efficiency. Another technical difficulty lies in lead recovery. Due to the high boiling points of these organic solvents, direct precipitation of lead iodide is difficult, often requiring an additional lead-fixing step. For example, one research team has used ion exchange resins to recover lead ions from DMF solutions, but the overall process remains complex. Existing recovery methods generally suffer from high costs, poor safety, and environmental limitations, severely hindering their industrial application. Therefore, the development of new, green, safe, and economical perovskite recovery technologies is of great practical significance and application value. Future research should focus on exploring environmentally friendly alternative solvents and optimizing recovery process routes to achieve sustainable development throughout the life cycle of perovskite solar cells. Summary of the Invention

[0005] To address the challenges of the prior art, the present invention aims to provide a method for recovering lead salts and substrates from discarded perovskite solar cells using an oxidative pickling process. This method utilizes a pickling process to simultaneously recover and recycle lead salts and the conductive substrate from discarded perovskite solar cells. This technical solution addresses the technical bottlenecks of existing recycling methods, such as the high toxicity of organic solvents, high costs, and complex processes, providing a new, environmentally friendly, safe, and economically viable recycling approach.

[0006] The present invention is specifically implemented through the following technical solutions:

[0007] A method for recovering lead salts and substrates from discarded perovskite devices based on an oxidative pickling method, the method comprising the following steps:

[0008] 1) Place the discarded perovskite device in a vacuum plasma cleaning machine for oxidation;

[0009] 2) Prepare an organic weak acid solution of a set concentration with a pH value between 3 and 6;

[0010] 3) immersing the discarded perovskite device oxidized in step 1) in the organic weak acid solution prepared in step 2) and ultrasonically producing a lead salt solution and cleaning and recovering the conductive substrate of the perovskite device;

[0011] 4) evaporating the lead salt solution in step 3) to obtain lead salt powder, adding appropriate amounts of formamidine salt and hydrohalic acid, and stirring for a period of time to obtain perovskite powder, and washing and drying the perovskite powder with isopropyl alcohol and diethyl ether to obtain perovskite powder crystals;

[0012] 5) using the conductive substrate recovered in step 2) and the perovskite powder crystals prepared in step 4) to re-prepare a perovskite photovoltaic device.

[0013] The present application proposes an innovative perovskite solar cell closed-loop recycling scheme, the core technology of which is to realize sustainable recycling of materials by a three-step method. First, the perovskite active layer in the waste device is selectively converted into lead oxide by a room-temperature controllable oxidation process, which avoids the energy consumption problem caused by high-temperature treatment. Second, an environmentally friendly weak acid (such as acetic acid) cleaning process is innovatively adopted to realize non-destructive recovery of the substrate (ITO / FTO) under mild conditions, while solving the substrate corrosion problem caused by traditional strong acid treatment. Finally, the recovered product is directly converted into high-purity perovskite powder through an optimally designed recrystallization process, realizing the recycling of raw materials. This recycling scheme has multiple technical advantages: first, the entire process is carried out at room temperature and atmospheric pressure, significantly reducing energy consumption costs; second, green chemical reagents are used to replace traditional toxic organic solvents, greatly improving the environmental friendliness of the process; third, the innovative "oxidation-dissolution-regeneration" technical path realizes efficient closed-loop utilization of materials, providing a new idea for solving the stability problem of perovskite devices. This sustainable recycling strategy not only effectively extends the life cycle of materials, but also provides strong support for the commercialization of perovskite solar cells by reducing raw material costs.

[0014] Specifically, the oxidation in step 1) uses a rapid oxidation method, and the oxidation time is 5-20 minutes, which can quickly convert halide perovskite into lead oxide, which can be quickly removed by green and environmentally friendly organic weak acid.

[0015] Specifically, the organic weak acid in step 2) is any one of formic acid, acetic acid, propionic acid, and ascorbic acid, and the pH value is between 3-6.

