Lead-free high-efficiency flexible perovskite solar cell and preparation method thereof

Abstract

The invention provides a preparation method of a lead-free high-efficiency flexible perovskite solar cell, and relates to the field of new energy photoelectric conversion. The preparation method comprises the following steps: S1, substrate pretreatment: cleaning a polyimide flexible substrate, and then carrying out plasma treatment; s2, quantum dot synthesis: CsI, AgI and SbI3 are dissolved in a mixed solvent, and a Cs2AgSbI6 quantum dot solution is obtained; s3, quantum dot solution coating: coating a polyimide substrate with the quantum dot solution; s4, annealing treatment: carrying out annealing treatment in a nitrogen atmosphere; and S5, preparing an electrode: depositing an ITO transparent conductive electrode on the surface of the quantum dot film through radio frequency magnetron sputtering, and preparing a silver back electrode on the other side of the polyimide substrate through thermal evaporation coating, thereby obtaining the solar cell. According to the lead-free perovskite solar cell adopting the Cs2AgSbI6 quantum dots as the light absorption layer, the efficiency and the stability of the cell are improved, the cost is reduced, the comprehensive performance of the lead-free perovskite solar cell is further improved, and the development of the lead-free perovskite solar cell in practical application is promoted.

Description

Technical Field

[0001] The present invention relates to the field of new energy photoelectric conversion, and in particular to a lead-free, high-efficiency, flexible perovskite solar cell and a preparation method thereof. Background Art

[0002] Perovskite solar cells, as a new type of photoelectric conversion device, are currently experiencing rapid development, demonstrating tremendous potential in terms of photoelectric conversion efficiency. Flexible perovskite solar cells, in particular, are attracting significant attention due to their potential applications in wearable devices and flexible electronic devices.

[0003] However, mainstream perovskite solar cell fabrication technologies mostly utilize lead-containing perovskite materials, such as methylamine lead iodide perovskite. While these lead-containing materials achieve high photoelectric conversion efficiencies, the toxicity of lead poses environmental risks and potential health hazards, severely limiting their large-scale commercial application and widespread use in safety-critical applications. Furthermore, the fabrication processes for some existing flexible perovskite solar cells still have room for improvement in terms of efficiency, stability, process complexity, and cost control.

[0004] Most of the existing lead-free perovskite solar cells use tin-based, germanium-based material systems, but these materials still have certain limitations, such as tin-based perovskites are easily oxidized and germanium-based perovskites are expensive. Three-dimensional (3D) iodide double perovskites have attracted attention due to their potential narrow band gap and efficient carrier transport capabilities. However, iodide ions (I - The large ionic radius of ) leads to lattice instability, making 3D iodide double perovskite materials extremely rare. Currently, only about 14 types have been isolated, and most of them are wide-bandgap insulators and cannot be used in solar cell manufacturing. This patent successfully synthesized a new 3D iodide double perovskite Cs2AgSbI6 nanocrystal, bypassing the thermodynamic limitations of traditional synthesis and exhibiting a pure phase cubic elpasolite structure with excellent photoelectric conversion performance. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing lead-free, high-efficiency, flexible perovskite solar cells. The technical solution uses Cs2AgSbI6 quantum dots as the light-absorbing layer of the lead-free perovskite solar cell, aiming to solve the problems of low efficiency, poor stability and material cost in the existing technology, further improve the comprehensive performance of lead-free perovskite solar cells, and promote their development in practical applications.

[0006] Another object of the present invention is to provide a lead-free, high-efficiency, flexible perovskite solar cell using 3D iodide double perovskite Cs2AgSbI6 nanocrystals as the photoelectric conversion material, which bypasses the thermodynamic limitations of traditional synthesis, presents a pure phase cubic elpasolite structure, and has excellent photoelectric conversion performance.

[0007] The present invention solves the technical problem by adopting the following technical solutions.

