Perovskite material and preparation method thereof, photoelectric device and power utilization device

Abstract

The invention discloses a perovskite material and a preparation method thereof, a photoelectric device and an electric device. The perovskite material provided by the invention comprises a perovskite crystal and a hindered Lewis acid-base pair combined with the perovskite crystal, the hindered Lewis acid-base pair comprises Lewis acid and Lewis base, the Lewis acid comprises a three-coordinate boron compound, and the Lewis base comprises at least one of a three-coordinate nitrogen compound and a three-coordinate phosphorus compound. The perovskite material has Lewis acid and Lewis base at the same time based on the hindered Lewis acid-base pair, so that the hindered Lewis acid-base pair can be used for passivating two defects of a perovskite crystal boundary, namely anions with insufficient coordination and cations with insufficient coordination, and the perovskite material has good conversion efficiency and stability.

Description

Technical Field

[0001] The present application belongs to the field of perovskite technology, and specifically relates to a perovskite material and a preparation method thereof, a photoelectric device and an electrical device. Background Art

[0002] Perovskite materials are a type of semiconductor materials with uniform size and high color purity. Their elemental composition has a crystal structure similar to that of the mineral CaTiO3. Perovskite materials have strong light absorption capacity and a wide absorption range, and have great advantages in the field of optoelectronics. For example, perovskite solar cells (PSCs) with organic-inorganic hybrid perovskite materials as light-absorbing layers are developing rapidly.

[0003] In an ideal perovskite crystal structure, each atom has its own corresponding position, but actual perovskites are prone to surface defects due to the influence of crystal growth and post-processing. The grain boundary defect states formed in perovskite crystals easily lead to non-radiative recombination of carriers, thus affecting its photoelectric conversion efficiency. Summary of the invention

[0004] In view of the above problems, the present application provides a perovskite material and a preparation method thereof, a photoelectric device and an electrical device, aiming to solve the technical problem of how to reduce perovskite grain boundary defects.

[0005] In a first aspect, an embodiment of the present application provides a perovskite material, comprising a perovskite crystal and a hindered Lewis acid-base pair combined with the perovskite crystal, wherein the hindered Lewis acid-base pair comprises a Lewis acid and a Lewis base, wherein the Lewis acid comprises a tricoordinate boron compound, and the Lewis base comprises at least one of a tricoordinate nitrogen compound and a tricoordinate phosphorus compound.

[0006] The hindered Lewis acid-base pair (Frustrated Lewis Pair, FLP) includes both Lewis acid (Lewis Acid, LA) and Lewis base (Lewis Base, LB), specifically, the Lewis acid includes a tricoordinated boron compound, and the Lewis base includes at least one of a tricoordinated nitrogen compound and a tricoordinated phosphorus compound. In this way, the hindered Lewis acid-base pair can be used to passivate two defects of the perovskite crystal boundary, namely, insufficiently coordinated anions and insufficiently coordinated cations. On the one hand, the Lewis acid in the hindered Lewis acid-base pair can receive electrons from anions at the edge of the perovskite crystal to passivate the insufficiently coordinated anions of the perovskite crystal. On the other hand, the lone electron pair of the Lewis base in the hindered Lewis acid-base pair can be provided to the insufficiently coordinated cations to passivate the anion vacancy defects of the perovskite crystal. Therefore, the embodiment of the present application can better passivate the surface defects of the perovskite crystal, thereby improving the conversion efficiency and stability of the perovskite.

[0007] In some embodiments, the Lewis acid binds to a monovalent anion that is under-coordinated to the perovskite crystal, and the Lewis base binds to a divalent cation that is under-coordinated to the perovskite crystal.

[0008] In this way, the hindered Lewis acid-base pairs can be used to passivate the monovalent anions and divalent cations that are insufficiently coordinated at the perovskite grain boundaries.

[0009] In some embodiments, the chemical formula of the tricoordinate boron compound includes BR3; wherein R includes at least one of an aryl group and a substituted aryl group, and the substituent group in the substituted aryl group includes halogen and C 1-6 At least one of the alkyl groups.

[0010] The tri-coordinated boron compound BR3, as a Lewis acid of a hindered Lewis acid-base pair, can receive electrons from anions at the edge of the perovskite crystal to passivate anions that are insufficiently coordinated in the perovskite crystal.

[0011] In some embodiments, R comprises at least one of a perhalo-substituted phenyl group and a mesityl group.

[0012] The tri-coordinated boron compound BR3 formed by fully halogenated phenyl and mesitylene can not only better accept lone electron pairs, but also has large steric hindrance, and has a better passivation effect on anions that are insufficiently coordinated in perovskite crystals.

[0013] In some embodiments, the chemical formula of the tri-coordinate nitrogen compound includes NR'3; wherein R' includes at least one of an alkyl group and an aryl group;

[0014] The general chemical formula of the tricoordinate phosphorus compound includes PR"3; wherein R" includes at least one of an alkyl group and an aryl group.

[0015] The above-mentioned tricoordinate nitrogen compound and tricoordinate phosphorus compound, as Lewis bases of hindered Lewis acid-base pairs, can provide lone pair electrons to insufficiently coordinated cations to passivate anion vacancy defects in perovskite crystals.

[0016] In some embodiments, the alkyl group in R' comprises C 3-6 The aryl group in R' includes phenyl.

