Halogen-assisted iodine-based perovskite solar cell and preparation method thereof

Abstract

The invention discloses an iodine-based perovskite solar cell assisted by a halogen simple substance and a preparation method thereof, and the method comprises the steps: introducing the halogen simple substance into a precursor solution of a perovskite optical active layer in a preparation process, thereby achieving the effect of improving the quality of a thin film and the performance of a device; the introduced halogen elementary substance can leave the perovskite in the high-temperature annealing processing process, and cannot remain in the perovskite solar cell, so that the negative influence on the stability of the cell is avoided. The iodine-based perovskite solar cell prepared by the method is an organic-inorganic hybrid iodine-based perovskite solar cell assisted by a halogen elementary substance, is provided with a positive electrode and a negative electrode, uses small organic molecules, polymers or inorganic matters as electron and hole transport materials, and adopts an organic-inorganic hybrid lead-iodine perovskite material as a perovskite photoactive layer; the iodine-based perovskite solar cell has very high photoelectric conversion efficiency and excellent long-term stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to a halogen-assisted iodine-based perovskite solar cell and a preparation method thereof. Background Art

[0002] Thanks to the excellent photoelectric properties of organic-inorganic hybrid metal halide perovskite materials, perovskite solar cells have continuously refreshed the record of photoelectric conversion efficiency in the past decade, becoming a research hotspot in the photovoltaic field. However, compared with atomic crystals such as crystalline silicon and gallium arsenide, perovskite is a soft ion crystal, which is more prone to bond twisting and breaking, resulting in poor material intrinsic stability and device stability. Further improving the intrinsic stability of the perovskite light-absorbing layer and the stability of the device is the key to the industrialization of perovskite photovoltaic technology.

[0003] For example, for iodine-based perovskite solar cells, among the many perovskite components, FAPbI3 (formamidinium lead iodide perovskite) is currently considered in the field to have both excellent photoelectric properties and photothermal stability, and can effectively inhibit ion migration and phase separation. However, pure phase FAPbI3 perovskite is prone to grain aggregation during the crystallization process, the resulting thin film crystal quality is poor, and the phase transition is not complete, requiring MACl (methylammonium chloride) and other additives to assist film formation. The introduced additives remain in the annealed FAPbI3 film, and then decompose or migrate to induce the phase change of the perovskite, which has potential hazards to the long-term stability of perovskite solar cells.

[0004] Therefore, developing an iodine-based perovskite solar cell with high photoelectric conversion efficiency and excellent long-term stability is a key scientific problem that needs to be urgently solved in this field at this stage. Summary of the invention

[0005] To achieve the above objectives, the present invention is intended to provide a halogen-assisted iodine-based perovskite solar cell and a preparation method thereof.

[0006] In one aspect, the present invention provides a method for preparing a halogen-assisted iodine-based perovskite solar cell, the preparation method comprising the following steps:

[0007] S1. Cleaning the transparent conductive substrate;

[0008] S2, preparing a first transmission layer on a transparent conductive substrate;

[0009] S3, using iodide to prepare a precursor solution of a perovskite photoactive layer, and using the precursor solution to prepare a perovskite photoactive layer on a first transport layer, and performing annealing heat treatment; wherein a halogen element is introduced when preparing the precursor solution, and for the precursor solution, the iodide includes a first iodide and a second iodide, and the molar ratio of the introduced halogen element and the second iodide is between 5% and 30%;

[0010] S4, preparing a second transport layer on the perovskite photoactive layer;

[0011] S5. Prepare an electrode layer on the second transport layer, that is, prepare a halogen-assisted iodine-based perovskite solar cell.

[0012] Preferably, in the above step S1, the transparent conductive substrate is cleaned by ultrasonic method.

[0013] Preferably, in the above step S2, a window layer, ie, the first transmission layer, is prepared on the transparent conductive substrate by spin coating, spray coating or electrochemical method.

[0014] Preferably, in the above step S3, a perovskite photoactive layer can be prepared on the first transport layer by a two-step method (first depositing an inorganic species and then depositing an organic species), specifically: dissolving a first iodide in a first solvent to prepare a mixed solution, using the mixed solution to prepare a thin film on a transparent conductive substrate, and performing annealing heat treatment; dissolving a halogen element and a second iodide in a second solvent to prepare a cationic solution, using the cationic solution to prepare a perovskite photoactive layer on the thin film, and performing annealing heat treatment.

