A method for preparing lead-tin doped perovskite material in an aqueous solvent

Abstract

The present invention belongs to the technical field of perovskite material preparation, and specifically discloses a method for preparing a lead-tin doped perovskite material in an aqueous solvent, comprising the following steps: stirring and mixing a halogen source, a reducing agent, an antioxidant and a solvent in a high-temperature bath; adding a lead ion source and a tin ion source, reacting in the air to form a uniform solution; then adding an A-position cation source, cooling and cooling to obtain lead-tin doped perovskite microcrystals; dissolving the prepared lead-tin doped perovskite microcrystals in a solvent two, adding a reducing agent and an antioxidant, forming a film by an anti-solvent method, and forming a lead-tin doped perovskite film after annealing. The present invention adopts the above-mentioned method for preparing a lead-tin doped perovskite material in an aqueous solvent, which is environmentally friendly, low-cost, and simple in synthesis conditions, and the prepared perovskite microcrystals and films have smooth surfaces, high density, few defects, and good air stability.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite material preparation, and in particular to a method for preparing a lead-tin doped perovskite material in an aqueous solvent. Background Art

[0002] The general chemical formula of perovskite materials is ABX3. Typical halide perovskite materials have a face-centered cubic structure, with vertex A being a metal or organic ion Rb + , Cs + 、CH3NH3 + (MA + ) and CH(NH2)2 + (FA + ) etc.; Sn with +2 valence at the body center B position 2+ , Pb 2+ etc.; the face-centered X position is a halogen ion Cl - Br - ,I - . Perovskite materials are widely used in many fields such as solar cells, photodetectors, lasers, LED display lighting, etc. due to their high absorption coefficient, high carrier mobility, long carrier lifetime, adjustable band gap, low-temperature solution growth, and unique defect tolerance. In different application scenarios, the band gap requirements for the perovskite material itself are different. The widely studied lead-based perovskites mainly show strong absorption in the visible light range, and their optical band gap is about ~1.55eV. In application scenarios such as infrared photodetection and perovskite stacked solar cells, perovskites are required to have a lower band gap. Experiments have shown that tin-doping of lead-based perovskites can effectively reduce the band gap of perovskite materials to ~1.2eV, and can expand the absorption range from the visible light region to the near-infrared light region above 1100nm, which can meet different band gap requirements. However, tin-based perovskites are super sensitive to water and oxygen. Trace amounts of water and oxygen will cause Sn 2+ Oxidized to Sn 4+ , which makes it impossible for users to obtain the target perovskite phase or causes an increase in defects in the material, seriously affecting the performance of the device.

[0003] In the current existing technology, the preparation of tin-based perovskite films mostly uses stannous iodide as the tin source, supplemented with different antioxidants or reducing agents, and combined with different A-site cations to form perovskite films. For example, in the Chinese invention patent of a tin-based perovskite photovoltaic device and its preparation method (CN117729783A), stannous iodide is used as the tin source, stannous fluoride is used as an antioxidant, and formamidine hydroiodide is used as a source of formamidine cations, and then a tin-based perovskite film is formed by spin coating and annealing. In the Chinese invention patent of a perovskite precursor solution and preparation method (CN115108917B), lead iodide and stannous iodide are used as the sources of lead and tin, iodomethylamine and iodoformamide are used as the sources of methylamine and formamidine cations, and an amine reducing agent is used as Sn. 2+ The protective reducing agent of ions is mixed under the protection of inert atmosphere to form FA x MA 1-x Pb y Sn 1-y I3 perovskite precursor solution is used for the preparation of perovskite film. China invention patent A method for preparing large-area lead-tin perovskite film for large-scale mass production (CN117642047A) discloses a method for preparing large-area lead-tin perovskite film for large-scale mass production. The lead and tin sources are Pb 2+ and Sn 2+ The blended solution is prepared by adding a dopant to a lead-tin blended perovskite precursor solution, wherein the dopant forms coordination bonds with the lead ions and tin ions in the perovskite, thereby regulating the crystallization of the lead-tin blended perovskite, improving the uniformity of the film, and improving the quality of the film.