[0008] In one aspect, an embodiment of the present invention provides a method for preparing a lead-free, high-efficiency, flexible perovskite solar cell, comprising:

[0009] S1 Substrate pretreatment: clean and dry the polyimide flexible substrate; use oxygen as the working gas to perform plasma treatment on the polyimide flexible substrate;

[0010] Synthesis of S2 quantum dots: CsI, AgI, and SbI3 were dissolved in a mixed solvent of oleic acid and octadecene under nitrogen atmosphere, heated and stirred to obtain a Cs2AgSbI6 quantum dot solution;

[0011] S3 quantum dot solution coating: coating the synthesized Cs2AgSbI6 quantum dot solution on the polyimide substrate treated in step S1 to obtain a wet quantum dot film;

[0012] S4 annealing treatment: placing the polyimide substrate deposited with the wet quantum dot film in an annealing furnace and performing annealing treatment under a nitrogen atmosphere;

[0013] S5 electrode preparation: Under an inert atmosphere, an ITO transparent conductive electrode is deposited on the surface of the quantum dot film by radio frequency magnetron sputtering, and a silver back electrode is prepared on the other side of the polyimide substrate by thermal evaporation coating to obtain the solar cell.

[0014] In some embodiments of the present invention, in step S1 , the power of the plasma treatment is 100-150 W, and the working pressure is 0.6-0.8 Pa.

[0015] In some embodiments of the present invention, in step S2, in the mixed solvent, the molar ratio of CsI, AgI, and SbI3 is 1:1:1.

[0016] In some embodiments of the present invention, in step S3, the coating is performed by spin coating or inkjet printing;

[0017] The spin coating parameters are: coating at a rate of 1000 rpm for 5 s, and then coating at a rate of 3000 rpm for 35-40 s;

[0018] The parameters of the inkjet printing are: nozzle height 1.5 mm, inkjet speed 500 mm / s, ink drop size 50-55 pl, layer-by-layer printing and drying.

[0019] In some embodiments of the present invention, in step S4, the annealing treatment is: heating from room temperature to 150-160° C. at a heating rate of 5-8° C. / min, and annealing at this temperature for 20-25 minutes.

[0020] In some embodiments of the present invention, in step S5, the RF magnetron sputtering has a sputtering power of 180-200 W, a gas pressure of 2-2.5 Pa, an inert gas flow rate of 15 sccm, and a deposition time of 15-20 min.

[0021] In some embodiments of the present invention, in step S5, the evaporation rate of the thermal evaporation coating is 0.5 A / s, and the evaporation pressure is 5×10 -4 Pa.

[0022] A lead-free high-efficiency flexible perovskite solar cell is prepared by the above-mentioned preparation method.

[0023] In some embodiments of the present invention, the thickness of the wet quantum dot film is 300-400 nm.

[0024] In some embodiments of the present invention, the thickness of the silver back electrode is 150-200 nm.

[0025] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0026] The solar cell and preparation method provided by the present invention adopt a perovskite material system of lead-free Cs2AgSbI6 quantum dots, which completely eliminates the environmental pollution, health and safety hazards brought by the lead element in traditional lead-containing perovskite solar cells, meets the requirements of environmental protection and sustainable development, and is conducive to promotion and use in more application scenarios, especially in fields with high environmental protection requirements.

[0027] Improved photoelectric conversion efficiency: Through optimized preparation processes, including precursor solution preparation, deposition process parameters, and annealing conditions, high-quality lead-free perovskite films can be prepared with high crystallinity and low defect state density, thereby effectively improving the photoelectric conversion efficiency of solar cells and making them more competitive in performance. It is expected to approach or even match the efficiency level of some lead-containing perovskite cells, promoting the application and development of perovskite solar cells in the field of high-efficiency power generation.

[0028] Enhanced stability: The optimization of the preparation process and the optimized combination of the characteristics of the lead-free perovskite material itself help to improve the stability of solar cells under different environmental conditions, including thermal stability, moisture stability and light stability, reduce the attenuation of battery performance, extend its service life, reduce maintenance costs and replacement frequency during use, and improve the overall reliability and economy of the system.

