A preparation method of a double-cation synergistic chelating passivated perovskite thin film and device

Abstract

The present invention discloses a preparation method of a double-cation synergistic chelation passivated perovskite thin film and device, belonging to the technical field of photovoltaic device manufacturing. The preparation method of the present invention includes the following steps: (1) coating a copper complex solution on a substrate and heating to form a film as a base layer thin film; (2) coating a perovskite solution containing a zinc complex on the base layer thin film and heating to obtain the double-cation synergistic chelation passivated perovskite thin film. By using a copper complex and a zinc complex to assist in the preparation of a CsPbI2Br battery, through a specific preparation process, that is, first coating a layer of copper complex solution and then spin-coating a perovskite solution containing another zinc complex, the passivation effect can be significantly improved, and the photoelectric efficiency and long-term humidity stability of the perovskite battery can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic device manufacturing, and particularly relates to a preparation method of a double-cation synergistic chelation passivated perovskite thin film and device. Background Art

[0002] In the face of the current energy crisis and environmental pollution, solar energy, as a renewable energy source, is one of the important methods to meet the growing energy demand globally. An effective way to convert solar energy into electrical energy is to prepare solar cells based on the photovoltaic effect. Developing new solar cells with high efficiency and low cost is the technical basis for the wide application of solar photovoltaic power generation. The gradually emerging advantages of high-efficiency and low-cost perovskite cells have increasingly become the research focus of photovoltaic cell technology.

[0003] The instability of perovskite under conditions such as heat, oxygen, ultraviolet light, and water is the biggest problem facing its further commercial application; and in the process of preparing perovskite thin films by solution methods, the generation of defects and trap sites is often inevitable, and most of them are distributed on the surface and / or interface of perovskite with relatively low nucleation energy. Usually, these defects are the main channels for non-radiative recombination of perovskite and also the active sites for perovskite degradation. In response to the above defects, a series of optimization schemes have been proposed, and among them, additive passivation has been proven to be one of the effective strategies to obtain high-quality and stable perovskite devices. Introducing corresponding chelating agents is a novel and effective way to stabilize perovskite. However, relying on single passivation often cannot achieve the optimal passivation effect. Therefore, based on functional chelating molecules, simultaneously introducing different cations to passivate perovskite will have better advantages in reducing defects in the perovskite bulk and surface / interface.

[0004] Chinese Patent Application CN202010217117.0 discloses a chelated perovskite material, thin film, device, and their preparation methods and applications, which are prepared by adding a chelating agent to a perovskite solution; the chelating agent includes a complexing agent or chelating agent capable of generating coordination with metal ions through coordination atoms, or a chelate or complex formed after the coordination reaction of the complexing agent or chelating agent with the corresponding metal ions; this invention effectively passivates the bulk defects and surface defects of perovskite thin films, reduces the non-radiative recombination of carriers, and thus effectively improves the efficiency and long-term operation stability of perovskite solar cells. However, there is still a large room for improvement in its passivation effect.

[0005] Currently, the demand for high-quality perovskite thin films is still very large. Therefore, it is necessary to develop a more efficient preparation method for perovskite thin films with more significant passivation effects.

[0006] In view of this, the present invention utilizes dual-cation synergistic chelation to passivate perovskite, and through a specific preparation process, it achieves the function of double-passivating the defects of the film body and surface, greatly improving the quality of the perovskite film, and effectively enhancing the efficiency and long-term stability of the corresponding battery devices. Summary of the Invention

[0007] The object of the present invention is to provide a preparation method for a dual-cation synergistic chelation passivated perovskite film and device. The inventors of the present invention have found that when preparing a CsPbI2Br battery assisted by a copper complex and a zinc complex, through a specific preparation process, first coating a copper complex solution and then spin-coating a perovskite solution containing another zinc complex can significantly improve the passivation effect and enhance the photoelectric efficiency and long-term humidity stability of the perovskite battery.

