Square acid compound or salt thereof, solar cell, power generation device, and power utilization device

Abstract

The invention provides a squaric acid compound or a salt thereof, a solar cell, a power generation device, and a power utilization device. The compounds are represented by the following general formula (I); wherein Z is: # imgabs0 # or a substituted or unsubstituted five or six membered heteroaryl group containing at least one heteroatom, where the heteroatoms comprise O, S and N; substituent groups of the heteroaryl group comprise-OH, carboxyl,-CONR2,-CHO, halogen,-NH2 and-CN; r'each independently includes-NH2,-NHR,-NHC (0) R,-OH,-SH, and C1-C4 alkyl, R ''each independently includes a phosphate group, a sulfonic acid group, a boronic acid group,-Si (OR) 3,-NR2,-NR3 +,-CONR2,-COOR, and halogen, where R'each independently includes H and C1-C4 alkyl, and when R' 'includes a plurality of Rs, the plurality of Rs are the same or different.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and particularly to a squaric acid compound or its salt, a solar cell, a power generation device, and an electric device. Background Art

[0002] A perovskite solar cell is a solar cell that uses a perovskite-type organometallic halide semiconductor as a light-absorbing material. It belongs to the third generation of solar cells and is also called a new concept solar cell. With the rapid development of the new energy field, solar cells have been widely used in military, aerospace, industrial, commercial, agricultural, and communication fields. Due to the great development of solar cells, higher requirements have been put forward for their performance and so on.

[0003] The electron transport layer, the light-absorbing layer, and the hole transport layer, as important components of a solar cell, have an important impact on its performance. However, the current solar cells still cannot meet the requirements of long-term stable operation. Summary of the Invention

[0004] This application is made in view of the above problems, and its purpose is to provide a squaric acid compound or its salt that can passivate defects in a perovskite solar cell to improve the long-term operation stability of the perovskite solar cell. In addition, this application also provides a solar cell, a power generation device, and an electric device including the above squaric acid compound or its salt.

[0005] To achieve the above object, this application provides a squaric acid compound or its salt, a solar cell, a power generation device, and an electric device.

[0006] In the first aspect of this application, a squaric acid compound or its salt is provided, and the compound is represented by the following general formula (I):

[0007]

[0008] Wherein, Z is: Or a substituted or unsubstituted five- or six-membered heteroaryl containing at least one heteroatom,

[0009] Wherein, the heteroatoms include O, S, and N; the substituents of the heteroaryl include -OH, carboxyl, -CONR2, -CHO, halogen, -NH2, and -CN;

[0010] Each R’ independently includes -NH2, -NHR, -NHC(O)R, -OH, -SH, and C1-C4 alkyl;

[0011] Each R” independently includes a phosphoric acid group, a sulfonic acid group, a boric acid group, -Si(OR)3, -NR2, -NR3 +, -CONR2, -COOR, and halogen, where each R independently includes H and C1-C4 alkyl; when R” includes multiple Rs, the multiple Rs are the same or different.

[0012] The squaric acid compound or its salt provided by the present application can passivate the cation defects or halogen anion defects of the perovskite in the perovskite solar cell, thereby improving the long-term operation stability of the perovskite solar cell.

[0013] In some embodiments, each R” independently includes a phosphate group, a sulfonic acid group, a boric acid group, and a carboxyl group.

[0014] When R” in the squaric acid compound is the above-mentioned substituent, the effect of passivating perovskite is further improved. In addition, when R” in the squaric acid compound is the above-mentioned substituent, it can further combine with the metal in the metal oxide (if any) in the hole transport layer or the electron transport layer, preventing the valence state change of the metal in the metal oxide from further causing perovskite degradation.

[0015] In some embodiments, the C1-C4 alkyl includes methyl and ethyl.

[0016] In some embodiments, the heteroaryl includes:

[0017] X represents O, S, or N; each R”’ independently includes -OH.

[0018] When Z is the above-mentioned heteroaryl, the squaric acid compound has a better passivation effect on the anion defects in perovskite.

[0019] In some embodiments, the salt includes an alkali metal salt and an ammonium salt.

[0020] In some embodiments, the compound includes:

[0021]

[0022]

[0023] The second aspect of the present application provides a solar cell, which includes an electron transport layer, a light absorption layer, and a hole transport layer stacked in sequence, where the light absorption layer includes a perovskite material.

[0024] The solar cell further includes at least one of the squaric acid compound and its salt of the first aspect of the present application, where the compound exists in its own form and / or in its ionic form.

[0025] Thus, in this application, by adding the above-mentioned squaric acid compound or its salt into a solar cell, defects in the perovskite solar cell are passivated to improve the long-term operation stability of the perovskite solar cell.

[0026] In some embodiments, the compound is included in at least one of the electron transport layer, the light absorption layer, and the hole transport layer; alternatively, the solar cell further includes a first passivation layer containing the compound located between the hole transport layer and the light absorption layer, and / or a second passivation layer containing the compound located between the electron transport layer and the light absorption layer.

[0027] Doping the squaric acid compound or its salt into at least one of the electron transport layer, the light absorption layer, and the hole transport layer, or forming a first passivation layer and / or a second passivation layer with the above-mentioned squaric acid compound or its salt can passivate the perovskite material in the light absorption layer, or prevent the degradation of the perovskite material caused by the change of the metal valence state in the metal oxide when the electron transport layer or the hole transport layer contains a metal oxide.

[0028] In some embodiments, the perovskite material is represented by the general formula (P):

[0029] ABX3 General formula (P);

[0030] where A is a first cation, B is a second cation, and X is an anion;

[0031] where the general formula (P) satisfies at least one of the following:

[0032] A includes MA + , FA + , Cs + , K + , Rb + and Li + at least one of them;

[0033] B includes Pb 2+ , Sn 2+ , Fe 2+ , Mn 2+ , Ni 2+ , Ge 2+ , Co 2+ and Sb 2+ at least one of them;

[0034] X includes Br - , I - , Cl - and F - at least one of them.

[0035] In some embodiments, the perovskite material is represented by the general formula (Q):

[0036] A2CDX6 General formula (Q);

[0037] where A is a first cation, C is a third cation, D is a fourth cation, and X is an anion;

[0038] where the general formula (Q) satisfies at least one of the following:

[0039] A includes MA + , FA + , Cs + , K + , Rb + and Li + at least one of;

[0040] C includes Ag + , Cs + , K + and Ru + at least one of;

[0041] D includes Bi 3+ , Sb 3+ , In 3+ , Ni 3+ , Fe 3+ and Cu 3+ at least one of;

[0042] X includes Br - , I - , Cl - and F - at least one of.

[0043] In some embodiments, the compound is contained in the light-absorbing layer at a content of 0.1 mol% to 10 mol% relative to the perovskite material.

[0044] In some embodiments, the content of the compound in the light-absorbing layer is 0.5 mol% to 5 mol% relative to the perovskite material.

[0045] When the squaric acid compound has the above content in the light-absorbing layer, it can effectively play its role in passivating the perovskite defects in the light-absorbing layer, thereby improving the long-term operation stability of the perovskite solar cell.

[0046] In some embodiments, the solar cell includes the first passivation layer containing the compound, wherein the HOMO energy level of the compound is between -5.0 eV and -5.8 eV. In some embodiments, the HOMO energy level of the compound is in the range of -5.2 eV to -5.6 eV.

