Performance optimization design method of all-inorganic two-dimensional perovskite photoelectric material

Abstract

The invention relates to the technical field of solar cell materials, and discloses a performance optimization design method of an all-inorganic two-dimensional perovskite photoelectric material, which comprises the following steps: S1, researching the influence of different element components on the stability and photoelectric properties of all-inorganic two-dimensional perovskite, and carrying out optimization screening on the all-inorganic two-dimensional perovskite; s1.1, optimizing crystal lattices of different element component materials by utilizing a de novo molecular dynamics method, simulating oscillation conditions of energy of supercells along with time at different temperatures, and judging the stability at room temperature; s1.2, calculating dissociation energy delta E of the materials screened in the step S1.1, and analyzing the stability of the materials; s1.3, calculating lattice vibration of the material screened in the step S1.2 by using a density functional perturbation theory (DFPT), and analyzing the stability of the material from a phonon spectrum; and S1.4, judging the photoelectric property of the material screened in the step S1.3 by using a density functional theory. According to the technical scheme, the stability and the photoelectric property of the all-inorganic two-dimensional perovskite photoelectric material can be optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell materials, and in particular to a performance optimization design method for an all-inorganic two-dimensional perovskite photoelectric material. Background Art

[0002] New energy technologies play a vital role in the sustainable development of human society. Among many new energy technologies, solar energy is inexhaustible, safe and pollution-free, and is not restricted by geographical conditions. It is one of the best ways to solve the energy crisis and environmental pollution problems. The key to using solar energy to replace traditional fossil energy is to develop efficient and low-cost solar cells. Organic-inorganic hybrid lead-iodine perovskite has become a hot topic in the current photovoltaic field due to its high photoelectric conversion efficiency, rich element content and simple preparation process.

[0003] However, at room temperature, the organic-inorganic hybrid iodine-lead perovskite material will decompose rapidly. There are two main ways of decomposition: first, hydration and oxidation reactions will occur under the action of external water vapor and oxygen; second, the material will decompose due to internal ion diffusion. For the first decomposition reaction, it can be suppressed by isolating the air through packaging technology. However, for the second decomposition reaction, due to the lower ion transition barrier, even if the packaging is intact, the ion diffusion inside the perovskite material will still trigger the second decomposition reaction, resulting in poor stability of the organic-inorganic hybrid iodine-lead perovskite material.

[0004] All-inorganic structure and two-dimensional structure are two very promising ways to improve the stability of lead halide perovskites. However, they both have their own advantages and disadvantages. Combining the advantages of the two and developing new all-inorganic two-dimensional perovskite materials has brought new opportunities to improve the stability of perovskite solar cells. Kanatzidis's research group was the first to synthesize all-inorganic two-dimensional perovskites Cs2PbI2Cl2 and Cs2SnI2Cl2 by solid-state method. It was observed that these materials were placed in the air for up to 4 months without material decomposition, and the stability was excellent. Then, Pan and Xu et al. used density functional theory to study the photoelectric properties of Cs2PbI2Cl2; Akkerman, Dutta and Acharyya et al. successively explored manganese-doped and nanostructured Cs2PbI2Cl2 and its photoelectric properties, and explored its application potential in the field of optoelectronics. However, due to the presence of chlorine, the band gap of Cs2PbI2Cl2 is large, which is not suitable for direct use as a light-absorbing material for solar cells. At present, only a very small number of all-inorganic two-dimensional perovskite materials have been experimentally synthesized, and there is still a lack of systematic and in-depth research on the stability, optoelectronic properties, and the effects of element doping and substitution on the properties of other all-inorganic two-dimensional perovskite structures. Therefore, it is necessary to conduct more in-depth research and exploration on all-inorganic two-dimensional perovskite materials to optimize their stability and optoelectronic properties. Summary of the invention

[0005] The present invention aims to provide a performance optimization design method for an all-inorganic two-dimensional perovskite photoelectric material to optimize the stability and photoelectric properties of the all-inorganic two-dimensional perovskite photoelectric material.