[0017] C 3-6 The tricoordinate nitrogen compounds formed by the cycloalkyl or phenyl groups serve as the Lewis base of the hindered Lewis acid-base pair, which can not only better provide lone electron pairs, but also have large steric hindrance and better passivation effect on the anion vacancy defects in the perovskite crystal.

[0018] In some embodiments, the alkyl group in R" includes C 3-6 The aryl group in R" includes phenyl.

[0019] C 3-6The tricoordinated phosphorus compound formed by the cycloalkyl or phenyl group serves as the Lewis base of the hindered Lewis acid-base pair, which can not only better provide lone electron pairs, but also has large steric hindrance and better passivation effect on the anion vacancy defects in the perovskite crystal.

[0020] In some embodiments, the molar ratio of the perovskite crystals to the Lewis acid and Lewis base is 1:(0.0001-0.02):(0.0001-0.02).

[0021] The hindered Lewis acid-base pairs in the above ratio can fully passivate the surface defects of the perovskite crystal and significantly improve the conversion efficiency and stability of the perovskite.

[0022] In a second aspect, the present embodiment provides a method for preparing the perovskite material provided in the first aspect of the present embodiment, comprising:

[0023] preparing a perovskite precursor solution;

[0024] The hindered Lewis acid-base pair is added to the perovskite precursor solution, and then annealing is performed to obtain the perovskite material.

[0025] A hindered Lewis acid-base pair is added to the prepared perovskite precursor solution. During the perovskite crystallization process after annealing, on the one hand, the hindered Lewis acid-base pair slows down the crystallization process of the perovskite, thereby increasing the grain size of the perovskite. On the other hand, the Lewis acid and Lewis base in the hindered Lewis acid-base pair have a passivation effect at the perovskite grain boundary, passivating under-coordinated anions and under-coordinated cations, respectively, thereby reducing the defect density of the perovskite layer and further improving the conversion efficiency and stability of the perovskite.

[0026] In a third aspect, an embodiment of the present application provides a photoelectric device, comprising a perovskite layer, wherein the perovskite layer comprises the perovskite material provided in the first aspect of the embodiment of the present application and / or the perovskite material prepared by the preparation method provided in the second aspect of the embodiment of the present application.

[0027] Because the perovskite layer of the optoelectronic device provided in the embodiment of the present application includes a unique perovskite material, there are few grain boundary defects in such a perovskite layer, so that the optoelectronic device has good photoelectric conversion efficiency and stability.

[0028] In one embodiment, the optoelectronic device comprises a solar cell.

[0029] The solar cell uses the perovskite material unique to the embodiment of the present application, which can better convert light energy into electrical energy, so that the solar cell has good photoelectric conversion efficiency and stability.

[0030] In a fourth aspect, an embodiment of the present application provides an electrical device, comprising the optoelectronic device provided in the third aspect of the embodiment of the present application.

[0031] By adopting the optoelectronic device provided in the third aspect of the embodiment of the present application, such an electrical device has high photoelectric conversion efficiency and good stability, and can work better.

[0032] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0034] Figure 1 is a schematic diagram comparing the perovskite of an embodiment of the present application before and after being passivated by a hindered Lewis acid-base pair;

[0035] Figure 2 is a schematic flow chart of a method for preparing a perovskite material according to an embodiment of the present application;

[0036] Figure 3 is a schematic structural diagram of a solar cell according to an embodiment of the present application;

[0037] Description of reference numerals:

[0038] 1-first electrode; 2-hole transport layer; 3-perovskite layer; 4-electron transport layer; 5-second electrode. DETAILED DESCRIPTION

[0039] The following embodiments of the technical solution of the present application will be described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0041] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0042] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0043] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0044] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), and similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces). "At least one" refers to more than one (including one, two, three, etc.).

[0045] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0046] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0047] As traditional energy resources are increasingly scarce, the development of new energy sources has received increasing attention. Due to the new demand for green energy in modern society, optoelectronic devices such as solar cells that convert light energy into electrical energy through the photoelectric effect have developed rapidly. At present, solar cells have developed to the third generation, namely perovskite solar cells (PSCs). Perovskite solar cells have the advantages of high photoelectric conversion efficiency and low power generation cost, and have the potential to be integrated with buildings. They are expected to become a substitute for curtain wall decoration of high-rise buildings, thereby achieving lighting and power generation at the same time.

[0048] Perovskite solar cells are solar cells that use perovskite-type organic metal halide semiconductors as light-absorbing materials. Perovskite, as a synthetic material, has become popular since it was applied to the field of photovoltaic power generation due to its excellent performance, low cost and huge commercial value. The quality of the perovskite layer, as the light-absorbing layer in perovskite solar cells, directly affects the conversion efficiency and stability of the device.

[0049] Perovskite is susceptible to surface defects due to the influence of crystal growth and its post-processing. For example, there are two main defects formed at the perovskite grain boundary: (1) insufficient coordination of cations such as divalent cations due to iodide vacancies; (2) insufficient coordination of anions such as halide ions due to cation vacancies resulting in uncoordinated anions at the boundary. The surface defect states formed in perovskite crystals easily lead to non-radiative recombination of carriers, thus affecting its photoelectric conversion efficiency. Currently, perovskite surface defects can be passivated by molecular modification, but generally they are modified with molecules with a single property, such as Lewis base molecules. For example, there are reports of modifying perovskite with 1-benzyl-3-hydroxypyridinium chloride (1B3HPC). 1B3HPC, as a Lewis base, can passivate the low-coordinated divalent cations (such as Pb) on the perovskite surface as Lewis acids. 2+ ), generating Lewis adducts, but they cannot passivate under-coordinated halide ions, thus improving the performance of solar cells to a limited extent.