[0016] Specifically, the conductive substrate in step 3) is any one of ITO, FTO, AZO, or IZO.

[0017] Specifically, the formamidine salt in step 4) is any one of formamidine acetate, formamidine hydroiodide, formamidine hydrochloride, formamidine hydrobromide, formamidine formate, and formamidine propionate.

[0018] Specifically, the hydrogen halide acid in step 4) is any one of hydrochloric acid, hydrobromic acid, and hydroiodic acid.

[0019] Specifically, the above-mentioned recycled materials are used to re-prepare a perovskite solar cell, realizing the recycling of perovskite solar cells, and using the conductive substrate recovered in step 2) and the perovskite powder crystals prepared in step 4) to re-prepare a perovskite photovoltaic device.

[0020] The photovoltaic device includes, from bottom to top, a conductive substrate, a hole transport layer, a perovskite light absorbing layer film, an electron transport layer, a buffer layer and a top electrode. The hole transport layer includes but is not limited to 2PACz, MeO-2PACz, Py3, PTAA, NiOx, piro-OMeTAD, etc. The hole transport layer can be prepared by spin coating, blade coating, slit coating, screen printing, spray coating, ink printing, roll-to-roll process or evaporation. The perovskite light absorbing layer film includes but is not limited to lead-based perovskite, tin-based perovskite or tin-lead perovskite, etc. The perovskite light absorbing layer film can be prepared by spin coating, blade coating, slit coating, screen printing, spray coating, ink printing, roll-to-roll process or evaporation. The electron transport layer can be prepared by C 60 、C 70 、PC 61 BM or PC 71 The BM is prepared by methods such as spin coating, blade coating, evaporation, atomic deposition, or magnetron sputtering. The buffer layer can be prepared using BCP, TPBi, TiO2, ZnO, or ZnO2 by methods such as spin coating, blade coating, evaporation, atomic deposition, or magnetron sputtering. The top electrode includes but is not limited to Ag, Cu, Au, Al, Cr, ITO, IZO, FTO, AZO, or C electrode, and can be prepared by methods such as blade coating, slit coating, screen printing, thermal evaporation, atomic deposition, or magnetron sputtering.

[0021] The perovskite solar cell can be prepared as a single-sided or double-sided device.

[0022] The perovskite solar cell can be used as a single-cell device or as one of the sub-cells of a four-terminal silicon / perovskite tandem solar cell, a CIG second / perovskite tandem solar cell or an organic / perovskite tandem solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a technical route for the simultaneous recovery and recycling of lead salts and conductive substrates in discarded perovskite solar cells through the oxidation pickling process;

[0024] Figure 2 It is a graph of the changes in the process of waste P seconds C seconds oxidation pickling;

[0025] Figure 3 (a) XRD patterns of new and regenerated FAPbI3 powders, a photo of the regenerated FAPbI3 powder is attached to the figure; (b) EM image of the regenerated FAPbI3 powder;

[0026] Figure 4 The following are AFM images and c-AFM images of the ITO substrate before and after recycling.

[0027] Figure 5 are the JV curves of freshly prepared and four-cycle recycled inverted FAPbI3 solar cells;

[0028] Figure 6 These are the statistical results of the photovoltaic parameters of the newly prepared four-cycle regenerated inverted FAPbI3 solar cells.

[0029] Figure 7 This is the JV curve of the newly prepared recycled inverted FAPbI3 solar cell module. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with specific embodiments to facilitate a better understanding of the present technical solution.

