Perovskite precursor sol and preparation method thereof, perovskite thin film and perovskite solar cell

Abstract

The invention provides a perovskite precursor sol and a preparation method thereof, a perovskite thin film and a perovskite solar cell, the perovskite precursor sol comprises an ether solvent, organic amine hydriodate and / or organic ammonium iodide, lead iodide and an additive, and the molar ratio of the ether solvent to the organic amine hydriodate and / or organic ammonium iodide to the lead iodide to the additive is 1: (0.67-1.05): (0.001-0.2). Complex lead-iodine agglomerates in the perovskite precursor sol provided by the invention are less, the perovskite precursor sol has the advantages of uniform nucleation and high perovskite phase purity, and the used main solvent is an ether solvent with low polarity and low boiling point, and has the advantages of high volatilization speed and easy removal. In the process of preparing the perovskite thin film by adopting a one-step method, the method has the advantage that anti-solvent assistance is not needed, and the method is more suitable for large-area production.

Description

Technical Field

[0001] The present invention relates to a perovskite precursor sol and a preparation method thereof, a perovskite thin film and a perovskite solar cell, belonging to the technical field of solar energy applications. Background Art

[0002] The perovskite precursor sol is the key to preparing the light absorption layer of perovskite solar cells. In the perovskite ABX 3 composition, A is usually methylammonium ion CH 3 NH 3 + , formamidinium ion CH(NH 2 ) 2 + and Cs + , B is Pb 2+ , Sn 2+ , and X is a halide ion (I - , Br - ). The perovskite thin film is usually prepared by a one-step method or a two-step method (Wiley A. Dunlap-Shohl.et al., Chemical Reviews, 2019, 119(5), 3193-3295). Among them, the perovskite precursor solution used in the one-step method is obtained by dissolving the precursors AX and BX 2 in the same solvent, and then the perovskite thin film is obtained in one step by spin coating, blade coating, spraying, etc.; in the two-step method, the two solutions of AX and BX 2 are respectively prepared. First, a BX 2 film (such as PbI 2 ) is obtained in one step by spin coating, blade coating, spraying, etc., and then AX is introduced by evaporation coating, spin coating, blade coating, spraying, etc. to convert the BX 2 film into an ABX 3 perovskite thin film. The one-step method has the advantages of convenience, easy control of composition, and less residual BX 2 phase.

[0003] To obtain good solubility of BX 2 , most of the perovskite precursor sols used in the one-step method use high-polarity solvents such as dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP) (B. Parida et al., Advanced Science, 2022, 9(14), 2200308), etc. Although high-polarity solvents have good solubility for BX 2has good solubility but usually has a high boiling point. An anti-solvent (a solvent that does not dissolve the perovskite precursor) is needed to accelerate the removal of the highly polar solvent, triggering explosive nucleation, thereby obtaining a perovskite film with better quality. However, the optimal time window for introducing the anti-solvent is usually dozens of seconds, which is not suitable for the preparation of large-area perovskite films (Daiyu Li et al., Advanced Functional Materials, 2022, 31(12), 2008621). Low-polarity solvents have low boiling points and are easy to remove, avoiding the use of anti-solvents, but the poor solubility of low-polarity solvents in BX 2 hinders its application.

