A flexible perovskite solar cell based on slit-coated carbon electrode and a preparation method thereof

Abstract

The application discloses a kind of flexible perovskite solar cell based on slit coating carbon electrode and preparation method thereof, belong to perovskite solar cell technical field.Preparation method includes preparing hole transport layer on flexible conductive substrate, preparing perovskite light absorption layer on hole transport layer, preparing electron transport layer on perovskite light absorption layer, to obtain substrate;Carbon paste is coated on electron transport layer by slit coating mode, the substrate is heated in the coating process, and hot air is sprayed to the carbon paste wet film coated after slit, to generate carbon electrode;The carbon paste includes uniformly mixed carbon material, binder, solvent and polyether modified siloxane.The present application greatly reduces the aggregation point and pinhole defect in electrode layer by adding polyether modified siloxane in carbon paste;The synergistic drying process of substrate heating and hot air knife balances the solvent evaporation rate and film stress release, avoids the carbon film crack caused by simply high-temperature baking.

Description

Technical Field

[0001] This invention relates to a flexible perovskite solar cell based on a slit-coated carbon electrode and its fabrication method, belonging to the field of perovskite solar cell technology. Background Technology

[0002] Flexible perovskite solar cells, due to their advantages such as being lightweight, flexible, and capable of continuous roll-to-roll production, show broad application prospects in portable power supplies, wearable devices, and building-integrated photovoltaics. Electrode materials and fabrication processes are among the key factors determining the performance and stability of flexible perovskite solar cells.

[0003] Carbon materials are considered ideal candidates to replace noble metal electrodes due to their abundant reserves, low cost, good chemical stability, and work function matching with perovskite materials. Currently, carbon electrodes are mostly prepared using methods such as screen printing and blade coating. However, these methods have many limitations for large-area, high-efficiency, and continuous production of flexible substrates: screen printing has stringent requirements on the rheological properties of the paste and the cost of the screen is high; blade coating makes it difficult to precisely control the uniformity of film thickness on flexible substrates.

[0004] Slit coating, as a pre-quantitative coating technology, boasts significant advantages such as high coating speed, controllable film thickness, high material utilization, and ease of scale-up, making it highly suitable for the large-scale manufacturing of flexible electronic devices. However, applying slit coating technology to the fabrication of carbon electrodes for flexible perovskite solar cells faces two major challenges: First, there is the issue of dispersion stability in carbon paste. Carbon particles in carbon paste are extremely prone to agglomeration. Carbon particles refer to graphite, carbon black, etc., and air bubbles are easily trapped during the preparation and coating process of carbon paste. This leads to defects such as agglomerated particles, pinholes, and pits in the coated electrode layer, which seriously affects the conductivity of the electrode and the yield of the device.

[0005] Second, there is the issue of cracks on the substrate. To quickly dry the carbon paste and achieve good conductivity, the coated carbon paste wet film is usually heated. However, on the substrate, the mismatch in the coefficients of thermal expansion between the substrate and the carbon paste wet film during heating, as well as the internal stress generated by the rapid evaporation of the solvent, can easily lead to microcracks in the carbon electrode layer, thereby increasing the series resistance and reducing the battery efficiency.

[0006] Therefore, there is an urgent need to develop a new process that can solve the above problems, is suitable for flexible substrates, and enables the large-area fabrication of high-quality carbon electrodes. Summary of the Invention

[0007] The purpose of this invention is to provide a flexible perovskite solar cell based on a slit-coated carbon electrode and its preparation method, thereby solving the problems of carbon paste dispersion stability and substrate cracking in the prior art.

[0008] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides a method for fabricating a flexible perovskite solar cell based on a slit-coated carbon electrode, comprising: A hole transport layer is prepared on a flexible conductive substrate, a perovskite light absorption layer is prepared on the hole transport layer, and an electron transport layer is prepared on the perovskite light absorption layer to obtain a substrate. Carbon paste is coated onto the electron transport layer by slit coating. During the coating process, the substrate is heated, and hot air is sprayed onto the coated carbon paste wet film behind the slit to generate a carbon electrode. The carbon paste contains a uniformly mixed carbon material, binder, solvent, and polyether-modified siloxane.

[0009] Furthermore, the polyether-modified siloxane accounts for 0.1-1% of the mass of the carbon material.

[0010] Furthermore, the polyether-modified siloxane is a polyether-modified trisiloxane with the chemical formula C0. 12 H 32 O4Si3.

[0011] Furthermore, heating the substrate during the coating process includes heating the substrate to 50~90°C during the coating process.

