Solar cell based on exciton fission mechanism and preparation method of solar cell

Abstract

The invention discloses a solar cell based on an exciton fission mechanism and a preparation method of the solar cell, and belongs to the technical field of photovoltaics. The solar cell comprises an electron transport layer, a light absorption layer, a hole transport layer and an electrode which are stacked, wherein the light absorption layer comprises a perovskite thin film and an exciton fission material which is uniformly distributed on the perovskite thin film. The exciton fission material is doped in the perovskite thin film, so that the exciton fission material is synergistically embedded into or distributed in crystal grains and crystal boundaries in a perovskite crystal forming process, and a composite light absorption layer with exciton fission capability is constructed. According to the composite structure, a single high-energy photon can excite two carriers through exciton fission, so that the photon utilization rate of the solar cell is improved.

Description

Technical Field

[0001] This application belongs to the field of photovoltaic technology, specifically relating to a solar cell based on exciton fission mechanism and a method for preparing the solar cell. Background Technology

[0002] Perovskite solar cells have seen rapid development in the photovoltaic field in recent years due to their excellent light absorption, high carrier mobility, long diffusion distance, and low-cost solution processing characteristics.

[0003] Despite the continuous improvement in the performance of perovskite solar cells, current perovskite solar cells still mainly rely on the single exciton excitation-separation-transmission process, which limits their utilization efficiency of high-energy photons and prevents them from breaking through the Shockley-Queisser theoretical efficiency limit (approximately 33%) of single-junction devices, thus restricting further development. Summary of the Invention

[0004] The purpose of this application is to provide a solar cell based on the exciton fission mechanism and a method for fabricating the solar cell, which can solve the problem of low photon utilization efficiency in current perovskite solar cells.

[0005] In a first aspect, embodiments of this application provide a solar cell based on an exciton fission mechanism. The solar cell includes an electron transport layer, a light absorption layer, a hole transport layer, and electrodes stacked together. The light absorption layer includes a perovskite thin film and an exciton fission material uniformly distributed on the perovskite thin film.

[0006] Optionally, the exciton fission material includes at least one of the following: pentacene and its derivatives, tetraphenylene and its derivatives, bianthracite compounds, or other materials with exciton fission capability other than pentacene and its derivatives, tetraphenylene and its derivatives, and bianthracite compounds.

[0007] Optionally, the perovskite active material of the perovskite film has a three-dimensional perovskite structure with the general formula ABX3;

[0008] Wherein, A includes one of cesium, formamidine, and methylamine, or a mixture of multiple of cesium, formamidine, and methylamine;

[0009] B includes one of lead and tin, or a mixture of lead and tin;

[0010] C includes one of chlorine, bromine, and iodine, or a mixture of multiple of chlorine, bromine, and iodine.

[0011] Secondly, embodiments of this application provide a method for preparing a solar cell, the method comprising:

[0012] Obtain a first solvent, the first solvent comprising DMF and DMSO;

[0013] The first solvent is mixed with the exciton fission material to obtain the second solvent;

[0014] The second solvent is mixed with the perovskite active material to obtain a precursor solution;

[0015] The precursor solution is spin-coated onto the electron transport layer to form a light absorption layer;

[0016] The solar cell is obtained by stacking the electron transport layer, the light absorption layer, the hole transport layer, and the electrode layer.

[0017] Optionally, the exciton fission material includes at least one of the following: pentacene and its derivatives, tetraphenylene and its derivatives, bianthracite compounds, or other materials with exciton fission capability other than pentacene and its derivatives, tetraphenylene and its derivatives, and bianthracite compounds.

[0018] Optionally, the perovskite active material has a three-dimensional perovskite structure with the general formula ABX3;

[0019] Wherein, A includes one of cesium, formamidine, and methylamine, or a mixture of multiple of cesium, formamidine, and methylamine;

[0020] B includes one of lead and tin, or a mixture of lead and tin;

[0021] C includes one of chlorine, bromine, and iodine, or a mixture of multiple of chlorine, bromine, and iodine.

[0022] Optionally, the step of spin-coating the precursor solution into the electron transport layer to form a light-absorbing layer includes:

[0023] The precursor solution is added dropwise to the electron transport layer;

[0024] The precursor solution on the electron transport layer is spin-coated for the first time at a first rotation speed of 6s-10s, and the first rotation speed is 800rpm-1200rpm.