[0004] CN111430554A discloses a method for preparing perovskite films and cells by adding triiodide, and its cells. BX 2 , AX and triiodide are added to an organic solvent to obtain a perovskite precursor solution, and perovskite films and cells are obtained by a two-step method or an anti-solvent-assisted one-step method. The organic solvent includes a main solvent and a solvent additive. The main solvent is any one of amide solvents, sulfone / sulfoxide solvents, ester solvents, hydrocarbons, halogenated hydrocarbon solvents, alcohol solvents, ketone solvents, ether solvents, aromatic hydrocarbon solvents, and the solvent additive is any one of amide solvents, sulfone / sulfoxide solvents, ester solvents, hydrocarbons, halogenated hydrocarbon solvents, alcohol solvents, ketone solvents, ether solvents, aromatic hydrocarbon solvents. Specifically, the main solvent is any one of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), γ-butyrolactone (GBL), and the solvent additive is at least one of DMSO, NMP, 1,3-dimethyl-2-imidazolidinone (DMI), 1,8-diiodooctane (DIO), N-cyclohexyl-2-pyrrolidone (CHP), chlorobenzene (CB), toluene. The defects of this technology or the deficiencies compared with the present invention are as follows: (1) The main solvents used in this technology are mainly DMF, DMSO, NMP, and GBL, which have high boiling points, and an anti-solvent (a solvent that does not dissolve the perovskite precursor) is needed to accelerate the removal of the highly polar solvent; (2) This technology provides a method for adding triiodide additives to solve the problems such as long time required and easy introduction of by-products in the existing technology of doping triiodide ions.

[0005] CN106486602A discloses a method for preparing high-quality perovskite films by introducing inexpensive additives. This method introduces ammonium salt additives into the perovskite precursor solution or the anti-solvent, and provides a method for preparing perovskite films by an anti-solvent-assisted one-step method. The ammonium salts are NH 4 I, NH 4 Cl, NH 4 Br or NH 4F. The solvent used for preparing the precursor solution is a mixed solvent of dimethyl sulfoxide and dimethylformamide. Defects or deficiencies of this technology compared to the present invention: (1) The solvent used in this technology has a relatively high boiling point, and an anti-solvent (a solvent that does not dissolve the perovskite precursor) is required to accelerate the removal of the highly polar solvent; (2) In the solvent used in this technology, the ammonium salt improves the film morphology, promotes grain growth, and enhances the crystallization performance of the perovskite material.

[0006] Therefore, providing a novel perovskite precursor sol based on ether solvents, a preparation method thereof, a perovskite film, and a perovskite solar cell has become an urgent technical problem to be solved in this field. Summary of the Invention

[0007] To address the above-mentioned drawbacks and deficiencies, one object of the present invention is to provide a perovskite precursor sol based on ether solvents. The perovskite precursor sol provided by the present invention can overcome the problem of poor solubility of the perovskite precursor in ether solvents, thereby reducing lead iodide aggregates in the perovskite precursor sol, and thus can be applied to the one-step preparation of perovskite films without anti-solvent assistance.

[0008] Another object of the present invention is to provide a preparation method for the above-mentioned perovskite precursor sol based on ether solvents.

[0009] Another object of the present invention is to provide a perovskite film prepared from the above-mentioned perovskite precursor sol.

[0010] Another object of the present invention is to provide a perovskite solar cell, the light absorption layer of which is the above-mentioned perovskite film.

[0011] To achieve the above objects, on the one hand, the present invention provides a perovskite precursor sol, wherein the perovskite precursor sol comprises an ether solvent, an organic amine hydroiodide and / or an organic ammonium iodide, lead iodide, and an additive, and the molar ratio of the organic amine hydroiodide and / or the organic ammonium iodide, lead iodide, and the additive is 1:0.67 - 1.05:0.001 - 0.2, preferably 1:0.67 - 1.05:0.01 - 0.2.

[0012] As a specific embodiment of the above-mentioned perovskite precursor sol of the present invention, the ether solvent comprises one or a combination of several of ethylene glycol methyl ether, ethylene glycol dimethyl ether, ethylene glycol propyl ether, and poly(ethylene glycol) methyl ether, etc.

[0013] As a specific embodiment of the above-mentioned perovskite precursor sol of the present invention, in the Raman spectrum of the perovskite precursor sol, it is located at 103 - 108 cm -1 and 122 - 127 cm -1The peak intensity ratio is greater than 0.95.

[0014] As a specific embodiment of the perovskite precursor sol described above in the present invention, wherein, based on the total volume of the ether solvent, the molar concentration of the organic amine hydroiodide and / or the organic ammonium iodide in the ether solvent is 0.5 - 2 mol / L.

