Perovskite thin film passivation modifier, perovskite thin film and preparation method thereof, and perovskite solar cell

Abstract

The invention provides a perovskite thin film passivation modifier, a perovskite thin film and a preparation method thereof, and a perovskite solar cell. The passivation modifier comprises passivation molecules providing passivation groups; the passivation groups and uncoordinated lead ions or other defect sites in the perovskite thin film form coordinate bonds; the passivation group is amino. Amino groups in the passivation modifier have relatively strong coordination capability and can form coordination bonds with uncoordinated lead ions or other defect sites in the perovskite material, so that grain boundary and surface defects are passivated, and in addition, the three-dimensional structure of the passivation modifier is beneficial to preventing moisture and oxygen from invading the perovskite thin film; and the stability of the perovskite thin film is further improved.

Description

Technical Field

[0001] The present application relates to the technical field of perovskite solar cell preparation, and particularly relates to a perovskite thin film passivation modifier, a perovskite thin film, a preparation method thereof, and a perovskite solar cell. Background Art

[0002] Due to its excellent optoelectronic properties, such as high absorption coefficient, long carrier lifetime, and adjustable bandgap, perovskite materials have become a research hotspot for a new generation of photovoltaic devices. However, perovskite thin films are prone to grain boundary defects and surface defects during the preparation process. These defects lead to non-radiative recombination of carriers, thereby reducing the energy conversion efficiency and stability of the battery. In the prior art, although various passivators are used to repair perovskite defects, the effect has not yet reached the optimal level. Summary of the Invention

[0003] The present application aims to solve at least one of the technical problems in the related art to some extent. The present application provides a perovskite thin film passivation modifier, a perovskite thin film, a preparation method thereof, and a perovskite solar cell. The passivation molecules in the present application have a unique three-dimensional structure and passivation group activity. The passivation group forms a coordination bond with the uncoordinated lead ions or other defect sites in the perovskite thin film, thereby passivating grain boundary and surface defects. When the perovskite thin film modified by the passivation modifier is applied to a perovskite solar cell, the performance and stability of the perovskite solar cell can be improved.

[0004] To achieve the above object, according to the first aspect of the present application, a perovskite thin film passivation modifier is provided, which includes a passivation molecule providing a passivation group; the passivation group forms a coordination bond with the uncoordinated lead ions or other defect sites in the perovskite thin film; the passivation group is an amino group.

[0005] In some embodiments, the passivation molecule is a nitrogen- and phosphorus-containing derivative with a three-dimensional structure, and its structural formula is C 10-x-y N x P y H 16-2x-2y , where 1 ≤ x ≤ 4; 1 ≤ y ≤ 2.

[0006] In some embodiments, the nitrogen- and phosphorus-containing derivative is a nitrogen- and phosphorus-containing adamantane;

[0007] The nitrogen- and phosphorus-containing adamantane includes 1,3,5-triaza-7-phosphaadamantane, and its structural formula is

[0008] In some embodiments, the passivation molecule is dissolved in isopropanol or ethanol to prepare a solution.

[0009] According to a second aspect of the present application, a method for preparing a perovskite thin film is provided, which includes preparing a first perovskite thin film by adding the passivation modifier described in any one of the above embodiments to a perovskite precursor solution; the addition ratio of the passivation molecule to the perovskite precursor solution is 1 mg / ml - 10 mg / ml; or

[0010] Coating the surface of the base thin film formed by the perovskite precursor solution with the passivation modifier described in any one of the above embodiments, and performing heat treatment to form a modification layer to obtain a second perovskite thin film; wherein the addition ratio of the passivation molecule in the passivation modifier is 0.01 mg / ml - 5 mg / ml.

[0011] In some embodiments, during the preparation of the second perovskite thin film, the modification layer is formed by coating or doctor blading the passivation modifier; the passivation time is 30 s - 5 min, and the temperature is 100°C - 150°C;

[0012] and / or, the heat treatment parameters of the modification layer are 80°C - 120°C, lasting for 5 - 30 min.

