Two-dimensional / three-dimensional perovskite heterojunction based on amidino cations and application of two-dimensional / three-dimensional perovskite heterojunction in solar cell

Abstract

The invention discloses an amidino cation-based two-dimensional / three-dimensional perovskite heterojunction and an application thereof in a solar cell, belongs to the technical field of solar cells, and realizes the formation of the two-dimensional / three-dimensional heterojunction by forming an amidino two-dimensional perovskite layer on the surface of a perovskite film. The amidino cation has a relatively high acid dissociation constant, so that condensation reaction between the amidino two-dimensional material and formamidine cation of the three-dimensional perovskite thin film under a high-temperature illumination condition can be effectively avoided, and the photo-thermal stability of the device is further improved. In addition, the amidino two-dimensional layer can also passivate defects at the grain boundary and the surface, reduce non-radiative recombination, enhance the carrier transport capability and improve the photoelectric conversion efficiency of the device. The perovskite heterojunction is suitable for a new strategy for constructing a perovskite solar cell with both high efficiency and long-term stability, and has a wide practical application prospect.

Description

Technical Field

[0001] The present invention belongs to the field of solar cells, and particularly relates to a two-dimensional / three-dimensional perovskite heterojunction based on amidinium cations and its application in solar cells. Background Art

[0002] Organic-inorganic hybrid perovskite solar cells have attracted extensive attention in recent years due to their excellent optoelectronic properties, low cost, and easy processing. Especially within just over a decade, the power conversion efficiency of small-area devices in the laboratory has exceeded 27%, showing great commercial potential. However, the stability issue of perovskite cells during long-term operation remains one of the key factors restricting their commercialization. To improve the stability and efficiency of the devices, constructing two-dimensional / three-dimensional perovskite heterojunctions has become one of the hot research directions currently.

[0003] In a two-dimensional / three-dimensional heterostructure, the two-dimensional perovskite layer can effectively passivate the defects on the surface of the three-dimensional perovskite thin film, regulate the band alignment, inhibit non-radiative recombination, improve the carrier transport performance, and introduce hydrophobicity to enhance environmental stability. The currently widely used two-dimensional layer mainly uses amine-based cations such as phenethylamine and butylamine. Although these structures have good stability at room temperature, they are prone to degradation under high-temperature light conditions such as 85°C. The main reason is that the amine-based cations are prone to deprotonation and undergo a condensation reaction with formamidine (FA + in the perovskite thin film, resulting in the instability of the two-dimensional / three-dimensional structure and the degradation of device performance. Summary of the Invention

[0004] To overcome the problem of poor stability of the existing two-dimensional / three-dimensional perovskite heterojunction under high-temperature light conditions, the present invention provides a two-dimensional / three-dimensional perovskite heterojunction based on amidinium cations and its application in solar cells. Using amidinium cations with a relatively high acid dissociation constant as the cations of the two-dimensional perovskite layer can effectively inhibit the deprotonation reaction at high temperatures and avoid the condensation reaction between amine-based cations and formamidinium cations in the three-dimensional perovskite, thereby improving the thermal stability of the device under high-temperature light conditions.

[0005] To achieve the above object, the present invention is implemented by the following technical solutions: The first object of the present invention is to provide a two-dimensional / three-dimensional perovskite heterojunction based on amidinium cations, wherein the two-dimensional perovskite layer is deposited on the surface of the three-dimensional perovskite layer, and the spacer cations of the two-dimensional perovskite layer are amidinium cations.

[0006] Preferably, the two-dimensional perovskite layer is prepared by the following method: depositing the perovskite precursor solution A on the surface of the three-dimensional perovskite layer and performing annealing treatment to form the two-dimensional perovskite layer; the perovskite precursor solution A contains an amidine salt derivative.

[0007] Further preferably, the amidinium salt derivative includes 3-aminopyridine hydrochloride, 2-phenylacetamidine hydrochloride, benzamidine hydrochloride, 4-methoxybenzamidine hydrochloride or 4-phenylbenzamidine hydrochloride.

[0008] Further preferably, the annealing temperature of the two-dimensional perovskite layer is 100-120 °C, and the annealing time is 5-10 min.

[0009] Preferably, the thickness of the two-dimensional perovskite layer is 1-10 nm.

[0010] The second object of the present invention is to disclose the application of a two-dimensional / three-dimensional perovskite heterojunction based on amidinium cations in a solar cell.

