Trans-inverted perovskite solar cell based on phosphonic acid SAMs and preparation method thereof

Abstract

The invention discloses a phosphonic acid SAMs-based inverted perovskite solar cell and a preparation method thereof, the phosphonic acid SAMs-based inverted perovskite solar cell comprises a substrate layer, a conductive substrate, a hole transport layer, a perovskite light absorption layer, an electron transport layer and a top electrode layer, and SAMs of the hole transport layer are carbazolyl phosphonic acid compounds. The phosphonic acid group in the carbazolyl phosphonic acid compound has very strong binding energy, the stability and performance of SAMs can be remarkably improved, the carbazole derivative is used for improving surface coverage, changing surface properties and generating dipole moment, and the working function of a substrate can be adjusted; the obtained hole transport layer material passivates corresponding defects through interaction with a perovskite layer, the quality of a perovskite thin film is improved, the open-circuit voltage and the filling factor of a thin film cell device are remarkably improved, and finally the photoelectric conversion efficiency of a solar cell is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, and relates to an inverted perovskite solar cell based on phosphonic acid SAMs and its preparation method. Background Technology

[0002] Perovskite solar cells have attracted considerable attention due to their high efficiency, low cost, simple manufacturing process, and broad spectral absorption range. In particular, inverted perovskite solar cells, especially those with an inverted structure, are particularly attractive for both single-junction and tandem solar cells due to their long lifetime, scalability, low cost, and compatibility with silicon in tandem solar cells. In inverted perovskite cell structures, the hole transport layer (HTL) plays a crucial role. The HTL directly contacts the transparent conductive oxide (TCO) and the perovskite layer, and its performance and interaction with the perovskite layer directly affect the overall performance of the solar cell. Therefore, the selection and optimization of HTL materials are key to improving cell efficiency and stability.

[0003] Currently, research on HTL materials covers a variety of types, including polymers, metal oxides, CuSCN, copper oxide, and self-assembled monolayers (SAMs). Among these materials, SAMs stand out due to their low cost, simple synthesis process, and dopant-free nature. Therefore, researchers have developed several promising SAM materials as efficient hole-selective layers (HSLs) in pin-structured perovskite solar cells. Summary of the Invention

[0004] The problem solved by this invention is to provide an inverted perovskite solar cell based on phosphonic acid SAMs and its preparation method. The invention uses novel SAMs materials to improve the performance of the hole transport layer, reduce costs, and improve the stability of the cell.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An inverted perovskite solar cell based on phosphonic acid SAMs includes a substrate layer, a conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and a top electrode layer. The SAMs in the hole transport layer are carbazole-phosphonic acid compounds with the following structural formula:

[0007]

[0008] Wherein, L is a C1-C6 alkylene ring, benzene ring, or deuterated benzene ring; R1 is H, benzene ring, or deuterated benzene ring; R2 is H, benzene ring, or deuterated benzene ring.

[0009] The substrate layer is a soda-lime glass or a borosilicate glass layer;

[0010] The conductive substrate is one or more of the following: F-doped tin oxide layer, In-doped tin oxide layer, and Al-doped zinc oxide layer;

[0011] The hole transport layer is formed by spin-coating a liquid prepared from a carbazole phosphonic acid compound and an organic solvent onto a conductive substrate.

[0012] The perovskite light-absorbing layer is formed by depositing a perovskite precursor solution and an antisolvent on a hole transport layer in one step, followed by annealing.

[0013] The electron transport layer is an electron transport layer obtained by vapor deposition on a perovskite light-absorbing layer.

[0014] The top electrode layer is formed by vapor deposition of Ag or Au on the electron transport layer.

[0015] The hole transport layer is prepared by mixing a carbazole phosphonic acid compound with an organic solvent to form a liquid, wherein the concentration of the carbazole phosphonic acid compound is 0.1-1.0 mg / mL, and then spin-coating it onto a conductive substrate.

[0016] The chemical formula of the perovskite precursor solution is Cs. 0.05 (MA 0.05 FA 0.95 ) 0.95 Pb(Br 0.05 I 0.95 3; The antisolvent is chlorobenzene.

