Post-processing reshaping method and device for carbon-based mesoscopic perovskite solar cell

Abstract

The invention belongs to the related technical field of perovskite solar cells, and discloses a post-processing reshaping method and device for a carbon-based mesoscopic perovskite solar cell. Comprising the steps that a carbon electrode layer of the carbon-based mesoscopic perovskite solar cell is softened, an isolation layer and a buffer layer are sequentially arranged on the surface of the softened carbon-based mesoscopic perovskite solar cell, the carbon-based mesoscopic perovskite solar cell is subjected to hot pressing under preset parameters, heating is conducted under the preset parameters, a solvent is rapidly removed, and the carbon-based mesoscopic perovskite solar cell is obtained. And curing and shaping the carbon electrode layer. The conductivity of the carbon electrode and the interface contact condition of the carbon electrode and the perovskite crystal layer are effectively improved by developing a relatively convenient post-processing mode, and the equivalent series resistance of the device is greatly reduced, so that the performance of the prepared device is improved again on the original basis.

Description

Technical Field

[0001] This invention belongs to the technical field of perovskite solar cells, and more specifically, relates to a post-processing and reshaping method and apparatus for carbon-based mesoscopic perovskite solar cells. Background Technology

[0002] Since its emergence in 2009, perovskite solar cells have developed rapidly. The power conversion efficiency of single-junction perovskite solar cells has increased from 3.8% initially to the current 27.0%, demonstrating enormous commercial potential and the potentially huge cost-effectiveness of this emerging photovoltaic technology in solar power generation. The conventional structure of a perovskite solar cell includes a front electrode, a perovskite light-absorbing layer, a carrier transport layer, and a counter electrode.

[0003] The counter electrode (also known as the back electrode), as one of the important components of perovskite solar cells, is mainly made of precious metals, such as gold and silver. However, the use of metal electrodes is one of the major obstacles that need to be overcome in the large-scale production of perovskite solar cells. On the one hand, there are physical and chemical limitations, as the ion migration and corrosion of precious metals can jeopardize the stability of the device; on the other hand, there are limitations in technology and financial resources, as the deposition of metal electrodes requires specialized equipment and high-vacuum technology under inert conditions, making the deposition conditions on large-area substrates harsh and costly.

[0004] Carbon materials are widely available, possess excellent chemical inertness, cost-effectiveness, and good electrical conductivity, while also exhibiting a work function similar to gold. Combined with simple and mild fabrication processes such as blade coating, screen printing, and inkjet printing, carbon electrodes have become the most attractive alternative to traditional metal electrodes. Carbon electrodes are typically deposited from carbon slurry, which mainly consists of carbon particles and a binder. The carbon particles act as the conductive substrate, while the binder serves as a functional additive, binding the carbon particles together and improving the film-forming properties of the slurry.

[0005] The counter electrode provides a channel for charge carrier transport in perovskite solar cells, allowing holes to flow to the external circuit and generate operating current. Conductivity is a crucial characteristic for evaluating the performance of carbon electrodes. Low resistance enables the electrode to transport charge more efficiently, while poor conductivity of the counter electrode hinders charge carrier transport, further limiting device performance. Currently, the conductivity of carbon material counter electrodes is approximately 4.88 × 10⁻⁶. 3 S / m) and 4.10×10 of the gold electrode 7The significant difference in S / m is one of the main reasons for the performance differences between carbon-based perovskite solar cells and metal-based perovskite solar cells. The resistance of the carbon electrode mainly comes from the resistance of the carbon material itself and the contact resistance between carbon particles. Several standards are used for preparing carbon slurries: micron-sized particles, uniform distribution, high purity, and low light absorption capacity. Therefore, existing carbon slurries often use graphite as the main component (i.e., the main conductive particles). Larger graphite particles have poor contact, and current technologies often use carbon black as the conductive medium. The addition of carbon black can bridge the spaces between graphite particles and improve interparticle conductivity. However, since the fabrication of mesoscopic perovskite solar cells requires filling the perovskite precursor solution into the lower layers through the pores of the carbon electrode and controlling the crystallization process, the carbon electrode needs to have a certain porosity. This makes the contact resistance of the porous carbon electrode a major factor hindering the improvement of conductivity.