[0050] Based on the above considerations, in order to simultaneously overcome the various defects of current perovskites, the embodiments of the present application are designed to add a hindered Lewis acid-base pair including a Lewis acid and a Lewis base to the perovskite material, so that the above two types of defects of the perovskite can be passivated at the same time, thereby further improving the performance of the perovskite. Therefore, the following technical solution is proposed.

[0051] Perovskite materials

[0052] In a first aspect, an embodiment of the present application provides a perovskite material, comprising: (1) a perovskite crystal, and (2) a hindered Lewis acid-base pair. The hindered Lewis acid-base pair is combined with the perovskite crystal, and the hindered Lewis acid-base pair comprises a Lewis acid and a Lewis base, wherein the Lewis acid comprises a tricoordinate boron compound, and the Lewis base comprises at least one of a tricoordinate nitrogen compound and a tricoordinate phosphorus compound.

[0053] According to the Lewis acids and bases theory, also known as the acid-base electronic theory: any substance (molecule, ion or atom group) that can accept an electron pair is called a Lewis acid (LA), and any substance (molecule, ion or atom group) that can donate an electron pair is called a Lewis base (LB). Lewis acids are electron pair acceptors, and Lewis bases are electron pair donors. A hindered Lewis acid-base pair (FLP) is a pair of compound molecules in which both a Lewis acid center and a Lewis base center exist. However, due to the large steric hindrance of the side groups, these two centers cannot contact each other (conformation or steric hindrance). The resulting pair of compounds is called a hindered Lewis acid-base pair.

[0054] In the perovskite material provided in the embodiment of the present application, the hindered Lewis acid-base pair used has both a Lewis acid and a Lewis base. Specifically, the Lewis acid includes a tricoordinated boron compound, and the Lewis base includes at least one of a tricoordinated nitrogen compound and a tricoordinated phosphorus compound. The tricoordinated nitrogen compound or the tricoordinated phosphorus compound can give an electron pair, and the tricoordinated boron compound as a Lewis acid can accept an electron pair. Therefore, the embodiment of the present application is based on the fact that the hindered Lewis acid-base pair can be used to passivate two defects at the perovskite grain boundary, namely, insufficiently coordinated anions and insufficiently coordinated cations. Specifically: (1) the tricoordinated boron compound as a Lewis acid can receive electrons from anions at the edge of the perovskite crystal to passivate the insufficiently coordinated anions of the perovskite crystal, (2) the tricoordinated nitrogen compound or the tricoordinated phosphorus compound as a Lewis base, and its lone electron pair can be provided to the insufficiently coordinated cations to passivate the anion vacancy defects of the perovskite crystal. Therefore, the embodiment of the present application can better passivate the surface defects of the perovskite crystal, thereby improving the conversion efficiency and stability of the perovskite.

[0055] In some embodiments, the perovskite chemical formula of the present application embodiment can be ABX3; wherein A is a monovalent cation, which can be an organic cation or an inorganic cation, and can specifically include CH3NH3 + 、CH(NH2)2 + , Cs + At least one of; B is a divalent cation, which may specifically include Pb 2+ Sn 2+ At least one of; X is a monovalent anion, which may specifically include Cl- Br - and I - At least one of .

[0056] In some embodiments, the Lewis acid in the hindered Lewis acid-base pair binds to the monovalent anions that are insufficiently coordinated to the perovskite crystal, and the Lewis base in the hindered Lewis acid-base pair binds to the divalent cations that are insufficiently coordinated to the perovskite crystal. In this way, the hindered Lewis acid-base pair can be used to passivate the monovalent anions and divalent cations that are insufficiently coordinated to the perovskite grain boundary.

[0057] In some embodiments, the divalent cation in the perovskite is Pb 2+ , monovalent anion is I - For example. Figure 1 As shown, before adding the hindered Lewis acid-base pair ( Figure 1 In a), there are two defects in the perovskite grain boundary: insufficiently coordinated iodine ions (i.e., lead ion vacancies) and insufficiently coordinated lead ions (i.e., iodide vacancies). After using hindered Lewis acid-base pairs in perovskite ( Figure 1 In b), the Lewis acid LA of the hindered Lewis acid-base pair can combine with the under-coordinated iodine ions and passivate the under-coordinated iodine ions in the perovskite crystal by receiving electrons from the iodine ions at the edge of the perovskite crystal; the Lewis base LB of the hindered Lewis acid-base pair can combine with the under-coordinated lead ions and provide lone electron pairs to the bound lead ions to passivate the iodine ion vacancy defects in the perovskite crystal.

[0058] The hindered Lewis acid-base pair provided in the embodiments of the present application is based on the fact that the tricoordinated boron compound and the tricoordinated nitrogen compound or the tricoordinated phosphorus compound have high steric hindrance. Therefore, the Lewis acid and the Lewis base in the hindered Lewis acid-base pair FLP are not easy to combine with each other, and tend to combine with the defects on the surface of the perovskite to form adducts, which can passivate the two grain boundary defects of the perovskite well and improve the conversion efficiency and stability of the perovskite material.