[0029] Simple process and manageable costs: This preparation method features a relatively simple overall process flow, is easy to operate, and is easily controllable and scalable. Furthermore, the selected materials offer certain cost-effectiveness advantages, potentially reducing the production cost of flexible perovskite solar cells, improving their price competitiveness in the market, and promoting their large-scale commercial application and industrial development.

[0030] The present invention provides 3D iodide double perovskite Cs2AgSbI6 nanocrystals, which bypass the thermodynamic limitations of traditional synthesis, present a pure phase cubic elpasolite structure, and have excellent photoelectric conversion performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 is a graph showing the relationship between current density and voltage of two batteries in the test example;

[0033] Figure 2 is a continuous illumination efficiency curve of the solar cell of Example 1;

[0034] Figure 3 The normalized efficiency and time relationship curves of the two batteries in the test example are shown. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0036] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to specific embodiments.

[0037] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0038] Example 1

[0039] Preparation of Cs2AgSbI6 quantum dot perovskite solar cells by spin coating:

[0040] S1 Substrate Pretreatment: A polyimide (PI) flexible substrate was ultrasonically cleaned in acetone, deionized water, and anhydrous ethanol, sequentially for 15 minutes each, and then blown dry with a nitrogen gun. The cleaned substrate was then placed in a plasma cleaning device and treated with oxygen plasma for 3 minutes at a power of 100W and a pressure of 0.6Pa to improve the substrate's hydrophilicity and conductivity, ensuring uniform adhesion of the perovskite quantum dot layer to the substrate surface.

[0041] S2, Cs2AgSbI6 quantum dot synthesis: Under a nitrogen atmosphere, 0.1 mmol of CsI, 0.1 mmol of AgI, and 0.1 mmol of SbI3 were dissolved in a mixed solvent of 5 ml of oleic acid and 10 ml of octadecene. The solution was heated to 180°C and stirred for 30 minutes to obtain a Cs2AgSbI6 quantum dot solution. This solution was then mixed with appropriate amounts of oleic acid and oleylamine. The size and morphology of the quantum dots were controlled by adjusting the reaction time and temperature.

[0042] S3 quantum dot solution spin coating: The synthesized Cs2AgSbI6 quantum dot solution was spin coated on the pretreated polyimide substrate at a spin coating speed of 3000 rpm for 40 seconds, with pre-spin coating at a low speed of 1000 rpm for the first 5 seconds to form a uniform wet quantum dot film with a film thickness of about 300-400 nm.

[0043] S4 annealing treatment: Place the substrate with the wet quantum dot film deposited in a tubular annealing furnace. In a nitrogen atmosphere, heat the temperature to 150°C at a rate of 5°C / min and anneal at this temperature for 20 minutes to fully crystallize the quantum dot film and improve its optoelectronic performance and stability.

[0044] S5 electrode preparation: A 120nm thick ITO transparent conductive electrode was deposited on the surface of the quantum dot film using radio frequency magnetron sputtering technology. The sputtering power was 180W, the pressure was 2Pa, the argon flow rate was 15sccm, and the deposition time was 15min. A 150nm thick silver (Ag) back electrode was deposited on the other side of the polyimide substrate using thermal evaporation technology. The evaporation rate was 0.5A / s and the evaporation pressure was 5×10 -4 Pa.

[0045] Example 2

[0046] Preparation of Cs2AgSbI6 quantum dot perovskite solar cells by inkjet printing:

[0047] S1 Substrate pretreatment: The substrate pretreatment method is the same as that in Example 1. The cleaning and plasma treatment steps ensure that the polyimide substrate has good hydrophilicity and conductivity, providing ideal surface conditions for the subsequent deposition of the quantum dot layer.

[0048] S2, Cs2AgSbI6 quantum dot synthesis: Prepare Cs2AgSbI6 quantum dot solution according to the synthesis method in Example 1, but extend the reaction time to 40 min to obtain quantum dots of different sizes, thereby adjusting the optical and electrical properties of the material.

