A method for preparing a wide band gap perovskite photoactive layer

Abstract

The application discloses a preparation method of a wide-bandgap perovskite photoactive layer, and comprises the following steps: S1, lead iodide powder, cesium iodide powder and ytterbium bromide powder are proportioned according to a proportioning molar ratio, and an inorganic target material is prepared by using a hot-press sintering process; S2, formamidinium hydriodide powder and methylammonium bromide powder are proportioned according to a proportioning molar ratio, and an organic target material is prepared by using a normal-temperature preparation process; S3, a pretreated substrate is placed on a magnetron sputtering sample table, the target materials prepared in steps S1 and S2 are respectively installed on corresponding radio frequency sputtering targets, and the background of a magnetron sputtering system is vacuumized; S4, high-purity argon gas is used as a sputtering gas, and a wide-bandgap perovskite thin film is prepared by using a magnetron co-sputtering method; the sputtering power of the inorganic target material prepared in step S1 is controlled, the sputtering power of the organic target material prepared in step S2 is controlled, and the thickness of the thin film is controlled, so that the high-quality thin film is prepared by using the differential target material preparation process.

Description

Technical Field

[0001] This invention relates to the field of thin-film solar energy technology, and specifically to a method for preparing a wide-bandgap perovskite photoactive layer. Background Technology

[0002] Perovskite solar cells have become a research hotspot in the photovoltaic field due to their excellent photoelectric performance and low-cost potential, with their cell conversion efficiency soaring from the initial 3.8% to over 26.1%. Among them, wide-bandgap perovskites offer significant advantages to semiconductor devices due to their large bandgap energy. Typically, their bandgap range is between 1.7 and 2.4 eV, which allows them to effectively absorb high-energy photons while reducing heat loss, making them particularly suitable for applications requiring high photovoltage and selective photon absorption.

[0003] However, the preparation of wide-bandgap perovskite thin films currently relies mainly on the traditional solution spin-coating method. While the solution method uses simple equipment, it suffers from the following significant problems: 1) It relies on large amounts of organic solvents, such as DMF and DMSO, which are toxic and difficult to recycle, thus not in line with the trend of green manufacturing; 2) Poor uniformity of large-area film formation makes it difficult to adapt to industrial production; 3) Wide-bandgap perovskites (usually rich in bromine) are prone to phase separation and crystal quality degradation under light, resulting in severe open-circuit voltage loss.

[0004] Physical vapor deposition techniques, such as magnetron sputtering, offer advantages such as solvent-free processing, dense film formation, and good large-area uniformity. However, they face significant challenges in preparing hybrid perovskites: the physical properties of organic components, such as MAI / FAI, differ greatly from those of inorganic components, such as PbI2 / PbBr2, in terms of melting point, sputtering yield, and heat resistance. Direct mixing and sintering of the target materials can lead to the decomposition of the organic components at high temperatures; while simple co-sputtering, without precise target process design and energy control, struggles to obtain perovskite phases with accurate stoichiometry.

[0005] Furthermore, deep-level defects and lattice stress within wide-bandgap perovskites are also bottlenecks limiting their efficiency improvement, necessitating the introduction of effective doping modification methods. To address these issues, we provide a method for preparing a photoactive layer in wide-bandgap perovskites. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for preparing a wide-bandgap perovskite photoactive layer. By using differentiated target preparation processes formed by inorganic hot pressing and organic cold pressing, combined with dual-source magnetron co-sputtering technology, a solvent-free, stoichiometrically controllable high-quality thin film preparation is achieved. At the same time, the rare earth element ytterbium is introduced for doping, which effectively passivates defects and improves the stability of the thin film.