[0017] The present invention also provides a method for fabricating the inverted perovskite solar cell based on phosphonic acid SAMs, comprising the following operations:

[0018] 1) Pre-treat the conductive substrate on the substrate layer;

[0019] 2) Prepare a hole transport layer on top of a conductive substrate: Mix carbazole phosphonic acid compound with anhydrous ethanol evenly, spin coat it onto a conductive substrate, and anneal at a certain temperature;

[0020] 3) A perovskite layer was prepared by spin-coating the perovskite precursor liquid onto the hole transport layer using a one-step spin-coating method;

[0021] 4) An electron transport layer is prepared above the perovskite light-absorbing layer;

[0022] 5) A top electrode layer is fabricated above the electron transport layer to obtain a perovskite solar cell.

[0023] When the carbazophosphonic acid compound is mixed with anhydrous ethanol, the concentration of the carbazophosphonic acid compound is 0.1-1.0 mg / mL;

[0024] Spin-coat it onto the prepared ITO surface and anneal at 100-150℃ for 10-15 minutes.

[0025] Furthermore, this invention proposes the application of carbazole phosphonic acid compounds as hole transport layers (SAMs) in the fabrication of perovskite solar cells.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. This invention improves the performance of the hole transport layer by using carbazole-based phosphonic acid compounds as SAMs materials, while reducing costs and improving battery stability. The phosphonic acid (PA) group has a strong binding energy, which significantly improves the stability and performance of SAMs. The phosphorus atom in the phosphonic acid group forms a PO-In bond with the oxygen atom on the ITO surface. This strong binding energy ensures that the SAMs are firmly attached to the substrate, preventing desorption during perovskite precursor solution processing or device operation, thereby improving interface stability. Furthermore, the oxygen atom in the phosphonic acid group binds with the Pb in the perovskite... 2 + Coordination (such as P=O→Pb) forms stable interfacial interactions. This combination can passivate perovskite surface defects and reduce nonradiative recombination.

[0028] The hole transport layer material of this invention passivates corresponding defects through interaction with the perovskite layer, thereby improving the quality of the perovskite thin film, significantly increasing the open-circuit voltage and fill factor of the thin-film battery device, and ultimately greatly improving the photoelectric conversion efficiency of the solar cell. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the perovskite solar cell of the present invention;

[0030] Figure 2 This is a device performance test diagram of the perovskite solar cell of the present invention. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0032] like Figure 1 As shown, an inverted perovskite solar cell based on phosphonic acid SAMs includes a substrate layer, a conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and a top electrode layer. The SAMs in the hole transport layer are carbazole-phosphonic acid compounds with the following structural formula:

[0033]

[0034] Wherein, L is a C1-C6 alkylene ring, benzene ring, or deuterated benzene ring; R1 is H, benzene ring, or deuterated benzene ring; R2 is H, benzene ring, or deuterated benzene ring.

[0035] Furthermore, the substrate layer is a soda-lime glass or a borosilicate glass layer;

[0036] The conductive substrate is one or more of the following: F-doped tin oxide layer, In-doped tin oxide layer, and Al-doped zinc oxide layer;

[0037] The hole transport layer is formed by spin-coating a liquid prepared from a carbazole phosphonic acid compound and an organic solvent onto a conductive substrate.

[0038] The perovskite light-absorbing layer is formed by depositing a perovskite precursor solution and an antisolvent on a hole transport layer in one step, followed by annealing; the antisolvent is chlorobenzene.

[0039] The electron transport layer is an electron transport layer obtained by vapor deposition on a perovskite light-absorbing layer.

[0040] The top electrode layer is formed by vapor deposition of Ag or Au on the electron transport layer.

[0041] This invention uses carbazole phosphonic acid compounds as SAMs materials, wherein the phosphonic acid (PA) group has a strong binding energy, which can significantly improve the stability and performance of SAMs; moreover, the oxygen atom of the phosphonic acid group coordinates with Pb2+ in the perovskite (e.g., P=O→Pb), forming a stable interfacial interaction. This binding energy passivates perovskite surface defects and reduces non-radiative recombination.

[0042] Terminal groups in carbazole phosphonic acid compounds, such as carbazole (Cz) derivatives, help improve surface coverage, alter surface properties, and generate dipole moments, which can adjust the substrate working function (WF) and further optimize battery performance. When L is a C1-C6 alkylene group in the substituent, different lengths of alkylene groups affect the intermolecular distance and spatial arrangement. If L is a benzene ring or a deuterated benzene ring, the rigid structure of the benzene ring can provide steric hindrance, preventing excessive aggregation of molecules during self-assembly and contributing to the formation of a uniform molecular layer. The presence of deuterated benzene atoms increases its mass, further affecting the vibrational and rotational properties of the molecule, thus fine-tuning the molecular arrangement.