[0008] To achieve the above object, the technical solution of the present invention is as follows:

[0009] On the one hand, the present invention provides a preparation method for a dual-cation synergistic chelation passivated perovskite film, comprising the following steps:

[0010] (1) Coating a copper complex solution on a substrate and heating to form a film as the base layer film;

[0011] (2) Coating a perovskite solution containing a zinc complex on the base layer film obtained in step (1) and heating to obtain the dual-cation synergistic chelation passivated perovskite film.

[0012] The copper complex refers to a compound formed by the coordination of a complexing agent and copper ions, and the zinc complex refers to a compound formed by the coordination of a complexing agent and zinc ions. The complex can be directly purchased, or the corresponding complex can be prepared by the coordination reaction of a complexing agent and a cation.

[0013] The complexing agent is a non-metallic element containing a lone pair of electrons or an organic molecule that can perform single or multi-coordination with a cation, preferably at least one of cyanide, citrate, oxalate, carboxylate, sulfate, phosphate, pyrophosphate, thiosulfate, sodium nitrilotriacetate (NTA), and ethylenediaminetetraacetate. The cation in the salt can be a metal ion in the periodic table, such as aluminum, calcium, lead, zinc, copper, iron, nickel, etc., or a non-metallic cation, such as NH 3+ , NH 4+ ammonium ions, etc.

[0014] Preferably, the copper complex is copper diethyldithiocarbamate (Cu(DDTC)2).

[0015] Preferably, the zinc complex is zinc diethyldithiocarbamate (Zn(DDTC)2).

[0016] Preferably, the concentration of Cu(DDTC)2 coated on the substrate ranges from 0 to 150 mg / mL. Preferably, the concentration of Cu(DDTC)2 coated on the substrate is 1.5 mg / mL. The concentration of Zn(DDTC)2 doped in the perovskite solution ranges from 0 to 150 mg / mL. Preferably, the concentration of Zn(DDTC)2 doped in the perovskite solution is 0.5 mg / mL.

[0017] Preferably, in step (1), the heating is carried out at 150 - 200 °C for 5 - 10 min.

[0018] Preferably, in step (2), the heating is first carried out at 40 - 50 °C for 1 - 5 min, and then at 140 - 190 °C for 5 - 15 min.

[0019] The perovskite solution is the main component solution of the perovskite absorption layer. For example, for a CsPbI2Br perovskite solar cell, the corresponding solution is CsPbI2Br solution. For example, a 1.2 M CsPbI2Br inorganic perovskite solution can be prepared by dissolving 312 mg of cesium iodide, 220 mg of lead bromide, and 277 mg of lead iodide in 1 mL of dimethyl sulfoxide solvent, and stirring at room temperature for 8 - 16 h to form a CsPbI2Br perovskite solution.

[0020] The substrate is selected from conductive glass, flexible substrate, or conductive glass or flexible substrate covered with a layer of electron or hole transport material.

[0021] On the other hand, the present invention provides the application of the double - cation synergistic chelation - passivated perovskite thin film prepared by the above - mentioned preparation method in perovskite solar cells.

[0022] Preferably, the application is to improve the conversion efficiency, photoelectric efficiency, and long - term humidity stability of perovskite solar cells.

[0023] The beneficial effects of the present invention are as follows:

[0024] (1) Chelate - passivate perovskite with a double - cation synergistic complexing agent, and through a specific coating sequence, improve the effect of synergistic passivation, further effectively passivate the defects of the film body and the surface and interface, and greatly improve the efficiency and stability of perovskite devices.

[0025] (2) For a CsPbI2Br battery assisted by the thin film prepared by this method, the corresponding conversion efficiency can reach more than 17.2%, and effectively improve the photoelectric conversion efficiency and long - term humidity stability of perovskite solar cells. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the binding energy of Cu(DDTC)2 and Zn(DDTC)2 metal complex products;

[0027] Figure 2 It is the stability test curve graph corresponding to the CsPbI2Br perovskite devices prepared in Example 1 and Comparative Example 1. Detailed implementation manners

[0028] The following non-limiting examples can enable those of ordinary skill in the art to more comprehensively understand the present invention, but do not limit the present invention in any way. The following content is merely an exemplary illustration of the scope claimed in the present application. Those skilled in the art can make various changes and modifications to the invention of the present application based on the disclosed content, and it should also fall within the scope claimed in the present application.