[0015] As a specific embodiment of the perovskite precursor sol described above in the present invention, wherein the organic amine hydroiodide includes methylamine hydroiodide and / or formamidine hydroiodide, etc.;

[0016] The organic ammonium iodide includes one or a combination of several of ethylammonium iodide, n-propylammonium iodide, n-butylammonium iodide, guanidinium iodide, etc.

[0017] As a specific embodiment of the perovskite precursor sol described above in the present invention, wherein the additive includes one or a combination of several of aprotic polar solvents, Lewis bases, carboxyl-containing compounds, halogen elements, halogen-containing and / or pseudohalogen-containing compounds, etc.

[0018] The additive used in the present invention can promote the dissolution of the perovskite precursor in the ether solvent and can regulate the properties of the colloidal particles in the perovskite precursor sol based on the ether solvent, solving the problem that the solubility of the perovskite precursor in the ether solvent is poor compared to highly polar organic solvents such as dimethyl sulfoxide and dimethylformamide.

[0019] As a specific embodiment of the perovskite precursor sol described above in the present invention, wherein the aprotic polar solvent includes one or a combination of several of DMSO, DMF, NMP, etc.

[0020] As a specific embodiment of the perovskite precursor sol described above in the present invention, wherein the Lewis base includes one or a combination of several of urea, thiosemicarbazide, thiophene, etc.

[0021] As a specific embodiment of the perovskite precursor sol described above in the present invention, wherein the carboxyl-containing compound includes one or a combination of several of methylamine acetate, formamidine acetate, phthalic acid, amino acids, etc.

[0022] As a specific embodiment of the perovskite precursor sol described above in the present invention, wherein the halogen-containing and / or pseudohalogen-containing compound includes one or a combination of several of potassium triiodide, ammonium chloride, fluorophenylhydrazine hydrochloride, ammonium thiocyanate, cesium iodide, etc.

[0023] As a specific embodiment of the perovskite precursor sol described above in the present invention, wherein the halogen element includes iodine element, etc.

[0024] On the other hand, the present invention also provides a method for preparing the perovskite precursor sol described above, wherein the preparation method includes:

[0025] Fully dissolve an organic amine hydroiodide and / or an organic ammonium iodide, lead iodide, and an additive in an ether solvent to obtain a perovskite precursor sol;

[0026] Or fully dissolve a perovskite powder and an additive in an ether solvent to obtain a perovskite precursor sol; wherein, the perovskite powder includes methylammonium lead iodide (MAPbI 3 ), formamidinium lead iodide (FAPbI 3 ), a MA-FA binary mixed cation perovskite, and a MA-FA-Cs ternary mixed cation perovskite, or a combination of several of them.

[0027] As a specific embodiment of the above preparation method of the present invention, wherein the full dissolution is achieved by stirring, the temperature of the stirring is 20-80°C, and the speed of the stirring is 200-1000 rpm.

[0028] As a specific embodiment of the above preparation method of the present invention, the mixing method of the raw materials can be any one of simultaneous mixing and batch mixing. In some embodiments of the present invention, an organic amine hydroiodide and / or an organic ammonium iodide, lead iodide, and an additive are successively and fully dissolved in an ether solvent.

[0029] On another aspect, the present invention provides a perovskite thin film, wherein the perovskite thin film is prepared from the perovskite precursor sol described above.

[0030] The perovskite precursor sol provided by the present invention is suitable for preparing a perovskite thin film by a one-step method, such as preparing a perovskite thin film by spin coating or blade coating the perovskite precursor colloidal solution. Before preparing the perovskite thin film, the present invention preferably heats the perovskite precursor sol at 50-100°C first, and then allows it to stand to 20-70°C before use.

[0031] On yet another aspect, the present invention also provides a perovskite solar cell, wherein the light absorption layer of the perovskite solar cell is the perovskite thin film described above.