[0012] Furthermore, the temperature of the hot air is 60~100℃, and the airflow velocity of the hot air is 10~20m / s.

[0013] Furthermore, the angle between the direction of the hot air and the substrate is 50~70°.

[0014] Furthermore, the hot air is provided by a hot air knife, and the distance between the outlet of the hot air knife and the surface of the carbon slurry wet film is 20~40mm.

[0015] Furthermore, the thickness of the carbon slurry wet film is 1.5~4.5μm.

[0016] In a second aspect, the present invention provides a flexible perovskite solar cell based on a slit-coated carbon electrode, which is prepared by any of the preparation methods described in the first aspect.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are: This invention provides a flexible perovskite solar cell based on slit-coated carbon electrodes and its preparation method. By adding a specific proportion of polyether-modified siloxane to the carbon paste, the surface tension of the carbon paste is significantly reduced, the dispersion of carbon particles in the carbon material in the solvent is improved, particle agglomeration is effectively suppressed, and the rapid escape of bubbles during the coating process is promoted. This significantly reduces agglomeration points and pinhole defects in the electrode layer, and improves the density and conductivity uniformity of the electrode. The invention innovatively adopts a synergistic drying process of substrate heating and hot air knife. The substrate provides basic preheating, reducing the initial energy barrier for solvent evaporation. The hot air knife provides directional and controllable hot airflow, which quickly removes solvent vapor from the surface of the carbon paste wet film, accelerating the drying process. This gentle and efficient drying method balances the solvent evaporation rate and film stress release, effectively avoiding carbon film cracks caused by simple high-temperature baking, and ensuring the integrity and adhesion of the electrode on the flexible substrate. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a flexible perovskite solar cell based on a slit-coated carbon electrode provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the carbon paste coating process provided in an embodiment of the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solution of the present invention more clearly, and should not be used to limit the scope of protection of the present invention.

[0020] Example 1

[0021] This embodiment describes the fabrication of a flexible perovskite solar cell with an effective area of ​​100mm × 100mm using the following method. Its structure is as follows: Figure 1 As shown.

[0022] Step S1: Substrate Preparation. Provide a flexible, transparent, conductive PET-ITO substrate, and ultrasonically clean it sequentially with a cleaning agent, deionized water, and isopropanol, then dry it with nitrogen. (Example: ...) Figure 1 As shown, the structure of the PET-ITO flexible transparent conductive substrate consists of a bottom glass substrate and a transparent indium tin oxide layer on top of it.

[0023] Step S2: Hole transport layer preparation. A nickel oxide layer is deposited on a transparent indium tin oxide layer using magnetron sputtering to form a nickel oxide layer. Then, MeO-2PACz is modified on the nickel oxide layer using a slot coating method to form a self-assembled molecular layer. The nickel oxide layer and the self-assembled molecular layer thereon constitute the hole transport layer.

[0024] Step S3: Preparation of the perovskite light-absorbing layer. A FAPbI3-based perovskite precursor solution was coated onto the self-assembled molecular layer using a slit coating method. Crystallization was assisted by vacuum flash evaporation, followed by annealing to form a high-quality perovskite light-absorbing layer.

[0025] Step S4: Electron transport layer fabrication. A PCBM layer and a BCP layer are sequentially deposited on the perovskite light-absorbing layer using a slot coating method. The PCBM layer and the BCP layer constitute the electron transport layer.

[0026] Step S5: Carbon paste preparation. Graphite and carbon black are mixed in a 3:1 mass ratio to form a carbon material. This carbon material is then mixed with polyurethane and cyclohexanone, wherein the carbon material comprises 30 wt%, cyclohexanone 50 wt%, and polyurethane resin 20 wt%. 0.5% of the total mass of the carbon material is added to this mixture as a polyether-modified trisiloxane. The mixture is thoroughly dispersed and mixed using a planetary centrifugal mixer to obtain a uniform and stable carbon paste. In this embodiment, polyurethane (specifically grade 6820) is used as the binder, and cyclohexanone is used as the solvent (specifically, the polyether-modified siloxane has the chemical formula C). 12 H 32 O4Si3 has the corresponding CAS number 67674-67-3.

[0027] Step S6: Slit coating of carbon electrode. Using... Figure 2 The arrangement shown involves using a slit coater to uniformly coat the carbon paste onto the BCP layer, resulting in a 3μm thick wet carbon paste film. During coating, the hot air knife is positioned 5cm away from the carbon paste blade head, and is activated at the start of coating. The heating platform below the substrate is set to 70°C. Simultaneously, the slit-type hot air knife above the substrate sprays a hot air stream of 80°C at 15 m / s onto the wet film surface at a 70° angle and a distance of 25 mm for 20 seconds, rapidly drying and solidifying the carbon paste wet film.