[0029] The "ranges" disclosed herein are in the form of lower and upper limits. There can be one or more lower limits, and one or more upper limits respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundary of a particular range. All ranges that can be defined in this way are inclusive and combinable, that is, any lower limit can be combined with any upper limit to form a range. For example, for a specific parameter, ranges of 60 - 120 and 80 - 110 are listed, and ranges of 60 - 110 and 80 - 120 are understood to be contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 2, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5.

[0030] In the present invention, unless otherwise stated, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations.

[0031] In the present invention, if there is no special indication, all the implementation manners and preferred implementation manners mentioned herein can be combined with each other to form new technical solutions.

[0032] The present invention will be further described below by way of specific examples. All chemical reagents used in the examples of the present invention are obtained through conventional commercial channels unless otherwise specified.

[0033] In the following examples, the film preparation is completed in a nitrogen glove box.

[0034] In the following examples, the substrates used are all TiO2 / FTO substrates, that is, FTO glass substrates covered with TiO2 films; the TiO2 films are prepared by immersing the corresponding FTO glass in a 0.35M titanium tetrachloride solution for 40 min at a temperature of 65°C, and then calcining in a muffle furnace at 500°C.

[0035] All calculations were performed using the VASP (Vienna Ab initio Simulation Package) software package based on first-principles density functional theory (DFT). The interaction between electrons and ions was treated with the projector augmented wave (PAW) method, and the valence electron structures of each element were Cu: 3d 10 4s 1 , Zn: 3d 10 4s 2 , S: 3s 2 3p 4 , C: 2s 2 2p 2 , N: 2s 2 2p 3 and H: 1s 1 . The exchange-correlation potential between electrons was described by the Perdew-Burke-Ernzerhof (PBE) functional of the generalized gradient approximation (GGA). In this work, the DFT-D3 method was used for the calculations with dispersion correction. The energy of self-consistent calculations converged within 10 -5 eV after full structural relaxation, and the force on each atom was less than 0.01 eV / Å. The binding energy [ΔE coh (eV)] of each complex molecule was calculated as follows:

[0036] ΔE coh = E tot - 2E DDTC - E M

[0037] where E tot is the energy of the complex molecule, and the values for Cu(DDTC)2 and Zn(DDTC)2 are -201.518 eV and -200.144 eV, respectively; E DDTC is the energy of an isolated DDTC molecule (-100.847 eV); E M (M = Cu, Zn) is the average energy of each metal atom in its bulk structure, and the values for Cu(DDTC)2 and Zn(DDTC)2 are -4.239 eV and -1.468 eV, respectively.

[0038] Figure 1 are the binding energies of the corresponding Cu(DDTC)2 and Zn(DDTC)2 complexes.

[0039] Example 1

[0040] First, weigh 0.5 mg of Zn(DDTC)2, 272 mg of cesium iodide, 187 mg of lead bromide, and 235.5 mg of lead iodide powder, and dissolve them in 1 mL of dimethyl sulfoxide solvent. Then, stir the solution at room temperature for 12 hours to form a perovskite CsPbI2Br solution containing Zn(DDTC)2 (abbreviated as Zn(DDTC)2-CsPbI2Br). Do not filter and set aside for later use.

[0041] Weigh 1.5 mg of Cu(DDTC)2 and dissolve it in 1 mL of dimethyl sulfoxide solvent to obtain a Cu(DDTC)2 solution. Then, take 50 μL of the Cu(DDTC)2 solution and spin-coat it on the substrate, and heat it at 180 °C for 8 minutes to form a Cu(DDTC)2 bottom layer film.

[0042] Take 40 μL of the Zn(DDTC)2-CsPbI2Br solution and spin-coat it on the above-mentioned substrate. Heat it at 43 °C for 2 minutes and then at 160 °C for 10 minutes to form a perovskite absorption layer film.