[0006] To achieve the above object, the present invention adopts the following technical solution: a performance optimization design method for an all-inorganic two-dimensional perovskite photoelectric material, comprising the following steps:

[0007] S1: Study the effects of different elemental components on the stability and photoelectric properties of all-inorganic two-dimensional perovskites, and optimize the screening of all-inorganic two-dimensional perovskites;

[0008] S1.1: Use ab initio molecular dynamics to optimize the lattice of materials with different elemental components, simulate the energy oscillation of supercells at different temperatures over time, and judge the stability at room temperature; if the energy is dispersed, it means that the material has poor stability; if the energy is convergent, it means that the material has good stability;

[0009] S1.2: Calculate the dissociation energy ΔE of the materials screened in S1.1 to analyze the stability of the materials; if the dissociation energy ΔE is positive, it means that the material is relatively stable; if the dissociation energy is negative, it means that the material is unstable;

[0010] S1.3: Use density functional perturbation theory (DFPT) to calculate the lattice vibration of the materials selected in S1.2, and analyze the stability of the materials from the phonon spectrum; if there is an imaginary frequency in the phonon spectrum, it means that the material is unstable; if there is no imaginary frequency in the phonon spectrum, it means that the material is relatively stable;

[0011] S1.4: Use density functional theory to determine the optoelectronic properties of the materials screened in S1.3.

[0012] Preferably, the all-inorganic two-dimensional perovskite photoelectric material in S1 is any one of the Ruddlesden–Popper phase, the Dion-Jacobson phase and the Aurivillius phase.

[0013] Preferably, the chemical formula of the Ruddlesden–Popper phase is A n+1 B n X 3n+1 , where A represents a monovalent inorganic cation, B represents a divalent metal cation, and X represents a halogen anion. The optimization method for elements in the Ruddlesden–Popper phase is to first replace B with a non-toxic divalent metal cation, and then replace X with different halogen anions.

[0014] Preferably, the chemical formula of the Dion-Jacobson phase is A n B n X 3n+1 , where A represents a monovalent inorganic cation, B represents a divalent metal cation, and X represents a halogen anion. The optimization method for elements in the Dion-Jacobson phase is to first replace B with a non-toxic divalent metal cation, and then replace X with a different halogen anion.

[0015] Preferably, the chemical formula of the Aurivillius phase is A`2X`2·A n-1 B n X 3n+1 , wherein A represents a monovalent inorganic cation; B represents a divalent metal cation; X represents a halogen anion; A` represents another monovalent inorganic cation; X, represents another halogen anion; the optimization method of the elements in the Aurivillius phase is: first replace B with a non-toxic divalent metal cation, and then replace any one or two of X and X` with different halogen anions.

[0016] Preferably, in S1.4, using density functional theory to determine the photoelectric properties of the material screened in S1.3 comprises the following steps:

[0017] S1.4.1: Use density functional theory to calculate the electronic band structure of the materials screened in S1.3;

[0018] S1.4.2: Use density functional theory to calculate the light absorption coefficient α of the materials screened in S1.4.1;

[0019] S1.4.3: Use density functional theory to calculate the effective carrier mass m* of the materials selected in S1.4.2;

[0020] S1.4.4: Use density functional theory to calculate the exciton binding energy Eb of the materials screened in S1.4.2.

[0021] Preferably, in S1.4.1, the electronic band structure is obtained by hybrid functional combined with spin-orbit coupling calculations.

[0022] Preferably, in S1.4.2, the light absorption coefficient is calculated as follows:

[0023]

[0024] Where ω is the photon frequency, c is the speed of light, εr and εi are the real and imaginary parts of the dielectric function, respectively.

[0025] Preferably, in S1.4.3, the effective mass of the carrier is calculated by fitting the energy bands at the top of the valence band and the bottom of the conduction band according to the following formula:

[0026]

[0027] Among them, E is the band edge energy, k is the wave vector, and h is the reduced Planck constant.

[0028] Preferably, in S1.4.4, the calculation formula for the exciton binding energy is:

[0029]

[0030] Where e is the charge of the electron; is the reduced Planck constant; μ is the reduced effective mass of the exciton, and ε is the high-frequency dielectric constant of the material.