[0049] S3 Quantum Dot Solution Inkjet Printing: Using inkjet printing technology, the synthesized quantum dot solution is evenly printed onto a pretreated polyimide substrate. The inkjet printing parameters are set to: nozzle height 1.5mm, inkjet speed 500mm / s, droplet size approximately 50pl, and layer-by-layer printing and drying until a quantum dot film with a thickness of approximately 350-450nm is formed.

[0050] S4 annealing treatment: Place the substrate printed with the quantum dot film in an annealing furnace. In a nitrogen atmosphere, heat the temperature to 140°C at a rate of 5°C / min and anneal for 25 minutes to crystallize the quantum dot film and improve its photoelectric performance.

[0051] S5 electrode preparation: The electrode preparation method is the same as that in Example 1. The ITO transparent conductive electrode (thickness 120nm) is deposited by radio frequency magnetron sputtering technology, and the silver (Ag) back electrode (thickness 150nm) is prepared on the other side of the polyimide substrate by thermal evaporation coating technology to complete the preparation of the solar cell.

[0052] Test example:

[0053] 1. The Cs2AgSbI6 quantum dot solar cell of Example 1 and the common FASnI3 tin-based perovskite were used as test objects to test the efficiency of the two cells. The results are as follows: Figure 1 As shown, from Figure 1 It can be concluded that the efficiency of ordinary FASnI3 tin-based perovskite cells is 12.28%, while the efficiency of lead-free perovskite cells based on Cs2AgSbI6 quantum dots reaches 16%. The test method is: using a Keithley 2400 source meter under light conditions. Using a solar simulator (Newport, OrielSol3A Class AAA), the light intensity is set to 100mW / cm 2(AM 1.5G standard). Calibration was performed using a standard silicon cell certified by NREL as a reference cell. The scan voltage step size was 0.02V and the delay time was set to 40ms. An aperture of 0.1cm was used. 2 The mask calibrates the effective illumination area.

[0054] 2. The Cs2AgSbI6 quantum dot solar cell of Example 1 was used as the test object to test its battery efficiency under continuous illumination. The unpackaged battery was tested at the maximum power point (MPP) under AM 1.5G illumination (100mW / cm 2 ) and nitrogen (N2) atmosphere. Light is generated by a solar simulator based on an LED light source. The bias voltage at the MPP is automatically applied after calculation, and the light intensity is calibrated using a Newport standard silicon reference cell. The initial voltage of the MPP is obtained by JV scanning and then updated using a perturb-and-observe algorithm. The results are shown in Figure 2 As shown, from Figure 2 It can be concluded that the lead-free perovskite battery based on Cs2AgSbI6 quantum dots has good stability under continuous illumination. After 600 hours of continuous illumination, the efficiency of the battery can still reach 90%.

[0055] 3. The Cs2AgSbI6 quantum dot solar cell of Example 1 and the conventional FASnI3 tin-based perovskite were used as test objects. The samples were placed in a homemade humidity-controlled chamber equipped with a humidity sensor, controller, humidifier, and dehumidifier to maintain the ambient humidity near the set value. The JV curves were taken out every 50 hours for testing. The corresponding JV curves were measured in a glove box filled with nitrogen (N2) using a Keithley 2400 source meter and a solar simulator. The illumination conditions were AM 1.5G (100mW / cm 2 ). The battery efficiency of the two batteries after being placed in the air was tested, and the results are as follows Figure 3 As shown, from Figure 3 It can be concluded that the lead-free perovskite battery based on Cs2AgSbI6 quantum dots has good environmental stability and its efficiency does not decay after being placed in the air for 600 hours.

[0056] In summary, the solar cell and preparation method thereof provided in the embodiments of the present invention adopt a perovskite material system of lead-free Cs2AgSbI6 quantum dots, which completely eliminates the environmental pollution, health and safety hazards brought by the lead element in traditional lead-containing perovskite solar cells, meets the requirements of environmental protection and sustainable development, and is conducive to promotion and use in more application scenarios, especially in fields with high environmental protection requirements.

