An organic fluorescent material and its application in the preparation of perovskite-crystalline silicon tandem solar cells

Abstract

The present invention provides an organic fluorescent material and its application in the preparation of perovskite-crystalline silicon tandem solar cells. The molecular formula of the organic fluorescent material is as follows: During the preparation process of perovskite-crystalline silicon tandem solar cells, the organic fluorescent material is added to a perovskite film precursor solution to prepare a perovskite solution-conversion material composite solution for coating the perovskite light-absorbing layer. This can avoid ultraviolet light damage to the perovskite, and the perovskite can also absorb the emitted visible light and generate electricity, thereby improving the photoelectric conversion efficiency of the battery. No additional light-conversion film functional layer is required, simplifying the battery preparation process steps. In addition, the organic fluorescent material, as an additive, can passivate crystal defects in the perovskite light-absorbing layer, improve the quality of the perovskite film, increase its carrier lifetime, and improve the photoelectric conversion performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to an organic fluorescent material and its application in the preparation of perovskite-crystalline silicon stacked solar cells. Background Art

[0002] Perovskite solar cells (PSCs) are considered one of the most promising technologies for the next generation of thin-film solar cells due to their excellent optoelectronic properties, simple fabrication process, and low cost. Perovskite materials can easily adjust their band gaps through compositional manipulation, and their diverse fabrication methods allow them to be widely used in the fabrication of tandem solar cells, potentially breaking the Shockley–Queisser limit (SQ limit) of single-cell solar cells and further improving the photovoltaic efficiency of solar cells. However, ultraviolet light in the solar spectrum is highly destructive to perovskite materials, easily causing degradation and phase transitions, leading to device failure. Existing UV absorption technologies directly absorb this light, preventing solar cells from utilizing the energy for power generation. Photoconversion membrane technologies introduce additional process complexity and increase cell manufacturing costs. Finding a convenient and cost-effective way to prevent UV damage to perovskites while maintaining the photovoltaic efficiency of the cells remains a pressing technical challenge for the industry. Summary of the Invention

[0003] The present invention aims to provide an organic fluorescent material and its application in the preparation of perovskite-crystalline silicon tandem solar cells. This organic fluorescent material, incorporated into the perovskite light-absorbing layer, protects the perovskite from damage by ultraviolet light while allowing the perovskite to absorb the emitted visible light and generate electricity, thereby improving the cell's photoelectric conversion efficiency. This eliminates the need for an additional light-conversion functional layer, simplifying the cell manufacturing process.

[0004] In order to achieve the above objectives, this application adopts the following technical solutions:

[0005] In a first aspect, the present invention provides an organic fluorescent material, the molecular formula of the organic fluorescent material is as follows:

[0006]

[0007] In a second aspect, the present invention provides a method for preparing the above-mentioned organic fluorescent material, wherein the organic fluorescent material is prepared using CA1 and CA2 molecules as raw materials, tetrahydrofuran as a reaction solvent, reacting at 25°C, and purifying the material by a silica gel chromatography column after the reaction.

[0008] The molecular formulas of CA1 and CA2 are as follows:

[0009]

[0010] In a second aspect, the present invention provides an application of the above-mentioned organic fluorescent material in the preparation of perovskite-crystalline silicon tandem solar cells.

[0011] In the above technical solution, during the preparation of perovskite-crystalline silicon tandem solar cells, the organic fluorescent material is added to the perovskite film precursor solution to prepare a perovskite solution-conversion material composite solution for coating the perovskite light-absorbing layer.

[0012] In a third aspect, the present invention provides a perovskite solution-conversion material composite solution, wherein the perovskite solution-conversion material composite solution comprises a perovskite film precursor solution and the above-mentioned organic fluorescent material.

[0013] In the above technical solution, the concentration of the organic fluorescent material in the perovskite solution-conversion material composite solution is between 0.5 and 3 mg / ml.

[0014] In the above technical solution, the perovskite components in the perovskite film precursor solution are rubidium iodide, cesium iodide, methylamine bromide, formamidine iodine and lead iodide in a molar ratio of 0.02-0.05:0.02-0.05:0.02-0.05:(0.85-0.88):(0.85-0.9), the total molar concentration of the perovskite components is 1.2-1.5 mol / L, and the solvent is a mixed solvent of DMF and DMSO in a volume ratio of (4-6):1.

[0015] In a fourth aspect, the present invention provides a perovskite-crystalline silicon tandem solar cell, wherein the perovskite-crystalline silicon tandem solar cell includes a perovskite light-absorbing layer, and the perovskite light-absorbing layer is coated with a perovskite solution-conversion material composite solution, and the perovskite solution-conversion material composite solution includes a perovskite thin film precursor solution and the organic fluorescent material according to claim 1.