[0031] Compared with the prior art, the beneficial effects of this solution are:

[0032] (1) This technical solution provides theoretical and experimental basis for material design and device optimization of new perovskite solar cells by establishing the relationship between different elemental components and the stability and photoelectric properties of all-inorganic two-dimensional perovskites.

[0033] (2) In existing perovskite materials, the metal cation represented by B is usually Pb 2+However, lead ions are toxic and can easily cause serious pollution to the ecological environment during the production, use and subsequent treatment of materials, and pose a potential health threat to organisms. This unfriendly characteristic greatly limits its widespread application and sustainable development.

[0034] This technical solution innovatively uses non-toxic divalent metal cations to replace toxic lead ions. At the same time, considering that in the periodic table of chemical elements, halogen elements show unique chemical property changes as the atomic number increases. When the atomic number increases, the band gap of the all-inorganic two-dimensional perovskite formed will gradually decrease. Based on this principle, by using different halogen anions to replace any one or two of X and X', the microstructure of the all-inorganic two-dimensional perovskite material can be precisely controlled. Through such control methods, the all-inorganic two-dimensional perovskite material formed not only has good stability, but also performs well in optoelectronic properties. At the same time, it greatly reduces the harm to the environment, making it an environmentally friendly material, which lays a solid foundation for the wide application of perovskite materials in many fields such as electronic devices, energy conversion and storage in the future, and promotes the development of materials science in a green and sustainable direction.

[0035] (3) This technical solution first optimizes the lattice of the material and preliminarily selects materials with good stability. Then, the material stability is further screened by calculating the dissociation energy of the material. Subsequently, the material stability is further screened based on the lattice vibration of the material to select materials with good stability. Finally, the electronic band structure, light absorption coefficient α, carrier effective mass m* and exciton binding energy Eb of the material are calculated in sequence using density functional theory, so as to conduct in-depth screening of the photoelectric properties of the material. Through this rigorous and orderly screening process, materials with excellent stability and photoelectric properties can be finally screened.

[0036] This type of screening has many significant advantages. From the perspective of accuracy, the step-by-step screening method can gradually eliminate materials that do not meet the requirements, from the lattice level to the energy level to the optoelectronic performance level, which is progressive and interlocking, greatly improving the accuracy of the screening results. In terms of efficiency, first performing stability screening can reduce the workload of subsequent optoelectronic performance calculations, because unstable materials do not need to undergo complex optoelectronic performance calculations, saving a lot of time and computing resources. From a comprehensive perspective, the two key factors of material stability and optoelectronic performance are comprehensively considered to avoid the problem of focusing on a single performance while ignoring other important characteristics. The screened materials can not only maintain structural stability in daily use, but also give full play to their excellent optoelectronic properties in application scenarios such as optoelectronic conversion and signal transmission, providing a solid and reliable guarantee for the application of materials in high-tech fields, and strongly promoting technological development and innovation in related fields.

[0037] (4) This technical solution uses density functional theory combined with experimental preparation methods to systematically study all-inorganic two-dimensional perovskites from the perspective of element substitution and structural regulation, revealing the influence mechanism of different elemental components on the stability and photoelectric properties of all-inorganic two-dimensional halide perovskites. It provides data accumulation and theoretical support for the development of efficient and stable perovskite photoelectric materials and the optimization of solar cell devices, which is of great significance for promoting the practical application of perovskite solar cell technology.

[0038] (5) Existing research on two-dimensional perovskites mainly focuses on organic-inorganic hybrid perovskites, while research on two-dimensional inorganic perovskites is relatively rare. Therefore, there are certain characteristics and innovations in the selection of research objects. DETAILED DESCRIPTION

[0039] The following is further described in detail through specific implementation methods:

[0040] Example 1

[0041] A performance optimization design method for an all-inorganic two-dimensional perovskite photoelectric material comprises the following steps:

