Passivation method for nickel oxide hole transport layer of large-area perovskite cell

Abstract

The present application relates to the technical field of metal passivation treatment, and in particular, to a passivation method for a nickel oxide hole transport layer of a large-area perovskite cell, comprising the following steps: S1, depositing a NiOx film on the surface of a substrate in a sputter coating mode; S2, carrying out plasma treatment on the surface of the NiOx film; S3, dropwise adding an acidic solution into an annealing furnace, and heating to 100°C-150°C to completely volatilize the acidic solution so as to form a slightly acidic atmosphere; and S4, feeding the substrate containing the NiOx film into the annealing furnace for annealing, heating the annealing furnace to 300°C-600°C, keeping the temperature for 30-80 min, and then cooling. According to the method, a common annealing furnace can be used to create an acidic atmosphere, so as to complete a passivation operation on the surface of a nickel oxide film, thereby solving the reagent, energy and device costs, and obtaining better surface morphology, surface wettability and transmittance; and perovskite cells prepared on the basis of passivated nickel oxide films obtain an interface having a low defect density, thereby effectively improving the open-circuit voltage and the photoelectric conversion efficiency of the perovskite cells.

Description

A passivation method for nickel oxide hole transport layer in large-area perovskite cells Technical Field

[0001] The present application relates to the technical field of metal passivation treatment, and in particular to a passivation method for a nickel oxide hole transport layer in a large-area perovskite battery. Background Art

[0002] Inverse perovskite cells have attracted the attention of many experts in and outside the field due to their low cost, relatively simple preparation process and easy area expansion. In inverse perovskite cells, nickel oxide (NiO) is prepared by physical vapor deposition (PVD) sputtering. x ) Hole transport layers are quite popular in the industrialization process due to their low cost and ease of large-area preparation.

[0003] However, PVD-prepared NiO x There are still some problems that restrict the development of thin films, such as the relatively hydrophobic surface weakens the adhesion of the perovskite precursor, which leads to shrinkage of the perovskite wet film and pinholes in the dry film during large-area coating. Storage in the air and treatment with commonly used hydrophilic methods will lead to the deterioration of NiO x A large amount of highly oxidized Ni (Ni 3+ and Ni 4+ ) and chemically reactive hydroxyl groups (NiOOH and -Ni(OH)2), which react with the A-site cations and halide ions in the perovskite, resulting in a decrease in the quality of the coated perovskite layer and a significant reduction in the stability of the perovskite layer.

[0004] To date, many efforts have been made to solve this problem and improve the quality of the film layer, but these methods each have their own defects, which seriously restrict the industrial production of large-area modules.

[0005] 1. China Patent CN109841740A adopts ultraviolet ozone surface treatment process to solve the problem of uneven thickness and easy generation of holes in the nickel oxide hole transport layer prepared by spin coating. Although a good coating substrate can be obtained, the oversaturated ozone atmosphere may cause some Ni 3+ Oxidized to harmful Ni 4+ , while reducing the film transmittance and increasing the defect state density.

[0006] 2. Chinese patent CN116426894A subjects the nickel oxide film to a two-stage heating treatment and a post-annealing treatment, so that the nickel oxide film is recrystallized after high-temperature annealing, thereby improving its crystallinity and density, and further enhancing its corrosion resistance. However, the two-stage heating and post-annealing treatment requires high energy consumption, is difficult to process, and the annealing process is difficult to quantify.

[0007] 3. Chinese patent CN114759147A uses acidic aqueous solution to soak NiO x The substrate passivates the transmission bottom interface of the perovskite battery device and can effectively reduce the interface defects between the perovskite and the transmission layer. However, soaking in an acidic aqueous solution is not conducive to large-area membrane surface treatment. In the subsequent drying process, it is difficult to evenly remove the acidic aqueous solution on the surface, resulting in coating holes and patches.

[0008] Therefore, it is necessary to design a new passivation method to avoid the above problems.

[0009] Summary of the Invention

[0010] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0011] The present application provides a passivation method for the nickel oxide hole transport layer of a large-area perovskite battery, which is not only applicable to the passivation needs of large-area perovskite batteries, but also can avoid solution residue and improve the passivation effect.

[0012] The present application provides a method for passivating a nickel oxide hole transport layer in a large-area perovskite cell, the steps of which include:

[0013] S1. Deposit NiO on the surface of the substrate by sputtering x film;

[0014] S2. NiO x The surface of the film is plasma treated;

[0015] S3. The acidic aqueous solution is dripped into the annealing furnace and heated to 100-150 ° C to completely evaporate it to form a slightly acidic atmosphere;

[0016] S4. Containing NiO x The substrate of the film is sent to the annealing furnace for annealing. The annealing furnace is heated to 300-600°C, kept warm for 30-80 minutes, and then cooled.