[0011] The third object of the present invention is to disclose a perovskite solar cell, and the structure of the solar cell includes a transparent conductive substrate, a hole transport layer, the aforementioned two-dimensional / three-dimensional perovskite heterojunction based on amidinium cations, an electron transport layer, and a metal back electrode, which are sequentially arranged from bottom to top.

[0012] Preferably, the three-dimensional perovskite layer is prepared by the following method: coating a perovskite precursor solution B on the hole transport layer to form a perovskite liquid film, and obtaining the three-dimensional perovskite layer after evacuation crystallization annealing.

[0013] Preferably, the thickness of the three-dimensional perovskite layer is 400-800 nm.

[0014] Preferably, during the preparation of the three-dimensional perovskite layer, the evacuation crystallization time is 10-50 s, the annealing treatment temperature is 100-120 °C, and the annealing time is 20-30 min.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a two-dimensional / three-dimensional perovskite heterostructure based on amidinium cations and its application in the field of solar cells, which can overcome the problem of poor stability of existing two-dimensional / three-dimensional perovskite heterojunctions under high-temperature light illumination. In this structure, the amidinium cation serves as the cation of the two-dimensional perovskite layer and has a relatively high acid dissociation constant, which can effectively inhibit the deprotonation reaction at high temperatures and avoid the condensation reaction between the amino-group cations and the formamidinium cations in the three-dimensional perovskite, thereby improving the thermal stability of the device under high-temperature light illumination. At the same time, the amidinium cation also has excellent interfacial defect passivation ability, which can effectively reduce the non-radiative recombination loss at the interface and improve the photoelectric conversion efficiency of the device. By constructing this two-dimensional / three-dimensional perovskite heterostructure based on amidinium cations, the solar cells of the present invention exhibit better device performance than those of traditional amino-group cations in terms of both efficiency and stability. The present invention effectively solves the problems of structural instability and performance degradation caused by the easy deprotonation of traditional amino-group cations under high-temperature light illumination and the subsequent condensation reaction with the formamidinium cations in the three-dimensional perovskite by introducing amidinium cations with a high acid dissociation constant as the spacer cations of the two-dimensional perovskite layer. In contrast, the amidinium cation has higher thermochemical stability, is not easily deprotonated, and can significantly inhibit the structural disintegration caused by ion migration or interfacial reactions in the heterostructure, fundamentally improving the photothermal stability of the device. At the same time, the amidinium cation forms hydrogen bonds with the uncoordinated lead ions or iodine ions on the perovskite surface, thereby effectively passivating the surface defect states, reducing non-radiative recombination, and increasing the open-circuit voltage and fill factor of the device.

[0016] The two-dimensional / three-dimensional perovskite heterostructure based on amidinium cations proposed by the present invention is applied to perovskite solar cells, which has high thermal and optical stability, high defect passivation ability, high-efficiency output, and excellent interfacial compatibility, providing a new material design and device engineering path for realizing high-efficiency, long-life, and scalable perovskite photovoltaic devices, and having important scientific significance and industrial application prospects. Brief Description of the Drawings

[0017] Figure 1 It is a schematic structural diagram of a two-dimensional / three-dimensional perovskite heterojunction solar cell based on amidinium cations in an embodiment of the present invention; Figure 2 It is a schematic diagram of a two-dimensional / three-dimensional perovskite heterostructure based on amidinium cations in an embodiment of the present invention; Figure 3 It is the XRD result of a two-dimensional / three-dimensional perovskite thin film in an embodiment of the present invention; Figure 4 It is the test result of the current-voltage characteristics of a solar cell prepared in an embodiment of the present invention; Figure 5Stability test results of the solar cell prepared in the embodiment of the present invention under illumination and at 85°C; Among them, 1 - transparent conductive substrate, 2 - hole transport layer, 3 - self-assembled monolayer, 4 - three-dimensional perovskite active layer, 5 - two-dimensional perovskite layer, 6 - electron transport layer, 7 is a hole blocking layer, 8 is a conductive electrode, 51 - amidinium two-dimensional layer, 41 - formamidinium cation (FA + ), or cesium cation (Cs + ). Detailed implementation manners

[0018] To enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0019] In the following embodiments, conventional instrument equipment in the art is used, and various raw materials and reagents (such as solvents, etc.) used are all commercially available products unless otherwise specified. Their specifications are conventional specifications in the art, or can be prepared or formulated by known methods or reagent instructions. The experimental methods without specific conditions noted in the following embodiments are usually carried out under conventional conditions, or according to the conditions recommended by the manufacturer.