[0047] In some embodiments, the hole transport layer comprises a first metal oxide.

[0048] In some embodiments, the compound comprises at least one compound selected from the compounds in which Z in the general formula (I) is In some embodiments, the compound exists in its ionic form.

[0049] When the hole transport layer comprises a first metal oxide, the compound defined above present in the first passivation layer can, on the one hand, passivate the perovskite defects in the light-absorbing layer, and on the other hand, bind to the metal of the first metal oxide in the hole transport layer to avoid valence change of the metal, or passivate the defects of the metal oxide with a changed valence state, preventing the metal with a changed valence state from causing degradation of the perovskite, so as to improve the long-term operation stability of the perovskite solar cell.

[0050] In some embodiments, the first metal oxide comprises at least one of nickel oxide, copper oxide, cuprous chromite, lithium copper nickel oxide, and nickel magnesium lithium oxide.

[0051] In some embodiments, the thickness of the first passivation layer is from 0.1 nm to 50 nm. In some embodiments, the thickness of the first passivation layer is from 0.1 nm to 10 nm.

[0052] When the first passivation layer has a thickness within the above range, the double passivation effect of the squaric acid molecule on the light-absorbing layer and the hole transport layer can occur sufficiently, and the photoelectric efficiency loss of the perovskite solar cell can be reduced.

[0053] In some embodiments, the hole transport layer comprises an organic hole transport material.

[0054] In some embodiments, the organic hole transport material comprises at least one of 2,2',7,7'-tetrakis(N,N-p-methoxyanilino)-9,9'-spirobifluorene (Spiro-OMeTAD), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid, methoxytriphenylamine-fluoromethamidine, poly(3,4-ethylenedioxythiophene), poly(styrenesulfonic acid), poly(3-hexylthiophene), triphenylamine with a triptycene core, 3,4-ethylenedioxythiophene-methoxytriphenylamine, N-(4-anilino)carbazole-spirobifluorene, polythiophene, phosphoric acid-based single molecule, carbazole-based single molecule, sulfonic acid-based single molecule, triphenylamine-based single molecule, and aromatic-based single molecule.

[0055] In some embodiments, the solar cell includes the second passivation layer containing the compound, wherein the LUMO energy level of the compound is between -3.6 eV and -4.4 eV. In some embodiments, the LUMO energy level of the compound is in the range of -3.8 eV to -4.2 eV.

[0056] In some embodiments, the electron transport layer includes a second metal oxide.

[0057] In some embodiments, the compound includes at least one of the compounds in which Z in the general formula (I) is selected from and the compound exists in its ionic form in some embodiments.

[0058] When the defined compound is included in the second passivation layer, it can passivate the defects of perovskite in the light-absorbing layer and at the same time passivate the defects of the second metal compound in the electron transport layer, so as to improve the long-term operation stability of the perovskite solar cell.

[0059] In some embodiments, the second metal oxide includes at least one of tin dioxide, zinc oxide, titanium dioxide, barium stannate and zinc stannate.

[0060] In some embodiments, the thickness of the second passivation layer is from 0.1 nm to 100 nm. In some embodiments, the thickness of the second passivation layer is from 0.1 nm to 10 nm.

[0061] When the second passivation layer has a thickness within the above range, the double passivation effect of the squaric acid molecule on the light-absorbing layer and the electron transport layer can occur sufficiently, and the photoelectric efficiency loss of the perovskite solar cell can be reduced.

[0062] In some embodiments, the electron transport layer includes an organic electron transport material.

[0063] In some embodiments, the organic electron transport material includes at least one of [6,6]-phenyl C 61 butyric acid methyl ester PC 61 BM, [6,6]-phenyl C 71 butyric acid methyl ester PC 71 BM and fullerene.

[0064] The third aspect of the present application provides a power generation device, and the power generation device includes the solar cell of the second aspect of the present application. The power generation device has excellent long-term operation stability.

[0065] The fourth aspect of the present application provides an electrical device, and the electrical device includes the solar cell of the second aspect of the present application. The electrical device has excellent long-term operation stability. Description of the Drawings

[0066] Figure 1 It is a schematic structural diagram of a solar cell with a normal structure according to an embodiment of the present application;

[0067] Figure 2 It is a schematic structural diagram of a solar cell with an inverted structure according to an embodiment of the present application;

[0068] Figure 3 It is a schematic structural diagram of a solar cell with a normal structure including a first passivation layer according to an embodiment of the present application;

[0069] Figure 4 It is a schematic structural diagram of a solar cell with an inverted structure including a first passivation layer according to an embodiment of the present application;

[0070] Description of reference numerals:

[0071] 110, substrate; 120, electron transport layer; 130, light absorption layer; 140, hole transport layer; 150, electrode layer; 160, first passivation layer; 210, substrate; 220, hole transport layer; 230, light absorption layer; 240, electron transport layer; 250, electrode layer; 260, first passivation layer. Detailed implementation manners

[0072] Hereinafter, embodiments of the squaric acid compound or its salt, solar cell, power generation device, and power consumption device of the present application will be specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0073] The "ranges" disclosed in this application are defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, 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 specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values of 1 and 2 are listed, and if the maximum range values of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In this application, 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" represents that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0074] If there is no special instruction, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions.

[0075] If there is no special instruction, all technical features and optional technical features of this application can be combined with each other to form new technical solutions.

[0076] If there is no special instruction, the terms used in this application have the well-known meanings commonly understood by those skilled in the art.

[0077] If there is no special instruction, the numerical values of the various parameters mentioned in this application can be measured using various commonly used testing methods in the art. For example, they can be measured according to the testing methods given in this application.

[0078] The working principle of a perovskite solar cell is as follows: When sunlight shines on the perovskite solar cell, when the photon energy of sunlight is greater than the bandgap, the perovskite light-absorbing layer absorbs photons to generate "electron-hole pairs". The electron transport layer transports the separated electrons to the negative electrode; the hole transport layer transports the holes separated from the electrons to the positive electrode, and further forms a directional movement of charges in the external circuit, thereby generating an electric current and achieving the conversion of light energy into electrical energy.

[0079] Perovskite light - absorbing layers often have a large number of defects. These defects accumulate on the surface of the perovskite light - absorbing layer, causing non - radiative recombination losses and affecting the device efficiency of the corresponding perovskite solar cells. In addition, external water, oxygen, etc. can still penetrate the single - layer passivation layer from the surface to damage the perovskite light - absorbing layer, affecting the durability of the solar cells. Exemplarily, the light - absorbing layer is, for example, HAPbI3. As shown in the following formulas 1, 2, and 3, due to ion migration, the light - absorbing layer HAPbI3 itself may degrade to generate PbI2, gas of the A - site element, and iodine vapor.

[0080]

[0081]

[0082]

[0083] In addition, in inverted perovskite solar cells, nickel oxide is an inorganic hole - transporting layer material with relatively good performance. However, as time goes by, as shown in formula 4, the nickel oxide in the hole - transporting layer may slowly oxidize to generate trivalent nickel ions. As shown in formula 5, the trivalent nickel ions can react with the perovskite in the light - absorbing layer, such as HAPbI3, causing the light - absorbing layer HAPbI3 to degrade to generate PbI2, gas of the A - site element, and iodine vapor. To sum up, after the degradation reaction occurs and the gas escapes, there may be some defects in the solar cell, posing a threat to the long - term operation stability of the solar cell.

