Perovskite solar cell and passivation method thereof

Abstract

The present application relates to a kind of perovskite solar cells and its passivation method, the electron blocking layer is made of acyl chloride group derivative, on the one hand, the carbonyl group in acyl chloride group can be coordinated with the Pb 2+ Ion forms Lewis acid-base pair, thereby significantly reduce the defect state density of perovskite surface.Let go of group Cl ‑ Ion can increase the grain size of perovskite, improve the crystalline quality of perovskite layer.In addition, acyl chloride group and perovskite component reaction generates electron blocking layer cesium acetate, reduces the charge recombination at interface, while it can promote energy level gradient arrangement, effectively improve the separation and extraction capacity of carrier, successfully improve the photoelectric conversion efficiency and stability of carbon-based hole-free all-inorganic perovskite solar cell, and significantly reduce the hysteresis effect.The present application process is simple and has universality, is conducive to promoting the commercialization of perovskite, has wide market demand and application prospect.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to a perovskite solar cell and its passivation method. Background Technology

[0002] While the photoelectric conversion efficiency of organic-inorganic hybrid perovskite solar cells is currently comparable to that of crystalline silicon solar cells, their stability is relatively poor. All-inorganic perovskite solar cells (CsPbX3, X:Cl,Br,I) formed by replacing volatile organic cations with inorganic Cs ions exhibit excellent thermal stability. Compared to metal electrodes, inexpensive carbon electrodes possess excellent chemical inertness and can be prepared in various ways, making them flexible for application in various perovskite fabrication processes. Furthermore, the bipolar transport properties of the perovskite layer and the inherent hole extraction capability of the carbon electrode provide a theoretical basis for fabricating hole-free, all-inorganic carbon-based perovskite solar cells.

[0003] However, compared to perovskite solar cells with metal electrodes and hole transport layers, the photoelectric conversion efficiency of carbon-based hole-free all-inorganic perovskite solar cells remains relatively low. This is partly due to the direct contact between the carbon electrode and the perovskite layer, which places high demands on the crystal quality of the perovskite layer, especially the defect state density on the perovskite surface. Perovskite defects are mainly concentrated on the surface, and these surface defects are one of the main reasons for the reduced photoelectric conversion efficiency and poor stability of perovskite solar cells. Another reason is the significant energy level barrier between the carbon electrode and the perovskite in all-inorganic perovskite solar cells, which greatly affects the carrier separation efficiency at the perovskite / carbon interface and leads to severe carrier recombination.

[0004] Currently, common methods for passivating perovskite surface defects in existing technologies involve chemical passivation using organic molecules or polymers, or physical covering of structural defects with hydrophobic organic materials to achieve the effect of passivating surface defects. However, these methods do not simultaneously address the energy level matching issue between the carbon electrode and the all-inorganic perovskite. Both of these issues must be resolved simultaneously to effectively improve the stability and photoelectric conversion efficiency of carbon-based hole-free all-inorganic perovskite solar cells. Summary of the Invention

[0005] To simultaneously passivate perovskite defects and reduce the energy level barrier between the carbon electrode and the perovskite in an all-inorganic perovskite solar cell, this invention provides a perovskite solar cell and its passivation method. This invention employs acyl chloride groups and their derivatives to passivate the perovskite solar cell. On one hand, the carbonyl group in the acyl chloride group can interact with uncoordinated Pb on the perovskite surface. 2+ Ions form Lewis acid-base pairs, thus significantly reducing the defect state density on the perovskite surface. On the other hand, the leaving group Cl... -Ions can increase the grain size of perovskite and improve the crystallinity of the perovskite layer. In addition, the acyl chloride groups react with the perovskite components to form an electron-blocking layer of cesium acetate chloride, reducing charge recombination at the interface and promoting energy level gradient alignment. This effectively improves the carrier separation and extraction capability, successfully enhancing the photoelectric conversion efficiency and stability of carbon-based hole-free all-inorganic perovskite solar cells and significantly reducing hysteresis. Furthermore, the process of this invention is simple and universal, which is conducive to promoting the commercial application of perovskite and has broad market demand and application prospects.