[0020] The method of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0021] As Figure 2 shown, the present invention provides a two-dimensional / three-dimensional perovskite heterojunction based on amidinium cations, wherein the two-dimensional perovskite layer 5 is deposited on the surface of the three-dimensional perovskite active layer 4, and the spacer cation of the two-dimensional perovskite layer 5 is an amidinium cation. The amidinium two-dimensional layer 51 formed by the amidinium cations can effectively passivate the surface defects of the three-dimensional perovskite active layer 4, reduce non-radiative recombination losses, improve the open-circuit voltage and fill factor, and enhance the conversion efficiency and photothermal stability of the device.

[0022] In some embodiments of the present invention, the two-dimensional perovskite layer 5 is prepared by the following method: depositing the perovskite precursor solution A on the surface of the three-dimensional perovskite active layer 4, and annealing to form the two-dimensional perovskite layer 5; the perovskite precursor solution A contains an amidine salt derivative.

[0023] In some embodiments of the present invention, the amidine salt derivative includes 3-aminopyridine hydrochloride, 2-phenylacetamidine hydrochloride, benzamidine hydrochloride, 4-methoxybenzamidine hydrochloride, or 4-phenylbenzamidine hydrochloride.

[0024] In some embodiments of the present invention, the annealing temperature of the two-dimensional perovskite layer 5 is 100-120 °C, and the annealing time is 5-10 min.

[0025] In some embodiments of the present invention, the thickness of the two-dimensional perovskite layer 5 is 1-10 nm.

[0026] Some embodiments of the present invention disclose the application of a two-dimensional / three-dimensional perovskite heterojunction based on amidinium cations in a solar cell.

[0027] Some embodiments of the present invention disclose a perovskite solar cell, as Figure 1 shown, the structure of the solar cell includes a transparent conductive substrate 1, a hole transport layer 2, the aforementioned two-dimensional / three-dimensional perovskite heterojunction based on amidinium cations, an electron transport layer 6, and a metal back electrode 8, which are sequentially arranged from bottom to top.

[0028] The preparation method of the above-mentioned perovskite solar cell includes the following steps: 1) Prepare a hole transport layer 2 on the transparent conductive substrate 1; 2) Coat the precursor solution B on the hole transport layer 2 to form a perovskite liquid film, subject the perovskite liquid film to air extraction crystallization treatment, and finally perform annealing treatment to obtain a three-dimensional perovskite active layer 4; 3) Deposit the amidine material precursor solution A on the surface of the three-dimensional perovskite active layer 4 through a solution process, and perform annealing treatment to form an amidinium two-dimensional perovskite layer 5; 4) Subsequently, coat an electron transport layer 6 and a conductive electrode 8 on the two-dimensional perovskite layer 5 in sequence.

[0029] In some embodiments of the present invention, the three-dimensional perovskite active layer 4 is prepared by the following method: coat a perovskite precursor solution B on the hole transport layer 2 to form a perovskite liquid film, and obtain the three-dimensional perovskite active layer 4 after air extraction crystallization annealing.

[0030] In some embodiments of the present invention, the thickness of the three-dimensional perovskite active layer 4 is 400-800 nm.

[0031] In some embodiments of the present invention, during the preparation of the three-dimensional perovskite active layer 4, the time for air extraction crystallization is 10-50 s, the annealing temperature is 100-120 °C, and the annealing time is 20-30 min.

[0032] The following is specifically described in conjunction with embodiments.