[0025] The precursor solution on the electron transport layer is spin-coated a second time at a second rotation speed of 3500 rpm to 4500 rpm for a duration of 25 s to 35 s.

[0026] The electron transport layer after the second spin coating is annealed to form the light absorption layer on the electron transport layer.

[0027] Optionally, before annealing the electron transport layer after the second spin coating is completed, and before forming the light absorption layer on the electron transport layer, the method further includes:

[0028] Within 8-12 seconds before the end of the second spin coating process, an antisolvent, anisole, is dropped onto the coating surface of the electron transport layer.

[0029] Optionally, annealing the electron transport layer after the second spin coating to form the light absorption layer includes:

[0030] The electron transport layer after the second spin coating is annealed in a first temperature range to form the light absorption layer on the electron transport layer. The first temperature range is 100℃-120℃.

[0031] Optionally, the volume ratio of DMF to DMSO in the first solvent is 4:1 to 9:1, and the content of exciton fission material in the second solvent is 0.08 mg / mL to 0.12 mg / mL.

[0032] In this embodiment, by incorporating exciton fission materials into the perovskite thin film, these materials are synergistically embedded or distributed within the grains and grain boundaries during perovskite crystal formation, thus constructing a composite light-absorbing layer with exciton fission capability. This composite structure can achieve the excitation of two charge carriers by a single high-energy photon through exciton fission, thereby improving the photon utilization rate of the solar cell. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is one of the schematic flowcharts of a method for fabricating a solar cell provided in an embodiment of this application;

[0035] Figure 2 This is a second schematic flowchart illustrating the method for fabricating a solar cell according to an embodiment of this application. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0037] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0038] This application provides a solar cell based on exciton fission mechanism, including an electron transport layer, a light absorption layer, a hole transport layer and electrodes stacked together. The light absorption layer includes a perovskite thin film and an exciton fission material uniformly distributed in the perovskite thin film.

[0039] The performance of the solar cell in this embodiment is compared with that of a comparative example of a perovskite thin film without exciton fission materials, as shown in Table 1:

[0040]

[0041] Table 1

[0042] A comparison of the examples and comparative examples shows that introducing exciton fission materials (such as pentacene) into the perovskite absorber layer can significantly improve the short-circuit current and device efficiency of perovskite solar cells, with the short-circuit current density increasing from 24.71 mA cm⁻¹. -2 Increased to 25.64 mA cm -2 The device efficiency increased from 21.8% to 23.4%.

[0043] In this embodiment, by incorporating exciton fission materials into the perovskite thin film, these materials are synergistically embedded or distributed within the grains and grain boundaries during the formation of the perovskite crystal, thus constructing a composite light-absorbing layer with exciton fission capability. This composite structure can achieve the excitation of two charge carriers by a single high-energy photon through exciton fission, thereby improving the photon utilization rate of the solar cell.

[0044] Optionally, the exciton fission material includes at least one of the following: pentacene and its derivatives, tetraphenylene and its derivatives, bianthracite compounds, or other materials with exciton fission capability other than pentacene and its derivatives, tetraphenylene and its derivatives, and bianthracite compounds.

[0045] This embodiment provides a variety of materials with exciton fission capabilities, which is equivalent to providing multiple production methods for light absorption layers. During production, multiple production methods can be used simultaneously, thereby improving production efficiency.

[0046] Optionally, the perovskite active material of the perovskite film has a three-dimensional perovskite structure with the general formula ABX3;

[0047] Wherein, A includes one of cesium, formamidine, and methylamine, or a mixture of multiple of cesium, formamidine, and methylamine;

[0048] B includes one of lead and tin, or a mixture of lead and tin;

[0049] C includes one of chlorine, bromine, and iodine, or a mixture of multiple of chlorine, bromine, and iodine.

[0050] Similar to the above embodiments, this embodiment provides a variety of perovskite active materials, which is equivalent to providing multiple production methods for the light absorption layer. In the actual production process, the corresponding production method can be flexibly selected according to the needs and available conditions.

[0051] This application also provides a method for preparing a solar cell, such as... Figure 1 As shown, it includes the following steps:

[0052] Step 101: Obtain a first solvent, which includes DMF and DMSO.

