Solar cell based on 2, 2-bis (4, 5-dimethylimidazole) passivated perovskite and preparation method thereof

Abstract

The invention discloses a solar cell based on 2, 2-bis (4, 5-dimethylimidazole) passivated perovskite and a preparation method thereof, and relates to the technical field of solar cells. The solar cell sequentially comprises a substrate, a first functional layer, a perovskite layer, a second functional layer, a transparent electrode and a metal electrode layer from bottom to top, wherein one of the first functional layer and the second functional layer comprises a hole transport layer, and the other one comprises an electron transport layer. A perovskite precursor solution of the perovskite absorption layer contains organic molecules with a certain concentration, the molecules are 2, 2-bis (4, 5-dimethylimidazole), and the concentration of the organic molecules is 0.05-10.00 mol%. In the solar cell, 2, 2-bis (4, 5-dimethylimidazole) is used as an in-vivo doping material of the perovskite layer, the perovskite crystal quality can be improved, and the cell performance is further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to a solar cell based on 2,2-bis(4,5-dimethylimidazole) body passivation perovskite and a preparation method thereof. Background Art

[0002] Tandem cells fabricated by combining wide-bandgap perovskites with crystalline silicon can break through the theoretical efficiency limitations of single-junction cells. Producing highly efficient wide-bandgap perovskite solar cells is crucial for improving the performance of tandem cells. Currently, solution spin coating is a popular method in various laboratories.

[0003] However, with the in-depth study of wide bandgap perovskite films, the solution spin coating method has also exposed many difficult problems. Generally speaking, widening the perovskite bandgap requires the addition of cesium ions (Cs + ), or by incorporating halogen ions such as bromide ions (Br - ), but excessive incorporation of these two ions will cause the perovskite crystallization rate to be too fast, resulting in poor film crystallization quality and the generation of a large number of deep energy level defects within the perovskite film. During battery operation, these defects can easily become carrier recombination centers, significantly affecting battery performance. Furthermore, the solubility of cesium salts during crystallization is often relatively low, which can easily induce undesirable secondary phases during the crystallization process of the perovskite film, interfering with crystallization. Similarly, the low solubility of lead bromide can also cause the crystallization rate to be too fast, affecting the quality of the perovskite film. In addition, I - With Br - There is a big difference in the crystallization rate between the two different halide ions. - It will also induce self-aggregation, resulting in uneven distribution of halides, forming iodine-rich phase and bromine-rich phase, leading to higher opening pressure loss.

[0004] At present, wide-bandgap perovskite films are plagued by problems such as poor crystallization quality and high defect density. For this reason, there are two main targeted solutions. The first strategy hopes to directly improve the crystallization quality of the film, aiming to control the generation of defects from the root. This requires precise control of various parameters and conditions in the crystallization process, so that the perovskite crystals can grow in an ideal environment and obtain the highest possible quality perovskite films. The second strategy is to introduce special functional molecules, such as additives such as methylamine hydrochloride (MACl), to regulate the perovskite crystallization process: they can promote further growth of the grains, making the original grains larger, and at the same time, effectively reducing the number of defects in the film. Organic amine salts are also commonly used passivators. For example, organic amine salts such as phenylethylamine (PEA) salts are directly introduced into the perovskite precursor solution to promote the formation of 2D / 3D heterojunctions. This unique structure can effectively passivate defects, thereby enhancing the stability of the device. On the one hand, they can react with Pb in the precursor solution. 2+The coordination of equal-depth energy level defects can effectively control the direction of crystallization; on the other hand, the negative electron or positive electron functional groups carried by itself can be used to accurately passivate charged defects. Summary of the Invention

[0005] To address the current crystallization and defect problems of wide-bandgap perovskites, the present invention adds a multifunctional molecular additive, 2,2-bis(4,5-dimethylimidazole) (tmbiimH2), to the precursor solution of a one-step solution process. The -NH groups contained in the material interact with the perovskite, effectively passivating the internal defects of the perovskite by means of the steric hindrance effect, while improving the crystallization quality of the perovskite and thereby enhancing battery performance.