[0084]

[0085]

[0086] Based on this, the present application proposes a squaric acid compound or its salt, a solar cell, a power generation device, and an electrical device. The squaric acid compound can effectively passivate the defects of perovskite.

[0087] In the first aspect of the present application, a squaric acid compound or its salt is provided, and the compound is represented by the following general formula (I):

[0088]

[0089] Where Z is: Or a substituted or unsubstituted five - or six - membered heteroaryl containing at least one heteroatom,

[0090] Where the heteroatoms include O, S, and N; the substituents of the heteroaryl include - OH, carboxyl, - CONR2, - CHO, halogen, - NH2, and - CN;

[0091] Each R’ independently includes -NH2, -NHR, -NHC(O)R, -OH, -SH and C1-C4 alkyl;

[0092] Each R” independently includes a phosphate group, a sulfonic acid group, a boronic acid group, -Si(OR)3, -NR2, -NR3 + , -CONR2, -COOR and a halogen, where each R independently includes H and C1-C4 alkyl; when R” includes multiple Rs, the multiple Rs are the same or different.

[0093] For the squaric acid compound or its salt provided in the present application, through the R” group in the phenyl group substituted with R’ and R” in the squaric acid compound, and when Z is a heteroaryl group, it can passivate the cation defects or halogen anion defects of the perovskite in the perovskite solar cell, thereby improving the long-term operation stability of the perovskite solar cell. When the squaric acid compound exists in its own form, the whole can maintain charge balance; when the squaric acid compound exists in ionic form, the acid can ionize to form an acid radical, and the whole can carry a negative charge.

[0094] As mentioned in the present application, “heteroaryl” is an aryl group having 1 to 3 heteroatoms selected from O, S and N in the ring structure. Examples of heteroaryl include but are not limited to pyrrole, furan, thiophene, pyridine and pyran.

[0095] As mentioned in the present application, “C1-C4 alkyl” includes a straight-chain alkyl or a straight-chain alkyl having 1 to 4 carbon atoms. For example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl and tert-butyl.

[0096] As mentioned in the present application, “halogen” includes fluorine, chlorine, bromine and iodine.

[0097] A perovskite solar cell generally includes an electron transport layer, a perovskite light absorption layer and a hole transport layer. The present application has no particular limitation on the perovskite as the light absorption layer. In some embodiments, the perovskite in the perovskite light absorption layer can be represented as ABX3 and A2CDX6, where A is the first cation, B is the second cation, C is the third cation, D is the fourth cation, and X is an anion. For example, A can include MA + (methylammonium ion (CH3NH3 + )), FA + (formamidinium ion (NH=CHNH3 + )), and Cs + and at least one of them, B can include Pb 2+ and / or Sn 2+ and other metal ions, C can include Ag + , D can include Bi 3+ , Sb 3+ and In3 + At least one of them, X may include Br - and / or I - In this application, the electron transport layer and the hole transport layer can be metal oxides or other organic materials.

[0098] Specifically, the defects in the solar cell can be divided into two categories. The first category is the defects in the light-absorbing layer. Among them, the defects in the light-absorbing layer include anion defects and cation defects. The second category is the defects in the hole transport layer or the electron transport layer. Among them, the defects in the hole transport layer or the electron transport layer refer to the defects that exist when the hole transport layer or the electron transport layer is a metal oxide (for example, nickel oxide). When Z is phenyl, what kind of defects the squaric acid compound can passivate mainly depends on the R” group. When Z is a five- or six-membered heteroaryl group, the squaric acid compound mainly passivates the anion defects in the light-absorbing layer.

[0099] As mentioned in this application, "anion defect" refers to that after the perovskite in the light-absorbing layer undergoes a degradation reaction, a gas is generated, such as iodine vapor. After the gas escapes, the space originally occupied by the anion forms a vacancy defect. When the squaric acid compound provided in this application passivates the anion defect, Z is a five- or six-membered heteroaryl group containing at least one heteroatom, or Z is a phenyl group substituted with R” at the para position. R” independently includes a phosphate group, a sulfonic acid group, a boric acid group, -CONR2, -COOR, and a halogen, where R independently includes H and C1-C4 alkyl groups.

[0100] As mentioned in this application, "cation defect" refers to that after the perovskite in the light-absorbing layer undergoes a degradation reaction, a gas is generated, such as the gas of the A-site element. The space originally occupied by the cation forms a vacancy defect. When the squaric acid compound provided in this application passivates the cation defect, Z is a phenyl group substituted with R” at the para position. R” independently includes a phosphate group, a sulfonic acid group, a boric acid group, a carboxylic acid group, -NR2, and -NR3 + where R independently includes H and C1-C4 alkyl groups.

[0101] Optionally, R” independently includes a sulfonic acid group, a carboxylic acid group, -NR2, and -NR3 + It is easier in the synthesis method.

[0102] In the technical solution of this application, the function of the squaric acid compound or its salt in passivating the light-absorbing layer is to occupy the vacancies of anions or cations of perovskite in the light-absorbing layer, making the structure of the light-absorbing layer more stable. For example, when Z is a phenyl group substituted with R" at the para position, and each R" independently includes a phosphate group, a sulfonic acid group, a boric acid group, and -Si(OR)3, it has a better passivation effect on cation vacancies. When Z is a phenyl group substituted with R" at the para position, and each R" independently includes a halogen, it has a better passivation effect on halogen anion vacancies.

[0103] In the technical solution of this application, the function of the squaric acid compound or its salt in passivating the metal oxide is to combine with metal ions, preventing the metal ions from contacting the light-absorbing layer and thus causing degradation of the light-absorbing layer.

[0104] In addition, when the squaric acid compound provided in this application passivates metal oxide defects, Z is a phenyl group substituted with R" at the para position, and each R" independently includes a phosphate group, a sulfonic acid group, a boric acid group, or -Si(OR)3, and it also has a better passivation effect.

[0105] Optionally, when R" is the above-mentioned substituent, a salt of the squaric acid compound can be formed, and the cations are removed by subsequent washing. Each R" independently includes a phosphate root, a sulfonate root, and a borate root, and it has a better passivation effect on metal oxides.

[0106] Optionally, each R" independently includes a sulfonic acid group and a carboxylic acid group. It is easier in terms of the synthesis method.

[0107] In some embodiments, for example, to passivate the defects of the hole transport layer of a metal oxide (such as nickel oxide), the above-mentioned squaric acid compound or its salt can be added to the hole transport layer, or the above-mentioned squaric acid compound or its salt can be used to form a first passivation layer located between the hole transport layer and the light-absorbing layer.

[0108] In some embodiments, for example, to passivate the defects of the electron transport layer of a metal oxide (such as nickel oxide), the above-mentioned squaric acid compound or its salt can be added to the electron transport layer, or the above-mentioned squaric acid compound or its salt can be used to form a second passivation layer located between the electron transport layer and the light-absorbing layer.