[0004] The existing technology uses SnI2 as Sn 2+ The source of supply is, firstly, high-purity SnI2 itself is expensive, and the source of supply of perovskite A-site cations and halogens, such as formamidine hydroiodide, is also extremely expensive, so the raw material cost of the prior art is high; secondly, the raw materials used in the prior art are easily oxidized and the use conditions are harsh, and all preparation processes need to be completed in a high-purity inert gas atmosphere, which places high requirements on the equipment and also increases the difficulty and cost of preparing the perovskite film; thirdly, in order to improve the oxidation resistance of the perovskite film in the prior art, a reducing agent or antioxidant is usually added to the precursor solution to complete it, but the formed film cannot be preserved in the air for a long time, and the antioxidant capacity is insufficient, which needs to be improved. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a lead-tin doped perovskite material in an aqueous solvent. The preparation method is environmentally friendly, low-cost, and has simple synthesis conditions. The prepared perovskite microcrystals and thin films have smooth surfaces, high density, few defects, and good air stability. At the same time, the method is pioneering in preparing tin-containing perovskite microcrystals in air and an aqueous system for the first time, and at the same time, the target crystal phase is obtained, and the absorption range of the perovskite is extended, providing a new method for the large-scale synthesis and application of lead-tin doped perovskites.

[0006] To achieve the above object, the present invention provides a method for preparing a lead-tin doped perovskite material in an aqueous solvent, comprising the following steps:

[0007] Step 1: Stir and mix the halogen source, reducing agent, antioxidant and solvent in a high temperature bath;

[0008] Step 2: Add a lead ion source and a tin ion source to step 1, react in air, the reaction temperature is 60-100° C., reflux and keep warm for 1-24 hours to form a uniform solution; then add an A-site cation source, reflux and keep warm for 2-8 hours to obtain a black precipitate, and after cooling, filter, wash and dry, obtain lead-tin doped perovskite microcrystals;

[0009] Step three: dissolving the lead-tin-doped perovskite microcrystals obtained in step two into solvent two. The preparation process is carried out in air or an inert atmosphere. Reducing agents and antioxidants are added. The anti-solvent method is used to form the film. After annealing, a dense lead-tin-doped perovskite film is formed.

[0010] Preferably, in step one, the halogen source includes one or more of hydrochloric acid, hydrobromic acid, and hydroiodic acid, the reducing agent includes one or more of hypophosphorous acid, sodium borohydride, tin particles, and sodium thiosulfate, the antioxidant includes one or more of formamidinesulfinic acid, ascorbic acid, tin fluoride, tea polyphenols, tocopherol, and tert-butylhydroquinone, and the solvent one includes one or more of water, ethanol, isopropanol, N-methylpyrrolidone, and valerolactone.

[0011] Preferably, in step 2, the source of A-site cations includes one or more combinations of monomethylamine, formamidine acetate, and cesium acetate, the source of lead ions includes one or more combinations of lead acetate, lead sulfate, and lead chloride, and the source of tin ions includes one or more combinations of tin acetate, tin sulfide, and stannous chloride.

[0012] Preferably, in step three, solvent two includes one or more combinations of dimethyl sulfoxide, N,N-dimethylformamide, valerolactone, γ-butyrolactone, acetonitrile, etc.

[0013] Preferably, the total addition amount of lead ions and tin ions is 1-2 g / mL, and the addition amount of the halogen source is 30-60 wt% based on the total reaction solution.

[0014] Preferably, the total addition amount of the reducing agent and the antioxidant is 1-10% of the total molar amount of the added lead ions and tin ions, and the addition amount of the A-site cation source is 1-2 times the total molar amount of the added lead ions and tin ions.

[0015] Preferably, the general chemical composition formula of the lead-tin doped perovskite is APb a Sn 1-a X3, where A is one or a combination of methylamine cation, formamidine cation, and cesium ion; where the value range of a is 0 < a < 1; where X is a halogen anion Cl - 、Br - 、I - or one or more of them.