[0006] The technical solution of the present invention is:

[0007] The purpose of the first aspect of the present invention is to provide a solar cell based on 2,2-bis(4,5-dimethylimidazole) body passivated perovskite, which comprises, from bottom to top, a substrate, a first functional layer, a perovskite absorption layer, a second functional layer, a transparent electrode and a metal electrode layer; wherein, one of the first functional layer and the second functional layer includes a hole transport layer, and the other includes an electron transport layer; the transparent conductive layer is prepared according to the specific needs of a single junction or a stacked cell; a buffer layer is provided between the second functional layer and the transparent conductive layer in the stacked cell structure; a certain concentration of organic molecules is added to the perovskite precursor solution of the perovskite absorption layer, the molecule being 2,2-bis(4,5-dimethylimidazole), and the concentration of the organic molecules is 0.05 to 10.00 mol%.

[0008] The second aspect of the present invention provides a method for preparing a 2,2-bis(4,5-dimethylimidazole) body-passivated inverted wide-bandgap perovskite solar cell, the method comprising:

[0009] (1) Cleaning a transparent conductive substrate and preparing a first functional layer on the transparent conductive substrate; the substrate is a silicon substrate with an intermediate connecting layer or a glass with a transparent electrode;

[0010] (2) spin coating a wide bandgap perovskite precursor solution doped with 2,2-bis(4,5-dimethylimidazole) on the first functional layer, and preparing a perovskite absorption layer after annealing;

[0011] (3) preparing a second functional layer on the perovskite absorption layer;

[0012] (4) Preparing a metal electrode on the second functional layer.

[0013] In the present invention, the first functional layer and the second functional layer are either hole transport layers or electron transport layers. That is, if the first functional layer is a hole transport layer, the second functional layer is an electron transport layer; if the first functional layer is an electron transport layer, the second functional layer is a hole transport layer.

[0014] The transparent conductive substrate in step (1) is one of FTO and ITO conductive glass;

[0015] The hole transport layer in step (1) is NiO x , SAM, PTAA or a combination thereof;

[0016] The perovskite precursor solution solvent in step (2) is a mixed solution of dimethylformamide and dimethyl sulfoxide, and the solute is Cs 0.78 FA 0.22 Pb(I 0.85 Br 0.15 )3; the concentration of the solute is 1.3M;

[0017] The perovskite absorption layer described in step (2) is prepared by spin coating a perovskite precursor solution and then annealing, the spin coating speed is 3000-5000 rpm / min, and the spin coating time is 90-110s; annealing is carried out in nitrogen at 100-150°C for 10-15min to prepare the perovskite absorption layer;

[0018] The doping 2,2-bis(4,5-dimethylimidazole) in step (2) has a concentration of 0.05 to 10.00 mol%.

[0019] The electron transport layer in step (3) is PCBM, SnO2, C 60 One or a combination of;

[0020] The metal electrode described in step (4) is a silver electrode, a gold electrode or a metal grid line.

[0021] The third aspect of the present invention provides a method for passivating a perovskite based on 2,2-bis(4,5-dimethylimidazole), which is suitable for the following structural devices:

[0022] a. Inorganic perovskite single-junction solar cells;

[0023] b. Hybrid perovskite single-junction solar cells;

[0024] c. Perovskite / perovskite tandem solar cells;

[0025] d. Perovskite / crystalline silicon tandem solar cells.

[0026] The advantages and positive effects of the present invention are:

[0027] This paper innovatively explores the effective introduction of tmbiimH2 into perovskite precursor solutions and clearly demonstrates its positive effect on improving solar cell efficiency. The impact of the introduction of tmbiimH2 on the properties of wide-bandgap perovskite films was analyzed, and the following conclusions were drawn:

[0028] (1) The doping of tmbiimH2 effectively improves the purity of the perovskite phase, significantly improves the quality of the perovskite film, and enhances the overall electrical properties, creating favorable conditions for improving the performance of optoelectronic devices based on perovskite films.

[0029] (2) The -NH group on tmbiimH2 can bind to the uncoordinated Pb 2+ , I - The effect is to effectively reduce the defect state density, obtain a longer carrier lifetime, improve the carrier collection efficiency and reduce energy loss.