[0006] The perovskite solar cell provided by this invention comprises the following structure: conductive substrate, electron transport layer, perovskite layer, electron blocking layer, and electrode layer.

[0007] The electron blocking layer is composed of acyl chloride group derivatives. On the one hand, the carbonyl group in the acyl chloride group can interact with uncoordinated Pb on the perovskite surface. 2+ Ions form Lewis acid-base pairs, thus significantly reducing the defect state density on the perovskite surface. On the other hand, the leaving group Cl... - Ions can increase the grain size of perovskite and improve the crystallinity of the perovskite layer. In addition, acyl chloride groups react with perovskite components to form an electron-blocking layer of cesium acetate chloride, which reduces charge recombination at the interface and promotes energy level gradient alignment, effectively improving the carrier separation and extraction capability. This successfully improves the photoelectric conversion efficiency and stability of carbon-based hole-free all-inorganic perovskite solar cells and significantly reduces the hysteresis effect.

[0008] The present invention provides a perovskite solar cell and a passivation method thereof, the technical solution of which includes the following steps:

[0009] (1) Assemble an electron transport layer on the conductive surface of the cleaned conductive substrate;

[0010] (2) Weigh the perovskite reagents in stoichiometric proportions and dissolve them in solvent A. Stir until the solution is clear to obtain a perovskite precursor solution of a certain concentration. Dissolve the acyl chloride group derivative in solvent B in stoichiometric proportions to prepare a passivating agent solution containing acyl chloride groups of a certain concentration.

[0011] (3) Ozone the assembled electron transport layer substrate for 5-50 minutes; then drop a certain amount of perovskite precursor solution onto the upper surface of the electron transport layer, let it stand, spin coat at 200-2000 rpm for 3-30 seconds, and then spin coat at 500-5000 rpm for 10-60 seconds; after spin coating, quickly transfer the substrate to a hot stage at 40-90℃ for annealing for 1-10 minutes, and then transfer it to a hot stage at 130-300℃ for annealing for 5-60 minutes to form a perovskite layer;

[0012] (4) A certain amount of passivating agent solution containing acyl chloride groups is dropped onto the surface of the perovskite layer. After standing for 1-30 minutes, it is rotated at a speed of 500-5000 rpm for 5-30 seconds. Then it is placed on a hot stage at 30-110℃ for annealing for 5-60 minutes to prepare an electron blocking layer.

[0013] (5) Assemble the carbon electrode onto the electron blocking layer.

[0014] The blank control group consists of perovskite solar cells without an electron blocking layer. Except for step (4), the preparation method is the same for all other steps.

[0015] The preferred conductive substrate is any one of PET, FTO, and ITO;

[0016] The preferred electron transport layer is any one of PCBM, SnO2, ZnO, and TiO2;

[0017] The preferred solvent A is any one of DMSO and DMF or a mixture thereof in any ratio;

[0018] The preferred solvent B is any one or a mixture of any number of ethanol, ethyl acetate, propanol, isopropanol, chlorobenzene, and diethyl ether in any proportion;

[0019] Preferred acyl chloride derivatives are any one or any mixture of any number of the following in any proportion: trichloroacetyl chloride, benzoyl chloride, benzoyl chloride, sulfonyl chloride, oxalyl chloride, furfural chloride, benzenesulfonyl chloride, fluoroacetyl chloride, malonyl chloride, phenylbutyryl chloride, salicyl chloride, chloroacetyl chloride, succinyl chloride, octanoyl chloride, oleyl chloride, heptanyl chloride, decanoyl chloride, valeryl chloride, butyryl chloride, hexanoyl chloride, propionyl chloride, nonanoyl chloride, and phthaloyl chloride.