[0033] Example 1 The preparation method of the two-dimensional / three-dimensional perovskite heterojunction solar cell based on amidinium cations in this example includes the following steps: 1) A nanoparticle dispersion of NiO with a concentration of 10 mg / mL was coated on the transparent conductive substrate 1, spin-coated at 4000 r / 30 s, and annealed at 130 °C for 20 min to obtain a NiO hole transport layer 2 with a thickness of 20 nm. x 2) A solution of (4-(3,6-dimethyl-9H-carbazol-9-yl)butyl)phosphonic acid (Me-4PACz) with a concentration of 1 mg / mL was coated on the NiO hole transport layer 2, spin-coated at 3000 r / 30 s, and annealed at 100 °C for 10 min to obtain a self-assembled monolayer 3 after drying and annealing. x 4) 1.425 mmol of FAI, 0.075 mmol of CsI, 1.56 mmol of PbI2, and 0.225 mmol of MACl (methylammonium chloride) were dissolved in a 1 mL mixed solution of DMF (N,N-dimethylformamide) and DMSO (dimethyl sulfoxide) with a volume ratio of 4:1 to obtain a perovskite precursor solution B. The perovskite precursor solution B was coated on the self-assembled monolayer 3, spin-coated at 3500 r / 15 s to form a perovskite liquid film with a thickness of about 3 μm, and then the perovskite liquid film was subjected to a gas extraction crystallization treatment at a pressure of 10 Pa for 30 s. Finally, it was annealed at 100 °C to obtain a three-dimensional perovskite active layer 4 with a thickness of 600 nm. 2) A solution of (4-(3,6-dimethyl-9H-carbazol-9-yl)butyl)phosphonic acid (Me-4PACz) with a concentration of 1 mg / mL was coated on the NiO hole transport layer 2, spin-coated at 3000 r / 30 s, and annealed at 100 °C for 10 min to obtain a self-assembled monolayer 3 after drying and annealing. x 3) 1.425 mmol of FAI, 0.075 mmol of CsI, 1.56 mmol of PbI2, and 0.225 mmol of MACl (methylammonium chloride) were dissolved in a 1 mL mixed solution of DMF (N,N-dimethylformamide) and DMSO (dimethyl sulfoxide) with a volume ratio of 4:1 to obtain a perovskite precursor solution B. The perovskite precursor solution B was coated on the self-assembled monolayer 3, spin-coated at 3500 r / 15 s to form a perovskite liquid film with a thickness of about 3 μm, and then the perovskite liquid film was subjected to a gas extraction crystallization treatment at a pressure of 10 Pa for 30 s. Finally, it was annealed at 100 °C to obtain a three-dimensional perovskite active layer 4 with a thickness of 600 nm. 3) 1.425 mmol of FAI, 0.075 mmol of CsI, 1.56 mmol of PbI2, and 0.225 mmol of MACl (methylammonium chloride) were dissolved in a 1 mL mixed solution of DMF (N,N-dimethylformamide) and DMSO (dimethyl sulfoxide) with a volume ratio of 4:1 to obtain a perovskite precursor solution B. The perovskite precursor solution B was coated on the self-assembled monolayer 3, spin-coated at 3500 r / 15 s to form a perovskite liquid film with a thickness of about 3 μm, and then the perovskite liquid film was subjected to a gas extraction crystallization treatment at a pressure of 10 Pa for 30 s. Finally, it was annealed at 100 °C to obtain a three-dimensional perovskite active layer 4 with a thickness of 600 nm.

[0034] 4) 3-Amidinopyridine hydrochloride was dissolved in isopropanol to obtain a solution with a concentration of 2 mg / mL. This solution was coated on the surface of the three-dimensional perovskite active layer 4 and annealed at 100 °C for 10 min to form a two-dimensional perovskite layer 5 with a thickness of 1 - 10 nm.

[0035] 5) Subsequently, an electron transport layer 6 of [6,6]-phenyl-C61-butyric acid isopropyl ester with a thickness of 80 nm, a hole blocking layer 7 of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline with a thickness of 5 nm, and a Ag conductive electrode 8 with a thickness of 100 nm were sequentially deposited on the two-dimensional perovskite layer 5.

[0036] Please refer to Figure 2 As shown, in this example, 3-amidinopyridine hydrochloride was used to form a two-dimensional perovskite layer 5 on the upper surface of the perovskite. The prepared two-dimensional / three-dimensional perovskite heterojunction based on amidinium cations includes the two-dimensional perovskite layer 5, the three-dimensional perovskite active layer 4, the amidinium two-dimensional layer 51 formed by 3-amidinopyridine hydrochloride amidinium cations, the formamidinium cation FA + or the cesium cation Cs + 41.

[0037] See Figure 3, It can be seen from the XRD results that after the surface treatment of 3-aminopyridine hydrochloride, the corresponding two-dimensional peaks (7.2 o ).

[0038] See Figure 4 , It can be seen that after the 3-aminopyridine hydrochloride forms a two-dimensional perovskite layer 5 on the surface of the perovskite, the battery shows excellent open-circuit voltage, fill factor and photoelectric conversion efficiency.

[0039] See Figure 5 , It can be seen that after the 3-aminopyridine hydrochloride forms a two-dimensional perovskite layer 5 on the surface of the perovskite, the battery shows excellent stability under light illumination and at 85 °C.

[0040] Example 2 It is different from Example 1 in that in step 4), 2-phenylethanimidamide hydrochloride is dissolved in isopropanol to obtain a solution with a concentration of 2 mg / mL. This solution is coated on the surface of the three-dimensional perovskite active layer 4 film and annealed at 100 °C for 10 min to form a 1-10 nm two-dimensional perovskite layer.