[0013] and / or, the thickness of the modification layer is 2 nm - 10 nm.

[0014] In some embodiments, the method for preparing the perovskite precursor solution is: dissolving lead iodide, lead bromide, formamidinium iodide and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 in a mixed solution composed of DMF and DMSO with a volume ratio of 4:1.

[0015] In some embodiments, during the preparation of the first perovskite thin film, adding the passivation modifier to the perovskite precursor solution, preparing a perovskite wet film with a thickness of 50 μm - 300 μm, and annealing at 100°C for 20 - 30 min.

[0016] According to a third aspect of the present application, a perovskite thin film is provided, which includes the first perovskite thin film or the second perovskite thin film prepared by the modification method described in any one of the above embodiments.

[0017] According to a fourth aspect of the present application, a perovskite solar cell is provided, which includes the perovskite thin film described in any one of the above embodiments.

[0018] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present application. Description of the Drawings

[0019] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description of embodiments in conjunction with the accompanying drawings, in which:

[0020] Figure 1 is a schematic structural diagram of a first perovskite thin film in an embodiment of the present application;

[0021] Figure 2 is a schematic structural diagram of a second perovskite thin film in an embodiment of the present application;

[0022] Figure 3 is the current-voltage curve graph of the battery in Example 1 and Comparative Example 1 of the present application and their corresponding aged ones. Detailed Description of the Embodiments

[0023] Embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present application and should not be construed as limiting the present application. On the contrary, the embodiments of the present application include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0024] The present application is improved based on the following related technologies: Due to its excellent optoelectronic properties, such as high absorption coefficient, long carrier lifetime, and adjustable bandgap, perovskite materials have become a research hotspot for a new generation of photovoltaic devices. However, perovskite thin films are prone to grain boundary defects and surface defects during the preparation process, and these defects lead to non-radiative recombination of carriers, thereby reducing the energy conversion efficiency and stability of the battery. In the prior art, although various passivators are used to repair perovskite defects, their effects have not reached the optimal level.

[0025] The present application aims to solve at least one of the technical problems in the related technologies to some extent. To achieve the above object, according to a first aspect of the present application, a perovskite thin film passivation modifier is provided, which includes a passivation molecule providing a passivation group; the passivation group forms a coordination bond with uncoordinated lead ions or other defect sites in the perovskite thin film; the passivation group is an amino group.

[0026] In some embodiments, the passivation molecule is dissolved in isopropanol or ethanol to prepare a solution. The passivation molecule is a three-dimensional structure derivative containing nitrogen and phosphorus, and its structural general formula is C 10-x-y N x P y H 16-2x-2y, where 1 ≤ x ≤ 4; 1 ≤ y ≤ 2. In the nitrogen- and phosphorus-containing derivatives, the three-dimensional structure is based on adamantane, and some of the carbon atoms therein are replaced by nitrogen atoms. There are lone pairs of electrons on the N atom and P atom in the nitrogen- and phosphorus-containing derivatives, which can form a coordination effect with lead ions, thereby passivating defects. The nitrogen- and phosphorus-containing derivatives are nitrogen- and phosphorus-containing adamantanes including 1,3,5-triaza-7-phosphaadamantane, and its structural formula is

[0027]

[0028] According to the second aspect of the present application, a method for preparing a perovskite thin film is provided, including preparing a first perovskite thin film by adding the passivation modifier in any of the above embodiments into a perovskite precursor solution; the addition ratio of the passivation modifier to the perovskite precursor solution is 1 mg / ml - 10 mg / ml; or

[0029] Coating the surface of the base film formed by the perovskite precursor solution with the passivation modifier in any of the above embodiments and performing heat treatment to form a modification layer to obtain a second perovskite thin film; the addition ratio of the passivation molecules in the passivation modifier is 0.01 mg / ml - 5 mg / ml.