[0016] The advantages and beneficial effects of the present invention using the above preparation method of lead-tin doped perovskite material in an aqueous solvent are as follows:

[0017] 1. In the present invention, in an aqueous solution of hydrohalic acid, stable-in-air and low-cost divalent tin salts and lead salts are used as the source bodies of tin and lead respectively, and stable-in-air and low-cost organic amine salts or inorganic cesium salts are used as the source body of A-site cations. With the cooperation of a reducing agent and an antioxidant, high-purity lead-tin doped perovskite microcrystals are formed by reaction at high temperature in an air environment.

[0018] 2. The preparation method of the present invention has low cost, simple reaction conditions, and high air stability of the prepared microcrystals. After the microcrystals prepared by this method are redissolved in an organic solvent and formed into a film, the obtained lead-tin perovskite film has a flat and smooth surface, few defects, high film density, and the light absorption range extends to the near-infrared region. The obtained film has potential application value in the fields of photoelectric detection and tandem solar cells.

[0019] 3. The present invention is the first to prepare tin-containing perovskite microcrystals in an air and aqueous system, and at the same time obtains the target crystal phase, extending the light absorption range of perovskite, providing a new method for the large-scale synthesis and application of lead-tin doped perovskite.

[0020] The technical solutions of the present invention will be further described in detail below with reference to the drawings and examples. Description of the Drawings

[0021] Figure 1 It is the XRD pattern of the lead-tin doped perovskite microcrystals obtained in Example 1 of the present invention;

[0022] Figure 2This is the SEM spectrum of the lead-tin-doped perovskite microcrystals obtained in Example 1 of the present invention;

[0023] Figure 3 The XRD spectrum of the lead-tin-doped perovskite film obtained in Example 1 of the present invention;

[0024] Figure 4 This is a SEM image of the lead-tin-doped perovskite film obtained in Example 1 of the present invention;

[0025] Figure 5 This is the visible-near infrared absorbance spectrum of the lead-tin doped perovskite film obtained in Example 1 of the present invention;

[0026] Figure 6 The external quantum efficiency (EQE) spectrum of the photodetector obtained in Example 1 of the present invention;

[0027] Figure 7 The responsivity of the photodetector obtained in Example 1 of the present invention ( R ) Atlas;

[0028] Figure 8 is the specific detection rate of the photodetector obtained in Example 1 of the present invention ( D *) Atlas;

[0029] Fig. 9 This is the SEM spectrum of the lead-tin-doped perovskite microcrystal obtained in Comparative Example 1 of the present invention;

[0030] Fig.10 This is a SEM image of the lead-tin doped perovskite film obtained in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0032] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0033] Unless otherwise defined, the reagents and equipment used in the present invention are commercially available.

[0034] Example 1

[0035] FAP 0.5 Sn 0.5 The preparation of I3 perovskite microcrystals and thin films includes the following steps:

[0036] (1) First, measure 20 mL of hydroiodic acid solution (55-58% aqueous solution) and place it in a 100 mL round-bottom flask, then add 10 mL of deionized water, weigh 2 g of sodium thiosulfate and 1.5 g of formamidine sulfinic acid and add them to the above mixture, and place the round-bottom flask in an 80°C bath to dissolve. Then weigh 2 g of tin acetate and 3.2 g of lead acetate trihydrate respectively, add them to the above solution, and the reaction is carried out in the air. Continue to react in an 80°C bath for 8 hours to form a uniform brown-red solution. Then add 3.2 g of formamidine acetate to the solution, continue to reflux and keep the reaction for 2 hours to obtain black crystalline particles, filter the particles, rinse with dichloromethane until the solution is clear, filter again, and then place in a 70°C vacuum oven to dry overnight to obtain FAPb 0.5 Sn 0.5 I3 perovskite crystallites.