[0109] In some embodiments, for example, to passivate the defects of the perovskite light-absorbing layer, the above-mentioned squaric acid compound or its salt can be added to the light-absorbing layer, or the above-mentioned squaric acid compound or its salt can be used to form a first passivation layer located between the hole transport layer and the light-absorbing layer, and the above-mentioned squaric acid compound or its salt can also be used to form a second passivation layer located between the electron transport layer and the light-absorbing layer. In this way, the appropriate group can be selected according to the defects to be passivated.

[0110] In addition, in the squaric acid compound or its salt provided by the present application, the R' group and the O in the squaric acid have a hydrogen bond interaction. When the first passivation layer located between the hole transport layer and the light-absorbing layer or the second passivation layer located between the electron transport layer and the light-absorbing layer contains the above-mentioned squaric acid compound or its salt, due to thermal or other factors, the shrinkage / stretching stress between the hole transport layer and the light-absorbing layer or between the electron transport layer and the light-absorbing layer, the squaric acid compound will twist into an isomer without falling off or degrading. For example, as shown in Reference Formula 6, when R' is -NHC(O)R, the H in R' and the O in the squaric acid have a hydrogen bond interaction. Due to thermal or other factors, the shrinkage / stretching stress, the squaric acid compound twists into an isomer without falling off or degrading.

[0111]

[0112] Moreover, the R' group in the squaric acid compound or its salt provided by the present application can also be used to adjust the solubility of the squaric acid compound in different polar solvents. Adjusting the solubility is beneficial to optimizing the preparation method of the solar cell. A wider range of solvent selection is also more conducive to the selection of green solvents and reducing the toxicity to the environment.

[0113] In some embodiments, each R'' independently includes a phosphate group, a sulfonic acid group, a boronic acid group, and a carboxyl group.

[0114] When R'' in the squaric acid compound is the above-mentioned substituent, the effect of passivating perovskite is further improved.

[0115] In addition, when R'' in the squaric acid compound is the above-mentioned substituent, it can further combine with the metal in the metal oxide (if any) in the hole transport layer or the electron transport layer to prevent the valence change of the metal in the metal oxide from further causing perovskite degradation.

[0116] Optionally, each R'' independently includes a sulfonic acid group and a carboxyl group.

[0117] Thus, by further defining R'', the synthesis method of the present application is easier.

[0118] In some embodiments, the C1-C4 alkyl group includes a methyl group and an ethyl group.

[0119] In the above embodiments, R is a short-chain alkyl group, especially a methyl group or an ethyl group. A shorter molecular chain is more beneficial to the passivation effect.

[0120] In some embodiments, the heteroatom in the five-membered heteroaryl group can be ortho or meta to the substitution site; optionally, the heteroatom in the five-membered heteroaryl group and the substitution site are ortho. The synthesis method of such a compound is easier.

[0121] In some embodiments, the heteroatom in the six-membered heteroaryl group can be ortho, meta or para to the substitution site; optionally, the heteroatom in the six-membered heteroaryl group and the substitution site are para. The passivation effect is better, which is more conducive to improving the long-term operation stability of perovskite solar cells.

[0122] In some embodiments, the heteroaryl group includes:

[0123] X represents O, S or N; each R''' independently includes -OH.

[0124] When Z is the above-mentioned heteroaryl group, the heteroaryl group can occupy the anion vacancy in the perovskite. Therefore, the squaric acid compound has a better passivation effect on the anion defects in the perovskite.

[0125] In some embodiments, the salt includes alkali metal salts and ammonium salts. Optionally, the alkali metal salts include sodium salts and potassium salts. When the squaric acid compound is used in the form of a salt, the introduced cations are adverse to the performance of the solar cell, and the cations can be removed by washing after coating. Considering this, the alkali metal salts and ammonium salts of the squaric acid compound are advantageous.

[0126] In some embodiments, the compound includes:

[0127]

[0128] The second aspect of the present application provides a solar cell, which includes an electron transport layer, a light-absorbing layer, and a hole transport layer stacked in sequence, wherein the light-absorbing layer includes a perovskite material, and the solar cell further includes at least one of the squaric acid compound and its salt according to the first aspect of the present application, and the compound exists in its own form and / or in its ionic form.

[0129] According to the arrangement mode of the device structure, perovskite solar cells can include a normal structure and a reverse structure.

[0130] Reference Figure 1 , Figure 1 is a schematic structural diagram of a solar cell with a normal structure according to an embodiment of the present application. As Figure 1 shown, the perovskite solar cell includes a substrate 110, an electron transport layer 120, a light-absorbing layer 130, a hole transport layer 140, and an electrode layer 150 stacked in sequence from bottom to top.

[0131] Reference Figure 2 , Figure 2 is a schematic structural diagram of a solar cell with a reverse structure according to an embodiment of the present application. As Figure 2As shown, the perovskite solar cell includes a substrate 210, a hole transport layer 220, a light-absorbing layer 230, an electron transport layer 240, and an electrode layer 250 that are stacked in sequence from bottom to top.

[0132] In the technical solution of this application, the squaric acid compound can exist in its own form and / or in its ionic form, that is, the squaric acid compound can be ionized in solution. For example, R” can be an acid or an acid radical.

[0133] Optionally, when passivating the metal oxide, the passivation effect of the acid radical is better than that of the acid.

[0134] Optionally, when passivating the metal oxide, when R” is an acid, the passivation effect of phosphoric acid is better than that of other acids.

[0135] Thus, in this application, by adding the above-mentioned squaric acid compound or its salt to the solar cell, the defects in the perovskite solar cell are passivated to improve the long-term operation stability of the perovskite solar cell.

[0136] In some embodiments, the compound is included in at least one of the electron transport layer, the light-absorbing layer, and the hole transport layer; or, the solar cell further includes a first passivation layer containing the compound located between the hole transport layer and the light-absorbing layer, and / or a second passivation layer containing the compound located between the electron transport layer and the light-absorbing layer.

[0137] In some embodiments, in this application, by adding the above-mentioned squaric acid compound or its salt to the electron transport layer, the metal oxide defects in the electron transport layer can be passivated.

[0138] In some embodiments, by adding the above-mentioned squaric acid compound or its salt to the light-absorbing layer, the anion defects or cation defects in the light-absorbing layer can be passivated.

[0139] In some embodiments, by adding the above-mentioned squaric acid compound or its salt to the hole transport layer, the metal oxide defects in the hole transport layer can be passivated.

[0140] In some embodiments, by adding the above-mentioned squaric acid compound or its salt to the first passivation layer, the defects in both the light-absorbing layer and the hole transport layer can be passivated. Which defect is specifically passivated depends on the group on the squaric acid compound or its salt.

[0141] In some embodiments, by adding the above-mentioned squaric acid compound or its salt to the second passivation layer, the defects in both the light-absorbing layer and the electron transport layer can be passivated. Which defect is specifically passivated depends on the group on the squaric acid compound or its salt.

[0142] Thus, by doping the above-mentioned squaric acid compound or its salt into at least one of the electron transport layer, the light absorption layer, and the hole transport layer, or by forming the first passivation layer and / or the second passivation layer with the above-mentioned squaric acid compound or its salt, defects in the perovskite solar cell are passivated to improve the long-term operation stability of the perovskite solar cell.