[0020] The preferred volume of the perovskite precursor added is 50-150 μL;

[0021] The preferred molar concentration of the perovskite precursor is 0.5 M to 2.0 M;

[0022] The preferred perovskite layer is an all-inorganic perovskite CsPbX3 (X = Cl, Br, I), where the element at the X site is any one or any mixture of Cl, Br, and I in any ratio.

[0023] The preferred concentration of the passivating agent solution containing acyl chloride groups is 0.05 mg / ml to 50 mg / ml;

[0024] The preferred volume of the passivating agent solution containing acyl chloride groups added is 10-150 μL;

[0025] The electron blocking layer is generated by modifying a passivating agent solution containing acyl chloride groups. On the one hand, the carbonyl group in the acyl chloride group can interact with the uncoordinated Pb on the perovskite surface. 2+ Ions form Lewis acid-base pairs, thus significantly reducing the defect state density on the perovskite surface. On the other hand, the leaving group Cl... - Ions can increase the grain size of perovskite and improve the crystallinity of the perovskite layer. In addition, acyl chloride groups react with perovskite components to form an electron-blocking layer of cesium acetate chloride, reducing charge recombination at the interface. This also alters the energy levels on the perovskite film surface, promoting energy level gradient alignment with the carbon electrode and improving the contact between the perovskite layer and the electrode. This reduces the energy level barrier, making hole transfer and extraction more efficient, successfully improving the photoelectric conversion efficiency and stability of carbon-based hole-free all-inorganic perovskite solar cells. The general equation for the electron-blocking layer reaction is:

[0026] R-COCl+H2O→R-COOH+HCl↑ (1)

[0027] R-COOH+CsI→R-COOCs+HI↑ (2)

[0028] R-COOCs+R-COOH→R-COOCs·R-COOH (3)

[0029] Where R represents alkyl, phenyl, aldehyde, sulfonyl, furfural, and naphthyl groups with different carbon chain lengths.

[0030] The beneficial effect of this invention is that, after passivation modification with acyl chloride group derivatives, on the one hand, the carbonyl group in the acyl chloride group can interact with the uncoordinated Pb on the perovskite surface. 2+ Ions form Lewis acid-base pairs, thus significantly reducing the defect state density on the perovskite surface. On the other hand, the leaving group Cl... - Ions can increase the grain size of perovskite and improve the crystallinity of the perovskite layer. In addition, acyl chloride groups react with perovskite components to form an electron-blocking layer of cesium acetate chloride, reducing charge recombination at the interface. Simultaneously, this alters the energy levels on the perovskite film surface, promoting energy level gradient alignment with the carbon electrode and improving the contact between the perovskite layer and the electrode. This reduces the energy level barrier, making hole transfer and extraction more efficient, successfully improving the photoelectric conversion efficiency and stability of carbon-based hole-free all-inorganic perovskite solar cells. This invention features a simple process, high reproducibility, significant market value, and broad application prospects, accelerating the commercial application of perovskite solar cells.

[0031] The invention will be further described below with reference to the accompanying drawings.

[0032] Figure 1 This is a schematic diagram of the structure of a perovskite solar cell prepared according to Example 1 of the present invention.

[0033] 1-Substrate, 2-Electron transport layer, 3-Perovskite layer, 4-Electron blocking layer, 5-Carbon electrode layer.

[0034] Figure 2 This is a surface morphology diagram of a perovskite solar cell prepared according to Example 1.

[0035] Figure 3 This is an X-ray diffraction pattern of the perovskite layer prepared according to Example 1.

[0036] Figure 4 This is a diagram showing the energy level structure of a perovskite solar cell before and after passivation, prepared according to Example 1.

[0037] Figure 5 This is a JV curve diagram of the perovskite solar cell prepared according to Example 1 before and after passivation. Detailed Implementation

[0038] The present invention will be further described below through embodiments.

[0039] Example 1:

[0040] (1) The conductive substrate FTO was ultrasonically cleaned for 15 min in sequence with deionized water, ethanol, acetone and isopropanol; a dense TiO2 electron transport layer was prepared on its conductive surface.