[0017] Specifically, the sputtering conditions of step S1 are: the flow ratio of O2 and Ar is 0-5:100, the sputtering power is 2-4.5kW, and the NiO x The target material is doped with one or two of Cu, Mg, Li, Ag, K and Na.

[0018] Specifically, the solute of the acidic aqueous solution is one or more of hydroiodic acid, hydrobromic acid, hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid or acetic acid, and the concentration is 0.01-0.05 mol / L.

[0019] Specifically, the acidic aqueous solution is dripped around the substrate.

[0020] Specifically, the temperature rising process in step S4 lasts for 2 hours, and the temperature dropping from 300-600° C. to room temperature takes 3 hours.

[0021] Compared with the related art, this application has the following beneficial effects.

[0022] 1. This method is to sputter NiO x The film undergoes a plasma-induced oxidation process and a reduction process using an ordinary annealing furnace to create an acidic solvent atmosphere annealing to achieve passivation of the film layer. The equipment cost is low, which is conducive to promoting the industrialization process.

[0023] 2. The acidic atmosphere is formed by the evaporation of a small amount of acidic aqueous solution. The amount of acidic aqueous solution used is small. The annealing temperature required for acidic solvent atmosphere annealing is lower than that required for direct annealing, which shortens the time of the entire process and reduces energy consumption. Compared with drying after immersion in acidic aqueous solution, acidic solvent atmosphere annealing is more efficient and more suitable for uniform passivation of large-area films. It avoids subsequent coating problems caused by uneven solution removal due to drying, and also avoids waste of immersion solution and pollution to the environment.

[0024] 3. Sputtered NiO x The film contains a large amount of high-valent Ni and reactive groups that are harmful to perovskite. However, the transmittance of the passivated film is significantly improved, the charge mobility of nickel oxide is improved, and the interface non-radiative recombination is effectively suppressed, thereby obtaining an interface with low defect density, which effectively improves the open circuit voltage and photoelectric conversion efficiency of the perovskite battery.

[0025] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 shows sputtered NiO before and after passivation x Transmission (UV-Vis) spectra of thin films;

[0027] Figure 2 shows sputtered NiO before and after passivation x Water drop angle test diagram of the film;

[0028] Figure 3 shows sputtered NiO before passivation x Scanning electron microscopy (SEM) images of the films;

[0029] Figure 4 shows sputtered NiO after passivation x Scanning electron microscopy (SEM) images of the films;

[0030] Figure 5 shows sputtered NiO before and after passivation x Fluorescence (PL) spectra of perovskite films prepared on the films respectively;

[0031] Figure 6 shows the sputtered NiO before and after passivationx JV performance test curve of thin film inverse perovskite solar cell module. DETAILED DESCRIPTION

[0032] The present application is further described in detail below with reference to specific embodiments.

[0033] Example:

[0034] The following steps are used to passivate the nickel oxide hole transport layer of large-area perovskite cells:

[0035] S1. Deposit NiO on the surface of the substrate by sputtering x The sputtering conditions of the film are: the flow ratio of O2 and Ar is 0-5:100, the sputtering power is 2-4.5kW, NiO x The target material is doped with one or two of Cu, Mg, Li, Ag, K and Na.

[0036] In this step, electrons, accelerated by the electric field, collide with argon atoms as they fly toward the substrate, ionizing a large number of argon ions and electrons. The argon ions, accelerated by the electric field, bombard the target material, sputtering a large number of target atoms. These neutral target atoms (or molecules) are deposited on the substrate to form a film. Doping improves energy conversion efficiency.

[0037] S2. NiO x The surface of the film is plasma treated.

[0038] Sputtered NiO x In addition to the NiO skeleton, the film only contains Ni 3+ It is beneficial to the performance of semiconductors. High-energy plasma can induce the conversion of low-valent NiO and Ni(OH)2 to high-valent Ni 3+ oxidation process, thereby improving semiconductor performance.

[0039] S3. dripping the acidic aqueous solution into the annealing furnace and heating it to 100-150°C to completely volatilize it to form a slightly acidic atmosphere. The solute of the acidic aqueous solution is one or more of hydroiodic acid, hydrobromic acid, hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid or acetic acid, with a concentration of 0.01-0.05 mol / L.

[0040] Annealing in an acidic solvent atmosphere can selectively remove harmful Ni through reduction reactions. 4+ and -OH, but retains the beneficial Ni 3+ In actual processing, although the area of ​​the substrate is large, the NiO xThe thickness of the film is only about 20nm, and not all nickel participates in the reaction, so the amount of the above acidic substances does not need to be large. A sufficient amount of acidic aqueous solution can be selected according to the size of the treatment surface. The concentration range is mainly for safety considerations and does not affect the treatment results themselves. In addition, the annealing temperature required for annealing in an acidic solvent atmosphere is lower than that for direct annealing, and it is more efficient than immersion in an acidic aqueous solution, and is more suitable for uniform passivation of large-area films. The passivated film finally obtains a lower surface tension, a more stable surface, and stronger surface electrical properties.