[0016] In the above technical solution, the perovskite-crystalline silicon stacked solar cell includes a Si bottom cell, a transparent conductive composite layer, a hole transport layer, a perovskite light absorption layer, a post-processing layer, a first electron transport layer, a second electron transport layer, a transparent conductive thin film layer and an anti-reflection layer stacked in sequence from bottom to top.

[0017] In the above technical solution, the method for preparing the perovskite-crystalline silicon tandem solar cell comprises the following steps:

[0018] Step 1: using PVD magnetron sputtering technology to deposit a TCO transparent conductive substrate on the Si bottom cell, or using RPD evaporation technology to deposit a TCO transparent conductive substrate, or using a combination of the two technologies to form the transparent conductive composite layer;

[0019] Step 2: performing an O2-plasma treatment on the transparent conductive composite layer for 4 minutes to remove residual organic matter on the surface of the transparent conductive composite layer and improve the work function;

[0020] Step 3: coating the hole transport layer using Me-4PACz at a concentration of 0.5-1 mg ml-1, using ethanol as the solvent, and a spin coating process of 3000 (3000)*30s, followed by annealing at 100°C for 5-8min;

[0021] Step 4: coating the perovskite light absorbing layer using the perovskite solution-conversion material composite solution, with a coating process of 2000 (2000) * 10s + 5000 (5000) * 30s, adding 150 μL of chlorobenzene as an anti-solvent at 25 to 30s, and then annealing at 85 to 100°C for 10 to 15 minutes;

[0022] Step 5: coating the post-treatment layer using PEAI post-treatment salt with a solution concentration of 1-2 mg ml-1, using isopropyl alcohol as the solvent, and a spin coating process of 4000 (4000)*30s, followed by annealing at 100°C for 5-8min;

[0023] Step 6: Deposition of the first electron transport layer, C60 thermal evaporation, deposition rate 0.1-0.2 nm / s, deposition 35-50 nm;

[0024] Step 7: Deposition of the second electron transport layer: SnO2 is prepared by atomic layer deposition using tetraethyltin as a precursor, and the deposition is repeated for 250 cycles to a thickness of about 20 to 30 nm.

[0025] Step 8: Preparation of transparent conductive film layer: ITO transparent conductive electrode is plated by magnetron sputtering technology. The sputtering target is ITO, the sputtering power is 150W, the sputtering time is 10min, and the obtained ITO thickness is about 120nm±10nm;

[0026] Step 9: Evaporating silver as metal grid lines;

[0027] Step 10: Vapor-depositing MgF2 as the anti-reflection layer.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention incorporates a newly designed organic fluorescent material that absorbs ultraviolet light and emits visible light into the perovskite light-absorbing layer. While preventing ultraviolet light from damaging the perovskite, the perovskite can also absorb the emitted visible light and generate electricity, thereby improving the photoelectric conversion efficiency of the battery. There is no need to make an additional light-conversion film functional layer, simplifying the battery preparation process steps.

[0030] 2. The organic fluorescent material of the present invention, as an additive, can passivate crystal defects in the perovskite light-absorbing layer, improve the quality of the perovskite film, increase its carrier lifetime, and enhance the photoelectric conversion performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 This is a schematic diagram of the solar cell structure of the present invention;

[0033] Among them: 1. Si bottom battery; 2. Transparent conductive composite layer; 3. Hole transport layer; 4. Perovskite light absorption layer; 5. Post-processing layer; 6. First electron transport layer; 7. Second electron transport layer; 8. Transparent conductive film layer; 9. Anti-reflection layer. DETAILED DESCRIPTION

[0034] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0035] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0036] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0037] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present disclosure. The illustrations only show components related to the present disclosure and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0038] Additionally, in the following description, specific details are provided to provide a thorough understanding of the examples. However, one skilled in the art will appreciate that the aspects described can be practiced without these specific details.

[0039] The present invention provides a new organic fluorescent material, the molecular formula of which is as follows:

[0040]

[0041] Synthesis method: The organic fluorescent material is prepared by using CA1 and CA2 molecules as raw materials, tetrahydrofuran as reaction solvent, reacting at 25°C for 1 hour, and then purifying by silica gel chromatography.

[0042] The molecular formulas for CA1 and CA2 are as follows:

[0043]

[0044] Mechanism of action: The group represented by CA1 has the effect of absorbing ultraviolet light, which is transferred to the CA2 part through intramolecular energy relaxation and then emits light.