[0030] (3) The introduction of tmbiimH2 improved the energy level matching between the intrinsic absorption layer and the carrier transport layer in the battery, which is beneficial to carrier transport. Finally, the battery achieved the best PCE of 20.66%, which is a significant improvement compared with the control group. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the structure of the perovskite solar cell of the present invention;

[0032] Figure 2 The chemical structure diagram of 2,2-bis(4,5-dimethylimidazole) used in the present invention;

[0033] Figure 3 This is a comparison chart of the photoelectric conversion efficiency of solar cells at different doping concentrations according to a specific embodiment of the present invention;

[0034] Figure 4 is a graph showing the volt-ampere characteristic of a perovskite solar cell according to a comparative embodiment of the present invention;

[0035] Figure 5 This is a graph showing the volt-ampere characteristic of a perovskite solar cell to which a dopant is added according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] This invention provides a solar cell based on 2,2-bis(4,5-dimethylimidazole)-passivated perovskite and its preparation method. Using 2,2-bis(4,5-dimethylimidazole) to passivate the perovskite effectively improves the efficiency and stability of the perovskite solar cell. The cell structure consists of a transparent conductive substrate, a hole transport layer, a perovskite absorption layer, an electron transport layer, and a metal electrode stacked from bottom to top.

[0038] Example 1:

[0039] The present invention provides a solar cell based on 2,2-bis(4,5-dimethylimidazole) body-passivated perovskite and a preparation method thereof, comprising the following steps:

[0040] 1. Clean the ITO substrate (2×2cm 2 ): Place the substrate in diluted glass detergent and ultrasonically clean it for 30 minutes to remove all kinds of stains attached to the surface of the substrate. After completing this step, transfer the substrate to deionized water and soak it in deionized water for 30 minutes to further remove residual detergent and other water-soluble impurities. Then, place the substrate in isopropyl alcohol (IPA) and ultrasonicate it again for 30 minutes. After the cleaning process is completed, in order to prevent the surface of the substrate from being contaminated by impurities again, soak it in IPA and store it properly for subsequent use;

[0041] 2. NiO X After ultrasonic treatment, the colloidal solution (25 mg / ml, deionized water solvent) was filtered through a 0.45 μm filter, and 55 μL of the filtrate was collected;

[0042] 3. When using the substrate, first place the substrate in a UV-O3 cleaning machine for 15 minutes, then take the NiO X The colloidal solution is spin-coated on the ITO conductive glass substrate in step 1 at a rotation speed of 2000-3000 rpm / min for 20-30 s; then, annealed in ambient air at 100-130°C for 15-30 min to obtain a hole transport layer; then, a NiO X The surface was spin-coated with a 0.5 mg / ml Me-4PACz ethanol solution at 5000 rpm / s and thermally annealed at 100°C for 10 minutes to complete the preparation of the hole transport layer.

[0043] 4. Accurately calculate and weigh formamidinium iodide (FAI), lead iodide (PbI2), lead bromide (PbBr2), and cesium iodide (CsI), and dissolve them in a DMF / DMSO solvent mixture with a volume ratio of 4:1 to obtain a perovskite solution; add 2,2-bis(4,5-dimethylimidazole)tmbiimH2 to the perovskite solution at a concentration of 0.15 mol%;

[0044] 5. Spin-coat the perovskite solution obtained in step 4 onto the hole transport layer obtained in step 3 at a speed of 3000-5000 rpm / min for 90-110 s; anneal in nitrogen at 100-150° C. for 10-15 min to obtain a perovskite absorption layer;

[0045] 6. Add PCBM powder to chlorobenzene and stir until completely dissolved to obtain an electron transport layer solution;

[0046] 7. Spin-coat the electron transport layer precursor solution obtained in step 6 on the perovskite absorption layer prepared in step 5 using a one-step spin coating method at a spin coating speed of 3000 to 5000 rpm / min for 30 to 50 seconds to prepare an electron transport layer;

[0047] 8. Evaporate a silver film with a thickness of 80 to 100 nm on the electron transport layer in step 7 to obtain a perovskite solar cell.