[0007] To achieve the above objectives, the present invention employs a method for preparing a wide-bandgap perovskite photoactive layer, comprising the following steps: S1, Inorganic target material preparation: Lead iodide powder, cesium iodide powder and ytterbium bromide powder are mixed according to the molar ratio and prepared by hot pressing sintering process to obtain inorganic target material; S2, Organic target preparation: Formamidinium hydroiodide powder and methyl ammonium bromide powder are mixed according to the molar ratio and organic target is prepared by room temperature preparation process; S3, Target mounting and vacuuming: Place the pretreated substrate onto the magnetron sputtering sample stage, and mount the target materials prepared in steps S1 and S2 onto the corresponding RF sputtering targets. Then, evacuate the base vacuum of the magnetron sputtering system to 4.0 × 10⁻⁶. -5 Pa ~ 6.0 × 10 -5 Pa; S4, Magnetron co-sputtering deposition: High-purity argon gas is used as the sputtering gas to prepare wide-bandgap perovskite thin films by magnetron co-sputtering; the sputtering power of the inorganic target prepared in step S1 is controlled to be 30-60W, the sputtering power of the organic target prepared in step S2 is controlled to be 20-45W, the film thickness is controlled to be 350-600nm, and the sputtering substrate temperature is 100℃.

[0008] As a further optimization of the above scheme, in step S1, the molar ratio of lead iodide powder, cesium iodide powder and ytterbium bromide powder is 10:9:0.3.

[0009] As a further optimization of the above scheme, in step S2, the molar ratio of formamidinium hydroiodide powder and methyl ammonium bromide powder is 7:1.

[0010] As a further optimization of the above scheme, in step S1, the preparation of the inorganic target material specifically includes the following steps: S101, mix the prepared sample with anhydrous ethanol and ball mill it; S102, the raw material obtained after ball milling in step S101 is dried and passed through a 100-mesh sieve to obtain powder with uniform particles; S103, After loading the powder into the graphite mold, place it into the sintering furnace; S104, after evacuating the furnace to a vacuum of 2×10⁻² Pa, high-purity argon gas was introduced, the sintering temperature was 200℃, the sintering time was 2 h, and the sintering pressure was 50 MPa, to obtain an inorganic target material; wherein: In step S101, the mass ratio of the sample, zirconium oxide grinding balls, and anhydrous ethanol is 1:5:2.5; the ball mill speed is 450 rpm, and the ball milling time is 12 h. In step S102, the drying temperature is 70°C and the drying time is 3 hours.

[0011] As a further optimization of the above scheme, the preparation of the organic target material in step S2 specifically includes the following steps: S201, mix the prepared sample with anhydrous ethanol and ball mill it; S202, the raw material obtained after ball milling in step 201 is dried and passed through a 90-mesh sieve to obtain a powder with uniform particles; S203, the powder is loaded into a stainless steel mold and then pressurized. The mold is subjected to a pressure of 65 MPa and the holding time is 6 hours to obtain an organic target material, wherein: In step S201, the mass ratio of the sample, zirconium oxide grinding balls, and anhydrous ethanol is 1:4:2; the ball mill speed is 350 rpm, and the ball milling time is 10 h. In step S202, the drying temperature is 70°C and the drying time is 3 hours.

[0012] As a further optimization of the above scheme, in step S4, the purity of the high-purity argon gas is 99.99%.

[0013] As a further optimization of the above scheme, in step S4, the working vacuum is adjusted to 0.75 Pa during sputtering.

[0014] As a further optimization of the above scheme, in step S4, the film thickness is selected from 350nm, 500nm or 600nm.

[0015] As a further optimization of the above scheme, in step S4, the sputtering power of the inorganic target is selected from 30W, 45W or 60W, and the sputtering power of the organic target is selected from 20W, 30W or 45W.

[0016] As a further optimization of the above scheme, in step S3, the background vacuum is specifically selected from 4.0×10-5 Pa, 5.0×10-5 Pa, or 6.0×10-5 Pa.