[0006] On the other hand, when porous carbon electrodes are used in mesoscopic perovskite solar cells, they come into direct contact with the underlying crystallized perovskite layer. During cell operation, hole carriers are transferred through the contact area between the carbon electrode and the perovskite crystallized layer at the back interface. Ensuring good back contact is crucial for hole carrier migration. However, the requirements for the porosity of the carbon electrode itself and the screen printing fabrication method during device fabrication make it difficult to improve the interface contact, which also limits the reduction of the device's equivalent series resistance. This leads to hindered hole carrier transport, increased recombination during transport, and restricts the improvement of the photoelectric conversion efficiency of carbon-based perovskite solar cells. Summary of the Invention

[0007] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a post-processing reshaping method and apparatus for carbon-based mesoscopic perovskite solar cells. The purpose is to optimize the arrangement of the carbon electrode layers and the interface contact between the carbon electrode layers and the perovskite crystal layer by reshaping the carbon electrodes after the carbon-based mesoscopic perovskite solar cell device is fabricated. This solves the technical problem of high equivalent series resistance of the device due to the poor conductivity of the carbon electrodes themselves and the poor interface contact between the carbon electrodes and the perovskite crystal layer.

[0008] To achieve the above objectives, the present invention provides a post-processing and reshaping method for carbon-based mesoscopic perovskite solar cells, comprising: softening the carbon electrode layer of the carbon-based mesoscopic perovskite solar cell; sequentially setting an isolation layer and a buffer layer on the softened surface of the carbon-based mesoscopic perovskite solar cell; hot-pressing the carbon-based mesoscopic perovskite solar cell under preset parameters; rapidly removing the solvent used for softening by heating under preset parameters; and solidifying and shaping the carbon electrode layer.

[0009] Furthermore, the preset parameters include hot pressing temperature, hot pressing pressure and hot pressing time, heating temperature and heating time.

[0010] Furthermore, the hot pressing pressure range is 10-15 MPa, the hot pressing time is 0.5-1 min, and the hot pressing temperature is 50-60℃.

[0011] Furthermore, the heating temperature is 60-80℃, and the heating time is 5-8 minutes.

[0012] This invention also provides a post-processing and reshaping device for carbon-based mesoscopic perovskite solar cells, comprising a pre-processing module, an isolation layer, a buffer layer, a temperature-controlled pressurizing platform, and a hot stage. The pre-processing module is used to soften the carbon electrode layer of the carbon-based mesoscopic perovskite solar cell. The temperature-controlled pressurizing platform includes a parallel top surface and a bottom surface, and the temperature of the temperature-controlled pressurizing platform is controllable. The carbon-based mesoscopic perovskite solar cell to be processed is placed in the center area of ​​the bottom surface, with the carbon electrode layer of the cell facing upwards. An isolation layer and a buffer layer are respectively provided on the upper layer. During operation, the top surface is moved downwards for hot pressing, and finally the carbon electrode layer is solidified and shaped by heating with the hot stage, thereby realizing the post-processing of the carbon electrode of the carbon-based perovskite solar cell.

[0013] Furthermore, the insulating layer is a polytetrafluoroethylene film.

[0014] Furthermore, the buffer layer is a silicone sheet.

[0015] Furthermore, the hot pressing pressure range is 10-15 MPa, the hot pressing time is 0.5-1 min, and the hot pressing temperature is 50-60℃.

[0016] Furthermore, the heating temperature of the hot plate is 60-80℃, and the heating time is 5-8 minutes.

[0017] In summary, compared with the prior art, the reshaping post-processing method provided by the present invention has the following advantages: 1. A post-processing reshaping method was developed. Without affecting the early preparation of carbon-based mesoscopic perovskite solar cells, a more convenient post-processing method was developed to effectively improve the conductivity of carbon electrodes and the contact between carbon electrodes and perovskite crystal layers, significantly reducing the equivalent series resistance of the device and further improving the performance of the prepared device.

[0018] 2. A suitable hot-pressing molding method was optimized. By adding appropriate buffer and isolation layers, the carbon electrode of the device was subjected to uniform stress and the glass substrate and carbon electrode layer were prevented from breaking. The appropriate pressing method, pressing time, temperature and pressure were explored and optimized to achieve the best pressing molding effect.