[0032] Compared with the prior art, the beneficial technical effects that the present invention can achieve include:

[0033] The main solvent used in the perovskite precursor sol provided by the present invention is a low-polarity and low-boiling-point ether solvent, which has the advantages of fast evaporation rate and easy removal, has the advantage of not requiring an anti-solvent assistance during the process of preparing a perovskite thin film by a one-step method, and has the advantage of being more suitable for large-scale production.

[0034] By using additives and controlling the dosages of various components, the present invention can promote the dissolution of PbI 2 such that the peak intensity ratio between 103 - 108 cm -1 and 122 - 127 cm -1 in the Raman spectrum of the perovskite precursor sol is greater than 0.95. This peak intensity ratio is an indication of the types of colloidal particles in the perovskite precursor sol and reflects the solubility of the BX 2 species. A peak intensity ratio greater than 0.95 indicates that there are fewer complex lead iodide aggregates in the perovskite precursor sol provided by the present invention, which has the advantages of uniform nucleation and high perovskite phase purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0036] Figure 1a Optical microscope image of the perovskite precursor sol provided in Embodiment 1 of the present invention.

[0037] Figure 1b Optical microscope image of the perovskite precursor sol provided in Comparative Example 2.

[0038] Figure 2 XRD patterns of the perovskite precursor sols provided in Embodiment 1 and Comparative Example 3 of the present invention.

[0039] Figure 3 XRD patterns of the perovskite precursor sols provided in Embodiment 5 and Comparative Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] It should be noted that the term "comprising" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or devices.

[0041] The "ranges" disclosed in the present invention are given in the form of lower and upper limits. There may be one or more lower limits, and one or more upper limits respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundaries of a particular range. All ranges defined in this way are combinable, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a particular parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values listed are 1 and 2, and the maximum range values listed are 3, 4, and 5, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5.

[0042] In the present invention, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" are fully listed in the present invention, and "0 - 5" is only an abbreviated representation of these numerical combinations.

[0043] In the present invention, if there is no special instruction, all embodiments and preferred embodiments mentioned in the present invention can be combined with each other to form a new technical solution.

[0044] In the present invention, if there is no special instruction, all technical features and preferred features mentioned in the present invention can be combined with each other to form a new technical solution.

[0045] In the present invention, if there is no special instruction, all steps mentioned herein can be carried out sequentially or randomly, but preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out sequentially, or may also include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or may also include steps (a), (c), and (b), or may also include steps (c), (a), and (b), etc.

[0046] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the attached tables, drawings and embodiments. The following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be construed as limiting the scope of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchases.

[0047] Example 1

[0048] This example provides a perovskite precursor sol, which is prepared by a preparation method including the following specific steps:

[0049] Step 1): Add 1 mmol of methylammonium hydroiodide (MAI) to 1 ml of ethylene glycol methyl ether, and stir at 20 °C and 500 rpm until completely dissolved.

[0050] Step 2): Add 1 mmol of lead iodide (PbI 2 ) to the solution obtained in Step 1), and stir at 20 °C and 500 rpm until completely dissolved.

[0051] Step 3): Add 0.2 mmol of N-methylpyrrolidone (NMP) to the solution obtained in Step 2), and stir at 20 °C and 500 rpm for 6 h to obtain the perovskite precursor sol.

[0052] Example 2

[0053] This example provides a perovskite precursor sol, which is prepared by a preparation method including the following specific steps:

[0054] Step 1): Add 1.6 mmol of MAI and 0.4 mmol of formamidinium hydroiodide (FAI) to 1 ml of ethylene glycol dimethyl ether, and stir at 40 °C and 1000 rpm until completely dissolved.

[0055] Step 2): Add 1.34 mmol of PbI 2 , 0.02 mmol of phthalic acid to the solution obtained in Step 1), and stir at 40 °C and 1000 rpm until completely dissolved to obtain the perovskite precursor sol.

[0056] Example 3

[0057] This example provides a perovskite precursor sol, which is prepared by a preparation method including the following specific steps:

[0058] 0.75 mmol of MAI, 0.675 mmol of FAI, 0.075 mmol of n-butylammonium iodide, 1.2 mmol of PbI 2 , and 0.15 mmol of 4-fluorophenylhydrazine hydrochloride were added to 1 ml of ethylene glycol monoethyl ether, and stirred at 60 °C and 500 rpm until completely dissolved to obtain the perovskite precursor sol.