[0045] Based on this, the present invention applies this organic fluorescent material to the preparation of perovskite-crystalline silicon tandem solar cells. Before depositing the perovskite film, this independently designed organic fluorescent material is added to the perovskite film precursor solution. This molecule efficiently converts ultraviolet light into near-infrared light. Through molecular structural design, the common and inexpensive molecule coumarin (pure coumarin absorbs ultraviolet light and emits blue light, which does not meet the requirements of tandem solar cells) is chemically modified with our design to absorb ultraviolet light and emit infrared light, thus meeting the requirements of tandem solar cells and reducing the loss of the perovskite material after being irradiated by high-energy photons.

[0046] As one embodiment, the organic fluorescent material is formulated into a perovskite solution-conversion material composite solution. The perovskite solution-conversion material composite solution includes a perovskite film precursor solution and an organic fluorescent material. The perovskite components in the perovskite film precursor solution are rubidium iodide, cesium iodide, methylamine bromide, formamidine iodide, and lead iodide in a molar ratio of 0.05:0.05:0.05:0.85:1. The total molar concentration of the perovskite components is 1.4 mol / L. The solvent is a mixed solvent of DMF and DMSO in a volume ratio of 4:1. The concentration of the organic fluorescent material is 1 mg / ml.

[0047] The perovskite solution-conversion material composite solution prepared by adopting the organic fluorescent material can be used for preparing the perovskite light-absorbing layer of the perovskite-crystalline silicon stacked solar cell.

[0048] As one embodiment, a perovskite-crystalline silicon tandem solar cell includes a Si bottom cell 1, a transparent conductive composite layer 2, a hole transport layer 3, a perovskite light absorption layer 4, a post-processing layer 5, a first electron transport layer 6, a second electron transport layer 7, a transparent conductive thin film layer 8, and an anti-reflection layer 9, which are stacked in sequence from bottom to top. The preparation method includes the following steps:

[0049] Step 1: A TCO transparent conductive substrate (e.g., ITO, i.e., Indium Tin Oxide film, or AZO, Aluminum-Doped Zinc Oxide film) is deposited on the Si bottom cell 1 using PVD (Physical Vapor Deposition) magnetron sputtering technology, or a TCO transparent conductive substrate (e.g., IWO, i.e., Indium Tungsten Oxide film, or ICO, i.e., Indium Cadmium Oxide film) is deposited using RPD (Rapid Prototype Deposition) evaporation technology to form a transparent conductive composite layer 2.

[0050] If PVD technology is used, with an ITO target, a sputtering power of 150W, and a sputtering time of 8 minutes, the resulting ITO thickness is 80-100nm. The above technologies can be mixed and matched to deposit composite films to adjust electrical and optical properties.

[0051] Step 2: Perform O2-plasma treatment on the transparent conductive composite layer 2 for 4 minutes to remove residual organic matter on the surface of the transparent conductive composite layer 2 and improve the work function, reduce the battery recombination center, and improve the optical transmittance;

[0052] Step 3: coating of the hole transport layer 3, using Me-4PACz) at a concentration of 0.5-1 mg ml-1, using ethanol as the solvent, and a spin coating process of 3000 (3000)*30s, followed by annealing at 100°C for 5-8min;

[0053] Step 4: coating the perovskite light absorbing layer 4 using the perovskite solution-conversion material composite solution with a coating process of 2000(2000)*10s+5000(5000)*30s, adding 150 μL of chlorobenzene as an anti-solvent at 25-30s, and then annealing at 85-100°C for 10-15min;

[0054] Step 5: coating of post-treatment layer 5, using PEAI post-treatment salt, solution concentration of 1-2 mg ml-1, solvent is isopropanol, spin coating process is 4000 (4000) * 30s, followed by annealing at 100 ° C for 5-8min;

[0055] Step 6: Deposition of the first electron transport layer 6, C60 thermal evaporation, deposition rate 0.1-0.2 nm / s, deposition 35-50 nm;

[0056] Step 7: Deposition of the second electron transport layer 7: SnO2 is prepared by atomic layer deposition using tetraethyltin as a precursor, and the deposition is repeated for 250 cycles to a thickness of about 20 to 30 nm.

[0057] Step 8: Preparation of transparent conductive film layer 8: ITO transparent conductive electrode is plated by magnetron sputtering technology. The sputtering target is ITO, the sputtering power is 150W, the sputtering time is 10min, and the obtained ITO thickness is about 120nm±10nm;

[0058] Step 9: Evaporating silver as metal grid lines;

[0059] Step 10: Vapor-deposit MgF2 as the anti-reflection layer 9.