[0015] Preferably, in the above step S3, the perovskite photoactive layer can also be prepared by a one-step method (simultaneous deposition of inorganic and organic species), that is, the prepared precursor solution of the perovskite thin film containing the halogen element is prepared by a one-time film-forming method, specifically: the first iodide, the second iodide, and the halogen element are dissolved in a solvent to prepare a precursor solution, the precursor solution is used to prepare the perovskite photoactive layer on a transparent conductive substrate, and annealing heat treatment is performed.

[0016] Preferably, the first iodide is lead iodide (PbI2), and / or the first solvent is dimethylformamide and dimethyl sulfoxide, and / or the second iodide is formamidine iodide, and / or the halogen element is Cl2, Br2 or I2, and / or the second solvent is isopropanol.

[0017] Preferably, annealing heat treatment can be performed during the preparation of the above-mentioned thin film and the perovskite photoactive layer.

[0018] Preferably, in the above step S4, the second transmission layer is prepared on the perovskite photoactive layer by spin coating, spray coating or other processes.

[0019] Preferably, in the above step S5, under high vacuum conditions, a metal electrode is deposited on the second transmission layer by a process such as sputtering or evaporation, or a carbon electrode is deposited by printing.

[0020] Preferably, in steps S2 and S4, small organic molecules, polymers or inorganic substances may be used to prepare the first transport layer and / or the second transport layer.

[0021] On the other hand, the present invention further provides a halogen-assisted iodine-based perovskite solar cell prepared based on the above-mentioned preparation method, wherein the iodine-based perovskite solar cell is an organic-inorganic hybrid iodine-based perovskite solar cell, and its perovskite photoactive layer is an organic-inorganic hybrid lead-iodine perovskite material. The molar ratio of the halogen and the second iodide introduced when preparing the perovskite photoactive layer is between 5% and 30%.

[0022] Preferably, the thickness of the perovskite photoactive layer of the above-mentioned iodine-based perovskite solar cell is between 100-2000 nm.

[0023] Preferably, the iodine-based perovskite solar cell may be a formamidinium lead iodine perovskite solar cell.

[0024] Preferably, the iodine-based perovskite solar cell comprises a transparent conductive substrate, a first transmission layer, a perovskite photoactive layer, a second transmission layer and an electrode layer which are arranged in sequence.

[0025] Preferably, the transparent conductive substrate may be an indium tin oxide or fluorine-doped tin oxide transparent conductive substrate.

[0026] Preferably, the first transport layer or the second transport layer may be an electron transport layer or a hole transport layer, and organic small molecules, polymers or inorganic substances are used as electron and hole transport materials.

[0027] Preferably, the iodine-based perovskite solar cell has two positive and negative electrodes, wherein the light-receiving surface electrode is an indium tin oxide transparent electrode or a fluorine-doped tin oxide transparent electrode, and the back electrode is a metal electrode or a carbon electrode.

[0028] Compared with the prior art, the halogen-assisted iodine-based perovskite solar cell provided by the present invention has a high photoelectric conversion efficiency; the introduced halogen will leave the perovskite during the high-temperature annealing process, will not remain in the perovskite solar cell, and will not have a negative impact on the stability of the battery. The preparation method provided by the present invention, especially when preparing a pure phase FAPbI3 (formamidinium lead iodine perovskite) solar cell, has the best long-term stability among solar cells with the same components. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings. In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present invention, are used to provide a further understanding of the present invention, constitute a part of this application, and should not be regarded as limiting the scope of the present invention. Among them:

[0030] Figure 1 This is a test curve diagram of the photoelectric conversion efficiency of the perovskite solar cell prepared in Example 1 of the present invention;

[0031] Figure 2 This is a comparison chart of the long-term operation stability of the perovskite solar cells prepared in Example 1 of the present invention and the comparative example;

[0032] Figure 3 This is a test curve of the photoelectric conversion efficiency of the perovskite solar cell prepared in Example 2 of the present invention;

[0033] Figure 4 This is an operating stability curve of the perovskite solar cell prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and cannot be understood as limiting the present invention.

[0035] Embodiment 1

[0036] In this embodiment, a solar cell with a formal structure is prepared, iodine is selected as the halogen element, lead iodide is selected as the first iodide, and formamidine iodide is selected as the second iodide. A two-step method is used to prepare the perovskite photoactive layer. The specific steps are as follows:

[0037] The indium tin oxide transparent conductive substrate is cleaned by ultrasonic method.