[0031] Example 1

[0032] First, the discarded perovskite solar cell was heated on a 150°C hot plate for 5 minutes to soften the encapsulant and remove the backing glass. The disassembled perovskite solar cell was then ultrasonically cleaned in an ethyl acetate solution for 30 minutes. Once the metal electrodes on the surface of the perovskite solar cell were removed, the perovskite film was oxidized in a plasma cleaner for 10 minutes. Subsequently, the device was immersed in an aqueous acetic acid solution and ultrasonically cleaned for 5 minutes. The pH of the acetic acid solution was adjusted to 3-4, causing the lead oxide film to rapidly dissolve from the substrate. Because the organic hole transport layer, commonly used in inverted devices, also detaches from the substrate in aqueous solution, a clean ITO substrate can be recovered. The ITO substrate became transparent after approximately 5 minutes. Before reuse, the ITO substrate was ultrasonically cleaned again in a detergent solution, acetone, and anhydrous ethanol for 30 minutes each. The precipitate at the bottom of the bottle after acid cleaning was added to an appropriate amount of aqueous HI solution, adjusting the pH of the solution to 2-3. Concentrate and filter to obtain Pb(Ac)4. Mix Pb(Ac)4 with FAAc (adjust the Pb / FA ratio), add 10 ml of water, and stir in a 50 ml three-necked flask. Heat the mixture to 60°C in a water bath. Once completely dissolved, add an appropriate amount of aqueous hydroiodic acid and adjust the pH to 2-3. Stir for 60 minutes. Wash the precipitated FAPbI3 with IPA and filter. After filtration, dry the FAPbI3 powder in a 70°C forced air oven for several hours.

[0033] Example 2

[0034] The recycling of perovskite solar cells was achieved by first preparing fresh perovskite solar cells, then using the obtained perovskite powder and the substrate to prepare regenerated perovskite devices. The present embodiment was recycled 4 times. The steps are as follows: first, the ITO glass was ultrasonically cleaned with detergent, acetone and anhydrous ethanol for 30 minutes, respectively, and then dried with a nitrogen gun. The cleaned and dried ITO substrate was treated in a UV-ozone environment for 25 minutes. A 0.6 mg / mL Py3 solution was spin-coated at 1000 rpm for 10 seconds and then at 3000 rpm for 40 seconds in a nitrogen glove box. Subsequently, the thin film was annealed at 120°C for 10 minutes. A 1.7M perovskite precursor solution was prepared. The filtered perovskite precursor solution was spin-coated at 1000 rpm for 3 seconds and then at 5000 rpm for 60 seconds in a nitrogen glove box, and 300 μL of ethyl acetate antisolvent was added quickly at the 45th second of the second spin-coating. After spin-coating, the thin film was annealed at 90°C for 1 minute and at 150°C for 10 minutes, respectively. A 40 nm C 60 , 6 nm BCP and 120 nm Ag metal electrode were sequentially thermally evaporated and deposited on the perovskite film.

[0035] Example 3

[0036] The steps and experimental conditions are the same as in Example 2, except that the recycled and regenerated devices are perovskite solar cell modules. The preparation method of the module is as follows: a 5x6 cm 2A perovskite solar module containing 10 series-connected subcells was fabricated. The module's series connection was achieved using P1, P2, and P3 lines, which were patterned using a 1064 nm wavelength, 20 W laser scribing system. P1 (50 μm width) was scribed onto the FTO substrate at a speed of 300 mm / s using a laser with a frequency of 65 kHz, a pulse width of 120 nsec, and 60% power. The process used to deposit Py3 on the ITO substrate was identical to that used for small-area devices. Furthermore, the perovskite precursor deposition and preparation procedures were similar to those used for small-area solar cells, with the exception of the perovskite precursor concentration. The perovskite layer was prepared by spin coating using a 1.2 M concentration of FAPbI3 perovskite precursor. The perovskite precursor was spin-coated onto the substrate, similar to the small-area device. The perovskite film was annealed at 90°C for 1 minute and 150°C for 10 minutes, respectively, and then cooled to room temperature. Prior to the Ag evaporation process, the P2 line (150 μm wide) was scribed using a laser with an average power of 15%, a speed of 1000 mm / s, and a frequency of 65 kHz, with a pulse duration of 120 nsec. After evaporating a 100 nm thick Ag layer, the P3 line (100 μm wide) was created using the same scribing conditions as the P2 line. The distance between P1 and P3 was approximately 400 μm. The geometric fill factor (GFF) of the perovskite solar module was approximately 0.91.