[0042] S1: Study the effects of different elemental components on the stability and photoelectric properties of all-inorganic two-dimensional perovskites, and optimize the screening of all-inorganic two-dimensional perovskites; among them, the all-inorganic two-dimensional perovskite is any one of the Ruddlesden–Popper phase, Dion-Jacobson phase and Aurivillius phase; the chemical formula of the Ruddlesden–Popper phase is A n+1 B n X 3n+1 , where A represents a monovalent inorganic cation, such as cesium ion (Cs + ); B represents a divalent metal cation, such as tin ion (Sn 2+ ); X represents a halogen anion, such as an iodide ion (I - ), bromide ion (Br - ), chloride ion (Cl - ) etc.; The optimization method of the elements in the Ruddlesden–Popper phase is: first replace B with a non-toxic divalent metal cation, and then replace X with a different halogen anion. The chemical formula of the Dion-Jacobson phase is A n B n X 3n+1 , where A represents a monovalent inorganic cation, such as cesium ion (Cs + ); B represents a divalent metal cation, such as tin ion (Sn 2+ ); X represents a halogen anion, such as an iodide ion (I - ), bromide ion (Br- ), chloride ion (Cl - ) etc.; the optimization method of the elements in the Dion-Jacobson phase is: first replace B with a non-toxic divalent metal cation, and then replace X with a different halogen anion; the chemical formula of the Aurivillius phase is A`2X`2·A n-1 B n X 3n+1 , where A represents a monovalent inorganic cation; for example, cesium ion (Cs + ); B represents a divalent metal cation, such as tin ion (Sn 2+ ); X represents a halogen anion, such as an iodide ion (I - ), bromide ion (Br - ), chloride ion (Cl - ) etc.; A' represents another monovalent inorganic cation, such as rubidium ion (Rb + ); X' represents another halogen anion, such as fluoride ion (F - ); The optimization method of the elements in the Aurivillius phase is: first replace B with a non-toxic divalent metal cation, and then replace any one or two of X and X' with different halogen anions.

[0043] S1.1: Use ab initio molecular dynamics (AIMD) to optimize the lattice of materials with different elemental components, simulate the oscillation of the energy of supercells at different temperatures (such as 300K) over time (such as 1fs interval within 5ps time), and judge the stability at room temperature; use AIMD to calculate the energy within a certain period of time. If the energy is dispersed, it means that the material stability is poor; if the energy converges, it means that the material stability is good;

[0044] S1.2: Calculate the dissociation energy ΔE of the materials screened in S1.1 and analyze the stability of the all-inorganic two-dimensional perovskite; if the dissociation energy ΔE is positive, it means that the decomposition reaction is an endothermic reaction and the material is relatively stable; if the dissociation energy is negative, it means that the decomposition reaction is an exothermic reaction and the material is unstable;

[0045] Taking Ruddlesden–Popper phase perovskite as an example, its decomposition reaction is:

[0046] A n+1 B n X 3n+1 →(n+1)·AX+nBX2

[0047] The dissociation energy ΔE can be obtained by calculating the energy of the reactants and products separately according to the following formula:

[0048] ΔE=(n+1)E[AX]+nE[BX2]-E[A2BX4]

[0049] S1.3: Use density functional perturbation theory (DFPT) to calculate the lattice vibration of the material screened in S1.2, analyze the stability of the material from the phonon spectrum, and determine whether there is an imaginary frequency in the phonon spectrum. If there is an imaginary frequency, it indicates that the material is unstable;

[0050] S1.4: Use density functional theory to calculate the electronic band structure and carrier effective mass m of the materials selected in S1.3 respectively. * , exciton binding energy E b , light absorption coefficient α, and analyze the optical properties of all-inorganic two-dimensional perovskite;

[0051] S1.4.1: The electronic band structure was calculated using hybrid functional (HSE06) combined with spin-orbit coupling. The computer software used was Quantum ESPRESSO.