[0041] (2) According to the stoichiometric ratio, weigh out a certain amount of PbI2, PbBr2 and CsI in sequence, dissolve them in a solvent with a volume ratio of DMSO:DMF = 9:1, place them on a hot plate at 50℃ and stir for 24 hours to prepare a 1.5M perovskite precursor solution; dissolve trichloroacetyl chloride in isopropanol solution to prepare a 0.5mg / ml trichloroacetyl chloride solution;

[0042] (3) After ozone treatment of the substrate with TiO2 electron transport layer for 15 min, the substrate was transferred to a spin coater. 50 μL of 1.5 M perovskite precursor solution was dropped onto the substrate. After it was evenly spread, the substrate was first spin coated at 1000 rpm for 15 seconds, and then at 3000 rpm for 30 seconds. After spin coating, the substrate was quickly transferred to a hot stage at 75 °C for annealing for 5 minutes, and then transferred to a hot stage at 230 °C for annealing for 20 minutes to form a CsPbI2Br all-inorganic perovskite layer.

[0043] (4) After cooling the substrate prepared in the above steps to room temperature, 100 μL of trichloroacetyl chloride solution was dropped onto its surface. After standing for 15 minutes, it was rotated at 3000 rpm for 15 seconds. Then it was placed on a hot stage at 70°C for annealing for 20 minutes to prepare an electron blocking layer.

[0044] (5) Apply commercial carbon paste to the electron blocking layer and anneal at 110°C for 15 min.

[0045] The surface microstructure and X-ray diffraction results of the perovskite solar cell prepared in Example 1 are as follows: Figure 2 , Figure 3 As shown, a layer of needle-like cesium acetate crystals, which is the electron transport layer, is clearly formed on the surface of the perovskite. The X-ray diffraction pattern shows new crystallization peaks in the passivated perovskite. Comparison with standard X-ray spectra confirms that these new peaks are indeed cesium acetate crystallization peaks (JCPDS No. 29-1413). Figure 4 As shown, the electron transport layer alters the energy levels on the perovskite film surface, suppressing electron transfer to the carbon electrode, promoting energy level gradient alignment between the perovskite layer and the carbon electrode, and reducing the energy level barrier, thereby making hole transfer and extraction more efficient. Figure 5 It is evident that the photoelectric conversion efficiency, open-circuit voltage, and fill factor of perovskite solar cells containing electron transport layers have all been significantly improved.

[0046] Example 2:

[0047] (1) The conductive substrate FTO was ultrasonically cleaned for 15 min in sequence with deionized water, ethanol, acetone and isopropanol; a dense TiO2 electron transport layer was prepared on its conductive surface; then a mesoporous TiO2 electron transport layer was prepared.

[0048] (2) Weigh out a fixed amount of CsI, DMAI and PbI2 in sequence according to the stoichiometric ratio, dissolve them in DMF solvent, stir until the solution is clear, and prepare a 1M perovskite precursor solution; dissolve benzoyl chloride in chlorobenzene solution to prepare a benzoyl chloride solution with a concentration of 0.05 mg / ml.

[0049] (3) After ozone treatment of the substrate with the mesoporous TiO2 electron transport layer for 15 min, it was transferred to a spin coater. 70 μL of 1 M perovskite precursor solution was dropped onto its surface. After it was evenly spread, it was first spin coated at 1000 rpm for 20 seconds, and then at 4000 rpm for 40 seconds. After spin coating, the substrate was quickly transferred to a hot stage at 80°C for annealing for 8 minutes, and then transferred to a hot stage at 200°C for annealing for another 40 minutes to form a CsPbI3 all-inorganic perovskite layer.

[0050] (4) After cooling the substrate prepared in the above steps to room temperature, 70 μL of benzoyl chloride solution is dropped onto its surface. After standing for 20 minutes, it is rotated at 900 rpm for 20 seconds and then placed on a hot stage at 70°C for annealing for 30 minutes to prepare an electron blocking layer.