[0037] Sample analysis

[0038] The recovery route in Example 1 is as follows Figure 1As shown, this process uses only green solvents and does not consume any additional functional materials, minimizing its economic and environmental impact. The perovskite film is first placed in a plasma cleaner for oxidation. During this process, the organic materials in the device (such as the organic components in the hole transport layer and the perovskite layer) are completely oxidized and decomposed, leaving only inorganic lead oxides. Unlike commonly used organic solvents such as DMF and DMSO, aqueous acetic acid is then used as the primary solvent for stripping the material from the TCO substrate. These inorganic lead oxides can be directly dissolved and stripped by the acetic acid solution (Equation 1), while the TCO substrate is preserved and reused intact. The Pb(Ac)4 dissolved in the acetic acid solution is not wasted; the resulting Pb(Ac)4 can be reduced to Pb(Ac)2 with hydroiodic acid (Equation 2). Pb(Ac)2 is further utilized as a valuable intermediate. By adding aqueous FAAc and HI to the solution, lead acetate can be converted into high-value-added FAPbI3 powder, as shown in Equation 3. FAPbI3 is an important precursor material in perovskite solar cells. Its high purity and stability give it broad application prospects in the optoelectronic field. Through this conversion, the present application not only achieves efficient recovery of lead resources, but also converts them into products with higher economic value, thereby significantly improving the economic benefits of the recycling process. Compared with traditional recycling methods, the method of the present application has significant advantages. First, it completely avoids the reliance on highly toxic organic solvents (such as DMF or DMSO) and complex separation techniques (such as ion exchange resins) in traditional processes, thereby greatly reducing the environmental risks and operating costs of the recycling process. Secondly, due to the use of green solvents and simple chemical reactions, the entire recycling process is more efficient and easy to scale, suitable for industrial production. In addition, this method is highly versatile and can adapt to perovskite solar cells of different structures and compositions. Whether it is a device based on MAPbI3, FAPbI3 or a mixed perovskite system, efficient recovery can be achieved through this process.

[0039] PbO2+4HAc→Pb(Ac)4+2 H2O (1)

[0040] Pb(Ac)4+2HI→Pb(Ac)2+2HAc+I2 (2)

[0041] Pb(Ac)2+FAAc+3HI→FAPbI3+3HAc(3)

[0042] like Figure 2As shown in the figure, the original perovskite film exhibits a typical black feature. After oxidation treatment, the color of the film changes significantly, becoming nearly transparent but still slightly black. Subsequent acid washing further improves the transparency of the film, creating a clear visual contrast between the acid-washed and untreated areas.

[0043] Example 1 successfully synthesized FAPbI3 powder through the recycling process and attached it to Figure 3 In order to further verify the quality of the recovered powder, this application conducted an XRD analysis. The XRD pattern shows ( Figure 3 a), the recovered FAPbI3 powder showed obvious (100) and (201) crystal plane diffraction peaks, just like the new material. The synthesized yellow FAPbI3 powder was determined to belong to the hexagonal system, corresponding to the δ phase, and its rod-like morphology was observed ( Figure 3 b). In addition, no diffraction peaks of any other impurities or by-products were detected in the XRD pattern, indicating that the recovered FAPbI3 powder has extremely high purity and crystalline quality. In terms of electrical properties, Example 1 conducted a comparative test on the conductivity of fresh and recycled ITO substrates. Figure 4 As shown, both samples exhibited excellent electrical conductivity, fully meeting the carrier collection requirements of high-efficiency PSCs. High conductivity is another core performance criterion for ITO substrates as transparent electrodes, and the regenerated substrates performed just as well as fresh substrates in this regard, further demonstrating their suitability for device fabrication.