[0057] Improved photoelectric conversion efficiency: Through optimized preparation processes, including precursor solution preparation, deposition process parameters, and annealing conditions, high-quality lead-free perovskite films can be prepared with high crystallinity and low defect state density, thereby effectively improving the photoelectric conversion efficiency of solar cells and making them more competitive in performance. It is expected to approach or even match the efficiency level of some lead-containing perovskite cells, promoting the application and development of perovskite solar cells in the field of high-efficiency power generation.

[0058] Enhanced stability: The optimization of the preparation process and the optimized combination of the characteristics of the lead-free perovskite material itself help to improve the stability of solar cells under different environmental conditions, including thermal stability, moisture stability and light stability, reduce the attenuation of battery performance, extend its service life, reduce maintenance costs and replacement frequency during use, and improve the overall reliability and economy of the system.

[0059] The embodiments described above are some, but not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

Claims

1. A method for preparing a lead-free, high-efficiency, flexible perovskite solar cell, characterized in that: It includes the following steps: S1 Substrate pretreatment: clean and dry the polyimide flexible substrate; Using oxygen as the working gas, the polyimide flexible substrate was plasma treated; Synthesis of S2 quantum dots: CsI, AgI, and SbI3 were dissolved in a mixed solvent of oleic acid and octadecene under nitrogen atmosphere, heated and stirred to obtain a Cs2AgSbI6 quantum dot solution; S3 quantum dot solution coating: coating the synthesized Cs2AgSbI6 quantum dot solution on the polyimide substrate treated in step S1 to obtain a wet quantum dot film; S4 annealing treatment: placing the polyimide substrate deposited with the wet quantum dot film in an annealing furnace and performing annealing treatment under a nitrogen atmosphere; S5 electrode preparation: Under an inert atmosphere, an ITO transparent conductive electrode is deposited on the surface of the quantum dot film by radio frequency magnetron sputtering, and a silver back electrode is prepared on the other side of the polyimide substrate by thermal evaporation coating to obtain the solar cell.

2. The method for preparing a lead-free, high-efficiency, flexible perovskite solar cell according to claim 1, wherein: In step S1 , the power of the plasma treatment is 100-150 W, and the working gas pressure is 0.6-0.8 Pa.

3. The method for preparing a lead-free, high-efficiency, flexible perovskite solar cell according to claim 1, wherein: In the step S2, in the mixed solvent, the molar ratio of CsI, AgI, and SbI3 is 1:1:

1.

4. The method for preparing a lead-free, high-efficiency, flexible perovskite solar cell according to claim 1, wherein: In the step S3, the coating is performed by spin coating or inkjet printing; The spin coating parameters are: coating at a rate of 1000 rpm for 5 s, and then coating at a rate of 3000 rpm for 35-40 s; The parameters of the inkjet printing are: nozzle height 1.5 mm, inkjet speed 500 mm / s, ink drop size 50-55 pl, layer-by-layer printing and drying.

5. The method for preparing a lead-free, high-efficiency, flexible perovskite solar cell according to claim 1, wherein: In step S4, the annealing treatment is: heating from room temperature to 150-160° C. at a heating rate of 5-8° C. / min, and annealing at this temperature for 20-25 minutes.

6. The method for preparing a lead-free, high-efficiency, flexible perovskite solar cell according to claim 1, wherein: In the step S5, the RF magnetron sputtering has a sputtering power of 180-200 W, a gas pressure of 2-2.5 Pa, an inert gas flow rate of 15 sccm, and a deposition time of 15-20 min.

7. The method for preparing a lead-free, high-efficiency, flexible perovskite solar cell according to claim 1, wherein: In step S5, the evaporation rate of the thermal evaporation coating is 0.5 A / s, and the evaporation pressure is 5×10 -4 Pa.

8. A lead-free, high-efficiency, flexible perovskite solar cell, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

9. The lead-free, high-efficiency, flexible perovskite solar cell according to claim 8, characterized in that: The thickness of the wet quantum dot film is 300-400 nm.

10. The method for preparing a lead-free, high-efficiency, flexible perovskite solar cell according to claim 8, characterized in that: The thickness of the silver back electrode is 150-200 nm.

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