[0048] Example 2:

[0049] The present invention provides a solar cell based on 2,2-bis(4,5-dimethylimidazole) body-passivated perovskite and a preparation method thereof, comprising the following steps:

[0050] 1. Clean the ITO substrate (2×2cm 2 ): Place the substrate in diluted glass detergent and ultrasonically clean it for 30 minutes to remove all kinds of stains attached to the surface of the substrate. After completing this step, transfer the substrate to deionized water and soak it in deionized water for 30 minutes to further remove residual detergent and other water-soluble impurities. Then, place the substrate in isopropyl alcohol (IPA) and ultrasonicate it again for 30 minutes. After the cleaning process is completed, in order to prevent the surface of the substrate from being contaminated by impurities again, soak it in IPA and store it properly for subsequent use;

[0051] 2. NiO X After ultrasonic treatment, the colloidal solution (25 mg / ml, deionized water solvent) was filtered through a 0.45 μm filter, and 55 μL of the filtrate was collected;

[0052] 3. When using the substrate, first place the substrate in a UV-O3 cleaning machine for 15 minutes, then take the NiO X The colloidal solution is spin-coated on the ITO conductive glass substrate in step 1 at a rotation speed of 2000-3000 rpm / min for 20-30 s; then, annealed in ambient air at 100-130°C for 15-30 min to obtain a hole transport layer; then, a NiO X The surface was spin-coated with a 0.5 mg / ml Me-4PACz ethanol solution at 5000 rpm / s and thermally annealed at 100°C for 10 minutes to complete the preparation of the hole transport layer.

[0053] 4. Accurately calculate and weigh formamidinium iodide (FAI), lead iodide (PbI2), lead bromide (PbBr2), and cesium iodide (CsI), and dissolve these substances in a DMF / DMSO solvent mixed in a volume ratio of 4:1 to obtain a perovskite solution. 2,2-bis(4,5-dimethylimidazole)tmbiimH2 is added to the perovskite solution at a concentration of 0.30 mol%;

[0054] 5. Spin-coat the perovskite solution obtained in step 4 onto the hole transport layer obtained in step 3 at a speed of 3000-5000 rpm / min for 90-110 s; anneal in nitrogen at 100-150° C. for 10-15 min to obtain a perovskite absorption layer;

[0055] 6. Add PCBM powder to chlorobenzene and stir until completely dissolved to obtain an electron transport layer solution;

[0056] 7. Spin-coat the electron transport layer precursor solution obtained in step 6 on the perovskite absorption layer prepared in step 5 using a one-step spin coating method at a spin coating speed of 3000 to 5000 rpm / min for 30 to 50 seconds to prepare an electron transport layer;

[0057] 8. Evaporate a silver film with a thickness of 80 to 100 nm on the electron transport layer in step 7 to obtain a perovskite solar cell.

[0058] Example 3:

[0059] The present invention provides a solar cell based on 2,2-bis(4,5-dimethylimidazole) body-passivated perovskite and a preparation method thereof, comprising the following steps:

[0060] 1. Clean the ITO substrate (2×2cm 2 ): Place the substrate in diluted glass detergent and ultrasonically clean it for 30 minutes to remove all kinds of stains attached to the surface of the substrate. After completing this step, transfer the substrate to deionized water and soak it in deionized water for 30 minutes to further remove residual detergent and other water-soluble impurities. Then, place the substrate in isopropyl alcohol (IPA) and ultrasonicate it again for 30 minutes. After the cleaning process is completed, in order to prevent the surface of the substrate from being contaminated by impurities again, soak it in IPA and store it properly for subsequent use;

[0061] 2. NiO X After ultrasonic treatment, the colloidal solution (25 mg / ml, deionized water solvent) was filtered through a 0.45 μm filter, and 55 μL of the filtrate was collected;

[0062] 3. When using the substrate, first place the substrate in a UV-O3 cleaning machine for 15 minutes, then take the NiO X The colloidal solution is spin-coated on the ITO conductive glass substrate in step 1 at a rotation speed of 2000-3000 rpm / min for 20-30 s; then, annealed in ambient air at 100-130°C for 15-30 min to obtain a hole transport layer; then, a NiO XThe surface was spin-coated with a 0.5 mg / ml Me-4PACz ethanol solution at 5000 rpm / s and thermally annealed at 100°C for 10 minutes to complete the preparation of the hole transport layer.