[0044] The performance comparison of fresh and regenerated perovskite solar cells prepared in Example 2 is shown in FIG. Figure 5 The experimental results show that after four complete cycles, the performance of the device remains at a very high level. Specifically, the device after the fourth recycling can still achieve a PCE of 25.5%, which is almost the same as the efficiency of the initial device, fully demonstrating the stability and reliability of the regeneration strategy in this paper in long-term recycling. In order to more comprehensively analyze the changes in device performance, this application has conducted detailed statistics and comparisons on key photovoltaic parameters ( Figure 6 ). The results show that in the four-cycle process, V OC 、J SC , FF, and PCE did not change significantly. These data together indicate that the regeneration process of the present application can not only effectively restore the performance of the device, but also maintain its high efficiency and consistency over multiple cycles.

[0045] The performance comparison of fresh and recycled perovskite solar cell modules prepared in Example 3 is shown in FIG. Figure 7In order to verify the practical application value of this recycling strategy, this application further applied it to the preparation and regeneration of large-area PSCs, and successfully prepared a PSC with an effective pore area of ​​20.8 cm 2 The test results show that the module device made of fresh materials achieved a champion PCE of 21.7%, while the module device recycled with recycled materials achieved a PCE of 21.8%. It is particularly noteworthy that after a complete recycling-regeneration cycle, the performance parameters of the device (including open circuit voltage, short circuit current density and fill factor) remain at the same level as the initial device. This directly confirms that the recycled material can achieve a level of device performance comparable to that of the original material; secondly, this strategy has successfully achieved the goal of scaling from small area devices to large area modules (>20cm 2 ) scale-up, demonstrating good process compatibility.

Claims

1. A method for recovering lead salts and substrates from discarded perovskite devices based on an oxidative pickling method, characterized in that: The method comprises the following steps: 1) Place the discarded perovskite device in a vacuum plasma cleaner for oxidation; 2) Prepare an organic weak acid solution of set concentration with a pH value between 3-6; 3) immersing the discarded perovskite device oxidized in step 1) in the organic weak acid solution prepared in step 2) and ultrasonically preparing a lead salt solution to clean and recover the conductive substrate of the perovskite device; 4) Evaporating the lead salt solution from step 3) to obtain lead salt powder, adding appropriate amounts of formamidine salt and hydrohalic acid, and stirring for a period of time to obtain perovskite powder, and washing and drying the perovskite powder with isopropyl alcohol and ether to obtain perovskite powder crystals; 5) Re-preparing a perovskite photovoltaic device using the conductive substrate recovered in step 2) and the perovskite powder crystals prepared in step 4).

2. The method for recovering lead salts and substrates from discarded perovskite devices based on an oxidative pickling method according to claim 1, wherein: In step 1), the oxidation is carried out by a rapid oxidation method, and the oxidation time is 5-20 minutes.

3. The method for recovering lead salts and substrates from discarded perovskite devices based on an oxidative pickling method according to claim 1, characterized in that In step 2), the organic weak acid is any one of formic acid, acetic acid, propionic acid and ascorbic acid.

4. The method for recovering lead salts and substrates from discarded perovskite devices based on an oxidative pickling method according to claim 1, characterized in that In step 3), the conductive substrate is selected from any one of ITO, FTO, AZO or IZO.

5. The method for recovering lead salts and substrates from discarded perovskite devices based on an oxidative pickling method according to claim 1, characterized in that In step 4), the formamidine salt is any one of formamidine acetate, formamidine hydroiodide, formamidine hydrochloride, formamidine hydrobromide, formamidine formate, and formamidine propionate.

6. The method for recovering lead salts and substrates from discarded perovskite devices based on an oxidative pickling method according to claim 1, characterized in that In step 4), the hydrohalic acid is any one of hydrochloric acid, hydrobromic acid and hydroiodic acid.

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