[0051] (5) Apply commercial carbon paste to the electron blocking layer and anneal at 110°C for 10 min.

[0052] Example 3:

[0053] (1) The conductive substrate ITO was ultrasonically cleaned with deionized water, ethanol, acetone and isopropanol for 20 min in sequence; a dense SnO2 electron transport layer was prepared on its conductive surface.

[0054] (2) Weigh out a fixed amount of PbI2, PbBr2 and CsI in stoichiometric ratio, dissolve them in a solvent with a volume ratio of DMSO:DMF = 1:9, stir until the solution is clear, and prepare a 0.5M perovskite precursor solution; dissolve malonyl chloride in ethyl acetate solution to prepare a malonyl chloride solution with a concentration of 25 mg / ml.

[0055] (3) After ozone treatment of the substrate with SnO2 electron transport layer for 15 min, the substrate was transferred to a spin coater. 50 μL of 0.5 M perovskite precursor solution was dropped onto the substrate. After it was evenly spread, the substrate was first spin coated at 200 rpm for 3 seconds, and then at 500 rpm for 10 seconds. After spin coating, the substrate was quickly transferred to a hot stage at 40 °C for annealing for 10 minutes, and then transferred to a hot stage at 130 °C for annealing for another 5 minutes to form a CsPbIBr2 all-inorganic perovskite layer.

[0056] (4) After cooling the substrate prepared in the above steps to room temperature, 10 μL of malonyl chloride solution is dropped onto its surface, and after standing for 1 minute, it is rotated at 500 rpm for 5 seconds. Then it is placed on a hot stage at 30°C for annealing for 60 minutes to prepare an electron blocking layer.

[0057] (5) Apply commercial carbon paste to the electron blocking layer and anneal at 100°C for 20 min.

[0058] Example 4:

[0059] (1) The conductive substrate PET was ultrasonically cleaned for 10 min in sequence with deionized water, ethanol, acetone and isopropanol; a dense PCBM electron transport layer was prepared on its conductive surface.

[0060] (2) Weigh out a fixed amount of PbI2, PbBr2 and CsI in stoichiometric ratio, dissolve them in a solvent with a volume ratio of DMSO:DMF = 5:5, stir until the solution is clear, and prepare a 2M perovskite precursor solution; dissolve sulfonyl chloride in ethanol solution to prepare a sulfonyl chloride solution with a concentration of 50 mg / ml.

[0061] (3) After ozone treatment of the substrate with the PCBM electron transport layer for 20 min, it was transferred to a spin coater. 150 μL of a 2M perovskite precursor solution was dropped onto its surface. After it was evenly spread, it was first spin-coated at 2000 rpm for 30 seconds, and then at 5000 rpm for 60 seconds. After spin-coating, the substrate was quickly transferred to a 90℃ hot plate for annealing for 1 minute, and then transferred to a 300℃ hot plate for annealing for another 5 minutes to form CsPbI. 2.2 Br 0.8 All-inorganic perovskite layer;

[0062] (4) After cooling the substrate prepared in the above steps to room temperature, 150 μL of sulfonyl chloride solution is dropped onto its surface. After standing for 30 minutes, it is rotated at 5000 rpm for 30 seconds. Then it is placed on a hot stage at 110°C for annealing for 5 minutes to prepare an electron blocking layer.

[0063] (5) Apply commercial carbon paste to the electron blocking layer and anneal at 100°C for 15 min.

[0064] The embodiments described above are merely illustrative of the present invention and do not limit the scope of the invention. The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0065] The above description is based on the ideal embodiment of the present invention and is merely a specific example of the process parameters and requirements involved. Through the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of the present invention.