[0043] When R1 and R2 are H, their effect on the solubility of the compound is relatively small. If R1 and R2 are benzene rings, the hydrophobicity of the benzene ring will increase the solubility of the compound in some organic solvents, which will facilitate the solution processing of SAMs. Deuterated benzene rings are also hydrophobic, and due to the presence of deuterium atoms, their physicochemical properties will change to some extent, which will further optimize the solubility and processing performance of the compound. The R1 and R2 groups can affect the interfacial properties between SAMs and adjacent layers (such as perovskite layers or electrodes). The presence of benzene rings or deuterated benzene rings can improve interfacial contact and reduce interfacial defects.

[0044] Because deuterium has a greater mass than hydrogen, the vibrational frequency of CD bonds is lower than that of CH bonds. Therefore, processes involving CD bonds in chemical reactions or molecular motion are slower than those involving CH bonds; this phenomenon is called the kinetic isotope effect. In SAMs materials, deuteration can slow down molecular thermal motion, reducing molecular decomposition and rearrangement at high temperatures, thus improving the material's thermal stability. Deuteration also has some impact on the electronic properties of molecules. Although deuterium and hydrogen have similar electronegativity, deuteration may slightly alter the electron cloud distribution of molecules, thus affecting hole transport performance. Generally, as the degree of deuteration increases, the thermal stability of the material gradually improves. Furthermore, more CD bonds can more effectively slow down molecular thermal motion, reducing the possibility of thermal decomposition, and moderate deuteration may optimize the electronic structure of molecules, improving hole transport efficiency. However, excessive deuteration may disrupt the original molecular structure, leading to a decrease in hole transport performance. Therefore, it is necessary to find an appropriate degree of deuteration to balance thermal stability and hole transport performance.

[0045] The following are specific carbazole phosphonic acid compounds, among which compounds 13, 15, 16, 18, 25, 27, 34, and 36 show more significant performance improvements in perovskite solar cells.

[0046]

[0047]

[0048]

[0049]

[0050]

[0051] The method for fabricating an inverted perovskite solar cell based on phosphonic acid SAMs of the present invention includes the following operations:

[0052] 1) Pre-treat the conductive substrate on the substrate layer;

[0053] 2) Prepare a hole transport layer on top of a conductive substrate: Mix carbazole phosphonic acid compound with anhydrous ethanol evenly, then spin-coat it onto a conductive substrate and anneal it at a certain temperature.

[0054] 3) A perovskite layer was prepared by spin-coating the perovskite precursor liquid onto the hole transport layer using a one-step spin-coating method;

[0055] 4) An electron transport layer is prepared above the perovskite light-absorbing layer;

[0056] 5) A top electrode layer is fabricated above the electron transport layer to obtain a perovskite solar cell.

[0057] Specific implementation examples are given below.

[0058] Example 1:

[0059] The method for fabricating inverted perovskite solar cells based on phosphonic acid SAMs includes the following steps:

[0060] 1) ITO Pretreatment: First, sonicate the ITO substrate in a mixture of ultrapure water and glass cleaner (100:1 volume ratio) for 25 minutes, then sonicate twice more with ultrapure water, 20 minutes each time. Dry the cleaned ITO substrate in a 100℃ oven for 20 minutes. Then, treat the dried ITO substrate in a UV ozone generator for 25 minutes.

[0061] 2) Preparation of hole transport layer: Carbazole phosphonic acid compound (compound 16) was mixed with anhydrous ethanol to obtain a hole transport layer liquid with a concentration of 0.5 mg / mL. The liquid was spin-coated onto the prepared ITO surface and annealed at 100 °C for 10 min.

[0062] 3) Preparation of the perovskite light-absorbing layer:

[0063] PbI₂, MABr, PbBr, FAI, and CsI were dissolved in a mixed solution of DMF:DMSO = 4:1 (volume ratio) to form a solution with the chemical formula Cs. 0.05 (MA 0.05 FA 0.95 ) 0.95 Pb(Br 0.05 I 0.95 A perovskite precursor solution of 3 was used as an antisolvent to deposit a perovskite film on the hole transport layer in one step, followed by annealing at 100°C for 10 min.