[0060] Experimental process

[0061] The experimental group used the above preparation method to produce perovskite-crystalline silicon tandem solar cells. The control group used a perovskite thin film precursor solution (without organic fluorescent material) in step 4 to form a perovskite light-absorbing layer, with all other steps remaining unchanged. After the perovskite-crystalline silicon tandem solar cells were prepared, they were tested for cell efficiency, open-circuit voltage, short-circuit current, and UV stability. The test results are as follows:

[0062] Battery performance test results

[0063]

[0064] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An organic fluorescent material, characterized in that: The molecular formula of the organic fluorescent material is as follows:

2. A method for preparing the organic fluorescent material according to claim 1, characterized in that: The organic fluorescent material is prepared by using CA1 and CA2 molecules as raw materials, tetrahydrofuran as reaction solvent, reacting at 25°C, and purifying through a silica gel chromatography column after the reaction. The molecular formulas of CA1 and CA2 are as follows:

3. Use of the organic fluorescent material according to claim 1 in the preparation of perovskite-crystalline silicon tandem solar cells.

4. The application according to claim 3, characterized in that: During the preparation of perovskite-crystalline silicon tandem solar cells, the organic fluorescent material is added to a perovskite film precursor solution to prepare a perovskite solution-conversion material composite solution for coating a perovskite light-absorbing layer.

5. A perovskite solution-conversion material composite solution, characterized by: The perovskite solution-conversion material composite solution comprises a perovskite film precursor solution and the organic fluorescent material according to claim 1.

6. The perovskite solution-conversion material composite solution according to claim 5, characterized in that: The concentration of the organic fluorescent material in the perovskite solution-conversion material composite solution is between 0.5 and 3 mg / ml.

7. The perovskite solution-conversion material composite solution according to claim 5, characterized in that: The perovskite components in the perovskite film precursor solution include rubidium iodide, cesium iodide, methylamine bromide, formamidine iodine and lead iodide in a molar ratio of 0.02-0.05:0.02-0.05:0.02-0.05:0.85-0.88:0.85-0.9, the total molar concentration of the perovskite components is 1.2-1.5 mol / L, and the solvent is a mixed solvent of DMF and DMSO in a volume ratio of (4-6):

1.

8. A perovskite-crystalline silicon tandem solar cell, characterized in that: The perovskite-crystalline silicon tandem solar cell includes a perovskite light-absorbing layer, which is coated with a perovskite solution-conversion material composite solution, and the perovskite solution-conversion material composite solution includes a perovskite film precursor solution and the organic fluorescent material according to claim 1.

9. The perovskite-crystalline silicon tandem solar cell according to claim 8, characterized in that: The perovskite-crystalline silicon stacked solar cell comprises a Si bottom cell (1), a transparent conductive composite layer (2), a hole transport layer (3), a perovskite light absorption layer (4), a post-processing layer (5), a first electron transport layer (6), a second electron transport layer (7), a transparent conductive thin film layer (8) and an anti-reflection layer (9) which are stacked in sequence from bottom to top.

10. The perovskite-crystalline silicon tandem solar cell according to claim 9, characterized in that: The method for preparing the perovskite-crystalline silicon tandem solar cell comprises the following steps: Step 1: using PVD magnetron sputtering technology to deposit a TCO transparent conductive substrate on the Si bottom cell (1), or using RPD evaporation technology to deposit a TCO transparent conductive substrate, or using a combination of the two technologies to form the transparent conductive composite layer (2); Step 2: performing an O2-plasma treatment on the transparent conductive composite layer (2) for 4 minutes to remove organic matter remaining on the surface of the transparent conductive composite layer (2) and improve the work function; Step 3: The hole transport layer (3) is coated using Me-4PACz at a concentration of 0.5~1mg*ml -1 , the solvent was ethanol, and the spin coating process was 3000(3000)*30s, followed by annealing at 100℃ for 5-8min; Step 4: coating the perovskite light absorbing layer (4) using the perovskite solution-conversion material composite solution, with a coating process of 2000 (2000) * 10s + 5000 (5000) * 30s, adding 150µL of chlorobenzene as an anti-solvent at 25-30s, and then annealing at 85-100°C for 10-15min; Step 5: The post-treatment layer (5) is coated using PEAI post-treatment salt with a solution concentration of 1~2mg*ml -1 , the solvent was isopropyl alcohol, and the spin coating process was 4000(4000)*30 s, followed by annealing at 100 °C for 5~8 min; Step 6: Deposition of the first electron transport layer (6) by C60 thermal evaporation at a deposition rate of 0.1-0.2 nm / s and a deposition thickness of 35-50 nm; Step 7: Deposition of the second electron transport layer (7): SnO2 is prepared by atomic layer deposition using tetraethyltin as a precursor, with 250 cycles of deposition to a thickness of 20-30 nm; Step 8: Preparation of transparent conductive film layer (8): ITO transparent conductive electrode is plated by magnetron sputtering technology. The sputtering target is ITO, the sputtering power is 150W, the sputtering time is 10min, and the obtained ITO thickness is 120nm±10nm; Step 9: Evaporating silver as metal grid lines; Step 10: Vapor-depositing MgF2 as the anti-reflection layer (9).

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