[0043] Comparative Example 1

[0044] First, weigh 272 mg of cesium iodide, 187 mg of lead bromide, and 235.5 mg of lead iodide powder, and dissolve them in 1 mL of dimethyl sulfoxide solvent. Then, stir the solution at room temperature for 12 hours to form a CsPbI2Br perovskite solution. Do not filter and set aside for later use.

[0045] Take 40 μL of the CsPbI2Br solution and spin-coat it on the substrate. Heat it at 43 °C for 2 minutes and then at 160 °C for 10 minutes to form a perovskite absorption layer film.

[0046] Comparative Example 2

[0047] First, weigh 272 mg of cesium iodide, 187 mg of lead bromide, and 235.5 mg of lead iodide powder, and dissolve them in 1 mL of dimethyl sulfoxide solvent. Then, stir the solution at room temperature for 12 hours to form a CsPbI2Br perovskite solution. Do not filter and set aside for later use.

[0048] Weigh 1.5 mg of Cu(DDTC)2 and dissolve it in 1 mL of dimethyl sulfoxide solvent to obtain a Cu(DDTC)2 solution. Then, take 50 μL of the Cu(DDTC)2 solution and spin-coat it on the substrate, and heat it at 180 °C for 8 minutes to form a Cu(DDTC)2 bottom layer film.

[0049] Take 40 μL of the CsPbI2Br solution and spin-coat it on the substrate. Heat it at 43 °C for 2 minutes and then at 160 °C for 10 minutes to form a perovskite absorption layer film.

[0050] Comparative Example 3

[0051] First, weigh 272 mg of cesium iodide, 187 mg of lead bromide, 235.5 mg of lead iodide powder and 0.5 mg of Zn(DDTC)2 and dissolve them in 1 mL of dimethyl sulfoxide solvent. Then stir for 12 hours at room temperature to form a Zn(DDTC)2-CsPbI2Br perovskite solution, without filtration, for later use.

[0052] Subsequently, take 40 μL of the Zn(DDTC)2-CsPbI2Br solution and spin-coat it on the substrate, heat it at 43 °C for 2 min and then at 160 °C for 10 min to form a perovskite absorption layer film.

[0053] Comparative Example 4

[0054] First, weigh 272 mg of cesium iodide, 187 mg of lead bromide, 235.5 mg of lead iodide powder and 0.1 mg of Cu(DDTC)2 and dissolve them in 1 mL of dimethyl sulfoxide solvent. Then stir for 12 hours at room temperature to form a Cu(DDTC)2-CsPbI2Br perovskite solution, without filtration, for later use.

[0055] Subsequently, take 40 μL of the Cu(DDTC)2-CsPbI2Br solution and spin-coat it on the substrate, heat it at 43 °C for 2 min and then at 160 °C for 10 min to form a perovskite absorption layer film.

[0056] Comparative Example 5

[0057] First, weigh 0.1 mg of Cu(DDTC)2, 272 mg of cesium iodide, 187 mg of lead bromide, 235.5 mg of lead iodide powder and dissolve them in 1 mL of dimethyl sulfoxide solvent. Then stir for 12 hours at room temperature to form a perovskite CsPbI2Br solution containing Cu(DDTC)2 (abbreviated as Cu(DDTC)2-CsPbI2Br), without filtration, for later use.

[0058] Weigh 0.5 mg of Zn(DDTC)2 and dissolve it in 1 mL of dimethyl sulfoxide solvent to obtain a Zn(DDTC)2 solution. Then take 50 μL of the Zn(DDTC)2 solution and spin-coat it on the substrate, heat it at 180 °C for 8 min to form a Zn(DDTC)2 bottom layer film.

[0059] Take 40 μL of the Cu(DDTC)2-CsPbI2Br solution and spin-coat it on the above-mentioned substrate, heat it at 43 °C for 2 min and then at 160 °C for 10 min to form a perovskite absorption layer film.

[0060] Comparative Example 6

[0061] First, weigh 10.1 mg of Cu(DDTC)2, 0.5 mg of Zn(DDTC)2, 272 mg of cesium iodide, 187 mg of lead bromide, and 235.5 mg of lead iodide powder and dissolve them in 1 mL of dimethyl sulfoxide solvent. Then stir for 12 hours at room temperature to form a perovskite CsPbI2Br solution containing Cu(DDTC)2 and Zn(DDTC)2 (abbreviated as Cu(DDTC)2-Zn(DDTC)2-CsPbI2Br), without filtration, and set aside.