[0053] Step 102: Mix the first solvent with the exciton fission material to obtain the second solvent.

[0054] Step 103: Mix the second solvent with the perovskite active material to obtain a precursor solution.

[0055] Step 104: Spin-coat the precursor solution onto the electron transport layer to form a light absorption layer.

[0056] Step 105: Stack the electron transport layer, the light absorption layer, the hole transport layer, and the electrode layer to obtain the solar cell.

[0057] In this embodiment, DMF (i.e., N,N-dimethylformamide) and DMSO (i.e., dimethyl sulfoxide) are mixed. DMF's aprotic nature prevents it from donating protons, but it can stabilize negative ions through dipole interactions. DMSO accepts hydrogen bonds through the lone pair electrons of its oxygen atoms, dissolving substances containing proton groups such as hydroxyl and amino groups. The resulting solvent has strong dissolving power. An exciton fission material is added to the first solvent to obtain a second solvent containing the exciton fission material. Subsequently, a perovskite active material is added to the second solvent to obtain a precursor solution containing the exciton fission material. Spin-coating the precursor solution onto the electron transport layer forms a light-absorbing layer. The solar cell in this embodiment includes the electron transport layer, the light-absorbing layer, the hole transport layer, and electrodes.

[0058] By incorporating exciton fission materials into the precursor solution, these materials are synergistically embedded or distributed within the grains and grain boundaries during the formation of the perovskite crystals in the subsequent light-absorbing layer, thus constructing a composite light-absorbing layer with exciton fission capability. This composite structure can achieve the excitation of two charge carriers by a single high-energy photon through exciton fission, thereby improving the photon utilization rate of the solar cell.

[0059] Optionally, the exciton fission material includes at least one of the following: pentacene and its derivatives, tetraphenylene and its derivatives, bianthracite compounds, or other materials with exciton fission capability other than pentacene and its derivatives, tetraphenylene and its derivatives, and bianthracite compounds.

[0060] The content of this embodiment has already been described in the above embodiments of solar cells based on exciton fission mechanism, and will not be repeated here.

[0061] Optionally, the perovskite active material of the perovskite film has a three-dimensional perovskite structure with the general formula ABX3;

[0062] Wherein, A includes one of cesium, formamidine, and methylamine, or a mixture of multiple of cesium, formamidine, and methylamine;

[0063] B includes one of lead and tin, or a mixture of lead and tin;

[0064] C includes one of chlorine, bromine, and iodine, or a mixture of multiple of chlorine, bromine, and iodine.

[0065] The content of this embodiment has already been described in the above embodiments of solar cells based on exciton fission mechanism, and will not be repeated here.

[0066] Optionally, the step of spin-coating the precursor solution into the electron transport layer to form a light-absorbing layer includes:

[0067] The precursor solution is added dropwise to the electron transport layer;

[0068] The precursor solution on the electron transport layer is spin-coated for the first time at a first rotation speed of 6s-10s, and the first rotation speed is 800rpm-1200rpm.

[0069] The precursor solution on the electron transport layer is spin-coated a second time at a second rotation speed of 3500 rpm to 4500 rpm. The duration of the second spin coating is 25 s to 35 s.

[0070] The electron transport layer after the second spin coating is annealed to form the light absorption layer on the electron transport layer.

[0071] In this embodiment, after the precursor solution is added to the electron transport layer, two spin coating processes are required. In the first spin coating, the duration is 6-10 seconds, and the rotation speed is 800-1200 rpm, ensuring the precursor solution is uniformly spin-coated onto the electron transport layer and forms the base portion of the light absorption layer. In the second spin coating, the duration is 25-35 seconds, and the rotation speed is 3500-4500 rpm. After both spin coating processes, the precursor solution on the electron transport layer is annealed to remove solvent residue from the spin coating process and promote crystallization of the precursor solution to form the light absorption layer, maintaining high stability in its performance.

[0072] Optionally, before annealing the electron transport layer after the second spin coating is completed, and before forming the light absorption layer on the electron transport layer, the method further includes:

[0073] Within 8-12 seconds before the end of the second spin coating process, an antisolvent, anisole, is dropped onto the coating surface of the electron transport layer.