[0059] Example 4

[0060] This example provides a perovskite precursor sol, which is prepared by a preparation method including the following specific steps:

[0061] 1 mmol of MA 0.2 FA 0.8 PbI 3 (where 1 mmol of MA 0.2 FA 0.8 PbI 3 consists of 0.2 mmol of MAI, 0.8 mmol of FAI, and 1 mmol of PbI 2 ), and 0.15 mmol of thiosemicarbazide were added to 1 ml of ethylene glycol n-propyl ether, and stirred at 20 °C and 500 rpm until completely dissolved to obtain the perovskite precursor sol.

[0062] Example 5

[0063] This example provides a perovskite precursor sol, which is prepared by a preparation method including the following specific steps:

[0064] Step 1): 0.5 mmol of FAI and 0.5 mmol of PbI 2 were added to 1 ml of ethylene glycol monomethyl ether, and stirred at 20 °C and 200 rpm until completely dissolved.

[0065] Step 2): 0.05 mmol of I 2 was added to the solution obtained in Step 1), and stirred at 80 °C and 500 rpm until completely dissolved to obtain the perovskite precursor sol.

[0066] Comparative Example 1

[0067] This comparative example provides a perovskite precursor sol, and the difference in its preparation method from that of Example 5 is only that:

[0068] I 2 was not added.

[0069] Comparative Example 2

[0070] This comparative example provides a perovskite precursor sol, and the difference in its preparation method from that of Example 1 is only that:

[0071] The addition amount of NMP is 0.25 mmol.

[0072] Comparative Example 3

[0073] This comparative example provides a perovskite precursor sol, and the difference in its preparation method from that of Example 1 is only that:

[0074] PbI 2 The addition amount is 0.65 mmol.

[0075] Comparative Example 4

[0076] This comparative example provides a perovskite precursor sol, and the difference in its preparation method from that of Example 1 is only that:

[0077] PbI 2 The addition amount is 1.1 mmol.

[0078] There is undissolved PbI 2 in the sol obtained in this comparative example, which is in a suspension state and cannot be applied to the preparation of perovskite thin films. This indicates that the present invention must control the appropriate molar ratio of organic amine hydroiodide and / or organic ammonium iodide, lead iodide and additives (i.e., the molar ratio of the three needs to satisfy 1:0.67 - 1.05:0.001 - 0.2) to obtain a qualified perovskite precursor sol that can be used for the preparation of perovskite thin films.

[0079] Characterization Test Example 1

[0080] In this characterization test example, the perovskite precursor sols obtained in Examples 1 - 5 and Comparative Examples 1 - 3 were collected respectively, and Raman tests were performed on them. The excitation wavelength was 1030 or 785 nm, and the wavenumber range collected was 50 - 250 cm -1 , and then the obtained Raman spectra were subjected to peak fitting analysis to obtain the I (～107) / I (～122) Raman peak area ratio, that is, the peak intensity ratio of the peaks located at ~107 cm -1 and ~122 cm -1 in the Raman spectrum, as shown in Table 1 below.

[0081] Table 1

[0082] <![CDATA[I (～107) / I (～122) Raman peak area ratio]]> Example 1 1.11 Example 2 1.02 Example 3 0.99 Example 4 1.00 Example 5 0.97 Comparative Example 1 0.93 Comparative Example 2 1.20 Comparative Example 3 1.05

[0083] As can be seen from Table 1, in the Raman spectra of the perovskite precursor sols provided in Examples 1 - 5 of the present invention, the peaks located at ~107 cm -1 and ~122 cm -1The peak intensity ratios are all greater than 0.95. Compared with the perovskite precursor sol provided in Example 5, in the Raman spectrum of the perovskite precursor sol provided in Comparative Example 1, the peak intensity ratios at ~107 cm -1 and ~122 cm -1 are only 0.93, which is less than 0.95.