[0062] Take 40 μL of the Cu(DDTC)2-Zn(DDTC)2-CsPbI2Br solution and spin-coat it on the substrate. Heat it at 43 °C for 2 min and then at 160 °C for 10 min to form a perovskite absorption layer film.

[0063] Fabrication of Solar Cells

[0064] Cool the films prepared in the examples and comparative examples respectively. Then spin-coat a poly-3-hexylthiophene (P3HT) hole layer (a chlorobenzene solution of 15 mg / mL) and evaporate a silver electrode (80 nm thick) to assemble a perovskite solar cell. The effective area of the cell is 0.0625 cm 2 .

[0065] Test Examples

[0066] 1. Photovoltaic Conversion Efficiency Test

[0067] Through a solar simulator, under the irradiation of standard light at 100 mW cm -2 , test the photovoltaic conversion efficiency.

[0068] The results are shown in Table 1.

[0069] Table 1.

[0070]

[0071] It can be seen that compared with Comparative Examples 1-4, the preparation process of Example 1, which first coats the Cu(DDTC)2 solution and then coats the Zn(DDTC)2-CsPbI2Br perovskite solution, that is, the battery device prepared by the synergistic chelation passivation of Cu(DDTC)2 and Zn(DDTC)2 on the perovskite significantly improves the photovoltaic conversion efficiency of the device; compared with Comparative Examples 5-6, the preparation process of Example 1, which first coats the Cu(DDTC)2 solution and then coats the Zn(DDTC)2-CsPbI2Br perovskite solution, further improves the synergistic passivation effect and further improves the photovoltaic conversion efficiency of the device.

[0072] 2. Long-Term Stability Test

[0073] After assembling the "CsPbI2Br perovskite device without any modification in Comparative Example 1" and the "perovskite solar cell device in Example 1" using standard processes, they were simultaneously placed in an oven with a relative humidity of 12% ± 5% to test their humidity stability. From Figure 2 It can be seen that the long-term humidity stability of the device can be significantly improved by using Cu(DDTC)2 and Zn(DDTC)2 to synergistically chelate and passivate the perovskite in Example 1.

[0074] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a double-cation synergistic chelation passivated perovskite thin film, characterized in that, It includes the following steps: (1) First, coat a copper complex solution on a substrate and heat it to form a film as the base layer film; (2) Coat a perovskite solution containing a zinc complex on the base layer film obtained in step (1) and heat it to obtain the double-cation synergistic chelation passivated perovskite film; The copper complex is Cu(DDTC)2, and the zinc complex is Zn(DDTC)2.

2. The preparation method according to claim 1, wherein The copper complex refers to a compound formed by the coordination of a complexing agent and copper ions, and the zinc complex refers to a compound formed by the coordination of a complexing agent and zinc ions.

3. The preparation method according to claim 2, wherein, The complexing agent is a non-metallic element with lone pair electrons or an organic molecule that can perform single or multi-coordination with cations.

4. The preparation method according to claim 3, characterized in that, The complexing agent is at least one of cyanide, citrate, oxalate, carboxylate, sulfate, phosphate, pyrophosphate, thiosulfate, sodium nitrilotriacetate, and ethylenediaminetetraacetate.

5. The preparation method according to claim 4, characterized in that, The cation in the salt is a metal ion in the periodic table, NH 3+ or NH 4+ .

6. The preparation method according to claim 1, wherein The concentration of the copper complex solution is 0-150 mg / mL; the concentration range of Zn(DDTC)2 doped in the perovskite solution is 0-150 mg / mL.

7. The preparation method according to claim 1, wherein The substrate is selected from conductive glass, flexible substrate, or conductive glass or flexible substrate covered with a layer of electron or hole transport material.

9. Application of the double-cation synergistic chelation passivated perovskite film prepared by the preparation method according to any one of claims 1-7 in a perovskite solar cell.

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