[0030] Among them, according to the second aspect of the present application, a method for preparing a perovskite thin film includes two methods. The first method is the preparation of the first perovskite thin film, and the second method is the preparation of the second perovskite thin film. The preparation of the first perovskite thin film and the second perovskite thin film will be described separately below.

[0031] The preparation process of the first perovskite thin film is as follows: adding the passivation modifier in any of the above embodiments into the perovskite precursor solution to obtain a perovskite solution. The preparation method of the perovskite precursor solution includes dissolving lead iodide, lead bromide, formamidinium iodide, and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 in a mixed solution composed of DMF and DMSO with a volume ratio of 4:1. The addition ratio of the passivation modifier to the perovskite precursor solution is 1 mg / ml - 10 mg / ml. Exemplary addition ratios of the passivation modifier to the perovskite precursor solution are 1 mg / ml, 2 mg / ml, 3 mg / ml, 5 mg / ml, 6 mg / ml, 7 mg / ml, 9 mg / ml, 10 mg / ml, etc. If the addition ratio of the passivation modifier is too large, such as greater than 10 mg / ml, the resistance of the first perovskite thin film increases, hindering the transport of carriers; conversely, if the addition ratio of the passivation modifier is too small, such as less than 1 mg / ml, the defect passivation effect is not obvious and the passivation effect is poor.

[0032] Using the perovskite solution obtained above, a perovskite wet film with a thickness of 50 μm - 300 μm is prepared by spin coating / spray coating / blade coating, etc., and then annealed at 100 °C for 20 - 30 min to obtain the first perovskite film. Among them, spin coating / spray coating / blade coating and other methods can all adopt conventional technical methods in the art, which will not be elaborated here.

[0033] In some embodiments, the preparation process of the second perovskite film is as follows: Prepare a perovskite precursor solution, the method is referred to the above content and will not be elaborated here. Use spin coating / spray coating / blade coating and other methods to prepare a perovskite wet film with a set thickness from the perovskite precursor solution, and add ethyl acetate antisolvent after forming the perovskite wet film for 30 s, and then anneal at 100 °C for 20 - 30 min to obtain a base film.

[0034] The passivation modifier in any of the above embodiments is formed by coating or blade coating to form a modification layer on one surface of the base film, and then the heat treatment parameters of the modification layer are 80 °C - 120 °C for 5 - 30 min to obtain a modification layer with a thickness of 2 nm - 10 nm.

[0035] According to the third aspect of the present application, a perovskite film is provided, which includes the first perovskite film or the second perovskite film prepared by using the modification method in any of the above embodiments.

[0036] According to the fourth aspect of the present application, a perovskite solar cell is provided, which includes the perovskite film in any of the above embodiments.

[0037] In some embodiments, the perovskite solar cell further includes a substrate, a semiconductor material layer, a hole transport layer, a charge transport layer and a metal layer. The substrate can be a commercially available ITO film (including a glass plate), the semiconductor material layer can be nickel oxide (with a thickness of 20 nm, x ≤ 1), the hole transport layer can be a BCP hole blocking layer, the charge transport layer is a C60 electron transport layer, and the metal layer is an Au, Cu electrode, etc.

[0038] Among them, the first perovskite film is located between the hole transport layer and the charge transport layer as Figure 1 shown, the second perovskite film is located between the hole transport layer and the charge transport layer, and the modification layer in the second perovskite film faces the charge transport layer as Figure 2 shown.

[0039] To facilitate further understanding of the present application, the following further describes the solution of the present application with reference to embodiments. Those skilled in the art will understand that only some embodiments are described in the present application, and any other suitable specific embodiments are within the scope of the present application.

[0040] Example 1

[0041] This embodiment provides a perovskite thin film passivation modifier and a method for modifying a perovskite thin film using the perovskite thin film passivation modifier. The specific composition and preparation method are as follows: 1,3,5-triaza-7-phosphaadamantane is dissolved in isopropyl alcohol, and the addition ratio of the passivation molecules is 0.5 mg / ml.