[0037] (2) The FAPb obtained above 0.5 Sn 0.5 0.8g of I3 perovskite microcrystals were dissolved in 1mL of a mixed solution of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) (volume ratio 1:3). The preparation process can be carried out in air or inert atmosphere. At the same time, 0.02g of tin fluoride and 0.1g of tin particles were added. After stirring and dissolving, indium tin oxide (ITO) glass was used as a substrate for spin coating. The spin coating speed was 4000rpm, the acceleration was 1000rpm / s, and the spin coating time was 40s. Chlorobenzene antisolvent was quickly added 12s before the end of spin coating. After spin coating, it was placed on a heating table at 100°C for annealing for 30min to obtain FAPb. 0.5 Sn 0.5 I3 perovskite thin film.

[0038] FAPb 0.5 Sn 0.5 I3 perovskite microcrystals were subjected to XRD and SEM tests, such as Figure 1 and Figure 2 As shown, the microcrystals are the target crystal form of perovskite, and the grains are regular block crystals with sizes ranging from a few microns to tens of microns.

[0039] FAPb 0.5 Sn 0.5 I3 perovskite film was subjected to XRD, SEM and absorbance tests, such as Figure 3 , Figure 4 and Figure 5As shown, the obtained film is the target crystal form of perovskite, the film surface is smooth and dense, and the light absorption range of the film extends to more than 1100nm. The above lead-tin doped perovskite film is used as a functional layer in the visible-near infrared photodetector device structure. The thickness of the light absorption layer is 300-2000nm, and the light absorption range is 250-1100nm. The external quantum efficiency, responsivity and specific detection rate of the photodetector were tested and calculated, as shown in the figure. Figure 6 , Figure 7 and Figure 8 As shown, the external quantum efficiency (EQE) of the photodetector at 960nm in the near-infrared region can reach 67%, and the responsivity ( R ) can reach 0.52A / W, and the specific detection rate can reach 2.76×10 12 Jones, this performance result is comparable to that of commercial Si-based photodiodes.

[0040] Example 2

[0041] MAPb 0.2 Sn 0.8 The preparation of I3 perovskite microcrystals and thin films includes the following steps:

[0042] (1) First, measure 25 mL of hydroiodic acid solution (55-58% aqueous solution) and place it in a 100 mL round-bottom flask, then add 5 mL of isopropanol, weigh 5 g of hypophosphorous acid aqueous solution (25 wt%) and 2 g of tert-butyldiphenol and add them to the above mixture, and place the round-bottom flask in an 80°C bath to dissolve. Then weigh 5 g of tin acetate and 2 g of lead acetate trihydrate respectively, add them to the above solution, and react in the air. Continue to react in an 80°C bath for 8 hours to form a uniform brown-red solution. Then add 3 g of monomethylamine aqueous solution (40 wt%) to the solution, continue to reflux and keep the reaction for 2 hours to obtain black crystalline particles, filter the particles, rinse with dichloromethane until the solution is clear, filter again, and then place in a vacuum oven at 70°C to dry overnight to obtain MAPb. 0.2 Sn 0.8 I3 perovskite crystallites.

[0043] (2) The MAPb obtained above 0.2 Sn 0.80.6g of I3 perovskite microcrystals were dissolved in 1mL of a mixed solution of dimethyl sulfoxide (DMSO) and valerolactone (volume ratio 1:2). The preparation process can be carried out in air or inert atmosphere. At the same time, 0.02g of tin fluoride and 0.1g of tin particles were added. After stirring and dissolving, indium tin oxide (ITO) glass was used as a substrate for spin coating. The spin coating speed was 4000rpm, the acceleration was 1000rpm / s, and the spin coating time was 40s. Chlorobenzene antisolvent was quickly added 12s before the end of spin coating. After spin coating, it was placed on a heating table at 100°C for annealing for 30min to obtain MAPb. 0.2 Sn 0.8 I3 perovskite thin film.

[0044] Example 3

[0045] Cb 0.2 Sn 0.8 The preparation of Br3 perovskite microcrystals and thin films includes the following steps:

[0046] (1) First, measure 15 mL of hydrobromic acid solution (68% aqueous solution) and place it in a 100 mL round-bottom flask, then add 15 mL of deionized water, weigh 1 g of tin particles and 2 g of tea polyphenols and add them to the above mixture, and place the round-bottom flask in a 70°C bath to dissolve. Then weigh 5 g of tin acetate and 2 g of lead acetate trihydrate respectively, add them to the above solution, and react in the air. Continue to react in a 70°C bath for 6 hours to form a uniform reddish brown solution. Then add 6 g of cesium acetate to the solution, continue to reflux and keep the reaction for 3 hours to obtain black crystalline particles. Filter the particles, then rinse with ethyl acetate until the solution is clear and filter again, then place it in a vacuum oven at 80°C and dry overnight to obtain CsPb 0.2 Sn 0.8 Br3 perovskite crystallites.