[0063] 4. Accurately calculate and weigh formamidinium iodide (FAI), lead iodide (PbI2), lead bromide (PbBr2), and cesium iodide (CsI), and dissolve them in a DMF / DMSO solvent mixture with a volume ratio of 4:1 to obtain a perovskite solution. Add 2,2-bis(4,5-dimethylimidazole)tmbiimH2 to the perovskite solution at a concentration of 0.45 mol%;

[0064] 5. Spin-coat the perovskite solution obtained in step 4 onto the hole transport layer obtained in step 3 at a speed of 3000-5000 rpm / min for 90-110 s; anneal in nitrogen at 100-150° C. for 10-15 min to obtain a perovskite absorption layer;

[0065] 6. Add PCBM powder to chlorobenzene and stir until completely dissolved to obtain an electron transport layer solution;

[0066] 7. Spin-coat the electron transport layer precursor solution obtained in step 6 on the perovskite absorption layer prepared in step 5 using a one-step spin coating method at a spin coating speed of 3000 to 5000 rpm / min for 30 to 50 seconds to prepare an electron transport layer;

[0067] 8. Evaporate a silver film with a thickness of 80 to 100 nm on the electron transport layer in step 7 to obtain a perovskite solar cell.

[0068] Comparative Example:

[0069] The present invention provides a solar cell that does not contain 2,2-bis(4,5-dimethylimidazole) body-passivated perovskite and a preparation method thereof, comprising the following steps:

[0070] 1. Clean the ITO substrate (2×2cm 2 ): Place the substrate in diluted glass detergent and ultrasonically clean it for 30 minutes to remove all kinds of stains attached to the surface of the substrate. After completing this step, transfer the substrate to deionized water and soak it in deionized water for 30 minutes to further remove residual detergent and other water-soluble impurities. Then, place the substrate in isopropyl alcohol (IPA) and ultrasonicate it again for 30 minutes. After the cleaning process is completed, in order to prevent the surface of the substrate from being contaminated by impurities again, soak it in IPA and store it properly for subsequent use;

[0071] 2. NiO XAfter ultrasonic treatment, the colloidal solution (25 mg / ml, deionized water solvent) was filtered through a 0.45 μm filter, and 55 μL of the filtrate was collected;

[0072] 3. When using the substrate, first place the substrate in a UV-O3 cleaning machine for 15 minutes, then take the NiO X The colloidal solution is spin-coated on the ITO conductive glass substrate in step 1 at a rotation speed of 2000-3000 rpm / min for 20-30 s; then, annealed in ambient air at 100-130°C for 15-30 min to obtain a hole transport layer; then, a NiO X The surface was spin-coated with a 0.5 mg / ml Me-4PACz ethanol solution at 5000 rpm / s and thermally annealed at 100°C for 10 minutes to complete the preparation of the hole transport layer.

[0073] 4. Accurately calculate and weigh formamidinium iodide (FAI), lead iodide (PbI2), lead bromide (PbBr2), and cesium iodide (CsI), and dissolve them in a DMF / DMSO solvent mixed in a volume ratio of 4:1 to obtain a perovskite solution;

[0074] 5. Spin-coat the perovskite solution obtained in step 4 onto the hole transport layer obtained in step 3 at a speed of 3000-5000 rpm / min for 90-110 s; anneal in nitrogen at 100-150° C. for 10-15 min to obtain a perovskite absorption layer;

[0075] 6. Add PCBM powder to chlorobenzene and stir until completely dissolved to obtain an electron transport layer solution;

[0076] 7. Spin-coat the electron transport layer precursor solution obtained in step 6 on the perovskite absorption layer prepared in step 5 using a one-step spin coating method at a spin coating speed of 3000 to 5000 rpm / min for 30 to 50 seconds to prepare an electron transport layer;

[0077] 8. Evaporate a silver film with a thickness of 80 to 100 nm on the electron transport layer in step 7 to obtain a perovskite solar cell.

[0078] Different from Examples 1-3, no 2,2-bis(4,5-dimethylimidazole) organic molecules were added to the perovskite precursor solution of the perovskite absorber layer in this comparative example.