[0041] The acidic aqueous solution is preferably dripped around the substrate. Because the perovskite cell to be prepared is large, the space within the annealing furnace is also large. If dripped only in one location, it would take a long time for the vapor to fill the entire space. However, when dripped around the substrate, the acidic aqueous solution evaporates from all parts of the annealing furnace, distributing it more evenly throughout the space. This reduces preparation time and ensures that the acid mist fully contacts the nickel oxide surface, ensuring uniform treatment.

[0042] S4. Containing NiO x The substrate of the film is sent to the annealing furnace for annealing. The annealing furnace is heated to 300-600°C, kept warm for 30-80 minutes, and then cooled.

[0043] In the case of fast switching speeds, the loss of acid mist from the annealing furnace can be ignored.

[0044] The heating process lasts for 2 hours, and the cooling process from 300-600℃ to room temperature takes 3 hours. This can reduce the thermal shock to the substrate caused by rapid temperature changes and ensure the integrity of the product.

[0045] Sputtered NiO x The film appears black, which is due to the participation of oxygen in the sputtering process, which increases the content of high-valent nickel in the sputtered film, and the NiO x The light transmittance is enhanced and the black color of the film becomes lighter, which directly indicates that NiO x The medium and high valent nickel is reduced to low valent nickel by the ions in the perovskite. x The transmittance of the film is 64.7%, while the passivated NiO x The transmittance of the film is 73.2%, showing enhanced light transmission ability, as shown in Figure 1. In Figure 2, the left picture shows NiO before passivation x The water drop angle test diagram of the film, the test water drop angle is 17.05°, the right picture is the NiO after passivation x The water drop angle test diagram of the film shows that the water drop angle is 10.09°, which shows that the passivated NiO xThe better surface wettability of the film is conducive to the subsequent spreading of the perovskite coating, reducing the perovskite holes and recombination sites caused by poor surface wettability. Figures 3 and 4 show the passivated NiO x The grains are denser, which is conducive to the crystal growth of perovskite. Figure 5 shows that after passivation, NiO x The perovskite film prepared on the film has more significant fluorescence quenching, showing that the passivated modified nickel oxide film has stronger hole extraction ability and higher hole mobility, indicating that the non-radiative recombination at the interface between perovskite and nickel oxide is suppressed, which is beneficial to the increase in voltage.

[0046] Based on passivated NiO x The inverse perovskite solar cell module was manufactured. The module size was 182mm×182mm, the number of effective sub-cells was 20, and the effective area was 212cm 2 , and then conduct various tests. The test parameters are shown in the table below:

[0047] The table above shows that the short-circuit current and fill factor have basically not changed, but the open-circuit voltage and photoelectric conversion efficiency have improved to a certain extent, as shown in Figure 6, which reflects that NiO x Suppressed non-radiative recombination at the perovskite interface.

[0048] The focus of this technical solution is to use the evaporated acidic aqueous solution as the gas atmosphere in the early stage of annealing, thereby saving costs and improving product quality. Therefore, the selection of some reagents and the increase or decrease in the amount of use do not affect the achievement of the results.

[0049] The above are only some embodiments of the present application. For those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of the present application, and these all fall within the scope of protection of the present application.

Claims

1. A passivation method for nickel oxide hole transport layer of large-area perovskite solar cells, the steps of which include: S1. Deposit NiO thin film on the surface of the substrate by sputtering coating x film; S2. Plasma-treat the surface of the NiO x thin film; S3. Drop the acidic aqueous solution into the annealing furnace, heat it to 100 - 150 °C, and let it volatilize completely to form a slightly acidic atmosphere; S4. Feed the substrate with the NiO x thin film into an annealing furnace for annealing. Heat the annealing furnace to 300 - 600 °C, hold for 30 - 80 min, and then cool down.

2. The passivation method of nickel oxide hole transport layer for large-area perovskite solar cells according to claim 1, wherein, The sputtering conditions of the step S1 are as follows: the flow ratio of O2 and Ar introduced is 0 - 5:100, the sputtering power supply power is 2 - 4.5 kW, and the NiO x target is doped with one or two of Cu, Mg, Li, Ag, K, and Na.

3. The method for passivating the nickel oxide hole transport layer of the large-area perovskite solar cell according to claim 1, wherein, The solute of the acidic aqueous solution is one or several of hydroiodic acid, hydrobromic acid, hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid or acetic acid, and the concentration is 0.01 - 0.05 mol / L.

4. The passivation method of the nickel oxide hole transport layer of the large-area perovskite battery according to claim 1, wherein, The acidic aqueous solution is dropped around the substrate.

5. The passivation method of nickel oxide hole transport layer for large-area perovskite solar cells according to claim 1, wherein, The heating process in step S4 lasts for 2 h, and it takes 3 h to cool from 300 - 600 °C to room temperature.

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