[0047] (2) The CsPb obtained above 0.2 Sn 0.8 0.7g of Br3 perovskite microcrystals are dissolved in 1mL of a mixed solution of dimethyl sulfoxide (DMSO) and acetonitrile (volume ratio 1:3). The preparation process can be carried out in air or inert atmosphere. At the same time, 0.02g of tin fluoride and 0.1g of ascorbic acid are added. After stirring and dissolving, indium tin oxide (ITO) glass is used as a substrate for spin coating. The spin coating speed is 4000rpm, the acceleration is 1000rpm / s, and the spin coating time is 40s. Chlorobenzene antisolvent is quickly added 12s before the end of spin coating. After spin coating, it is placed on a heating table at 100°C for annealing for 30min to obtain CsPb 0.2 Sn 0.8 Br3 perovskite thin films.

[0048] The present invention uses air-stable raw materials as the source of A sites and lead and tin ions, and has low requirements on raw material purity because the microcrystal preparation process itself plays a purification role, which greatly reduces the cost of raw materials.

[0049] The lead-tin doped perovskite microcrystal synthesis process of the present invention is completely carried out in an air atmosphere, has no harsh environment and equipment requirements, has simple synthesis conditions, and greatly reduces equipment and synthesis costs.

[0050] In order to ensure that the tin ions in the aqueous solvent maintain a +2 valence and are not oxidized, and can form a perovskite phase with near-infrared light absorption properties, the synergistic effect of various raw materials is required in the synthesis process, and none of them can be missing. The A-site cation source, the lead ion source, and the tin ion source are the sources of the perovskite components. The halogen source, as a source of halogen ions, helps the dissolution of lead ions and tin ions in the aqueous solution, making it easier to participate in subsequent reactions. The reducing agent and antioxidant are mainly used to ensure that the tin ions maintain a +2 valence and are not oxidized, while enhancing the antioxidant and water resistance of the tin ions. The solvent is used to adjust the solution concentration and help the raw materials dissolve and participate in the reaction.

[0051] The lead-tin doped perovskite film of the present invention is prepared by dissolving the lead-tin doped perovskite microcrystals prepared in the present invention in an organic solvent and then forming a film by an anti-solvent method. Since the lead-tin perovskite microcrystals themselves have good antioxidant capacity, the film preparation process can be carried out in air or in an inert gas atmosphere.

[0052] The lead-tin doped perovskite microcrystal and film preparation process of the present invention are both suitable for large-scale production and have great application potential for the industrialization of the lead-tin perovskite functional layer.

[0053] Comparative Example 1

[0054] FAP 0.5 Sn 0.5 Preparation of I3 perovskite microcrystals and thin films:

[0055] In the process of preparing microcrystals in step (1) of Example 1, the reducing agent sodium thiosulfate is not added, and the rest of the contents are the same as in Example 1. The obtained microcrystals have less tin element content than lead element, and cannot form regular block crystals. The prepared film grains are not clear and there are many holes on the film surface. Fig. 9 and Fig.10 shown.

[0056] Comparative Example 2

[0057] FAP 0.5 Sn 0.5 Preparation of I3 perovskite microcrystals and thin films:

[0058] In the process of preparing microcrystals in step (1) of Example 1, the antioxidant formamidine sulfinic acid was not added, and the rest of the contents were the same as in Example 1. The surface of the obtained microcrystals was not smooth and had many holes, and the surface of the obtained film grains had flower-like protrusions, the film had poor density, and had many holes.