[0017] The method for preparing a wide-bandgap perovskite photoactive layer according to the present invention has the following beneficial effects: 1. A method for preparing a wide-bandgap perovskite photoactive layer according to the present invention comprises using a hot-pressing sintering process to prepare ytterbium-doped inorganic perovskite targets and a room-temperature cold-pressing process to prepare organic targets, and combining co-sputtering magnetron sputtering technology to prepare the wide-bandgap perovskite photoactive layer. This method not only allows for precise control of the proportion of each element in the photoactive layer, but also enables rapid film formation. The combined effect of ytterbium doping and vacuum in-situ annealing improves the crystallinity and uniformity of the photoactive layer, reduces deep-level defects in the film, and thus reduces non-radiative recombination. 2. The present invention provides a method for preparing a wide-bandgap perovskite photoactive layer. The prepared wide-bandgap perovskite photoactive layer can not only precisely control the proportion of each element, but also form a dense and uniform film. At the same time, it does not introduce any harmful solvents, making it environmentally friendly and pollution-free. In addition, the method has a simple process flow and can directly utilize existing vacuum coating equipment without upgrading or modifying the equipment, which can effectively reduce production costs.

[0018] Specific embodiments of the present invention are disclosed in detail with reference to the following description and accompanying drawings, indicating how the principles of the present invention can be adopted. It should be understood that the embodiments of the present invention are not limited in scope as a result, and the embodiments of the present invention include many changes, modifications and equivalents. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the preparation process of a wide-bandgap perovskite photoactive layer obtained according to the present invention. Figure 2 The image shows the XRD pattern of the actual sample obtained in Example 1 of this invention. Figure 3 This is a UV-VIS absorption spectrum test diagram of the actual sample prepared in Example 1 of the present invention; Figure 4 The graph shows the photoelectric conversion efficiency of a battery fabricated from the photoactive layer obtained in Example 1 of this invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.

[0021] It should be noted that when an element is referred to as "set on" or "provided with" another element, it can be directly on the other element or there may be an intermediate element. When an element is referred to as "connected to" or "connected to" another element, it can be directly connected to the other element or there may be an intermediate element at the same time. "Fixed connection" means fixed connection. There are many ways of fixed connection, which are not within the scope of protection of this document. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this document are only for illustrative purposes and do not represent the only implementation method.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in the specification herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. This invention provides a first embodiment of a method for preparing a wide-bandgap perovskite photoactive layer. In this embodiment, the preparation method includes the following steps: S1, Differentiated Target Material Preparation: Inorganic sputtering targets are prepared by mixing inorganic raw materials such as lead iodide, cesium iodide, and ytterbium bromide, and using a hot-pressing sintering process at 150℃-300℃ to ensure that no particles fall off during the sputtering process and that the glow is stable.

[0023] Organic targets are prepared by mixing organic raw materials, such as formamidine hydroiodide and methyl ammonium bromide, and using a room temperature cold pressing process at <50℃ and high pressure to strictly avoid the decomposition or carbonization of organic components caused by high temperature.

[0024] S2, magnetron co-sputtering deposition: In a vacuum chamber, the sputtering power of inorganic and organic targets is controlled separately and excited by radio frequency power supply. By adjusting the power ratio of the two, the high volatility of organic components in vacuum is precisely compensated to achieve dynamic balance of stoichiometry. At the same time, the substrate is kept at a certain temperature to assist nucleation. In some embodiments, the substrate temperature is kept at 60-120°C.

[0025] S3, in-situ vacuum annealing: After deposition, without breaking the vacuum, thermal annealing is performed directly in the chamber or the connected vacuum annealing chamber. In some embodiments, the thermal annealing temperature can be controlled at 140-180°C to induce the amorphous or microcrystalline precursor to transform into a long-range ordered perovskite crystal structure.

[0026] like Figure 1 As shown, this invention provides a second embodiment of a method for preparing a wide-bandgap perovskite photoactive layer. In this embodiment, the preparation method includes the following steps: S1. Lead iodide powder, cesium iodide powder and ytterbium bromide powder are mixed in a molar ratio of 10:9:0.3. After being mixed evenly, zirconium oxide grinding balls and anhydrous ethanol are added in sequence, with a mass ratio of 1:5:2.5.