[0143] In some embodiments, the perovskite material is represented by the general formula (P):

[0144] ABX3 General formula (P);

[0145] where A is a first cation, B is a second cation, and X is an anion;

[0146] where the general formula (P) satisfies at least one of the following:

[0147] A includes MA + , FA + , Cs + , K + , Rb + and Li + at least one of;

[0148] B includes Pb 2+ , Sn 2+ , Fe 2+ , Mn 2+ , Ni 2+ , Ge 2+ , Co 2+ and Sb 2+ at least one of;

[0149] X includes Br - , I - , Cl - and F - at least one of.

[0150] In some embodiments, the perovskite material is represented by the general formula (Q):

[0151] A2CDX6 General formula (Q);

[0152] where A is a first cation, C is a third cation, D is a fourth cation, and X is an anion;

[0153] where the general formula (Q) satisfies at least one of the following:

[0154] A includes MA + , FA + , Cs + , K + , Rb + and Li +at least one of;

[0155] C includes Ag + , Cs + , K + and Ru + at least one of;

[0156] D includes Bi 3+ , Sb 3+ , In 3+ , Ni 3+ , Fe 3+ and Cu 3+ at least one of;

[0157] X includes Br - , I - , Cl - and F - at least one of.

[0158] As described above, the perovskite in this application is not particularly limited, and the above perovskite can obtain a good photoelectric conversion rate.

[0159] In some embodiments, the thickness range of the light-absorbing layer is 200 nm to 1000 nm.

[0160] In some embodiments, the compound is included in the light-absorbing layer at a content of 0.1 mol% to 10 mol% relative to the perovskite material.

[0161] In some embodiments, the content of the compound in the light-absorbing layer is 0.5 mol% to 5 mol% relative to the perovskite material.

[0162] Thus, the light-absorbing layer in this application includes a squaric acid compound, and the squaric acid compound can passivate anion defects or cation defects in the light-absorbing layer. When the squaric acid compound has the above content in the light-absorbing layer, it can effectively play its role in passivating the perovskite defects in the light-absorbing layer, thereby improving the long-term operation stability of the perovskite solar cell.

[0163] In some embodiments, the solar cell includes the first passivation layer containing the compound, wherein the HOMO energy level of the compound is between -5.0 eV and -5.8 eV. In some embodiments, the HOMO energy level of the compound is in the range of -5.2 eV to -5.6 eV.

[0164] The first passivation layer is located between the hole transport layer and the light-absorbing layer. When a squaric acid compound is included, the squaric acid compound can be used to passivate the defects of the hole transport layer (for example, when nickel oxide is used) or the defects of the light-absorbing layer. By regulating the groups of the squaric acid compound to change the HOMO energy level of the first passivation layer, the HOMO energy level of the compound in the first passivation layer is located between the HOMO energy level of the hole transport layer and the HOMO energy level of the light-absorbing layer, which is more conducive to the transport of carriers and reduces the loss of the photoelectric efficiency of the perovskite solar cell.

[0165] In addition, when the HOMO energy level of the compound in the first passivation layer is located between the HOMO energy level of the hole transport layer and the HOMO energy level of the light-absorbing layer, the higher the LUMO energy level of the compound in the first passivation layer, the more conducive it is to block the electrons from the light-absorbing layer, avoid carrier recombination, and is beneficial to improving the long-term operation stability of the perovskite solar cell.

[0166] In the above embodiment, the hole transport layer includes a first metal oxide.

[0167] In the above embodiment, Z in the general formula (I) of the compound is selected from at least one of the compounds. In the above embodiment, the compound exists in its ionic form.

[0168] When the hole transport layer includes a first metal oxide, the squaric acid compound in the first passivation layer can be used to passivate the defects of the hole transport layer and the light-absorbing layer at the same time, having a dual passivation effect. Specifically, the squaric acid compound in the first passivation layer can passivate the perovskite defects in the light-absorbing layer, and can also combine with the metal of the first metal oxide in the hole transport layer to avoid the change of the valence state of the metal, or passivate the defects of the metal oxide with the changed valence state, preventing the metal with the changed valence state from causing the degradation of the perovskite, so as to improve the long-term operation stability of the perovskite solar cell.

[0169] Moreover, the compound existing in its ionic form can enhance the effect of passivating the defects in the hole transport layer. For example, R” can be an acid radical, and the passivation effect of the acid radical is better.

[0170] In some embodiments, the first metal oxide includes at least one of nickel oxide, copper oxide, cuprous chromite, lithium copper nickel oxide, and nickel magnesium lithium oxide.

[0171] In some embodiments, the thickness of the first passivation layer is from 0.1 nm to 50 nm. In some embodiments, the thickness of the first passivation layer is from 0.1 nm to 10 nm. The thinner the first passivation layer, the smaller the loss of the photoelectric efficiency of the perovskite solar cell.

[0172] In some embodiments, the hole transport layer comprises an organic hole transport material.

[0173] In some embodiments, the organic hole transport material comprises at least one of 2,2',7,7'-tetrakis(N,N-p-methoxyanilino)-9,9'-spirobifluorene (Spiro-OMeTAD), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid, methoxytriphenylamine fluoromethylformamidine, poly(3,4-ethylenedioxythiophene), polystyrenesulfonic acid, poly(3-hexylthiophene), triphenylene-based triphenylamine, 3,4-ethylenedioxythiophene-methoxytriphenylamine, N-(4-anilino)carbazole-spirobifluorene, polythiophene, phosphoric acid-based single molecule, carbazole-based single molecule, sulfonic acid-based single molecule, triphenylamine-based single molecule, and aromatic-based single molecule.

[0174] This application does not particularly limit the hole transport layer material, and any conventional material used as the hole transport layer can be used. The above materials are exemplary and have good hole transport performance.

[0175] In this embodiment, when the hole transport layer comprises an organic hole transport material, the squaric acid compound can also be disposed in the hole transport layer.

[0176] In some embodiments, the solar cell comprises the second passivation layer, wherein the LUMO energy level of the compound is between -3.6 eV and -4.4 eV. In some embodiments, the LUMO energy level of the compound is in the range of -3.8 eV to -4.2 eV.

[0177] The second passivation layer is located between the electron transport layer and the light-absorbing layer. When it comprises a squaric acid compound, the squaric acid compound can be used to passivate the defects of the electron transport layer (for example, when zinc oxide is used) or the defects of the light-absorbing layer. By regulating the groups of the squaric acid compound to change the LUMO energy level of the second passivation layer, the LUMO energy level of the compound in the second passivation layer is located between the LUMO energy levels of the electron transport layer and the light-absorbing layer, so as to reduce the photoelectric efficiency loss of the perovskite solar cell.

[0178] In addition, when the LUMO energy level of the compound in the second passivation layer is located between the LUMO energy levels of the electron transport layer and the light-absorbing layer, the lower the HOMO energy level of the compound in the second passivation layer, the more beneficial it is to block the holes from the light-absorbing layer, avoid carrier recombination, and is conducive to improving the long-term operation stability of the perovskite solar cell.

[0179] In some embodiments, the electron transport layer comprises a second metal oxide.

[0180] In some embodiments, the compound includes at least one of the compounds in which Z in the general formula (I) is selected from In the above embodiments, the compound exists in its ionic form.