[0074] In this embodiment, anisole is added as an antisolvent during the second spin coating process. Anisole has limited miscibility with the main solvent (such as DMF or DMSO), but it can quickly extract the main solvent, causing the solute (such as perovskite precursor) to reach a supersaturated state instantly, promoting uniform nucleation. In other words, it can suppress random nucleation, reduce grain boundary defects, and form a dense, large-grained thin film, thereby enhancing the photoelectric properties of the light absorption layer.

[0075] Optionally, annealing the electron transport layer after the second spin coating to form the light absorption layer includes:

[0076] The electron transport layer after the second spin coating is annealed in a first temperature range to form the light absorption layer on the electron transport layer. The first temperature range is 100℃-120℃.

[0077] In this embodiment, the annealing temperature range can be 100℃-120℃. Within this range, the annealing effect can be improved, the crystallization of the precursor solution can be promoted, the material fluidity can be enhanced during the annealing process, the micro-defects caused by spin coating can be filled, thereby improving the photoelectric performance of the light absorption layer.

[0078] Optionally, the volume ratio of DMF to DMSO in the first solvent is 4:1 to 9:1, and the content of exciton fission material in the second solvent is 0.08 mg / mL to 0.12 mg / mL.

[0079] In this embodiment, when the volume ratio between DMF and DMSO, and the content of the exciton fission material are within the above-mentioned range, the exciton fission material can be fully dissolved to facilitate subsequent reaction with the perovskite active material.

[0080] Please see further. Figure 2 , combined Figure 2 The fabrication process of the electron transport layer, light absorption layer, hole transport layer, and electrode will be described in the following examples:

[0081] Preparation of the electron transport layer: 5g SnCl4·5H2O was dissolved in 40mL ethylene glycol and stirred overnight. Then, 10mL of the above solution was transferred to a 100mL round-bottom flask, and 2mL of acetic acid and ammonia solution, and 1mL of tetramethylammonium hydroxide solution were added with stirring. After cooling to room temperature, the round-bottom flask was placed in an oil bath and heated at 150℃ for 30min. Then, ethanol was added for dispersion, and the supernatant was discarded after centrifugation. The precipitate was then dispersed again with ethanol. The mixture was centrifuged twice at 2500rpm (25min each time) and twice at 5000rpm (5min each time). Finally, the precipitate obtained by centrifugation was dispersed in about 30mL of ethanol to obtain a SnO2 nanocrystal solution with a concentration of 12.5mg / mL. The nanocrystal solution was spin-coated onto a transparent conductive electrode (glass-ITO substrate) at 2500rpm for 30s and annealed at 105℃ for 1.5h to obtain the SnO2 electron transport layer.

[0082] Preparation of the light-absorbing layer: Prepare 20 mL of blank solvent A (i.e., the first solvent) with a DMF:DMSO ratio of 8:2 (volume ratio). Weigh 0.5 mg of pentanebenzene into 5 mL of a mixed solvent with a DMF:DMSO ratio of 8:2 (volume ratio), obtaining solvent B (i.e., the second solvent) containing 0.1 mg / mL pentanebenzene. Weigh 1.28 mmol PbI₂, 0.067 mmol PbCl₂, 1.08 mmol FAI, 0.067 mmol FABr, and 0.2 mmol CsI respectively, dissolve them in 1 mL of solvent B, prepare a precursor solution, and stir overnight. Filter using a 0.22 μm polytetrafluoroethylene filter membrane for later use. Spin-coat the perovskite precursor solution onto the surface of the SnO₂ electron transport layer at 1000 rpm for 8 s, then at 4000 rpm for 30 s. Approximately 10 s before the end of spin-coating, rapidly add 110 μL of the antisolvent anisole. It was then transferred to a hot plate and annealed at 110°C for 15 minutes to form a light-absorbing layer.

[0083] Preparation of the hole transport layer: 72.3 mg of Spiro-OMeTAD powder was dissolved in 1 mL of chlorobenzene, and 28.8 μL of 4-tert-butylpyridine and 17.5 μL of lithium salt solution (520 mg dissolved in 1 mL of acetonitrile) were added. The mixture was stirred overnight. After filtering through a 0.22 μm polytetrafluoroethylene membrane, the solution was spin-coated onto the surface of a perovskite film at 4000 rpm for 30 s. The film was then stored overnight in a dehumidifier to oxidize Spiro-OMeTAD and improve its hole mobility.