[0027] The ball mill operates at 450 rpm for 12 hours. After milling, the mixed powder is dried in an oven at 70°C for 3 hours. The dried ball-mill mixture is then sieved for later use. The raw material is then passed through a 100-mesh sieve to obtain uniformly sized powder. A hot-pressing sintering process is employed, where the powder is loaded into a graphite mold and placed in a sintering furnace. The furnace is then evacuated to a vacuum level of 2×10⁻⁶. - 2 After Pa, high-purity argon gas was introduced, the sintering temperature was 200℃, the sintering time was 2h, and the sintering pressure was 50MPa to obtain an inorganic target material. S2, formamidinium hydroiodide powder and methyl ammonium bromide powder are mixed at a molar ratio of 7:1. After thorough mixing, zirconia grinding balls and anhydrous ethanol are added sequentially in a mass ratio of 1:4:2. The ball mill speed is 350 rpm, and the milling time is 10 hours. After milling, the mixed powder is placed in an oven and dried at 70°C for 3 hours. The dried ball-material mixture is then sieved for later use. The raw material is then passed through a 90-mesh sieve to obtain a uniform powder. Using a room temperature preparation process, the powder is loaded into a stainless steel mold and pressurized at a pressure of 65 MPa for 6 hours to obtain an organic target material. S3. Place the plasma-treated glass substrate onto the magnetron sputtering sample stage, and install inorganic target 1 and organic target 2 onto their respective RF sputtering targets. Then, evacuate the base vacuum of the magnetron sputtering system to 6.0 × 10⁻⁶. -5 Pa, 99.99% pure argon gas was introduced as sputtering gas, the working vacuum was adjusted to 0.75 Pa, the substrate temperature was heated to 100℃, the sputtering power supply of target 1 and target 2 was turned on respectively, and the sputtering power was set to 30W and 20W respectively. The film thickness was controlled to 350nm by the film thickness gauge. S4, without breaking the vacuum, perform in-situ annealing in the vacuum chamber for 30 minutes at a temperature of 160℃.

[0028] Combination Figures 2-4 As shown, the perovskite photoactive layer in this embodiment was subjected to XRD testing, and its crystal structure was cubic α-perovskite. The UV-VIS absorption spectrum of the sample was tested, and its absorption edge was closer to the short-wavelength direction, indicating that its band gap was increased. The JV curve of the final battery prepared according to the sample of Example 1 was tested, and its open-circuit voltage was 1.03V, short-circuit current was 24.1mA / cm2, fill factor was 60%, and conversion efficiency was 14.89%.

[0029] This invention provides a third embodiment of a method for preparing a wide-bandgap perovskite photoactive layer. In this embodiment, the preparation method includes the following steps: S1. Lead iodide powder, cesium iodide powder, and ytterbium bromide powder are mixed in a molar ratio of 10:9:0.3. After thorough mixing, zirconia grinding balls and anhydrous ethanol are added sequentially in a mass ratio of 1:5:2.5. The ball mill speed is 450 rpm, and the milling time is 12 hours. After milling, the mixed powder is placed in an oven and dried at 70°C for 3 hours. The dried ball-material mixture is then sieved for later use. The raw material is then passed through a 100-mesh sieve to obtain uniformly sized powder. A hot-pressing sintering process is used. The powder is loaded into a graphite mold and placed in a sintering furnace, where the furnace body is evacuated to a vacuum level of 2×10⁻⁶. -2 After Pa, high-purity argon gas was introduced, the sintering temperature was 200℃, the sintering time was 2h, and the sintering pressure was 50MPa to obtain an inorganic target material. S2, formamidinium hydroiodide powder and methyl ammonium bromide powder are mixed at a molar ratio of 7:1. After thorough mixing, zirconia grinding balls and anhydrous ethanol are added sequentially in a mass ratio of 1:4:2. The ball mill speed is 350 rpm, and the milling time is 10 hours. After milling, the mixed powder is placed in an oven and dried at 70°C for 3 hours. The dried ball-material mixture is then sieved for later use. The raw material is then passed through a 90-mesh sieve to obtain a uniform powder. Using a room temperature preparation process, the powder is loaded into a stainless steel mold and pressurized at a pressure of 65 MPa for 6 hours to obtain an organic target material. S3. Place the plasma-treated glass substrate onto the magnetron sputtering sample stage, and install inorganic target 1 and organic target 2 onto their respective RF sputtering targets. Then, evacuate the base vacuum of the magnetron sputtering system to 5.0 × 10⁻⁶. -5 Pa, 99.99% pure argon gas was introduced as sputtering gas, the working vacuum was adjusted to 0.75 Pa, the substrate temperature was heated to 100℃, the sputtering power supply of target 1 and target 2 was turned on respectively, and the sputtering power was set to 45W and 30W respectively. The film thickness was controlled to 500nm by the film thickness gauge. The wide-bandgap perovskite photoactive layer from this embodiment was used to fabricate the final battery, and JV curve testing was performed. The battery's open-circuit voltage was 1.04V, and its short-circuit current was 24.2mA / cm. 2 The fill factor is 65% and the conversion efficiency is 16.35%.