[0181] When the electron transport layer includes a second metal oxide, the squaric acid compound in the second passivation layer can be used to passivate the defects of both the electron transport layer and the light absorption layer, having a dual passivation effect. Specifically, the squaric acid compound in the second passivation layer can passivate the perovskite defects in the light absorption layer, and can also bind to the metal of the second metal oxide in the electron transport layer to avoid the change of the metal valence state, or passivate the defects of the metal oxide whose valence state has changed, preventing the perovskite degradation caused by the metal with changed valence state, so as to improve the long-term operation stability of the perovskite solar cell.

[0182] Moreover, the existence of the squaric acid compound in its ionic form can enhance the effect of passivating the defects in the electron transport layer. For example, R” can be an acid radical, and the passivation effect of the acid radical is better.

[0183] In some embodiments, the second metal oxide includes at least one of tin dioxide, zinc oxide, titanium dioxide, barium stannate and zinc stannate.

[0184] In some embodiments, the thickness of the second passivation layer is from 0.1 nm to 100 nm. In some embodiments, the thickness of the second passivation layer is from 0.1 nm to 10 nm. The thinner the second passivation layer, the smaller the loss of the photoelectric efficiency of the perovskite solar cell.

[0185] In some embodiments, the electron transport layer includes an organic electron transport material; optionally, the organic electron transport material includes [6,6]-phenyl C 61 butyric acid methyl ester PC 61 BM, [6,6]-phenyl C 71 butyric acid methyl ester PC 71 BM and at least one of fullerenes.

[0186] This application does not particularly limit the electron transport layer material, and any conventional material used as the electron transport layer can be used. The above materials are exemplary and have good electron transport performance.

[0187] In this embodiment, when the electron transport layer includes an organic electron transport material, the squaric acid compound can also be arranged in the electron transport layer.

[0188] Next, in combination with Figure 3 and Figure 4 , the preparation method of the solar cell will be described in detail.

[0189] Referring to Figure 3 ,Figure 3 is a schematic structural diagram of a solar cell with a formal structure including a first passivation layer. As Figure 3 shown, the solar cell includes a substrate 110, an electron transport layer 120, a light absorption layer 130, a first passivation layer 160, a hole transport layer 140, and an electrode layer 150, which are stacked in sequence from bottom to top.

[0190] The preparation method of the solar cell with a formal structure including a first passivation layer mainly includes the following steps:

[0191] Step 1: Prepare a squaric acid compound or its salt;

[0192] Step 2: Etch and clean the substrate, and dry it for later use;

[0193] Step 3: Prepare an electron transport layer on the substrate;

[0194] Step 4: Prepare a light absorption layer on the electron transport layer;

[0195] Step 5: Configure a solution containing a hole transport material and set it aside for later use;

[0196] Step 6: Prepare a first passivation layer and a hole transport layer on the light absorption layer;

[0197] Step 7: Prepare an electrode layer on the hole transport layer.

[0198] Refer to Figure 4 , Figure 4 is a schematic structural diagram of a solar cell with a trans structure including a first passivation layer. As Figure 4 shown, the solar cell includes a substrate 210, a hole transport layer 220, a first passivation layer 260, a light absorption layer 230, an electron transport layer 240, and an electrode layer 250, which are stacked in sequence from bottom to top.

[0199] The preparation method of the solar cell with a trans structure including a first passivation layer mainly includes the following steps:

[0200] Step 1: Prepare a squaric acid compound or its salt;

[0201] Step 2: Etch and clean the substrate, and dry it for later use;

[0202] Step 3: Configure a solution containing a hole transport material and set it aside for later use;

[0203] Step 4: Prepare a hole transport layer on the substrate;

[0204] Step 5: Prepare a first passivation layer and a light absorption layer on the hole transport layer;

[0205] Step 6: Prepare an electron transport layer on the light absorption layer;

[0206] Step 7: Prepare an electrode layer on the electron transport layer.

[0207] In some embodiments, the substrate may be a transparent conductive glass substrate, including glass and a transparent conductive oxide, and the transparent conductive oxide includes fluorine-doped tin oxide (FTO), indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), boron-doped zinc oxide (BZO), indium zinc oxide (IZO), and the like.

[0208] In some embodiments, in Step 2, the transparent conductive glass substrate can be cleaned, for example, by ultrasonic cleaning with water, acetone, and isopropanol in sequence for, for example, 1 to 30 minutes, then dried, and further cleaned in an ultraviolet ozone machine for, for example, 1 to 20 minutes.

[0209] In some embodiments, in Step 4, a solution containing a hole transport material is coated on the substrate and then annealed to obtain a hole transport layer.

[0210] In some embodiments, in Step 4, the coating method may include, but is not limited to, sol-gel method, sputtering method, suspension method, doctor blade method, and slot-die coating method. Optionally, spin coating can be performed at a rotation speed of 1000 rpm / s to 6000 rpm / s, and further optionally, spin coating can be performed at a rotation speed of 3000 rpm / s to 5000 rpm / s.

[0211] In some embodiments, in Step 5, a squaric acid compound or its salt is dissolved in an organic solvent, and a first passivation layer or a second passivation layer is formed by spin coating, spraying, doctor blade coating, or slot-die coating, and the organic solvent can be removed by vacuum or annealing.

[0212] In some embodiments, in Step 5, a perovskite precursor solution is coated on the first passivation layer and then annealed, for example, annealed at a temperature of 80 °C to 120 °C for 20 to 40 minutes, and a perovskite light-absorbing layer is obtained after cooling.

[0213] In some embodiments, in Step 5, the perovskite precursor solution can be prepared by the following steps: dissolving at least one of perovskite precursor materials, such as formamidinium iodide, lead iodide, methylammonium bromide, methylammonium iodide, etc., in a solvent (e.g., dimethylformamide (DMF), dimethyl sulfoxide (DMSO)), stirring evenly, and filtering to obtain the perovskite precursor solution.

[0214] In some embodiments, in Step 6, an electron transport layer can be prepared by using conventional methods in the art. For example, spin coating method, evaporation method, etc.

[0215] In some embodiments, in step 7, the electrode layer can be prepared by using conventional methods in the art. For example, vapor deposition method and the like.

[0216] In some embodiments, the electrode layer includes an organic or inorganic or organic-inorganic hybrid conductive material. The materials of the electrode layer include but are not limited to Ag, Cu, C, Au, Al, ITO, AZO, BZO, and IZO, etc.

[0217] When using a salt of a squaric acid compound, the methods of the above embodiments further include cleaning (using chloroform for cleaning) after coating the layer containing the squaric acid compound salt to remove unwanted ions. The squaric acid compound in ionic form binds to corresponding defects, such as vacancies or metal elements.

[0218] The third aspect of the present application provides a power generation device, and the power generation device includes the solar cell of the second aspect of the present application. The perovskite solar cell can be used as an energy storage unit of the power generation device to store the converted solar energy into electrical energy. The power generation device has excellent long-term operation stability.

[0219] The fourth aspect of the present application provides an electrical device, and the electrical device includes the solar cell of the second aspect of the present application. The perovskite solar cell can be used as a power source of the electrical device. The electrical device has excellent long-term operation stability.

[0220] The electrical device can be applied to, for example, the communication field, the transportation field, the industrial and agricultural fields, and the lighting field, etc. The electrical device can include mobile devices, vehicles, lighting, traffic lights, lighthouses, wireless phone booths, camping lights, etc., but is not limited thereto.