[0052] S1.4.2: The light absorption coefficient is calculated as:

[0053]

[0054] Where ω is the photon frequency, which is 0-5eV, and c is the speed of light, which is 3×10 8 m / s, ε r and ε i are the real and imaginary parts of the dielectric function, ε r and ε i All were obtained through Quantum ESPRESSO computer software;

[0055] S1.4.3: The effective mass of the carrier is calculated by fitting the energy bands of the valence band top (VBM) and the conduction band bottom (CBM) and taking the second-order derivative of the energy with respect to the wave vector as follows:

[0056]

[0057] Where E is the band edge energy, which can be obtained by Quantum ESPRESSO computer software; k is the wave vector, which is calculated based on the wavelength; h is the reduced Planck constant, which is 1.0545718×10 -34 J.s;

[0058] S1.4.4: The formula for calculating the exciton binding energy is:

[0059]

[0060] Where e is the charge of the electron, which is 1.602176634×10 -19 C; is the reduced Planck constant, which is 1.0545718×10-34 J·s; μ is the reduced effective mass of the exciton, ε is the high-frequency dielectric constant of the material, and the values ​​of μ and ε can be obtained by the Quantum ESPRESSO computer software.

[0061] Feasibility analysis: The electronic band structure calculated by S1.4.1 can predict the band gap of all-inorganic two-dimensional perovskite. The study found that the divalent metal cation (B) is Pb 2+ The 6s orbital of the lead element at the top of the valence band of the all-inorganic two-dimensional perovskite has a lone pair of electrons, which leads to a lower effective mass of holes and is conducive to the separation of photogenerated carriers. Theoretical studies on the properties of defects have found that B is Pb 2+ , X is I - Most of the defects in all-inorganic two-dimensional perovskites are shallow energy level defects, which are conducive to the diffusion of carriers. These theoretical calculation results not only reveal the reason why all-inorganic two-dimensional perovskite solar cells have high conversion efficiency, but also provide important theoretical guidance for the research and development of new materials. Therefore, it is feasible to use density functional theory to study the stability and optoelectronic properties of all-inorganic two-dimensional perovskites.

[0062] Example 2

[0063] On the basis of Example 1, S2 is also included, according to the optimization screening results of S1.4, synthesizing all-inorganic two-dimensional perovskite photoelectric materials, analyzing the crystal type and photoelectric properties of the materials, specifically, using N, N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) mixed solvent to prepare all-inorganic two-dimensional perovskite materials, and investigating the effects of preparation conditions on the crystallinity and morphology of all-inorganic two-dimensional perovskite materials. Optimize synthesis parameters and prepare high-quality all-inorganic two-dimensional perovskite light absorption thin film materials, and perform XRD, XPS, UPS, SEM, EDS, TEM and other analyses on the crystal form and photoelectric properties of the materials.

[0064] Example 3

[0065] On the basis of Example 2, S3 is also included. According to the optimization screening results of S2, a photovoltaic device is prepared using the synthesized all-inorganic two-dimensional perovskite photoelectric material, and measurement and characterization are performed. The experimental results are compared and analyzed with the theoretical calculation results to optimize the design of the all-inorganic two-dimensional perovskite photoelectric material; specifically, a fluorine-doped tin dioxide transparent conductive glass (FTO) is used as a substrate, TiO2 or SnO2 is used as an electron transport layer, an all-inorganic two-dimensional perovskite is used as a light absorption material, and a metal or carbon material is used as a back electrode to prepare an all-inorganic two-dimensional perovskite solar cell with (or without) a hole transport layer. The battery preparation process is optimized, including film formation properties and coverage of the active layer, and IV, IPCE, PL and other tests are performed to improve the photoelectric conversion performance of the battery. The voltage and current hysteresis effect of the device, the decay rate of the photoelectric conversion efficiency at room temperature, etc. are investigated, and the stability is optimized in combination with the theoretical calculation results.

[0066] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A performance optimization design method for all-inorganic two-dimensional perovskite photoelectric materials, characterized in that: The following steps are involved: S1: Study the effects of different elemental components on the stability and photoelectric properties of all-inorganic two-dimensional perovskites, and optimize the screening of all-inorganic two-dimensional perovskites; S1.1: Use ab initio molecular dynamics to optimize the lattice of materials with different elemental components, simulate the energy oscillation of supercells over time at different temperatures, and determine the stability at room temperature; If the energy is dispersed, it means that the material has poor stability; If the energy converges, it means that the material is stable; S1.2: Calculate the dissociation energy ΔE of the materials screened in S1.1 to analyze the stability of the materials; if the dissociation energy ΔE is positive, it means that the material is relatively stable; if the dissociation energy is negative, it means that the material is unstable; S1.3: Use density functional perturbation theory (DFPT) to calculate the lattice vibration of the materials selected in S1.2, and analyze the stability of the materials from the phonon spectrum; if there is an imaginary frequency in the phonon spectrum, it means that the material is unstable; if there is no imaginary frequency in the phonon spectrum, it means that the material is relatively stable; S1.4: Use density functional theory to determine the optoelectronic properties of the materials screened in S1.