[0084] The peak intensity ratios at ~107 cm -1 and ~122 cm -1 in the Raman spectrum are indicators of the types of colloidal particles in the perovskite precursor sol, reflecting the solubility of BX 2 species. The fact that this peak intensity ratio is greater than 0.95 indicates that compared with Comparative Example 1, due to the addition of additives in the perovskite precursor sol provided in the examples of the present invention, there are fewer complex lead iodide aggregates in this perovskite precursor sol, having the advantages of uniform nucleation and high perovskite phase purity.

[0085] Characterization Test Example 2

[0086] In this characterization test example, the perovskite precursor sols provided in Example 1 and Comparative Example 2 were first preheated at 60 °C, and then spin-coated on ITO glass at 60 °C and 4000 rpm for 30 s to obtain perovskite thin films. Then, optical microscope analysis was performed on the perovskite thin films respectively, and the obtained optical microscope images are shown in Figure 1a and Figure 1b respectively. By comparing Figure 1a and Figure 1b and combining the data in Table 1, it can be seen that although the peak intensity ratios at ~107 cm -1 and ~122 cm -1 in the Raman spectrum of the perovskite precursor sol provided in Comparative Example 2 are also greater than 0.95, its density is worse than that of the perovskite precursor sol provided in Example 1 of the present invention. This indicates that too high a proportion of NMP is not conducive to the rapid removal of the ether solvent, thereby degrading the quality of the perovskite thin film.

[0087] Characterization Test Example 3

[0088] In this characterization test example, the perovskite precursor sols provided in Example 1 and Comparative Example 3 were first preheated at 60 °C, and then spin-coated on ITO glass at 60 °C and 4000 rpm for 30 s to obtain perovskite thin films. Then, X-ray diffraction analysis was performed on the perovskite thin films respectively, and the obtained XRD patterns are shown in Figure 2 as shown. From Figure 2 and combining the data in Table 1, it can be seen that although the peak intensity ratios at ~107 cm -1 and ~122 cm -1The peak intensity ratio is also greater than 0.95, but there is an iodine-rich impurity phase in it, while the perovskite precursor sol provided in Example 1 of the present invention has no impurity phase. This indicates that in the perovskite precursor sol, the molar ratio of organic amine hydroiodide to lead iodide should not be higher than 1:0.67, but should be in line with 1:0.67 - 1.05.

[0089] Characterization Test Example 4

[0090] In this characterization test example, the perovskite precursor sols provided in Example 5 and Comparative Example 1 were first spin-coated on ITO glass at a temperature of 100 °C to obtain perovskite thin films, and then X-ray diffraction analysis was performed on the perovskite thin films respectively. The obtained XRD patterns are as Figure 3 shown. As can be seen from Figure 3 it, the perovskite precursor sol provided in Example 5 of the present invention is a perovskite phase, while the perovskite precursor sol provided in Comparative Example 1 is a mixture of non-perovskite phase and perovskite phase. This indicates that additive I 2 can increase the I (～107) / I (～122) ratio of the perovskite precursor sol, thereby improving the perovskite phase purity.

[0091] In summary, the main solvent used in the perovskite precursor sol provided in the embodiments of the present invention is an ether solvent with low polarity and low boiling point, which has the advantages of fast evaporation rate and easy removal. It has the advantage of not requiring an anti-solvent assistant in the process of preparing perovskite thin films by a one-step method, and is more suitable for large-scale production.

[0092] By using additives and adjusting the dosage of each component in the embodiments of the present invention, the dissolution of PbI 2 can be promoted, so that the peak intensity ratio of the perovskite precursor sol in the Raman spectrum located at 103 - 108 cm -1 and 122 - 127 cm -1 is greater than 0.95. This peak intensity ratio is an indication of the types of colloidal particles in the perovskite precursor sol and reflects the solubility of BX 2 species. The peak intensity ratio greater than 0.95 indicates that there are fewer complex lead iodide aggregates in the perovskite precursor sol provided in the embodiments of the present invention, and it has the advantages of uniform nucleation and high perovskite phase purity.