[0221] Examples

[0222] Hereinafter, examples of the present application will be described. The examples described below are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application. For those not specified in the examples regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the art or according to the product specifications. For reagents or instruments not indicated with the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0223] Preparation Example 1

[0224] Add 80 ml of n-propanol / toluene (volume ratio 50 / 50) to a flask equipped with a Dean-Stark apparatus, heat to 110 °C, collect the solvent and empty it manually once, then add squaric acid (2 mmol). After stirring at 110 °C for 15 minutes, add reactant 1 (4 mmol). The solution turns dark green, and after continuing the reaction for 20 h, the mixture is dark blue-green. Cool the reaction mixture, remove the solvent by rotary evaporation to obtain the crude product. The crude product is recrystallized with acetonitrile to obtain the pure product, denoted as squaric acid compound 1. The appearance of squaric acid compound 1 is a green solid. NMR test: 1H NMR (400 MHz, Chloroform-d): δ [ppm] = 3.16 (s, 12H), 6.14 (s, 2H), 6.41 (d, 2H), 7.86 (d, 2H). The following is the chemical reaction route according to Formula 7:

[0225]

[0226] Preparation Example 2

[0227] Preparation Example 2 was prepared similarly to Preparation Example 1, except that reactant 2 was used instead of reactant 1, and squaric acid compound 2 was obtained after the reaction. NMR test: 1H NMR (400 MHz, Chloroform-d): δ [ppm] = 2.06 (s, 6H), 3.02 (s, 12H), 6.61 (d, 2H), 6.80 (s, 2H), 7.26 (d, 2H), 10.02 (s, 2H). The following respectively show reactant 2 and squaric acid compound 2:

[0228]

[0229] Preparation Example 3

[0230] Preparation Example 3 was prepared similarly to Preparation Example 1, except that reactant 3 was used instead of reactant 1, and squaric acid compound 3 was obtained after the reaction. NMR test: 1H NMR (400 MHz, Chloroform-d): δ [ppm] = 2.87 (s, 6H), 3.17 (s, 12H), 6.61 (m, 4H), 8.90 (d, 2H). The following respectively show reactant 3 and squaric acid compound 3:

[0231]

[0232] Preparation Example 4

[0233] Preparation Example 4 was prepared in the same manner as Preparation Example 1, except that Reactant 4 was used instead of Reactant 1, and Squaric Acid Compound 4 was obtained after the reaction. NMR test: 1H NMR (400 MHz, Chloroform-d): δ [ppm] = 7.51 (d, 2H), 7.69 (d, 2H), 8.41 (s, 2H). Reactant 4 and Squaric Acid Compound 4 are shown below respectively:

[0234]

[0235] Preparation Example 5

[0236] Preparation Example 5 was prepared in the same manner as Preparation Example 1, except that Reactant 5 was used instead of Reactant 1, and Squaric Acid Compound 5 was obtained after the reaction. NMR test: 1H NMR (400 MHz, Chloroform-d): δ [ppm] = 6.75 (dd, 4H), 7.17 (d, 2H). Reactant 5 and Squaric Acid Compound 5 are shown below respectively:

[0237]

[0238] Preparation Example 6

[0239] Preparation Example 6 was prepared similarly to Preparation Example 5, except that Squaric Acid Compound 5 (4 mmol) and sodium hydroxide (4.4 mmol) were reacted to form the sodium salt, which is Squaric Acid Compound 6.

[0240] Preparation Example 7

[0241] Preparation Example 7 was prepared similarly to Preparation Example 1, except that Reactant 7 was used instead of Reactant 1, and Squaric Acid Compound 7 was obtained after the reaction. NMR test: 1H NMR (400 MHz, Chloroform-d): δ [ppm] = 7.06 (s, 2H), 7.10 (d, 2H), 7.13 (d, 2H). Reactant 7 and Squaric Acid Compound 7 are shown below respectively:

[0242]

[0243] Preparation Example 8

[0244] Preparation Example 8 was prepared similarly to Preparation Example 1, except that Reactant 8 was used instead of Reactant 1, and Squaric Acid Compound 8 was obtained after the reaction. NMR test: 1H NMR (400 MHz, Chloroform-d): δ [ppm] = 3.89 (s, 6H), 7.23 (d, 2H), 7.28 (d, 2H), 7.31 (s, 2H). Reactant 8 and Squaric Acid Compound 8 are shown below respectively:

[0245]

[0246] Example 1

[0247] The perovskite solar cell was prepared by the following method:

[0248] (1) Take an FTO conductive glass with a specification of 2.0 * 2.0 cm, and remove 0.35 cm of FTO from both ends by laser etching to expose the glass substrate; successively ultrasonic clean the etched FTO conductive glass several times with water, acetone, and isopropyl alcohol; dry the solvent of the FTO conductive glass under a nitrogen gun and put it into an ultraviolet ozone machine for further cleaning;

[0249] (2) Spin - coat an aqueous solution of nickel oxide nanoparticles with a concentration of 10 mg / mL on the FTO conductive glass treated with ultraviolet ozone at a rate of 4000 rpm, and anneal it on a hot plate at 100 °C for 30 minutes to obtain a 30 - nm hole - transporting layer;

[0250] (3) Dissolve the squaric acid compound 1 prepared above in isopropyl alcohol to obtain an isopropyl alcohol solution of squaric acid compound 1; spin - coat the isopropyl alcohol solution of squaric acid compound 1 on the hole - transporting layer at 3000 rpm, and obtain a 2 - nm first passivation layer by means of vacuum pumping or annealing;

[0251] (4) Weigh lead iodide, formamidinium iodide, cesium iodide, methylammonium bromide, and lead bromide (molar ratio of 1:0.95:0.05:0.02:0.02), dissolve them in a mixed solution of DMF and DMSO, stir for 3 h, filter with a 0.22 - μm organic filter membrane to obtain a perovskite precursor solution, spin - coat the perovskite precursor solution on the obtained first passivation layer at 3000 rpm, anneal at 100 °C for 30 minutes, and cool to room temperature to obtain a 500 - nm - thick perovskite material light - absorption layer.

[0252] (5) Spin - coat a solution of the electron - transporting layer PC 61 BM on the perovskite light - absorption layer at 1500 rpm, anneal at 100 °C for 10 minutes, and then immediately spin - coat a solution of BCP at 5000 rpm to form a 20 - nm hole - blocking layer.

[0253] (6) Put the device obtained in step (5) into an evaporation machine, evaporate the metal electrode Ag with a thickness of 10 nm to obtain a solar cell.

[0254] Examples 2 to 8

[0255] The perovskite solar cell was prepared according to the method of Example 1, except that squaric acid compounds 2 to 8 were used to replace squaric acid compound 1 respectively.

[0256] Comparative Example 1

[0257] The perovskite solar cells were prepared according to the method of Example 1, except that the first passivation layer containing a squaric acid compound was not prepared.

[0258] Performance testing of perovskite solar cells

[0259] 1. Testing of photoelectric conversion efficiency

[0260] The test was carried out in accordance with the national standard IEC61215. The test was carried out under illumination. The light source was provided by a solar simulator of Guangyan. The intensity of the light was calibrated using a crystalline silicon solar cell. The light emitted by the light source conforms to the AM 1.5 standard solar spectrum. The battery was connected to a digital source meter, and its photoelectric conversion efficiency was measured under illumination. The photoelectric conversion efficiencies on the 3rd day and the 30th day were selected as the short-term efficiency and long-term efficiency of the solar cell, respectively.