[0042] Clean the glass, and sputter a 150-nm ITO thin film on the glass by magnetron sputtering; spin-coat an aqueous solution of nickel oxide nanoparticles on the surface layer of the ITO thin film glass, 10 mg / ml, at 3000 revolutions per minute, and heat it on a hot stage at 100 °C for 10 min to obtain a dense nickel oxide thin film with a thickness of 15 nm. Dissolve lead iodide, lead bromide, formamidinium iodide, and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 in a mixed solution composed of DMF and DMSO with a volume ratio of 4:1 to obtain a perovskite precursor solution; take 200 μL of the perovskite precursor solution and uniformly spread it on the side where nickel oxide is to be spin-coated, and spin-coat it into a film at 4000 rpm for 40 s at room temperature of 25 °C. Add 300 μl of ethyl acetate antisolvent at the 30th second, and then anneal it at 100 °C for 20 min to obtain a 600-nm base thin film.

[0043] Take the perovskite thin film passivation modifier and uniformly spread it on one end of the surface of the prepared base thin film, spin-coat it at 4000 rpm for 20 s to form a film, and then anneal it at 100 °C for 20 min to obtain a modified layer to complete the preparation of the second perovskite thin film.

[0044] Evaporate a layer of C60 electron transport layer (40 nm) and BCP hole blocking layer on the surface of the above-prepared modified layer to obtain a perovskite solar cell. Transfer the electron transport layer to a thermal evaporation device, and start evaporating the copper electrode (Cu) under the condition that the vacuum degree reaches 1×10 -5 Pa to obtain a perovskite solar cell with a thickness of 100 nm.

[0045] Example 2

[0046] This embodiment provides a perovskite thin film passivation modifier and a method for modifying a perovskite thin film using the perovskite thin film passivation modifier. The specific composition and preparation method are as follows: Dissolve 1,3,5-triaza-7-phosphaadamantane in isopropyl alcohol. Clean the glass, and sputter a 150 nm ITO thin film on the glass by magnetron sputtering; Spin-coat an aqueous solution of nickel oxide nanoparticles on the surface layer of the ITO thin film glass, with a concentration of 10 mg / ml, at 3000 revolutions per minute, and heat it on a hot stage at 100 °C for 10 min to obtain a dense nickel oxide thin film with a thickness of 15 nm. Dissolve lead iodide, lead bromide, formamidinium iodide, and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 in a mixed solution composed of DMF and DMSO with a volume ratio of 4:1 to obtain a perovskite precursor solution; After mixing the passivation molecules and the perovskite precursor solution at an addition ratio of 0.1 mg / ml, spin-coat them into a perovskite wet film at 4000 rpm for 40 s at 25 °C room temperature. Add 300 μl of ethyl acetate antisolvent at the 30th second, and then anneal at 100 °C for 20 min to obtain the first perovskite thin film.

[0047] Evaporate a layer of C60 electron transport layer (40 nm) and BCP hole blocking layer on the surface of the first perovskite thin film prepared above to obtain a perovskite solar cell. Transfer the electron transport layer to a thermal evaporation device, and start evaporating the copper electrode (Cu) with a thickness of 100 nm under the condition that the vacuum degree reaches 1×10-5 Pa to obtain a perovskite solar cell.

[0048] Example 3

[0049] This embodiment provides a perovskite thin film passivation modifier and a method for modifying a perovskite thin film using the perovskite thin film passivation modifier. The specific composition and preparation method are as follows: Dissolve 1,3,5-triaza-7-phosphaadamantane in isopropyl alcohol, and the addition ratio of the passivation molecules is 1 mg / ml.