[0093] The above is only a specific embodiment of the present invention, and it cannot limit the scope of the invention implementation. Therefore, the replacement of its equivalent components, or the equivalent changes and modifications made according to the scope of the present invention patent protection, should still fall within the scope covered by this patent. In addition, the technical features in the present invention can be freely combined and used among technical features, between technical features and technical inventions, and between technical inventions.

Claims

1. A perovskite precursor sol, characterized in that, the perovskite precursor sol comprises an ether solvent, an organic amine hydroiodide and / or an organic ammonium iodide, lead iodide and an additive, wherein the molar ratio of the organic amine hydroiodide and / or the organic ammonium iodide, lead iodide and the additive is 1:0.67 - 1.05:0.001 - 0.

2.

2. The perovskite precursor sol according to claim 1, characterized in that, the ether solvent comprises one or a combination of several of ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol propyl ether and polyethyleneglycol monomethyl ether.

3. The perovskite precursor sol according to claim 1 or 2, characterized in that, The Raman spectrum of the perovskite precursor sol is located at 103-108 cm -1 and 122-127cm -1 The peak intensity ratio is greater than 0.

95.

4. The perovskite precursor sol according to claim 1 or 2, characterized in that, the molar concentration of the organic amine hydroiodide and / or the organic ammonium iodide in the ether solvent is 0.5 - 2 mol / L.

5. The perovskite precursor sol according to claim 1 or 2, characterized in that, the organic amine hydroiodide comprises methylamine hydroiodide and / or formamidine hydroiodide; the organic ammonium iodide comprises one or a combination of several of ethylammonium iodide, n-propylammonium iodide, n-butylammonium iodide and guanidinium iodide.

6. The perovskite precursor sol according to claim 1 or 2, characterized in that, the additive comprises one or a combination of several of an aprotic polar solvent, a Lewis base, a carboxyl group-containing compound, a halogen element, and a halogen-containing and / or pseudohalogen-containing compound.

7. The perovskite precursor sol according to claim 6, characterized in that, the aprotic polar solvent comprises one or a combination of several of DMSO, DMF and NMP.

8. The perovskite precursor sol according to claim 6, characterized in that, the Lewis base comprises one or a combination of several of urea, thiosemicarbazide and thiophene.

9. The perovskite precursor sol according to claim 6, characterized in that, the carboxyl group-containing compound comprises one or a combination of several of methylamine acetate, formamidine acetate, phthalic acid and amino acids.

10. The perovskite precursor sol according to claim 6, characterized in that, the halogen-containing and / or pseudohalogen-containing compound comprises one or a combination of several of potassium triiodide, ammonium chloride, fluorophenylhydrazine hydrochloride, ammonium thiocyanate and cesium iodide; preferably, the halogen element comprises iodine.

11. The preparation method of the perovskite precursor sol according to any one of claims 1 - 10, characterized in that, the preparation method comprises: fully dissolving the organic amine hydroiodide and / or the organic ammonium iodide, lead iodide and the additive in the ether solvent to obtain the perovskite precursor sol; or fully dissolving the perovskite powder and the additive in the ether solvent to obtain the perovskite precursor sol; wherein the perovskite powder comprises one or a combination of several of methylammonium lead iodide, formamidinium lead iodide, MA-FA binary mixed cation perovskite and MA-FA-Cs ternary mixed cation perovskite.

12. The preparation method according to claim 11, characterized in that, The sufficient dissolution is achieved by stirring, the temperature of the stirring is 20 - 80 °C, and the speed of the stirring is 200 - 1000 rpm.

13. A perovskite thin film, characterized in that, the perovskite thin film is prepared from the perovskite precursor sol according to any one of claims 1 - 10.

14. A perovskite solar cell, characterized in that, the light absorption layer of the perovskite solar cell is the perovskite thin film according to claim 13.

Images