[0261] The perovskite solar cells obtained in Examples 1 to 8 and Comparative Example 1 above were tested respectively according to the above process. The specific values can be referred to Table 1.

[0262] Table 1

[0263] Efficiency on the 3rd day Efficiency on the 30th day Example 1 21.25％ 19.67％ Example 2 21.03％ 19.06％ Example 3 21.75％ 19.37％ Example 4 21.31％ 19.61％ Example 5 22.63％ 20.82％ Example 6 22.67％ 20.07％ Example 7 21.88％ 19.18％ Example 8 21.91％ 19.90％ Comparative Example 1 18.86％ 15.14％

[0264] The perovskite solar cells provided in Examples 1 to 8 all include a first passivation layer containing a squaric acid compound, and the perovskite solar cell provided in Comparative Example 1 does not include the first passivation layer. As shown in Table 1, the photoelectric conversion efficiencies (including the photoelectric conversion efficiencies on the 3rd day and the 30th day) of the perovskite solar cells provided in Examples 1 to 8 are all higher than those of the perovskite solar cell provided in Comparative Example 1. Therefore, the first passivation layer in the perovskite solar cell provided in the present application can passivate the defects in the perovskite solar cell to improve the long-term operation stability of the perovskite solar cell.

[0265] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples. Embodiments having the same constitution and the same effect as the technical idea within the technical solution scope of the present application are all included in the technical scope of the present application. In addition, within the scope not departing from the gist of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other ways constructed by combining some constituent elements of the embodiments are also included in the scope of the present application.

Claims

1. A squaric acid compound or a salt thereof, wherein the compound is represented by the following general formula (I): in, Z is: or a substituted or unsubstituted five-membered or six-membered heteroaryl group containing at least one heteroatom, Wherein, the heteroatoms include O, S and N; the substituents of the heteroaryl group include -OH, carboxyl, -CONR2, -CHO, halogen, -NH2 and -CN; R' each independently includes -NH2, -NHR, -NHC(O)R, -OH, -SH and C1-C4 alkyl; R" independently includes phosphate, sulfonate, borate, -Si(OR)3, -NR2, -NR3 + , -CONR2, -COOR and halogen, wherein R each independently includes H and C1~C4 alkyl; when R" includes multiple R, the multiple R are the same or different.

2. The squaric acid compound or its salt according to claim 1, characterized in that R" independently includes a phosphoric acid group, a sulfonic acid group, a boric acid group and a carboxyl group.

3. The squaric acid compound or salt thereof according to claim 1 or 2, characterized in that The C1-C4 alkyl group includes a methyl group and an ethyl group.

4. The squaric acid compound or its salt according to claim 1, characterized in that The heteroaryl groups include: X represents O, S or N; R'' each independently includes -OH.

5. The squaric acid compound or salt thereof according to any one of claims 1 to 3, characterized in that Such salts include alkali metal salts and ammonium salts.

6. The squaric acid compound or its salt according to claim 1, characterized in that The compounds include:

7. A solar cell comprising an electron transport layer, a light absorbing layer and a hole transport layer stacked in sequence, wherein the light absorbing layer comprises a perovskite material, characterized in that: The solar cell further comprises at least one of the squaraine compounds and salts thereof according to any one of claims 1 to 6, wherein the compound exists in its own form and / or in its ionic form.

8. The solar cell according to claim 7, characterized in that The compound is contained in at least one of the electron transport layer, the light absorbing layer and the hole transport layer; Alternatively, the solar cell further comprises a first passivation layer comprising the compound located between the hole transport layer and the light absorbing layer, and / or a second passivation layer comprising the compound located between the electron transport layer and the light absorbing layer.

9. The solar cell according to claim 7 or 8, characterized in that The perovskite material is represented by the general formula (P): ABX3 general formula (P); Wherein, A is the first cation, B is the second cation, and X is the anion; Wherein, the general formula (P) satisfies at least one of the following: A includes MA + , FA + 、Cs + , K + , Rb + He Li + At least one of; B includes Pb 2+ 、Sn 2+ 、Fe 2+ 、Mn 2+ 、Ni 2+ 、Ge 2+ 、Co 2+ and Sb 2+ At least one of; X includes Br - , I - 、Cl - and F - At least one of .

10. The solar cell according to claim 7 or 8, characterized in that The perovskite material is represented by the general formula (Q): A2CDX6 general formula (Q); Wherein, A is the first cation, C is the third cation, D is the fourth cation, and X is an anion; Wherein, the general formula (Q) satisfies at least one of the following: A includes MA + , FA + 、Cs + , K + , Rb + He Li + At least one of; C includes Ag + 、Cs + , K + and Ru + At least one of; D includes Bi 3+ 、Sb 3+ 、In 3+ 、Ni 3+ 、Fe 3+ and Cu 3+ At least one of; X includes Br - , I - 、Cl - and F - At least one of .

11. The solar cell according to claim 9 or 10, characterized in that The compound is included in the light absorbing layer in an amount of 0.1 mol % to 10 mol % relative to the perovskite material.

12. The solar cell according to any one of claims 8 to 10, characterized in that The solar cell includes the first passivation layer including the compound, wherein the HOMO energy level of the compound is in a range of −5.0 eV to −5.8 eV.

13. The solar cell according to claim 12, wherein: The hole transport layer includes a first metal oxide.

14. The solar cell according to claim 13, characterized in that The compound includes the general formula (I) wherein Z is selected from at least one of the compounds.

15. The solar cell according to claim 13 or 14, characterized in that: The first metal oxide includes at least one of nickel oxide, copper oxide, cuprous chromite, lithium copper nickel oxide, and nickel magnesium lithium oxide.

16. The solar cell according to any one of claims 12 to 15, characterized in that The thickness of the first passivation layer is 0.1 nm to 50 nm.

17. The solar cell according to any one of claims 12 to 16, characterized in that The thickness of the first passivation layer is 0.1 nm to 10 nm.

18. The solar cell according to any one of claims 7 to 12, characterized in that The hole transport layer includes an organic hole transport material.

19. The solar cell according to any one of claims 8 to 10, characterized in that The solar cell includes a second passivation layer containing the compound, wherein the LUMO energy level of the compound is in a range of -3.6 eV to -4.4 eV.

20. The solar cell according to claim 19, characterized in that The electron transport layer includes a second metal oxide.

21. The solar cell according to claim 20, characterized in that The compound includes the general formula (I) wherein Z is selected from at least one of the compounds.

22. The solar cell according to claim 20 or 21, characterized in that The second metal oxide includes at least one of tin dioxide, zinc oxide, titanium dioxide, barium stannate and zinc stannate.

23. The solar cell according to any one of claims 19 to 22, characterized in that The thickness of the second passivation layer is 0.1 nm to 100 nm.

24. The solar cell according to any one of claims 19 to 23, characterized in that The thickness of the second passivation layer is 0.1 nm to 10 nm.

25. The solar cell according to any one of claims 7 to 12, characterized in that The electron transport layer includes an organic electron transport material.

26. A power generation device, characterized in that: The power generation device includes the solar cell according to any one of claims 7 to 25.

27. An electrical device, characterized in that: The electric device includes the solar cell according to any one of claims 7 to 25.

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