[0064] 4) Fabrication of the electron transport layer: A layer of C is sequentially deposited on the perovskite layer. 60 With BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), an electron transport layer is obtained.

[0065] 5) Preparation of cathode layer: A layer of Ag is deposited on the electron transport layer to obtain perovskite solar cell.

[0066] Example 2:

[0067] The hole transport material in Example 1 was replaced with Compound 18, while the other materials, structures and preparation methods were the same as in Example 1.

[0068] Comparative Example 1:

[0069] The hole transport material in Example 1 was replaced with Compound 9, while the other materials, structures and preparation methods were the same as in Example 1.

[0070] Comparative Example 2:

[0071] The hole transport material (HTL) in Example 1 was replaced with the conventional material PTAA, specifically doped PTAA (concentration 10 mg / mL, with added Li-TFSI and tBP), and the rest was the same as in Example 1; it may require oxidation doping, is highly sensitive to humidity, and has poor long-term stability.

[0072] Comparative Example 3:

[0073] For blank devices without HTL, the HTL layer is omitted, and perovskite is directly deposited on ITO. The rest is the same as in Example 1.

[0074] The battery performance was tested as shown in Table 1. Figure 2 As shown.

[0075] Table 1. Solar energy performance parameters of perovskites in the examples and comparative examples.

[0076]

[0077] From Table 1 and Figure 2 It is known that carbazole-terminated phosphonic acid compounds (such as compounds 16 and 18) enhance the VT by modulating the work function of ITO through strong dipole moment. oc Compared with FF; while the phosphonic acid group anchored to the ITO substrate (compound 16 / 18) can avoid the doping degradation problem of the traditional polymer HTL (comparative example 2); while the fill factor of carbazole terminal group after alkyl is mounted (comparative example 1) decreases significantly, possibly due to the unoptimized terminal group, weak interfacial hole extraction ability, and high recombination loss.

[0078] Figure 2 The figure shows the current density-voltage (JV) characteristic curves of perovskite solar cells, reflecting the electrical performance of the cells under different conditions. Short-circuit current density: from the intersection of the curve and the vertical axis. Open-circuit voltage: from the intersection of the curve and the horizontal axis. Figure 2This reflects that the current density, open-circuit voltage, and fill factor of Examples 1 and 2 are higher than those of Comparative Example 1, so their photoelectric conversion efficiency is also higher than that of Comparative Example 1.

[0079] The compound provided by this invention can also be adapted to different device requirements through multiple experiments by adjusting the linking group (L) and substituents (R1 / R2) to obtain a hole transport layer material; it interacts with the perovskite layer, wherein the phosphonic acid group contains oxygen atoms, and these oxygen atoms can react with lead ions (Pb) in the perovskite. 2+ Coordinate bonds are formed. The formation of these coordinate bonds can effectively fix lead ions on the perovskite surface, reduce the generation of lead-related defects (such as lead vacancies), and thus improve the crystallinity and stability of the perovskite.

[0080] Hydroxyl groups and other functional groups in the compound can form hydrogen bonds with components on the perovskite surface. Carbazole phosphonic acid compounds have a certain charge distribution, and the electron donors (such as carbazole groups) and acceptors (such as phosphonic acid groups) in their molecules can interact electrostatically with the charge distribution on the perovskite surface. This electrostatic interaction can regulate the charge distribution on the perovskite surface, neutralize some charge defects, reduce nonradiative recombination centers caused by uneven charge distribution, and improve the photoelectric properties of the perovskite. This passivates the corresponding defects, improves the quality of the perovskite thin film, significantly increases the open-circuit voltage and fill factor of thin-film solar cell devices, and ultimately greatly improves the photoelectric conversion efficiency of solar cells.

[0081] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A reverse-inverted perovskite solar cell based on phosphonic acid SAMs, characterized in that, It includes a substrate layer, a conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and a top electrode layer. The SAMs in the hole transport layer are carbazole phosphonic acid compounds with the following structural formula: Wherein, L is a C1-C6 alkylene ring, benzene ring, or deuterated benzene ring; R1 is H, benzene ring, or deuterated benzene ring; R2 is H, benzene ring, or deuterated benzene ring.