[0050] Clean the glass, and sputter a 150 nm ITO thin film on the glass by magnetron sputtering; Spin-coat an aqueous solution of nickel oxide nanoparticles on the surface layer of the ITO thin film glass, with a concentration of 10 mg / ml, at 3000 revolutions per minute, and heat it on a hot stage at 100 °C for 10 min to obtain a dense nickel oxide thin film with a thickness of 15 nm. Dissolve lead iodide, lead bromide, formamidinium iodide, and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 in a mixed solution composed of DMF and DMSO with a volume ratio of 4:1 to obtain a perovskite precursor solution; Take 200 μL of the perovskite precursor solution and evenly spread it on the side to be spin-coated with nickel oxide, and spin-coat it into a film at 4000 rpm for 40 s at 25 °C room temperature. Add 300 μl of ethyl acetate antisolvent at the 30th second, and then anneal at 100 °C for 20 min to obtain a 600 nm base film.

[0051] The perovskite thin film passivation modifier is evenly spread on one end of the prepared base film surface, and spin-coated at 4000 rpm for 20 s to form a film. Subsequently, annealing is carried out at 100 °C for 20 min to obtain a modified layer, completing the preparation of the second perovskite thin film.

[0052] A C60 electron transport layer (40 nm) and a BCP hole blocking layer are evaporated on the surface of the modified layer prepared above to obtain a perovskite solar cell. The electron transport layer is transferred to a thermal evaporation equipment, and when the vacuum degree reaches 1×10 -5 Pa, the copper electrode (Cu) is evaporated, with a thickness of 100 nm, to obtain a perovskite solar cell.

[0053] Comparative Example 1

[0054] This comparative example provides a perovskite solar cell, and its specific composition and preparation method are as follows: The glass is cleaned, and a 150-nm ITO thin film is sputtered on the glass by magnetron sputtering; an aqueous solution of nickel oxide nanoparticles with a concentration of 10 mg / ml is spin-coated on the surface of the ITO thin film glass, at 3000 revolutions per minute, and heated on a hot stage at 100 °C for 10 min to obtain a dense nickel oxide thin film with a thickness of 15 nm. Lead iodide, lead bromide, formamidinium iodide, and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 are dissolved in a mixed solution composed of DMF and DMSO with a volume ratio of 4:1 to obtain a perovskite precursor solution; 200 μL of the perovskite precursor solution is evenly spread on the side to be spin-coated with nickel oxide, and spin-coated at 4000 rpm for 40 s at 25 °C room temperature to form a perovskite wet film. 300 μl of ethyl acetate antisolvent is added dropwise at the 30th second, and then annealed at 100 °C for 20 min to obtain a 600-nm perovskite thin film.

[0055] A C60 electron transport layer (40 nm) and a BCP hole blocking layer are evaporated on the surface of the perovskite prepared above to obtain a perovskite solar cell. The electron transport layer is transferred to a thermal evaporation equipment, and when the vacuum degree reaches 1×10 -5 Pa, the copper electrode (Cu) is evaporated, with a thickness of 100 nm; a perovskite solar cell is obtained.

[0056] Experimental Example

[0057] The perovskite solar cells obtained in Example 1 and Comparative Example 1 are respectively placed at 25 °C and 25% relative humidity for 1000 h for aging to obtain Comparative Scheme 1 and Comparative Scheme 2. The perovskite solar cells prepared in each example, comparative example, and comparative scheme are tested for current density-voltage (JV) curves by PCE testing, and the testing is completed on a kethley2400 system; testing conditions: simulated light intensity is 100 mW cm-2 (AM 1.5G) The scanning rate is 0.1 V / s -1 (The step size is 0.02 V and the time delay is 200 ms). The scanning range is from 1.2 V to -0.2 V. The power output of the xenon lamp is calibrated by a KG5 standard Si perovskite solar cell of the NERL (National Renewable Energy Laboratory) standard. The test results are shown in Table 1 and Figure 3 as follows.