[0066] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0067] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A perovskite solar cell comprising the following structure: a conductive substrate, a mesoporous electron transport layer, a perovskite layer, an electron blocking layer, and a carbon electrode layer arranged sequentially; wherein the electron blocking layer is prepared from an acyl chloride group derivative, wherein the acyl chloride group reacts with the perovskite component to generate the electron blocking layer cesium acetate chloride; wherein the acyl chloride group derivative is any one or a mixture of any number of trichloroacetyl chloride, benzoyl chloride, oxalyl chloride, furfural chloride, fluoroacetyl chloride, malonyl chloride, phenylbutyryl chloride, salicylyl chloride, chloroacetyl chloride, succinyl chloride, octanoyl chloride, oleyl chloride, heptanyl chloride, decanoyl chloride, valeratel chloride, butyryl chloride, hexanoyl chloride, propionyl chloride, nonanoyl chloride, and phthaloyl chloride in any proportion; wherein the perovskite layer is an all-inorganic perovskite CsPbX3, and the element at the X-position is any one or a mixture of any number of Cl, Br, and I in any proportion.

2. A method for passivating perovskite solar cells, comprising the following steps: (1) Assemble a mesoporous electron transport layer on the conductive surface of the cleaned conductive substrate; (2) Weigh the perovskite raw materials in stoichiometric proportions and dissolve them in solvent A. Stir until the solution is clear to obtain a perovskite precursor solution of a certain concentration. Dissolve the acyl chloride group derivative in solvent B in a certain proportion to prepare a passivating agent solution containing acyl chloride group of a certain concentration. (3) Ozone treatment of the assembled electron transport layer substrate for 5-50 min; then drop a certain amount of perovskite precursor solution onto the upper surface of the electron transport layer, let it stand, spin coat at 200-2000 rpm for 3-30 seconds, and then spin coat at 500-5000 rpm for 10-60 seconds; after spin coating, quickly transfer the substrate to a hot stage at 40-90℃ for annealing for 1-10 minutes, and then transfer it to a hot stage at 130-300℃ for annealing for 5-60 minutes to form a perovskite layer; (4) A certain amount of passivating agent solution containing acyl chloride groups is dropped onto the surface of the perovskite layer. After standing for 1-30 minutes, it is rotated at 500-5000 rpm for 5-30 seconds. Then it is placed on a hot stage at 30-110 ℃ for annealing for 5-60 minutes to prepare an electron blocking layer. (5) Assemble the carbon electrode onto the electron blocking layer.

3. The method as described in claim 2, characterized in that: The acyl chloride derivative is any one or any mixture of any number of the following in any proportion: trichloroacetyl chloride, benzoyl chloride, oxaloyl chloride, furfural chloride, fluoroacetyl chloride, malonyl chloride, phenylbutyroyl chloride, salicylyl chloride, chloroacetyl chloride, succinyl chloride, octanoyl chloride, oleoyl chloride, heptanyl chloride, decanoyl chloride, valeryl chloride, butyroyl chloride, hexanoyl chloride, propionyl chloride, nonanoyl chloride, and phthaloyl chloride.

4. The method as described in claim 2, characterized in that: The concentration of the passivating agent solution containing acyl chloride groups is 0.05 mg / mL – 50 mg / mL.

5. The method as described in claim 2, characterized in that: The solvent A is any one of DMSO and DMF, or a mixture thereof in any ratio.

6. The method as described in claim 2, characterized in that: Solvent B is any one or a mixture of any number of ethanol, ethyl acetate, propanol, isopropanol, chlorobenzene, and diethyl ether in any proportion.

7. The method as described in claim 2, characterized in that: The electron blocking layer is generated by reacting an acyl chloride group derivative with a perovskite component, and the general formula of the reaction equation is: Wherein R is any one of chloro-substituted or unsubstituted alkyl; phenyl; aldehyde; furfural; naphthyl.

8. The method as described in claim 2, characterized in that: The molar concentration of the perovskite precursor is 0.5 M–2.0 M, and the prepared perovskite layer is an all-inorganic perovskite CsPbX3, where the element at the X-position is any one or any mixture of Cl, Br, and I in any ratio.

9. The method as described in claim 2, characterized in that: The volume of the passivating agent solution containing acyl chloride groups added is 10-150 μL.

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