[0038] A 2.5% by mass tin oxide aqueous solution was coated on an indium tin oxide transparent conductive substrate by spin coating to form a film, so as to prepare a first transmission layer.

[0039] 1 mL of a mixed solution of dimethylformamide and dimethyl sulfoxide (DMSO) with a concentration of 1.3 mmol / mL lead iodide was prepared, a lead iodide film was first prepared on the first transport layer by a spin coating process, and then an annealing heat treatment was performed at 80°C.

[0040] 0.08 mmol of iodine solid and 0.6 mmol of formamidine iodide solid were dissolved in 1 mL of isopropanol to prepare a cationic solution, and then the cationic solution was spin-coated on a lead iodide film to prepare a perovskite photoactive layer, and then annealed at 170°C.

[0041] The small molecule hole transport layer solution is coated on the prepared perovskite photoactive layer to prepare the second transport layer.

[0042] Under high vacuum conditions, a metal silver electrode is deposited on the second transport layer to prepare an electrode layer, thereby obtaining the halogen-assisted iodine-based perovskite solar cell of the present invention.

[0043] The photoelectric conversion efficiency curve of the above iodine-based perovskite solar cell was tested, and its photoelectric conversion efficiency can reach more than 23%, and the difference between the forward (from short-circuit current to open-circuit voltage) and reverse (scanning direction from open-circuit voltage to short-circuit current) scans is very small, showing excellent photoelectric conversion performance.

[0044] in, Figure 1 The photoelectric conversion efficiency test curve of the iodine-based perovskite solar cell is shown in Figure 1, which is obtained by scanning the voltage-current curve of the device under a standard sunlight, including forward scanning (from short-circuit current to open-circuit voltage) and reverse scanning (scanning direction from open-circuit voltage to short-circuit current). Figure 1 It can be seen that its photoelectric conversion efficiency exceeds 23%, and the difference between forward and reverse scanning is very small, showing excellent photoelectric conversion performance.

[0045] Comparative Example

[0046] In this comparative example, a perovskite solar cell was prepared according to the steps in Example 1, except that no halogen element was added to the prepared cationic solution. After testing, the photoelectric conversion efficiency of the finally prepared perovskite solar cell could only reach 17%.

[0047] Figure 2 This is a comparison chart of the long-term operation stability of the perovskite solar cell prepared in Example 1 of the present invention and the perovskite solar cell in the comparative example. That is, the cell continuously tracks the output power (photoelectric conversion efficiency) in an environment of about 90°C under standard sunlight. Figure 2It can be seen that after tracking for 642 hours at the maximum output power point under the same conditions as in Example 1, the efficiency of the solar cell in the comparative example only maintained 36% of the initial efficiency; while the solar cell in Example 1 still maintained 85% of the initial efficiency after running for 712 hours, with excellent stability performance.

[0048] Embodiment 2

[0049] In this embodiment, a solar cell with an inverted structure is prepared, iodine is selected as the halogen element, lead iodide is selected as the first iodide, and formamidine iodide is selected as the second iodide. A two-step method is used to prepare a perovskite photoactive layer, and the specific steps are as follows:

[0050] The indium tin oxide transparent conductive substrate is cleaned by ultrasonic method.

[0051] A 2 mg / mL chlorobenzene solution of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] was coated to form a film to prepare a first transport layer as a hole transport layer.

[0052] 1 mL of a mixed solution of dimethylformamide and dimethyl sulfoxide (DMSO) with a concentration of 1.3 mmol / mL lead iodide was prepared, a lead iodide film was first prepared on the first transport layer by a spin coating process, and then an annealing heat treatment was performed at 80°C.

[0053] 0.08 mmol of iodine solid and 0.6 mmol of formamidine iodide solid were dissolved in 1 mL of isopropanol to prepare a cationic solution, and then the cationic solution was spin-coated on a lead iodide film to prepare a perovskite photoactive layer, and then annealed at 170°C.

[0054] Fullerene C 60 The second transport layer is deposited on the prepared perovskite photoactive layer.

[0055] Under high vacuum conditions, a metal silver electrode is deposited on the second transport layer to prepare an electrode layer, thereby obtaining the halogen-assisted iodine-based perovskite solar cell of the present invention.