[0058] Table 1 Detection results of perovskite solar cells in each example and comparative example

[0059]

[0060] From Table 1 and Figure 3 it can be seen that the open-circuit voltage, short-circuit current and fill factor of the perovskite solar cells in Examples 1-3 have good effects. This is because after passivating molecules passivate and modify the base film formed by the perovskite precursor solution or the perovskite precursor solution, there are fewer interfacial defects and lower carrier transport resistance. After passivation modification, the perovskite solar cell maintained 92.89% of its original efficiency after accelerated aging, such as the passivated perovskite solar cell in Comparative Scheme 1. However, for the schemes shown in Comparative Example 1 and Comparative Scheme 2, the perovskite solar cell in Comparative Scheme 2 was only 73.00% of its original efficiency, indicating that the passivated perovskite solar cell has better stability.

[0061] It should be noted that in the description of this application, terms such as "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0062] Any process or method description shown in the flowchart or described in other ways herein can be understood as representing a module, segment or part of executable instructions including one or more steps for implementing a specific logical function or process. The scope of the preferred embodiments of this application includes additional implementations, where the functions can be executed in a substantially simultaneous manner or in the reverse order according to the functions involved, rather than in the order shown or discussed. This should be understood by those skilled in the technical field to which the embodiments of this application belong.

[0063] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

[0064] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A perovskite thin film passivation modifier, characterized in that, It includes a passivation molecule that provides a passivation group; the passivation group forms a coordination bond with uncoordinated lead ions or other defect sites in the perovskite film; the passivation group is an amino group.

2. The passivation modifier according to claim 1, wherein The passivating molecule is a three-dimensional nitrogen- and phosphorus-containing derivative, and its structural general formula is C 10-x-y N x P y H 16-2x-2y , where 1 ≤ x ≤ 4; 1 ≤ y ≤ 2.

3. The passivation modifier according to claim 2, characterized in that, The nitrogen- and phosphorus-containing derivative is an adamantane containing nitrogen and phosphorus; The nitrogen- and phosphorus-containing adamantane includes 1,3,5-triaza-7-phosphaadamantane, and its structural formula is 4. The passivation modifier according to any one of claims 1-3, characterized in that, The passivation molecule is dissolved in isopropanol or ethanol to prepare a solution.

5. A method for preparing a perovskite thin film, characterized in that, It includes preparing a first perovskite film by adding the passivation modifier described in any one of claims 1-4 to a perovskite precursor solution; the addition ratio of the passivation molecule to the perovskite precursor solution is 1 mg / ml - 10 mg / ml; Or Coating the surface of the base film formed from the perovskite precursor solution with the passivation modifier described in any one of claims 1-4 and performing heat treatment to form a modification layer to obtain a second perovskite film; wherein the addition ratio of the passivation molecule in the passivation modifier is 0.01 mg / ml - 5 mg / ml.

6. The method according to claim 5, wherein During the preparation process of the second perovskite film, the modification layer is formed by coating or doctor blading with the passivation modifier; And / or, the heat treatment parameters of the modification layer are 80°C - 120°C for 5 - 30 min; And / or, the thickness of the modification layer is 2 nm - 10 nm.

7. The method according to claim 5, wherein The preparation method of the perovskite precursor solution is: dissolving lead iodide, lead bromide, formamidinium iodide and cesium iodide with a molar ratio of 0.85:0.15:0.78:0.22 in a mixed solution composed of DMF and DMSO with a volume ratio of 4:

1.

8. The method according to claim 5, characterized in that, During the preparation process of the first perovskite film, adding the passivation modifier to the perovskite precursor solution, preparing a perovskite wet film with a thickness of 50 μm - 300 μm, and annealing at 100°C for 20 - 30 min.

9. A perovskite thin film, characterized in that, It includes a first perovskite film or a second perovskite film prepared by using the modification method described in any one of claims 5-8.

10. A perovskite solar cell, characterized in that, It includes the perovskite film described in claim 9.

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