[0079] Figure 1 Schematic diagram of the structure of the perovskite solar cell of the present invention;

[0080] Figure 2 The chemical structure diagram of 2,2-bis(4,5-dimethylimidazole) used in the present invention;

[0081] Figure 3 3 is a comparison chart of the photoelectric conversion efficiency of different solar cells under the specific embodiment of the present invention; it can be found that the cell efficiency is optimal at a doping concentration of 0.3 mol%.

[0082] Figure 4 This is a volt-ampere characteristic curve of an inverted wide bandgap perovskite solar cell in the comparative example of the present invention without adding 2,2-bis(4,5-dimethylimidazole) body passivation, and the cell photoelectric conversion efficiency is 19.47%.

[0083] Figure 5 This is a volt-ampere characteristic curve of an inverted wide-bandgap perovskite solar cell with 2,2-bis(4,5-dimethylimidazole) body passivation added according to an embodiment of the present invention, and the cell photoelectric conversion efficiency is 20.66%.

[0084] The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, and the embodiments shown do not cover all options of the technical solutions of the present invention. For example, in step 2 of the embodiment, the hole transport layer is made of NiO. x In addition to SAM and PTAA, one or more combinations can be selected. In addition to PCBM, C 60 , SnO2, or one or more combinations thereof, any of the above selected embodiments can achieve the purpose of the present invention and achieve the technical effects of the present invention. It should be understood that any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A solar cell based on 2,2-bis(4,5-dimethylimidazole) body-passivated perovskite, characterized in that: The solar cell comprises, from bottom to top, a substrate, a first functional layer, a perovskite absorption layer, a second functional layer, a transparent electrode and a metal electrode layer; wherein, one of the first functional layer and the second functional layer comprises a hole transport layer, and the other comprises an electron transport layer; a buffer layer is provided between the second functional layer and the transparent conductive layer in the stacked cell structure; a certain concentration of organic molecules is added to the perovskite precursor solution of the perovskite absorption layer, wherein the molecule is 2,2-bis(4,5-dimethylimidazole), and the concentration of the organic molecule is 0.05 to 10.00 mol%.

2. A method for preparing a solar cell based on 2,2-bis(4,5-dimethylimidazole) body-passivated perovskite according to claim 1, characterized in that: The following steps are involved: (1) preparing a first functional layer on a substrate, wherein the substrate is a silicon substrate with an intermediate connecting layer or a glass substrate with a transparent electrode; (2) spin coating a perovskite precursor solution containing a certain concentration of 2,2-bis(4,5-dimethylimidazole) on the first functional layer, and annealing to prepare a perovskite absorption layer; (3) preparing a second functional layer on the perovskite absorption layer; (4) sequentially preparing a transparent electrode and a metal electrode on the second functional layer; The concentration of the added 2,2-bis(4,5-dimethylimidazole) is 0.05 to 10.00 mol%.

3. The preparation method according to claim 2, wherein The perovskite precursor solution solvent is a mixed solution of dimethylformamide and dimethyl sulfoxide, and the solute is Cs 0.78 FA 0.22 Pb(I 0.85 Br 0.15 )3; the concentration of the solute is 1.3M.

4. The preparation method according to claim 2, wherein The perovskite absorption layer is prepared by spin coating a perovskite precursor solution and then annealing, the spin coating speed is 3000-5000 rpm / min, the spin coating time is 90-110s; and the solution is annealed in nitrogen at 100-150°C for 10-15min.

5. The preparation method according to claim 2, wherein The transparent electrode is one of FTO and ITO conductive glass; the first functional layer and the second functional layer are hole transport layers or electron transport layers, and the hole transport layer is NiO x , SAM, PTAA or a combination thereof, the electron transport layer is PCBM, C 60 , SnO2 or a combination thereof; the metal electrode is a silver electrode, a gold electrode or a metal grid line.

6. The use of the 2,2-bis(4,5-dimethylimidazole) body passivated perovskite according to claim 1, characterized in that: Perovskite is suitable for the following structural devices: a. Inorganic perovskite single-junction solar cells; b. Hybrid perovskite single-junction solar cells; c. Perovskite / perovskite tandem solar cells; d. Perovskite / crystalline silicon tandem solar cells.

Images