2. The inverted perovskite solar cell based on phosphonic acid SAMs as described in claim 1, characterized in that, The substrate layer is a soda-lime glass or a borosilicate glass layer; The conductive substrate is one or more of the following: F-doped tin oxide layer, In-doped tin oxide layer, and Al-doped zinc oxide layer; The hole transport layer is formed by spin-coating a liquid prepared from a carbazole phosphonic acid compound and an organic solvent onto a conductive substrate. The perovskite light-absorbing layer is formed by depositing a perovskite precursor solution and an antisolvent on a hole transport layer in one step, followed by annealing. The electron transport layer is an electron transport layer obtained by vapor deposition on a perovskite light-absorbing layer. The top electrode layer is formed by vapor deposition of Ag or Au on the electron transport layer.

3. The inverted perovskite solar cell based on phosphonic acid SAMs as described in claim 1, characterized in that, The hole transport layer is prepared by mixing a carbazole phosphonic acid compound with an organic solvent to form a liquid, wherein the concentration of the carbazole phosphonic acid compound is 0.1-1.0 mg / mL, and then spin-coating it onto a conductive substrate.

4. The inverted perovskite solar cell based on phosphonic acid SAMs as described in claim 1, characterized in that, The organic solvent is anhydrous ethanol.

5. The inverted perovskite solar cell based on phosphonic acid SAMs as described in claim 1, characterized in that, The chemical formula of the perovskite precursor solution is Cs. 0.05 (MA 0.05 FA 0.95 ) 0.95 Pb(Br 0.05 I 0.95 3; The antisolvent is chlorobenzene.

6. A method for fabricating an inverted perovskite solar cell based on phosphonic acid SAMs as described in claim 1, characterized in that, Includes the following operations: 1) Pre-treat the conductive substrate on the substrate layer; 2) Prepare a hole transport layer on top of a conductive substrate: Mix carbazole phosphonic acid compound with anhydrous ethanol evenly, spin coat it onto a conductive substrate, and anneal at a certain temperature; 3) A perovskite layer was prepared by spin-coating the perovskite precursor liquid onto the hole transport layer using a one-step spin-coating method; 4) An electron transport layer is prepared above the perovskite light-absorbing layer; 5) A top electrode layer is prepared above the electron transport layer to obtain a perovskite solar cell.

7. The method for fabricating an inverted perovskite solar cell based on phosphonic acid SAMs as described in claim 6, characterized in that, The first step includes the following steps: First, the substrate with conductive substrate is ultrasonically cleaned for 20-25 minutes using a cleaning solution. The weight ratio of ultrapure water to glass cleaning agent in the cleaning solution is 80-100:

1. Then, sonicate with ultrapure water 2-3 times, 15-20 minutes each time. Place the cleaned ITO substrate in a 100℃ oven to dry for 20-30 minutes. Place the dried substrate with conductive substrate in an ultraviolet ozone generator for 25-40 minutes and set aside.

8. The method for preparing an inverted perovskite solar cell based on phosphonic acid SAMs as described in claim 6, wherein when the carbazole phosphonic acid compound is mixed with anhydrous ethanol, the concentration of the carbazole phosphonic acid compound is 0.1-1.0 mg / mL; Spin-coat it onto the prepared ITO surface and anneal at 100-150℃ for 10-15 minutes.

9. The method for preparing an inverted perovskite solar cell based on phosphonic acid SAMs as described in claim 6, wherein the perovskite light-absorbing layer is prepared by dissolving PbI2, MABr, PbBr, FAI, and CsI in a mixed solution of DMF and DMSO to form a perovskite light-absorbing layer with the chemical formula CsI. 0.05 (MA 0.05 FA 0.95 ) 0.95 Pb(Br 0.05 I 0.95 A perovskite precursor solution of 3 was used as an antisolvent to deposit a perovskite film on the hole transport layer in one step, followed by annealing at 100-150℃ for 10-15 min. The electron transport layer is fabricated as follows: A layer of C is sequentially deposited on the perovskite light-absorbing layer. 60 An electron transport layer was obtained by reacting 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline.

10. Application of carbazole phosphonic acid compounds as hole transport layers (SAMs) in the fabrication of perovskite solar cells; The structural formula of the carbazole phosphonic acid compound is as follows: in, L is a C1-C6 alkylene ring, benzene ring, or deuterated benzene ring; R1 is H, benzene ring, or deuterated benzene ring; R2 is H, benzene ring, or deuterated benzene ring.

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