[0059] In some embodiments, the chemical formula of the tricoordinate boron compound includes BR3; wherein R includes at least one of an aryl group and a substituted aryl group, and the substituent group in the substituted aryl group includes halogen and C 1-5 At least one of the alkyl groups.

[0060] The tri-coordinate boron compound BR3, in which boron (B) has three valence electrons, forms a tri-coordinate boron compound with three R groups. The tri-coordinate boron compound as Lewis acid has an empty orbital that can accept electrons, is an electron-deficient body, and has good electron-accepting properties. R includes substituted aromatic groups, which have large steric hindrance and are less likely to combine with Lewis bases, so they can combine with defects on the surface of perovskite.

[0061] R in the tricoordinate boron compound BR3 includes at least one of an aryl group and a substituted aryl group. The aryl group refers to a cyclic aromatic hydrocarbon, including but not limited to phenyl, naphthyl and other similar groups, and the substituted aryl group refers to a substituted aryl group formed by substitution on the above cyclic aromatic hydrocarbon. The substituent group in the substituted aryl group includes halogen and C 1-6 At least one of the alkyl groups. Halogen can be fluorine, chlorine, bromine, iodine, etc. 1-6 The alkyl group may be an alkyl group having 1 to 6 carbon atoms, specifically a branched alkyl group, a branched alkyl group or a cycloalkyl group. The number of the substituent groups may be one or more, and may be ortho-, meta- or para-substituted on the aromatic group. The above-mentioned tri-coordinated boron compound BR3, as a Lewis acid of a hindered Lewis acid-base pair, can receive electrons from anions at the edge of the perovskite crystal to passivate anions that are insufficiently coordinated to the perovskite crystal.

[0062] In some embodiments, R in the tri-coordinate boron compound BR3 includes at least one of a perhalogen-substituted phenyl group and a mesitylene group. For example, the perhalogen-substituted phenyl group may be a pentafluorophenyl group (-C6F5), and the corresponding tri-coordinate boron compound BR3 is (C6F5)3B, and the tri-coordinate boron compound BR3 corresponding to mesitylene (-Mes) is Mes3B. The tri-coordinate boron compound BR3 formed by a perhalogen-substituted phenyl group or a mesitylene group can better accept lone electron pairs, and at the same time, it has a large steric hindrance, and has a better passivation effect on anions that are insufficiently coordinated to the perovskite crystal.

[0063] In some embodiments, the tricoordinate nitrogen compound has a general chemical formula comprising NR'3; wherein R' comprises at least one of an alkyl group and an aryl group.

[0064] The tri-coordinate nitrogen compound NR'3, in which nitrogen (N) forms a tri-coordinate nitrogen compound with three R' groups. The tri-coordinate nitrogen compound as Lewis base has a lone pair of electrons in the nitrogen atom, which can provide electrons. R' includes at least one of an alkyl group and an aryl group, which has a large steric hindrance and is less likely to combine with Lewis acidity, so it can combine with defects on the surface of the perovskite.

[0065] In the tri-coordinate nitrogen compound NR'3, R' includes at least one of an alkyl group and an aryl group. The alkyl group refers to a straight chain or a saturated fatty chain with a branch or a ring chain, including but not limited to methyl (-Me), ethyl (-Et), propyl such as isopropyl (-iPr), butyl such as tert-butyl (tBu), pentyl such as isopentyl, hexyl, cyclohexyl (-Cy) and other similar groups, for example, including but not limited to alkyl groups with 1 to 6 carbon atoms; aryl refers to a cyclic aromatic hydrocarbon, including but not limited to phenyl (-Ph), naphthyl and other similar groups. The above tri-coordinate nitrogen compound NR'3, as a Lewis base of a hindered Lewis acid-base pair, can provide electrons to insufficiently coordinated cations to passivate anion vacancy defects in perovskite crystals.

[0066] In some embodiments, the alkyl group in R' of the tricoordinate nitrogen compound NR'3 comprises C 3-6 The aryl group in R' includes phenyl. 3-6 The cycloalkyl group has 3 to 6 carbon atoms. 3-6 The tri-coordinated nitrogen compound formed by the cycloalkyl or phenyl group serves as the Lewis base of the hindered Lewis acid-base pair, which can not only better provide lone electron pairs, but also has large steric hindrance, and has a better passivation effect on the insufficiently coordinated cations caused by the anion vacancy defects in the perovskite crystal.

[0067] In some embodiments, the tricoordinate phosphorus compound has a general chemical formula comprising PR"3; wherein R" comprises at least one of an alkyl group and an aryl group.

[0068] The tricoordinate phosphorus compound PR"3, wherein phosphorus (P) forms a tricoordinate phosphorus compound with three R" groups. The tricoordinate phosphorus compound as a Lewis base has a lone pair of electrons in the phosphorus atom, which can provide electrons. R" includes at least one of an alkyl group and an aryl group, which has a large steric hindrance and is less likely to combine with Lewis acidity, thereby being able to combine with defects on the surface of the perovskite.

[0069] In the tri-coordinate phosphorus compound PR"3, R" includes at least one of an alkyl group and an aryl group. The alkyl group refers to a straight chain or a branched or cyclic saturated fatty chain, including but not limited to methyl (-Me), ethyl (-Et), propyl such as isopropyl (-iPr), butyl such as tert-butyl (tBu), pentyl such as isopentyl, hexyl, cyclohexyl (-Cy) and other similar groups, for example, including but not limited to alkyl groups with 1 to 6 carbon atoms, for example, including but not limited to alkyl groups with 1 to 6 carbon atoms; aryl refers to a cyclic aromatic hydrocarbon, including but not limited to phenyl, naphthyl and other similar groups. The above-mentioned tri-coordinate phosphorus compound NR"3, as a Lewis base of a hindered Lewis acid-base pair, can provide electrons to under-coordinated cations to passivate anion vacancy defects in perovskite crystals.