[0059] Comparative Example 3

[0060] FAP 0.5 Sn 0.5 Preparation of I3 perovskite microcrystals and thin films:

[0061] In the microcrystal preparation process of step (1) of Example 1, the amount of hydroiodic acid added was 5 mL, the amount of deionized water added was 25 mL, and the rest of the contents were the same as in Example 1. In the microcrystal synthesis stage, the raw materials could not be completely dissolved, and a black crystalline precipitate could not be obtained, and the product was orange-yellow.

[0062] Therefore, the present invention adopts the above-mentioned method for preparing lead-tin doped perovskite microcrystals and thin films in an aqueous solvent. The preparation method is environmentally friendly, low-cost, and has simple synthesis conditions. The prepared perovskite microcrystals and thin films have smooth surfaces, high density, few defects, and good air stability. At the same time, the method is pioneering in preparing tin-containing perovskite microcrystals in air and an aqueous system for the first time, and at the same time obtains the target crystal phase, extending the absorption range of the perovskite, and providing a new method for the large-scale synthesis and application of lead-tin doped perovskites.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a lead-tin doped perovskite material in an aqueous solvent, characterized in that: The steps include: Step 1: Stirring and mixing the halogen source, the reducing agent, the antioxidant and the solvent in a high temperature bath to uniformly mix; the reducing agent includes one or more of hypophosphorous acid, sodium borohydride, tin particles and sodium thiosulfate; the antioxidant includes one or more of formamidine sulfinic acid, ascorbic acid, tin fluoride, tea polyphenols, tocopherol and tert-butylhydroquinone; the solvent includes one or more of water, ethanol, isopropanol, N-methylpyrrolidone and valerolactone; Step 2: Add a lead ion source and a tin ion source to step 1, react in air, the reaction temperature is 60-100° C., reflux and keep warm for 1-24 hours to form a uniform solution; then add an A-site cation source, reflux and keep warm for 2-8 hours to obtain a black precipitate, and after cooling, filter, wash and dry, obtain lead-tin doped perovskite microcrystals; Step three: dissolving the lead-tin-doped perovskite microcrystals obtained in step two into solvent two. The preparation process is carried out in air or an inert atmosphere. Reducing agents and antioxidants are added. The anti-solvent method is used to form the film. After annealing, a dense lead-tin-doped perovskite film is formed.

2. The method for preparing a lead-tin doped perovskite material in an aqueous solvent according to claim 1, characterized in that: In step 1, the halogen source includes one or more of hydrochloric acid, hydrobromic acid, and hydroiodic acid.

3. The method for preparing a lead-tin doped perovskite material in an aqueous solvent according to claim 1, characterized in that: In step 2, the A-site cation source includes one or more combinations of monomethylamine, formamidine acetate, and cesium acetate, the lead ion source includes one or more combinations of lead acetate, lead sulfate, and lead chloride, and the tin ion source includes one or more combinations of tin acetate, tin sulfide, and stannous chloride.

4. The method for preparing a lead-tin doped perovskite material in an aqueous solvent according to claim 1, characterized in that: In step 3, solvent 2 includes one or more combinations of dimethyl sulfoxide, N,N-dimethylformamide, valerolactone, γ-butyrolactone, and acetonitrile.

5. The method for preparing a lead-tin doped perovskite material in an aqueous solvent according to claim 1, characterized in that: The total amount of lead ions and tin ions added is 1-2 g / mL, and the amount of the halogen source added is 30-60 wt % compared to the total reaction solution.

6. The method for preparing a lead-tin doped perovskite material in an aqueous solvent according to claim 1, characterized in that: The total amount of reducing agent and antioxidant added is 1-10% of the total molar amount of lead ions and tin ions added, and the amount of A-site cation source added is 1-2 times of the total molar amount of lead ions and tin ions added.

7. The method for preparing a lead-tin doped perovskite material in an aqueous solvent according to claim 1, characterized in that: The general chemical formula of lead-tin doped perovskite is APb a Sn 1-a X3, where A is one or a combination of methylamine cation, formamidine cation, cesium ion; where the value range of a is 0 < a < 1; where X is a halogen anion Cl - 、Br - 、I - or one or more of them.

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