[0028] Step S7, Post-processing. The prepared components are annealed in a vacuum drying oven at 100°C for 10 minutes to further remove residual solvent and optimize film contact.

[0029] The photoelectric performance of the fabricated 100mm×100mm flexible perovskite solar cell was tested under standard sunlight, where standard sunlight refers to AM1.5G and 100mW / cm². 2 The test results were as follows: open-circuit voltage was 22.5V, and short-circuit current density was 1.10mA / cm². 2 The fill factor is 72.4% and the photoelectric conversion efficiency is 19.4%.

[0030] Example 2

[0031] The difference between this embodiment and Embodiment 1 is that no polyether-modified siloxane was added to the carbon electrode.

[0032] Due to the absence of polyether-modified siloxane, the carbon slurry dispersion was extremely poor, resulting in surface defects such as cracks and abrasive particles on the carbon electrode coating. The root cause can be attributed to insufficient slurry dispersion. Specifically, the lack of polyether-modified siloxane in the formulation led to poor uniformity of carbon slurry dispersion during mixing, which in turn affected the density and smoothness of the coating, ultimately resulting in the aforementioned defects.

[0033] A 100mm × 100mm flexible perovskite solar cell was tested for its photoelectric performance under standard sunlight conditions. Standard sunlight refers to AM1.5G and 100mW / cm². 2 The test results were as follows: open-circuit voltage was 16V, and short-circuit current density was 0.7mA / cm². 2 The fill factor is 51.3% and the photoelectric conversion efficiency is 5.75%.

[0034] The data from the two embodiments above are recorded in Table 1 below: Table 1 - Example Data Table

[0035] The present invention, through the above embodiments, demonstrates that adding polyether-modified siloxane to the carbon paste significantly improves the dispersibility and coating uniformity of the carbon paste, effectively eliminating agglomeration and bubble defects. Simultaneously, the optimized process employing substrate heating and hot air knife synergistic drying balances drying rate and stress release, successfully avoiding carbon electrode cracking. This technology achieves a photoelectric conversion efficiency of over 19% on a 100mm × 100mm flexible perovskite solar cell, providing a practical solution for the low-cost, large-area, and efficient fabrication of flexible perovskite solar cells.

[0036] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for fabricating a flexible perovskite solar cell based on a slit-coated carbon electrode, characterized in that, include: A hole transport layer is prepared on a flexible conductive substrate, a perovskite light absorption layer is prepared on the hole transport layer, and an electron transport layer is prepared on the perovskite light absorption layer to obtain a substrate. Carbon paste is coated onto the electron transport layer by slit coating. During the coating process, the substrate is heated, and hot air is sprayed onto the wet film of the coated carbon paste behind the slit to generate a carbon electrode. The carbon paste contains a uniformly mixed carbon material, binder, solvent, and polyether-modified siloxane.

2. The method for fabricating a flexible perovskite solar cell based on a slit-coated carbon electrode according to claim 1, characterized in that, The polyether-modified siloxane accounts for 0.1-1% of the mass of the carbon material.

3. The method for fabricating a flexible perovskite solar cell based on a slit-coated carbon electrode according to claim 1, characterized in that, The polyether-modified siloxane is a polyether-modified trisiloxane with the chemical formula C. 12 H 32 O4Si3.

4. The method for fabricating a flexible perovskite solar cell based on a slit-coated carbon electrode according to claim 1, characterized in that, Heating the substrate during the coating process includes heating the substrate to 50~90°C during the coating process.

5. The method for fabricating a flexible perovskite solar cell based on a slit-coated carbon electrode according to claim 1, characterized in that, The temperature of the hot air is 60~100℃, and the airflow velocity of the hot air is 10~20m / s.

6. The method for fabricating a flexible perovskite solar cell based on a slit-coated carbon electrode according to claim 1, characterized in that, The angle between the direction of the hot air and the substrate is 50~70°.

7. The method for fabricating a flexible perovskite solar cell based on a slit-coated carbon electrode according to claim 1, characterized in that, The hot air is provided by a hot air knife, and the distance between the outlet of the hot air knife and the surface of the carbon slurry wet film is 20~40mm.

8. The method for fabricating a flexible perovskite solar cell based on a slit-coated carbon electrode according to claim 1, characterized in that, The thickness of the carbon paste wet film is 1.5~4.5μm.

9. A flexible perovskite solar cell based on a slit-coated carbon electrode, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 8.

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