3.

2. The performance optimization design method of an all-inorganic two-dimensional perovskite photoelectric material according to claim 1, characterized in that: The all-inorganic two-dimensional perovskite photoelectric material in S1 is any one of the Ruddlesden–Popper phase, Dion-Jacobson phase and Aurivillius phase.

3. The performance optimization design method of an all-inorganic two-dimensional perovskite photoelectric material according to claim 2, characterized in that: The chemical formula of the Ruddlesden–Popper phase is A n+1 B n X 3n+1 , where A represents a monovalent inorganic cation, B represents a divalent metal cation, and X represents a halogen anion. The optimization method for elements in the Ruddlesden–Popper phase is to first replace B with a non-toxic divalent metal cation, and then replace X with different halogen anions.

4. The performance optimization design method of an all-inorganic two-dimensional perovskite photoelectric material according to claim 2, characterized in that: The chemical formula of the Dion-Jacobson phase is A n B n X 3n+1 , where A represents a monovalent inorganic cation, B represents a divalent metal cation, and X represents a halogen anion. The optimization method for elements in the Dion-Jacobson phase is to first replace B with a non-toxic divalent metal cation, and then replace X with a different halogen anion.

5. The performance optimization design method of an all-inorganic two-dimensional perovskite photoelectric material according to claim 2, characterized in that: The chemical formula of Aurivillius phase is A 、 2X 、 2.A n-1 B n X 3n+1 , where A represents a monovalent inorganic cation; B represents a divalent metal cation; X represents a halogen anion; A 、 represents another monovalent inorganic cation; X 、 represents another halogen anion; the optimization method of the elements in the Aurivillius phase is to first replace B with a non-toxic divalent metal cation, and then replace X and X with different halogen anions. 、 Any one or both of .

6. A performance optimization design method for an all-inorganic two-dimensional perovskite photoelectric material according to any one of claims 3 to 5, characterized in that: In S1.4, density functional theory is used to determine the optoelectronic properties of the materials screened in S1.3, including the following steps: S1.4.1: Use density functional theory to calculate the electronic band structure of the materials screened in S1.3; S1.4.2: Use density functional theory to calculate the light absorption coefficient α of the materials screened in S1.4.1; S1.4.3: Use density functional theory to calculate the effective carrier mass m* of the materials selected in S1.4.2; S1.4.4: Use density functional theory to calculate the exciton binding energy Eb of the materials screened in S1.4.

2.

7. The performance optimization design method of an all-inorganic two-dimensional perovskite photoelectric material according to claim 6, characterized in that: In S1.4.1, the electronic band structure is obtained using hybrid functional combined with spin-orbit coupling calculations.

8. The performance optimization design method of an all-inorganic two-dimensional perovskite photoelectric material according to claim 7, characterized in that: In S1.4.2, the light absorption coefficient is calculated as: Where ω is the photon frequency, c is the speed of light, εr and εi are the real and imaginary parts of the dielectric function, respectively.

9. The performance optimization design method of an all-inorganic two-dimensional perovskite photoelectric material according to claim 8, characterized in that: In S1.4.3, the effective carrier mass is calculated by fitting the energy bands at the top of the valence band and the bottom of the conduction band according to the following formula: Among them, E is the band edge energy, k is the wave vector, and h is the reduced Planck constant.

10. The performance optimization design method of an all-inorganic two-dimensional perovskite photoelectric material according to claim 9, characterized in that: In S1.4.4, the exciton binding energy is calculated as: Where, e is the charge of the electron; is the reduced Planck constant; μ is the reduced effective mass of the exciton, and ε is the high-frequency dielectric constant of the material.

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