[0084] Electrode preparation: Vacuuming to <10 -4 Pa, gold plating rate The coating thickness is approximately 80 nm.

[0085] By stacking the aforementioned electron transport layer, light absorption layer, hole transport layer, and electrode layers, a solar cell can be obtained. In this process, by incorporating exciton fission materials into the perovskite thin film, these materials are synergistically embedded or distributed within the grains and grain boundaries during perovskite crystal formation, constructing a composite light absorption layer with exciton fission capability. This composite structure can achieve the excitation of two charge carriers by a single high-energy photon through exciton fission, thereby improving the photon utilization rate of the solar cell.

[0086] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0087] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A solar cell based on exciton fission mechanism, characterized in that, The solar cell includes an electron transport layer, a light absorption layer, a hole transport layer, and electrodes stacked together. The light absorption layer includes a perovskite thin film and an exciton fission material uniformly distributed on the perovskite thin film.

2. The solar cell based on exciton fission mechanism as described in claim 1, characterized in that, The exciton fission material includes at least one of the following: pentacene and its derivatives, tetraphenylene and its derivatives, bianthracite compounds, or other materials with exciton fission capability other than the pentacene and its derivatives, the tetraphenylene and its derivatives, and the bianthracite compounds.

3. The solar cell based on exciton fission mechanism as described in claim 2, characterized in that, The perovskite active material of the perovskite film has a three-dimensional perovskite structure with the general formula ABX3. Wherein, A includes one of cesium, formamidine, and methylamine, or a mixture of multiple of cesium, formamidine, and methylamine; B includes one of lead and tin, or a mixture of lead and tin; C includes one of chlorine, bromine, and iodine, or a mixture of multiple of chlorine, bromine, and iodine.

4. A method for preparing a solar cell, characterized in that, The method includes: Obtain a first solvent, the first solvent comprising DMF and DMSO; The first solvent is mixed with the exciton fission material to obtain the second solvent; The second solvent is mixed with the perovskite active material to obtain a precursor solution; The precursor solution is spin-coated onto the electron transport layer to form a light absorption layer; The solar cell is obtained by stacking the electron transport layer, the light absorption layer, the hole transport layer, and the electrode layer.

5. The method as described in claim 4, characterized in that, The exciton fission material includes at least one of the following: pentacene and its derivatives, tetraphenylene and its derivatives, bianthracite compounds, or other materials with exciton fission capability other than the pentacene and its derivatives, the tetraphenylene and its derivatives, and the bianthracite compounds.

6. The method as described in claim 5, characterized in that, The perovskite active material has a three-dimensional perovskite structure with the general formula ABX3. Wherein, A includes one of cesium, formamidine, and methylamine, or a mixture of multiple of cesium, formamidine, and methylamine; B includes one of lead and tin, or a mixture of lead and tin; C includes one of chlorine, bromine, and iodine, or a mixture of multiple of chlorine, bromine, and iodine.

7. The method according to any one of claims 4 to 6, characterized in that, The step of spin-coating the precursor solution into the electron transport layer to form a light-absorbing layer includes: The precursor solution is added dropwise to the electron transport layer; The precursor solution on the electron transport layer is spin-coated for the first time at a first rotation speed of 6s-10s, and the first rotation speed is 800rpm-1200rpm. The precursor solution on the electron transport layer is spin-coated a second time at a second rotation speed of 3500 rpm to 4500 rpm. The duration of the second spin coating is 25 s to 35 s. The electron transport layer after the second spin coating is annealed to form the light absorption layer on the electron transport layer.

8. The method as described in claim 7, characterized in that, Before annealing the electron transport layer after the second spin coating is completed, and before forming the light absorption layer on the electron transport layer, the method further includes: Within 8-12 seconds before the end of the second spin coating process, an antisolvent, anisole, is dropped onto the coating surface of the electron transport layer.

9. The method as described in claim 7, characterized in that, The process of annealing the electron transport layer after the second spin coating to form the light absorption layer includes: The electron transport layer after the second spin coating is annealed in a first temperature range to form the light absorption layer on the electron transport layer. The first temperature range is 100℃-120℃.

10. The method according to any one of claims 4 to 6, characterized in that, The volume ratio of DMF to DMSO in the first solvent is 4:1 to 9:1, and the content of exciton fission material in the second solvent is 0.08 mg / mL to 0.12 mg / mL.

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