[0030] This invention provides a fourth embodiment of a method for preparing a wide-bandgap perovskite photoactive layer. In this embodiment, the preparation method includes the following steps: S1. Lead iodide powder, cesium iodide powder, and ytterbium bromide powder are mixed in a molar ratio of 10:9:0.3. After thorough mixing, zirconia grinding balls and anhydrous ethanol are added sequentially in a mass ratio of 1:5:2.5. The ball mill speed is 450 rpm, and the milling time is 12 hours. After milling, the mixed powder is placed in an oven and dried at 70°C for 3 hours. The dried ball-material mixture is then sieved for later use. The raw material is then passed through a 100-mesh sieve to obtain uniformly sized powder. A hot-pressing sintering process is used. The powder is loaded into a graphite mold and placed in a sintering furnace, where the furnace body is evacuated to a vacuum level of 2×10⁻⁶. -2 After Pa, high-purity argon gas was introduced, the sintering temperature was 200℃, the sintering time was 2h, and the sintering pressure was 50MPa to obtain an inorganic target material. S2, formamidinium hydroiodide powder and methyl ammonium bromide powder are mixed at a molar ratio of 7:1. After thorough mixing, zirconia grinding balls and anhydrous ethanol are added sequentially in a mass ratio of 1:4:2. The ball mill speed is 350 rpm, and the milling time is 10 hours. After milling, the mixed powder is placed in an oven and dried at 70°C for 3 hours. The dried ball-material mixture is then sieved for later use. The raw material is then passed through a 90-mesh sieve to obtain a uniform powder. Using a room temperature preparation process, the powder is loaded into a stainless steel mold and pressurized at a pressure of 65 MPa for 6 hours to obtain an organic target material. S3. Place the plasma-treated glass substrate onto the magnetron sputtering sample stage, and install the inorganic target 1 and organic target 2 onto their respective RF sputtering targets. Then, evacuate the base vacuum of the magnetron sputtering system to 4.0 × 10⁻⁶. -5 Pa, 99.99% pure argon gas was introduced as sputtering gas, the working vacuum was adjusted to 0.75 Pa, the substrate temperature was heated to 100℃, the sputtering power supply of target 1 and target 2 was turned on respectively, and the sputtering power was set to 60W and 45W respectively. The film thickness was controlled to 600nm by the film thickness gauge. The wide-bandgap perovskite photoactive layer from this embodiment was used to fabricate the final battery, and JV curve testing was performed. The battery's open-circuit voltage was 1.04V, and its short-circuit current was 24.3mA / cm. 2 The fill factor is 68% and the conversion efficiency is 17.18%.