[0019] 3. A suitable method for softening and reshaping the carbon electrode layer and then curing it was developed. This method avoids damage to other structures of the device, such as the perovskite crystal layer, while effectively reducing the difficulty of shaping and optimizing the carbon electrode layer. The curing process retains the shaping and optimization effect. Attached Figure Description

[0020] Figure 1 This is a schematic flowchart of the post-processing and reshaping method for carbon-based mesoscopic perovskite solar cells provided by the present invention. Figure 2 The components used in hot pressing and reshaping are (a) a hot pressing equipment platform, (b) a buffer layer and an isolation layer, and (c) a carbon-based perovskite solar cell. Figure 3 These are the sheet resistance, film thickness, and resistivity of carbon electrodes after hot pressing and post-treatment at different times; Figure 4 These are the sheet resistance, film thickness, and resistivity of carbon electrodes after hot pressing at different pressures. Figure 5 These are the sheet resistance, film thickness, and resistivity of the carbon electrode after two months of storage following reshaping and post-processing. Figure 6 This is the JV curve of one of the batteries before and after processing; Figure 7 This is the cross-sectional morphology of the battery as detected by SEM; Figure 8 These are XRD detection spectral lines; Figure 9 It is an EIS scan impedance spectrum curve. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0022] This invention provides a post-processing and reshaping method for carbon-based mesoscopic perovskite solar cells, comprising: softening the carbon electrode layer of the carbon-based mesoscopic perovskite solar cell; sequentially setting an isolation layer and a buffer layer on the softened surface of the carbon-based mesoscopic perovskite solar cell; hot-pressing the carbon-based mesoscopic perovskite solar cell under preset parameters; rapidly removing the solvent used for softening by heating on a hot stage; and solidifying and shaping the carbon electrode layer.

[0023] Specifically, firstly, carbon-based mesoscopic perovskite solar cells that have already completed perovskite crystallization, such as... Figure 1 As shown, 10-20 μL / cm³ of solution was dropped onto the center of the carbon electrode surface.2 Organic antisolvents such as isopropanol or chlorobenzene for perovskites are used. After standing for 10-30 seconds, the solvent is allowed to fully diffuse to all parts of the carbon electrode layer, making the carbon electrode layer wet and softened, thus preparing it for reshaping.

[0024] Then through, as Figure 2 The apparatus shown allows for the proper initial reshaping of a softened carbon electrode layer by applying appropriate pressure and time through a suitable hot-pressing method at a temperature of 50-60°C. The hot-pressing equipment, buffer layer, insulating layer, and carbon-based perovskite solar cell used in the experiment are as follows: Figure 2 As shown. By adjusting the applied pressure and the area of ​​the buffer layer, the uniform pressure on the carbon electrode was controlled. Experiments revealed suitable hot-pressing time (30s-1min) and pressure (10-15MPa). The hot-pressing temperature was controlled at 50-60℃ to avoid damage to the perovskite crystal layer due to excessive temperature. The carbon-based perovskite solar cell device, after solvent impregnation, was stably placed in the center of the temperature-controlled pressurization platform. An isolation layer and a buffer layer were sequentially arranged on the carbon electrode. The hot-pressing temperature was controlled at 50-60℃, the pressure applied to the carbon electrode was controlled at 10-15MPa, and the hot-pressing time was 1min.

[0025] Finally, the initially shaped battery is placed on a hot plate at 60-80℃ and heated for 5-8 minutes to dry the solvent and solidify the reshaped carbon electrode layer. This completes the reshaping process.

[0026] Post-processing reshaping can circumvent the limitations on carbon electrode porosity and fabrication methods during device fabrication. After device fabrication, the carbon electrode arrangement can be re-optimized to improve the contact performance between the carbon electrode and the perovskite crystal layer. This can significantly reduce the equivalent series resistance of the cell, improve the stability (waterproof performance) of the device, and avoid the destructive effects of hot pressing on the cell structure. This pressurized post-processing technology can further improve the performance of carbon electrode solar cells after the perovskite layer of the device is fabricated.