[0070] In some embodiments, the alkyl group in R' of the tricoordinate phosphorus compound NR"3 comprises C 3-6 The aryl group in R' includes phenyl. 3-6 The cycloalkyl group has 3 to 6 carbon atoms. 3-6 The tricoordinated phosphorus compound formed by the cycloalkyl or phenyl group serves as the Lewis base of the hindered Lewis acid-base pair, which can not only better provide lone electron pairs, but also has large steric hindrance, and has a better passivation effect on the insufficiently coordinated cations caused by the anion vacancy defects in the perovskite crystal.

[0071] Furthermore, the Lewis base includes a tri-coordinate phosphorus compound, the phosphorus atom radius of the tri-coordinate phosphorus compound is larger than the nitrogen atom radius, and its n=3 electrons are more easily donated to electron acceptors (such as naked lead ions), so the passivation effect is better.

[0072] Specifically, the tricoordinate nitrogen compound of the Lewis acid may include (C6F5)3B, i.e. tri(pentafluorophenyl)borane, Mes3B, i.e. tri(2,4,6-trimethylphenyl)borane, the tricoordinate phosphorus compound of the Lewis base may include tBu3P, i.e. tri-tert-butylphosphine, iPr3P, i.e. triisopropylphosphine, Cy3P, i.e. tricyclohexylphosphane, Ph3P, i.e. triphenylphosphine, and the tricoordinate nitrogen compound of the Lewis acid may include tBu3N, i.e. tri-tert-butylamine, iPr3N, i.e. triisopropylamine, Cy3N, i.e. tricyclohexylamine, and Ph3N, i.e. triphenylamine. Specifically, the Lewis base of the hindered Lewis acid-base pair is Ph3P, and the Lewis acid of the hindered Lewis acid-base pair is (C6F5)3B as an example, in Lewis acid-base Ph3P, the phenyl space steric hindrance is the most moderate, and the π electron cloud on benzene can supply electrons to P, so that the Lewis base has more electron-donating ability, and then further improves the photoelectric conversion efficiency. In Lewis acid (C6F5)3B, -C6F5 is a better electron-withdrawing group, making B a better Lewis acid. And compared with the large organic groups of these charges diffused to the whole molecule, the divalent cations and anions in perovskite are relatively small, and the charge density is higher. The Lewis acid and Lewis base of the hindered Lewis acid-base pair are not easy to combine with each other, and tend to be combined with the defects on the surface of perovskite, so that the two defects of perovskite grain boundary, i.e., the under-coordinated anions and under-coordinated cations, can be passivated, and based on the organic hydrophobicity of the hindered Lewis acid-base pair itself, the moisture resistance of perovskite can be improved, so as to significantly improve the conversion efficiency of perovskite.

[0073] In some embodiments, the molar ratio of the perovskite crystal to the Lewis acid and Lewis base is 1:(0.0001-0.02):(0.0001-0.02). Since the Lewis acid and Lewis base of the hindered Lewis acid-base pair are used in conjunction with each other, the molar amount of the Lewis acid or Lewis base in the hindered Lewis acid-base pair can be adjusted according to the specific proportion of defect state types. If the perovskite crystal has more monovalent anions that are insufficiently coordinated, the proportion of the Lewis acid in the hindered Lewis acid-base pair can be appropriately increased. If the perovskite crystal has more divalent cations that are insufficiently coordinated, the proportion of the Lewis base in the hindered Lewis acid-base pair can be appropriately increased. In this way, the hindered Lewis acid-base pair can be used to fully passivate the monovalent anions and divalent cations that are insufficiently coordinated at the perovskite grain boundary. The Lewis acid and Lewis base of the hindered Lewis acid-base pair are used in conjunction with each other, and generally can be used in combination in an equimolar ratio.

[0074] For example, the molar ratio of the perovskite crystal ABX3 to the Lewis acid and Lewis base can be 1:0.0001:0.0001, 1:0.0002:0.0002, 1:0.0005:0.0005, 1:0.0006:0.0006, 1:0.0008:0.0008, 1:0.001:0.001, 1:0.01:0.01, 1:0.015:0.015, 1:0.021:0.02, etc. The hindered Lewis acid and base in the above ratio can fully passivate the surface defects of the perovskite crystal and significantly improve the conversion efficiency and stability of the perovskite.

[0075] Preparation method of perovskite material

[0076] In a second aspect, the present application embodiment provides a method for preparing the perovskite material provided in the first aspect of the present application embodiment, such as Figure 2 As shown, the following steps are included:

[0077] S01: prepare perovskite precursor solution;

[0078] S02: Adding a hindered Lewis acid-base pair to a perovskite precursor solution, and then annealing to obtain a perovskite material.

[0079] A hindered Lewis acid-base pair is added to the prepared perovskite precursor solution. During the perovskite crystallization process after annealing, on the one hand, the hindered Lewis acid-base pair slows down the crystallization process of the perovskite, thereby increasing the grain size of the perovskite. On the other hand, the Lewis acid and Lewis base in the hindered Lewis acid-base pair have a passivation effect at the perovskite grain boundary, passivating under-coordinated anions and under-coordinated cations, respectively, thereby reducing the defect density of the perovskite layer and further improving the conversion efficiency and stability of the perovskite.