[0031] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a wide-bandgap perovskite photoactive layer, characterized in that, Includes the following steps: S1, Inorganic target material preparation: Lead iodide powder, cesium iodide powder and ytterbium bromide powder are mixed according to the molar ratio and prepared by hot pressing sintering process to obtain inorganic target material; S2, Organic target preparation: Formamidinium hydroiodide powder and methyl ammonium bromide powder are mixed according to the molar ratio and organic target is prepared by room temperature preparation process; S3, Target mounting and vacuuming: Place the pretreated substrate onto the magnetron sputtering sample stage, and mount the target materials prepared in steps S1 and S2 onto the corresponding RF sputtering targets. Then, evacuate the base vacuum of the magnetron sputtering system to 4.0 × 10⁻⁶. -5 Pa ~ 6.0 × 10 -5 Pa; S4, Magnetron co-sputtering deposition: High-purity argon gas is used as the sputtering gas to prepare wide-bandgap perovskite thin films by magnetron co-sputtering; the sputtering power of the inorganic target prepared in step S1 is controlled to be 30-60W, the sputtering power of the organic target prepared in step S2 is controlled to be 20-45W, the film thickness is controlled to be 350-600nm, and the sputtering substrate temperature is 100℃; S5, in-situ annealing, is carried out in a vacuum chamber for 30 minutes at an annealing temperature of 160℃.

2. The method for preparing a wide-bandgap perovskite photoactive layer according to claim 1, characterized in that: In step S1, the molar ratio of lead iodide powder, cesium iodide powder, and ytterbium bromide powder is 10:9:0.

3.

3. The method for preparing a wide-bandgap perovskite photoactive layer according to claim 3, characterized in that: In step S2, the molar ratio of formamidinium hydroiodide powder to methyl ammonium bromide powder is 7:

1.

4. The method for preparing a wide-bandgap perovskite photoactive layer according to claim 1, characterized in that: In step S1, the preparation of the inorganic target material specifically includes the following steps: S101, mix the prepared sample with anhydrous ethanol and ball mill it; S102, the raw material obtained after ball milling in step S101 is dried and passed through a 100-mesh sieve to obtain powder with uniform particles; S103, After loading the powder into the graphite mold, place it into the sintering furnace; S104, evacuate the furnace body to 2×10 -2 After Pa, high-purity argon gas was introduced, the sintering temperature was 200℃, the sintering time was 2h, and the sintering pressure was 50MPa, to obtain an inorganic target material; wherein: In step S101, the mass ratio of the sample, zirconium oxide grinding balls, and anhydrous ethanol is 1:5:2.5; the ball mill speed is 450 rpm, and the ball milling time is 12 h. In step S102, the drying temperature is 70°C and the drying time is 3 hours.

5. A method for preparing a wide-bandgap perovskite photoactive layer according to any one of claims 1-4, characterized in that: The preparation of the organic target material in step S2 specifically includes the following steps: S201, mix the prepared sample with anhydrous ethanol and ball mill it; S202, the raw material obtained after ball milling in step 201 is dried and passed through a 90-mesh sieve to obtain a powder with uniform particles; S203, the powder is loaded into a stainless steel mold and then pressurized. The mold is subjected to a pressure of 65 MPa and the holding time is 6 hours to obtain an organic target material, wherein: In step S201, the mass ratio of the sample, zirconium oxide grinding balls, and anhydrous ethanol is 1:4:2; the ball mill speed is 350 rpm, and the ball milling time is 10 h. In step S202, the drying temperature is 70°C and the drying time is 3 hours.

6. The method for preparing a wide-bandgap perovskite photoactive layer according to claim 1, characterized in that: In step S4, the purity of the high-purity argon gas is 99.99%.

7. The method for preparing a wide-bandgap perovskite photoactive layer according to claim 1, characterized in that: In step S4, the working vacuum is adjusted to 0.75 Pa during sputtering.

8. The method for preparing a wide-bandgap perovskite photoactive layer according to claim 1, characterized in that: In step S4, the film thickness is selected from 350nm, 500nm, or 600nm.

9. The method for preparing a wide-bandgap perovskite photoactive layer according to claim 1, characterized in that: In step S4, the sputtering power of the inorganic target is selected from 30W, 45W or 60W, and the sputtering power of the organic target is selected from 20W, 30W or 45W.

10. The method for preparing a wide-bandgap perovskite photoactive layer according to claim 1, characterized in that: In step S3, the background vacuum is specifically selected from 4.0 × 10⁻⁶. -5 Pa, 5.0 × 10 -5 Pa or 6.0 × 10 -5 Pa.

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