[0056] Figure 3 The photoelectric conversion efficiency test curve of the iodine-based perovskite solar cell is shown, which is obtained by scanning the voltage-current curve of the device under a standard sunlight, including forward scanning and reverse scanning. Figure 3 It can be seen that its photoelectric conversion efficiency exceeds 23%, and the difference between forward and reverse scanning is very small.

[0057] Figure 4 The figure is a graph showing the stability of the above-mentioned inverse structure solar cell under a standard sunlight and 85°C. Figure 4It can be seen that during this period, the above solar cell tracked at the maximum output power point for 620 hours without any attenuation in efficiency, and also had excellent stability.

[0058] In summary, the above-mentioned preparation method provided by the present invention introduces a halogen element into the precursor solution of the perovskite photoactive layer during the preparation process, which plays a role in improving the film quality and device performance. The introduced halogen element will leave the perovskite during the high-temperature annealing process, and will not remain in the perovskite solar cell, and will not have a negative impact on the stability of the battery. The iodine-based perovskite solar cell prepared by this method is a halogen-assisted organic-inorganic hybrid iodine-based perovskite solar cell, which has two positive and negative electrodes, uses organic small molecules, polymers or inorganic substances as electron and hole transport materials, and its perovskite photoactive layer is an organic-inorganic hybrid lead-iodine perovskite material; the iodine-based perovskite solar cell has a high photoelectric conversion efficiency and excellent long-term stability.

[0059] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A method for preparing a halogen-assisted iodine-based perovskite solar cell, characterized in that: The preparation method comprises the following steps: S1. Cleaning the transparent conductive substrate; S2, preparing a first transmission layer on the transparent conductive substrate; S3, using iodide to prepare a precursor solution of a perovskite photoactive layer, and using the precursor solution to prepare a perovskite photoactive layer on the first transport layer, and performing annealing heat treatment; wherein a halogen element is introduced when preparing the precursor solution, and for the precursor solution, the iodide includes a first iodide and a second iodide, and the molar ratio of the introduced halogen element to the second iodide is between 5% and 30%; S4, preparing a second transmission layer on the perovskite photoactive layer; S5. Preparing an electrode layer on the second transport layer, that is, preparing the halogen-assisted iodine-based perovskite solar cell.

2. The preparation method according to claim 1, characterized in that: In the step S3, the perovskite photoactive layer is prepared on the first transport layer based on a two-step method, specifically: the first iodide is dissolved in a first solvent to prepare a mixed solution, a thin film is prepared on the transparent conductive substrate using the mixed solution, and an annealing heat treatment is performed; the halogen element and the second iodide are dissolved in a second solvent to prepare a cationic solution, the cationic solution is used to prepare the perovskite photoactive layer on the thin film, and an annealing heat treatment is performed.

3. The preparation method according to claim 1, characterized in that: In the step S3, the perovskite photoactive layer is prepared on the first transport layer based on a one-step method, specifically: the first iodide, the second iodide, and the halogen element are dissolved in a solvent to prepare the precursor solution, the perovskite photoactive layer is prepared on the transparent conductive substrate using the precursor solution, and an annealing heat treatment is performed.

4. The preparation method according to claim 2 or 3, characterized in that: In the step S3, the halogen element is Cl2, Br2 or I2.

5. The preparation method according to claim 4, characterized in that: The first iodide is lead iodide, and the second iodide is formamidine iodide.

6. The preparation method according to claim 1, characterized in that: In the steps S2 and S4, the first transport layer and / or the second transport layer are prepared using organic small molecules, polymers or inorganic substances.

7. A halogen-assisted iodine-based perovskite solar cell, characterized in that: The halogen-assisted iodine-based perovskite solar cell is prepared based on the preparation method according to any one of claims 1-6.

8. The iodine-based perovskite solar cell according to claim 7, characterized in that: The thickness of the perovskite photoactive layer of the iodine-based perovskite solar cell is between 100-2000 nm.

9. The iodine-based perovskite solar cell according to claim 7 or 8, characterized in that: The iodine-based perovskite solar cell has the transparent conductive substrate, the first transmission layer, the perovskite photoactive layer, the second transmission layer and the electrode layer which are arranged in sequence.

10. The iodine-based perovskite solar cell according to claim 9, characterized in that: The transparent conductive substrate is an indium tin oxide or fluorine-doped tin oxide transparent conductive substrate, and / or the first transport layer is an electron transport layer or a hole transport layer and correspondingly the second transport layer is a hole transport layer or an electron transport layer, and / or the electrode layer is a metal electrode or a carbon electrode.

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