[0080] In one embodiment, the hindered Lewis acid-base pair can be added separately as an additive to the perovskite precursor solvent, and then annealed and crystallized to obtain a perovskite material passivated by the hindered Lewis acid-base pair. Specifically, a perovskite precursor solution of perovskite ABX3 can be prepared first, and then the hindered Lewis acid-base pair is added and stirred evenly, annealed at 80-100°C for 20-40 minutes, and then cooled to room temperature to obtain a perovskite layer, that is, a perovskite material in the form of a film layer. During the annealing and crystallization process, on the one hand, the hindered Lewis acid-base pair slows down the crystallization process of the perovskite, thereby increasing the grain size of the perovskite. On the other hand, the hindered Lewis acid-base pair with Lewis acid and Lewis base has a passivation effect on the perovskite grain boundary, thereby reducing the defect density of the perovskite layer, thereby improving the conversion efficiency and stability of the perovskite.

[0081] In the above process, the amount of Lewis acid and Lewis base in the hindered Lewis acid-base pair added to the perovskite precursor solution can be 0.01 mol% to 2 mol% (the molar ratio of Lewis acid or Lewis base to perovskite ABX3); such an amount of hindered Lewis acid-base pair added can passivate the perovskite crystals well. Properly increasing the amount within the above range will have a better passivation effect.

[0082] Optoelectronic devices

[0083] In a third aspect, an embodiment of the present application provides a photoelectric device, comprising a perovskite layer, wherein the perovskite layer comprises the perovskite material provided in the first aspect of the embodiment of the present application and / or the perovskite material prepared by the preparation method provided in the second aspect of the embodiment of the present application.

[0084] Because the perovskite layer of the optoelectronic device provided in the embodiment of the present application includes a unique perovskite material, there are few grain boundary defects in such a perovskite layer, so that the optoelectronic device has good photoelectric conversion efficiency and stability.

[0085] In one embodiment, the optoelectronic device includes a solar cell. The solar cell uses the perovskite material unique to the embodiment of the present application, which can better convert light energy into electrical energy, so that the solar cell has good photoelectric conversion efficiency and stability.

[0086] In one embodiment, the optoelectronic device includes a stacked first electrode, a hole transport layer, a perovskite layer, an electron transport layer, and a second electrode. The optoelectronic device with this structure is conducive to the transport of holes and electrons in the device, and can improve the carrier transport performance of the device. At the same time, the amphiphilic molecules in the perovskite layer can be well matched with the material of the electron transport layer, which is conducive to the current extraction of the optoelectronic device, thereby further improving the photoelectric conversion efficiency.

[0087] In some embodiments, Figure 3As shown, the optoelectronic device includes a stacked first electrode 1, a hole transport layer 2, a perovskite layer 3, an electron transport layer 4, and a second electrode 5; wherein the perovskite layer 3 contains the perovskite material of the embodiment of the present application, and the perovskite crystal surface is modified and passivated with a hindered Lewis acid-base pair. The perovskite material has a large grain size and a low defect state density, so that the device has good photoelectric conversion efficiency and stability. At the same time, the optoelectronic device of this structure is conducive to the transmission of holes and electrons in the device, which can improve the carrier transport performance of the device, thereby further improving the photoelectric conversion efficiency.

[0088] In some embodiments, the first electrode 1 can be a transparent conductive substrate, including but not limited to the following materials: fluorine-doped tin oxide (FTO), indium-doped tin oxide (ITO), aluminum-doped zinc oxide (AZO), boron-doped zinc oxide (BZO), indium-doped zinc oxide (IZO), etc.

[0089] In some embodiments, the hole transport layer 2 can be at least one of the following materials and their derivatives and materials obtained by doping or passivation: poly [bis (4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA), poly-3-hexylthiophene (P3HT), triphenylamine with triptycene as the core (H101), 3,4-ethylenedioxythiophene-methoxytriphenylamine (EDOT-OMeTPA), N- (4-aniline) carbazole-spirobifluorene (CzPAF-SBF), poly (3,4-ethylenedioxythiophene): poly (styrene sulfone) (PEDOT:PSS), polythiophene, nickel oxide (NiO x ), molybdenum oxide (MoO3), cuprous iodide (CuI), cuprous oxide (CuO), etc.

[0090] In some embodiments, the electron transport layer 4 can be at least one of the following materials and their derivatives and materials obtained by doping or passivation: [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM), [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM), fullerene C 60 (C 60 ), Fullerene C 70 (C 70 ), tin dioxide (SnO2), zinc oxide (ZnO), etc.

[0091] In some embodiments, the second electrode 5 may be a metal electrode, or may be one or more of a conductive oxide electrode.

[0092] Taking the photoelectric device as a perovskite solar cell as an example, the preparation method includes: providing a first electrode 1, preparing a hole transport layer 2 on the first electrode 1, preparing a perovskite layer 3 on the hole transport layer 2 (specifically, a film formed by a perovskite material prepared by the preparation method of an embodiment of the present application), preparing an electron transport layer 4 on the perovskite layer 3, and preparing a second electrode 5 on the electron transport layer 4.