[0041] The preparation methods of the remaining layers are the same as those in Example 1.

[0042] Example 3 It is different from Example 1 in that in step 4), benzamidinehydroiodide is dissolved in isopropanol to obtain a solution with a concentration of 2 mg / mL. This solution is coated on the surface of the three-dimensional perovskite active layer 4 film and annealed at 100 °C for 10 min to form a 1-10 nm two-dimensional perovskite layer.

[0043] The preparation methods of the remaining layers are the same as those in Example 1.

[0044] Example 4 It is different from Example 1 in that in step 4), 4-methoxybenzamidinehydrochloride is dissolved in isopropanol to obtain a solution with a concentration of 2 mg / mL. This solution is coated on the surface of the three-dimensional perovskite active layer 4 film and annealed at 100 °C for 10 min to form a 1-10 nm two-dimensional perovskite layer.

[0045] The preparation methods of the remaining layers are the same as those in Example 1.

[0046] Example 5 It is different from Example 1 in that in step 4), 4-phenylbenzimidine hydrochloride (biphenyl-4-carboxamidine hydrochloride) is dissolved in isopropanol to obtain a solution with a concentration of 2 mg / mL. This solution is coated on the surface of the three-dimensional perovskite active layer 4 film and annealed at 100 °C for 10 min to form a two-dimensional perovskite layer with a thickness of 1-10 nm.

[0047] The preparation methods of the remaining layers are the same as those in Example 1.

[0048] The test results of the photoelectric conversion performance and stability of the perovskite solar cells prepared in Examples 1 to 5 of the present invention are shown in the following table:

[0049] It shows that parameters such as the short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (Fill Factor, FF), and photoelectric conversion efficiency (Photoelectric Conversion Efficiency, PCE) of the solar cells prepared in the examples of the present invention are relatively high, and the prepared perovskite solar cells have excellent photoelectric performance.

[0050] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A two-dimensional / three-dimensional perovskite heterojunction based on amidine cations, characterized in that: The two-dimensional perovskite layer is deposited on the surface of the three-dimensional perovskite layer, and the spacer cations of the two-dimensional perovskite layer are amidine cations.

2. The two-dimensional / three-dimensional perovskite heterojunction based on amidine cations according to claim 1, characterized in that: The two-dimensional perovskite layer is prepared by the following method: a perovskite precursor solution A is deposited on the surface of a three-dimensional perovskite layer, and a two-dimensional perovskite layer is formed after annealing; the perovskite precursor solution A contains an amidine salt derivative.

3. The two-dimensional / three-dimensional perovskite heterojunction based on amidine cations according to claim 2, characterized in that: The amidine salt derivatives include 3-aminopyridine hydrochloride, 2-phenylacetamidine hydrochloride, benzamidine hydrochloride, 4-methoxybenzamidine hydrochloride or 4-phenylbenzamidine hydrochloride.

4. The two-dimensional / three-dimensional perovskite heterojunction based on amidine cations according to claim 2, characterized in that: The annealing temperature of the two-dimensional perovskite layer is 100-120° C., and the annealing time is 5-10 minutes.

5. The two-dimensional / three-dimensional perovskite heterojunction based on amidine cations according to claim 1, characterized in that: The thickness of the two-dimensional perovskite layer is 1-10 nm.

6. Application of the two-dimensional / three-dimensional perovskite heterojunction based on amidine cations as claimed in claim 1 in solar cells.

7. A perovskite solar cell, characterized in that: The invention comprises a transparent conductive substrate, a hole transport layer, a two-dimensional / three-dimensional perovskite heterojunction based on amidine cations as claimed in claim 1, an electron transport layer and a metal back electrode which are arranged in sequence from bottom to top.

8. The perovskite solar cell according to claim 7, characterized in that The three-dimensional perovskite layer is prepared by the following method: coating a perovskite precursor solution B on a hole transport layer to form a perovskite liquid film, and then performing vacuum crystallization annealing to obtain a three-dimensional perovskite layer.

9. The perovskite solar cell according to claim 8, characterized in that: During the preparation of the three-dimensional perovskite layer, the time for vacuum crystallization is 10-50 seconds, the temperature for annealing is 100-120° C., and the annealing time is 20-30 minutes.

10. The perovskite solar cell according to claim 7, characterized in that: The thickness of the three-dimensional perovskite layer is 400-800 nm.

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