[0027] This invention also provides a post-processing and reshaping device for carbon-based mesoscopic perovskite solar cells, comprising a pre-processing module, an insulating layer, a buffer layer, a temperature-controlled pressurizing platform, and a hot stage. The pre-processing module is used to soften the carbon electrode layer of the carbon-based mesoscopic perovskite solar cell. The temperature-controlled pressurizing platform includes a parallel top surface and a bottom surface, and the temperature of the platform is controllable. The carbon-based mesoscopic perovskite solar cell to be processed is placed in the center region of the bottom surface, with the carbon electrode layer facing upwards. An insulating layer and a buffer layer are respectively disposed on top of the cell. During operation, the carbon electrode of the carbon-based perovskite solar cell is post-processed by hot pressing with the top surface moving downwards. Pressure is applied and controlled by the temperature-controlled pressurizing platform with two parallel planes. The appropriately sized, segmented cell device to be processed is placed flat in the center region of the bottom surface of the temperature-controlled pressurizing platform, with the carbon electrode layer facing upwards. An insulating layer and a buffer layer are respectively disposed on top of the cell. The isolation layer is made of a thin film material with a smooth surface, low surface energy, and chemical inertness, such as polytetrafluoroethylene (PTFE) film, which plays a role in physical and chemical isolation, preventing the device from reacting or adhering to other layers and causing damage after pressure is applied, and covering the area of ​​the battery device. The buffer layer is made of a gasket with a certain degree of elasticity, such as a silicone sheet, with a thickness of 1-2 mm, cut to an appropriate size (slightly larger than the carbon electrode area of ​​the device). The buffer layer ensures that the pressure is applied evenly to the carbon electrode area of ​​the battery and avoids uneven stress that could cause the glass substrate of the device to crack.

[0028] During the development of post-processing technology, the effect of post-processing hot-pressing time on the conductivity of carbon electrodes was experimentally investigated. The thickness and sheet resistance of the carbon electrodes were measured using a profilometer and a four-probe sheet resistance meter, respectively, and the resistivity was calculated. Figure 3 It can be seen that the hot pressing time has little effect on the resistivity of the carbon electrode, and a hot pressing time of 1 minute is more appropriate.

[0029] The effect of post-processing hot-pressing pressure on the conductivity of carbon electrodes was investigated experimentally. Figure 4 As shown, compared with the control group, the thickness and sheet resistance of the carbon electrode film after hot pressing were significantly reduced, and decreased with increasing pressure. The resistivity of the carbon electrode decreased significantly, with a 40% decrease at 10 MPa and a 70% decrease at 80 MPa. The trend of resistivity decrease tended to be gradual.

[0030] The carbon electrode, after being reshaped and processed, was stored for two months and then tested again. The data are as follows: Figure 5 As shown, the resistivity is basically consistent with the previous test results, proving that the effect of reshaping post-treatment on the conductivity of carbon electrode is long-term, and the reshaping effect has been well solidified.

[0031] The carbon electrode perovskite solar cell devices from the same batch that had completed perovskite crystallization were divided into three groups of 10 each. Each group underwent hot-pressing treatment at different pressures for 1 minute, with the temperature controlled at 50℃. The experimental results are shown in the table below.

[0032] Table 1

[0033] As shown in the table above, the average battery short-circuit current J after reshaping treatment using 40 MPa and 20 MPa is... SC While the fill factor (FF) and power conversion efficiency (PCE) increased compared to the previous values, the negative effects of excessively high pressure on the carbon electrode-perovskite crystal layer contact surface and back contact deterioration were observed. The decrease in open-circuit voltage (Voc) further supports this hypothesis. Therefore, reducing the post-treatment pressure was investigated. Experiments showed that at 10 MPa, the post-treated cells exhibited better performance, with increases in average short-circuit current and fill factor. This is attributed to the improved conductivity of the carbon electrode and reduced equivalent series resistance after post-treatment. Furthermore, the device efficiency increased from 17.51% to 17.96% after 10 MPa treatment, demonstrating that post-treatment can further enhance the performance of carbon-based perovskite solar cells after perovskite layer fabrication. Figure 6 The figure shows the voltage and current curves of one of the batteries before and after post-treatment at a pressure of 10 MPa. It can be seen that the voltage remains almost unchanged after post-treatment, while the current increases, and the fill factor and maximum efficiency are improved.