[0093] Electrical devices

[0094] In a fourth aspect, the embodiment of the present application further provides an electric device, which includes the optoelectronic device provided in the third aspect of the embodiment of the present application. The optoelectronic device can be used as a photoelectric conversion device of the electric device to convert light energy into electrical energy. Therefore, the electric device of the embodiment of the present application has high photoelectric conversion efficiency and good stability, and can work better.

[0095] The electrical device of the embodiment of the present application can be, but is not limited to, household lighting and power supply. For example, when the photovoltaic device used is a solar cell, the electrical device can be installed on a roof or a courtyard to convert solar energy into electrical energy to provide lighting and power supply for the household. As another example, the electrical device can be a solar power station. For example, solar cells can be used to build a solar power station to convert solar energy into electrical energy and transmit it to the power grid to provide clean energy for the city.

[0096] Example

[0097] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be obtained commercially.

[0098] Example 1

[0099] A perovskite solar cell includes a stacked ITO substrate, a hole transport layer, a perovskite layer, an electron transport layer and a copper electrode. The preparation steps are as follows:

[0100] Step 1: Take an ITO conductive glass with a specification of 2.0*2.0cm, remove 0.35cm of ITO at both ends by laser etching, and expose the glass substrate; ultrasonically clean the etched ITO conductive glass several times with water, acetone, and isopropanol in sequence; blow the ITO conductive glass dry with a nitrogen gun, and put it into a UV ozone machine for further cleaning to obtain an ITO substrate treated with UV ozone;

[0101] Step 2: Spin-coat 2 mg / mL of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) at a rate of 5000 rpm / s on the UV-ozone treated ITO substrate, and anneal on a hot plate at 100° C. for 10 minutes to obtain a hole transport layer.

[0102] Step 3: Prepare a MAPbI3 precursor solution with a concentration of 1.4M, and then add a hindered Lewis acid-base pair, namely, an equimolar amount of Lewis acid (C6F5)3B and a Lewis base tBu3P; wherein the amount of Lewis acid and Lewis base in the hindered Lewis acid-base pair is 0.1 mol% of MAPbI3 respectively. After stirring evenly, spin-coat on the hole transport layer at 3000 rpm / s, anneal at 100°C for 30 minutes, and cool to room temperature to obtain a MAPbI3 perovskite layer passivated by a hindered Lewis acid-base pair with a thickness of 650 nm.

[0103] Step 4: Spin-coat phenyl-C61-butyric acid methyl ester (PCBM) on the perovskite layer at 1000 rpm / s, anneal at 100° C. for 10 min, and then spin-coat its passivation layer bathocuproin (BCP) at 5000 rpm / s to obtain an electron transport layer.

[0104] Step 5, placing the wafer obtained in step 4 into a vapor deposition machine, and vapor depositing a copper electrode to 80 nm at a rate of 1 A / s to complete the preparation of the entire device.

[0105] Example 2

[0106] A perovskite solar cell, except that the hindered Lewis acid-base pair added to the precursor solution during the preparation of the perovskite layer is: Lewis acid (C6F5)3B and Lewis base iPr3P, and the rest is the same as Example 1.

[0107] Example 3

[0108] A perovskite solar cell, except that the hindered Lewis acid-base pair added to the precursor solution during the preparation of the perovskite layer is: Lewis acid (C6F5)3B and Lewis base Cy3P, and the rest is the same as Example 1.

[0109] Example 4

[0110] A perovskite solar cell, except that the hindered Lewis acid-base pair added to the precursor solution during the preparation of the perovskite layer is: Lewis acid (C6F5)3B and Lewis base Ph3P, and the rest is the same as Example 1.

[0111] Example 5

[0112] A perovskite solar cell, except that the hindered Lewis acid-base pair added to the precursor solution during the preparation of the perovskite layer is: Lewis acid Mes3B and Lewis base tBu3P, and the rest is the same as Example B1.

[0113] Example 6

[0114] A perovskite solar cell, except that the hindered Lewis acid-base pair added to the precursor solution during the preparation of the perovskite layer is: Lewis acid Mes3B and Lewis base iPr3P, and the rest is the same as Example 1.

[0115] Example 7

[0116] A perovskite solar cell, except that the hindered Lewis acid-base pair added to the precursor solution during the preparation of the perovskite layer is: Lewis acid Mes3B and Lewis base Cy3P, and the rest is the same as Example 1.

[0117] Example 8

[0118] A perovskite solar cell, except that the hindered Lewis acid-base pair added to the precursor solution during the preparation of the perovskite layer is: Lewis acid Mes3B and Lewis base Ph3P, and the rest is the same as Example 1.

[0119] Example 9

[0120] A perovskite solar cell, except that the hindered Lewis acid-base pair added to the precursor solution during the preparation of the perovskite layer is: Lewis acid (C6F5)3B and Lewis base Ph3N, and the rest is the same as Example 1.

[0121] Example 10

[0122] A perovskite solar cell, except that the hindered Lewis acid-base pair added to the precursor solution during the preparation of the perovskite layer is: Lewis acid Mes3B and Lewis base Ph3N, and the rest is the same as Example 1.

[0123] Embodiment 11

[0124] A perovskite solar cell is the same as Example 1 except that the amount of Lewis acid and Lewis base added to the hindered Lewis acid-base pair in the precursor solution is 0.01 mol% respectively when preparing the perovskite layer.