[0034] Figure 7 Scanning electron microscopy (SEM) was used to study the morphology of the battery cross-section before and after post-treatment at 10 MPa pressure. It was clearly observed that the conductive graphite sheets within the post-treated carbon electrode were more regularly arranged and had tighter contact, which is the main reason for the improved conductivity of the carbon electrode. Simultaneously, the porosity and voids between the underlying perovskite crystalline layer and the carbon electrode layer were significantly reduced, improving the interfacial contact. This also helps to reduce the device's equivalent series resistance and decrease the obstruction to hole carrier transport.

[0035] Figure 8 X-ray diffraction (XRD) was used to detect the information intensity of the perovskite crystal inside the battery before and after post-processing under 10 MPa pressure. It can be seen that the signal intensity of the main peaks 220, 110 and 310 on the spectrum of the perovskite crystal inside the battery did not decrease significantly before and after post-processing, indicating that the reshaping post-processing under 10 MPa pressure did not cause any loss to the perovskite crystal layer inside the battery.

[0036] Figure 9Electrochemical impedance spectroscopy (EIS) was used to detect the impedance spectrum of the battery device. As shown in the figure, the arc formed by the curve at lower frequencies represents the magnitude of the equivalent series resistance inside the device. The equivalent series resistance of the battery device after hot pressing at 10 MPa pressure is significantly reduced. This is because the conductivity of the carbon electrode of the battery is improved after hot pressing, and the contact between the carbon electrode layer and the perovskite crystal layer is improved, resulting in a reduction in the overall series resistance of the device.

[0037] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. It should be noted that the terms "in one embodiment," "for example," and "again" in this invention are intended to illustrate the invention and are not intended to limit the invention.

[0038] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A post-processing reshaping method for carbon-based mesoscopic perovskite solar cells, characterized in that, The method comprises the following steps: The carbon electrode layer of the carbon-based mesoscopic perovskite solar cell is softened, an isolation layer and a buffer layer are sequentially arranged on the surface of the softened carbon-based mesoscopic perovskite solar cell, the carbon-based mesoscopic perovskite solar cell is hot-pressed under preset parameters, and finally the carbon electrode layer is solidified and shaped by heating.

2. The method of claim 1, wherein, The preset parameters include hot-pressing temperature, hot-pressing pressure and hot-pressing time, heating temperature and heating time.

3. The method of claim 2, wherein, The hot-pressing pressure ranges from 10 to 15 MPa, the hot-pressing time is 0.5-1 min, and the hot-pressing temperature is 50-60 DEG C.

4. The method of claim 1, wherein, The heating temperature is 60-80 DEG C, and the heating time is 5-8 min.

5. A post-processing reshaping device for carbon-based mesoscopic perovskite solar cells, characterized in that, The method comprises a pretreatment module, an isolation layer, a buffer layer, a temperature control and pressure platform, and a hot stage. The pretreatment module is used to soften the carbon electrode layer of the carbon-based mesoscopic perovskite solar cell. The isolation layer and the buffer layer are sequentially arranged on the surface of the softened carbon-based mesoscopic perovskite solar cell. The temperature control and pressure platform comprises parallel top and bottom surfaces. The preset parameters of the temperature control and pressure platform are controllable. The carbon-based mesoscopic perovskite solar cell to be processed is placed in the center area of the bottom surface with the carbon electrode layer facing upwards, and the isolation layer and the buffer layer are arranged on the upper layer. During operation, the top surface moves downward to hot-press the carbon-based mesoscopic perovskite solar cell under the preset parameters, and finally the carbon electrode layer is solidified and shaped by heating the hot stage, thereby realizing the post-processing of the carbon electrode of the carbon-based perovskite solar cell.

6. The apparatus of claim 5, wherein, The isolation layer is a polytetrafluoroethylene film.

7. The apparatus of claim 5, wherein, The buffer layer is a silica gel sheet.

8. The apparatus of claim 5, wherein, The preset parameters include hot-pressing temperature, hot-pressing pressure and hot-pressing time, heating temperature and heating time.

9. The apparatus of claim 8, wherein, The hot-pressing pressure ranges from 10 to 15 MPa, the hot-pressing time is 0.5-1 min, and the hot-pressing temperature is 50-60 DEG C.

10. The apparatus of claim 8, wherein, The heating temperature of the hot stage is 60-80 DEG C, and the heating time is 5-8 min.

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