[0125] Example 12

[0126] A perovskite solar cell is the same as Example 1 except that the amount of Lewis acid and Lewis base added to the hindered Lewis acid-base pair in the precursor solution during the preparation of the perovskite layer is 0.2 mol %.

[0127] Comparative Example 1

[0128] A solar cell, which is the same as Example 1 except that the perovskite layer is prepared without hindered Lewis acid-base pair.

[0129] Comparative Example 2

[0130] A solar cell, which is the same as Example 1 except that 1-benzyl-3-hydroxypyridinium chloride is used to replace the hindered Lewis acid and base when preparing the perovskite layer.

[0131] Comparative Example 3

[0132] A solar cell is the same as Example 1 except that only Lewis acid (C6F5)3B is added during the preparation of the perovskite layer.

[0133] Comparative Example 4

[0134] A solar cell, which is the same as Example 1 except that only Lewis base tBu3P is added during the preparation of the perovskite layer.

[0135] Performance Testing

[0136] In standard simulated sunlight (AM 1.5G, 100mW / cm 2 ) to test the efficiency of the perovskite solar cell and its light stability. The effective area of ​​the test device is 0.08cm 2 .

[0137] a. Photovoltaic conversion efficiency test of perovskite solar cells:

[0138] In standard simulated sunlight (AM 1.5G, 100mW / cm 2 ) irradiation, the solar cell is tested to obtain the IV curve. According to the IV curve and the data fed back by the test equipment, the short-circuit current Jsc (unit: mA / cm 2 ), open circuit voltage Voc (unit V), maximum light output current Jmpp (unit mA) and maximum light output voltage Vmpp (unit V). The fill factor FF of the cell is calculated by the formula FF = (Jmpp × Vmpp) / Jsc × Voc, unit %. The photoelectric conversion efficiency PCE of the cell is calculated by the formula PCE = Jsc × Voc × FF / Pw, unit %; Pw represents the input power, unit mW.

[0139] b. Perovskite solar cell stability test:

[0140] The prepared solar cell device was placed in a dry room at 65° C. hot stage for accelerated testing, wherein the humidity was about 5%. The device efficiency was retested after 10 days, and the ratio of the efficiency to the initial efficiency was calculated.

[0141] The specific experimental results of the above tests are shown in Table 1.

[0142] Table 1

[0143]

[0144] From the test results in Table 1, it can be seen that the perovskite layer of the perovskite solar cell uses the hindered Lewis acid-base pair unique to the embodiment of the present application for passivation, so the embodiment of the present application not only has better light conversion efficiency than the comparative example, but also has better efficiency stability of the solar cell device of the embodiment of the present application. At the same time, the steric hindrance effect of the Lewis acid and the Lewis base in the hindered Lewis acid-base pair is improved, and the passivation effect is further improved. When the amount of the hindered Lewis acid-base pair added is appropriately increased within the range of 0.01 mol% to 2 mol%, the passivation effect is better.

[0145] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A perovskite material, characterized in that: The invention comprises a perovskite crystal and a hindered Lewis acid-base pair combined with the perovskite crystal, wherein the hindered Lewis acid-base pair comprises a Lewis acid and a Lewis base, wherein the Lewis acid comprises a tri-coordinated boron compound, and the Lewis base comprises at least one of a tri-coordinated nitrogen compound and a tri-coordinated phosphorus compound.

2. The perovskite material according to claim 1, characterized in that The Lewis acid binds to the monovalent anions that are insufficiently coordinated to the perovskite crystal, and the Lewis base binds to the divalent cations that are insufficiently coordinated to the perovskite crystal.

3. The perovskite material according to claim 1 or 2, characterized in that: The chemical formula of the tricoordinate boron compound includes BR3; wherein R includes at least one of an aryl group and a substituted aryl group, and the substituent group in the substituted aryl group includes halogen and C 1-6 At least one of the alkyl groups.

4. The perovskite material according to claim 3, characterized in that The R includes at least one of a perhalogen-substituted phenyl group and a mesitylene group.

5. The perovskite material according to any one of claims 1 to 4, characterized in that The chemical formula of the tri-coordinate nitrogen compound includes NR'3; wherein R' includes at least one of an alkyl group and an aryl group; The general chemical formula of the tri-coordinated phosphorus compound includes PR"3; wherein R" includes at least one of an alkyl group and an aryl group.

6. The perovskite material according to claim 5, characterized in that The alkyl group in R' includes C 3-6 The aryl group in said R' includes a phenyl group.

7. The perovskite material according to claim 5, characterized in that The alkyl group in R" includes C 3-6 The aryl group in said R" includes phenyl.

8. The perovskite material according to any one of claims 1 to 7, characterized in that The molar ratio of the perovskite crystal to the Lewis acid and the Lewis base is 1:(0.0001-0.02):(0.0001-0.02).

9. A method for preparing the perovskite material according to any one of claims 1 to 8, characterized in that: include: preparing a perovskite precursor solution; The hindered Lewis acid-base pair is added into the perovskite precursor solution, and then annealing is performed to obtain the perovskite material.

10. A photoelectric device comprising a perovskite layer, characterized in that: The perovskite layer comprises the perovskite material according to any one of claims 1 to 8 and / or the perovskite material prepared by the preparation method according to claim 9.

11. The optoelectronic device according to claim 10, characterized in that The photovoltaic device includes a solar cell.

12. An electrical device, characterized in that: The electrical device comprises the photovoltaic device according to claim 11.

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