Preparation method of solar cell containing carbonyl and C / S and capable of self-crosslinking dual-function interface layer

Abstract

The invention provides a bifunctional interface material with carbonyl and C = S double bonds and self-crosslinking capability, which is applied to a perovskite solar cell. The material can be self-crosslinked under heat treatment to form a compact moisture-resistant interface layer, so that the stability of a device is improved; the carbonyl group and the C = S group are used as Lewis base sites, Pb < 2 + > defects on the surface of perovskite can be passivated, non-radiative recombination is inhibited, and the service life of carriers is prolonged. Meanwhile, the material can regulate and control the energy level arrangement between perovskite and a hole transport layer and enhance the hole extraction and transmission efficiency, so that the photoelectric conversion efficiency and the environmental stability of the device are remarkably improved. According to the bifunctional molecule, collaborative optimization of structural design and interface functions is realized, and a new strategy is provided for constructing an efficient and stable perovskite battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to a method for preparing a solar cell having a self-crosslinkable dual-functional interface layer containing carbonyl and C=S. Background Art

[0002] Solar energy, as a clean energy with abundant reserves and no pollution, has become a hot topic in scientific research and commercial applications. Among them, solar cells can directly convert solar radiation into electrical energy without polluting the environment, making them an ideal way to obtain solar energy. As a representative of the third generation of solar cells, organic-inorganic hybrid perovskite solar cells (ABX3, A= CH3NH3 + NHCHNH3 + 、Cs + 、Ru + , K + etc., B = Pb 2+ and Sn 2+ etc., X = Cl - Br - and I - It has become a research hotspot in the field of solar cells due to its many advantages such as high photoelectric conversion efficiency, simple preparation process, low cost, solution preparation and large-area preparation, and has great application potential.

[0003] Perovskite solar cells are prepared using a solution-based process, which inevitably leads to the presence of numerous defect states at the interface between the perovskite light-absorbing layer and the hole-transporting layer. These defects not only trap charge carriers, causing non-radiative recombination and reducing carrier lifetime, but also serve as adsorption sites for water and oxygen in the air, causing degradation of the perovskite light-absorbing layer and severely compromising the long-term stability of the device. Furthermore, the poor alignment of the HOMO energy levels of conventional hole-transport materials such as poly(4-phenyl)(2,4,6-trimethylphenyl)amine) (PTAA) and 2,2",7,7"-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD) with those of the perovskite layer also compromises hole transport efficiency, leading to performance degradation. Therefore, the design and development of multifunctional interface materials that can optimize energy level alignment and passivate defects is crucial for achieving efficient and stable perovskite solar cells. Summary of the Invention

[0004] In view of the shortcomings of the background technology, the present invention provides a method for preparing a solar cell having a dual-functional interface layer containing carbonyl and C=S and capable of self-crosslinking.

[0005] A solar cell having a self-crosslinkable bifunctional interface layer containing carbonyl and C=S bonds, comprising a bifunctional interface layer; the bifunctional interface layer is a type of self-crosslinkable bifunctional interface material containing carbonyl and C=S double bonds, and has the structures shown in formulas (1) to (15).

[0006] In the present invention, specifically, the perovskite solar cell comprises, from bottom to top, a transparent conductive substrate 1, an electron transport layer 2, a perovskite light absorption layer 3, a dual-functional interface layer 4, a hole transport layer 5, and a metal electrode layer 6. The dual-functional interface layer 4 is located between the perovskite light absorption layer 3 and the hole transport layer 5.

[0007] The transparent conductive substrate 1 is FTO, ITO, etc.

[0008] The electron transport layer 2 is made of traditional electron transport materials such as tin dioxide (SnO2) or titanium dioxide (TiO2).

[0009] The chemical formula of the perovskite light absorbing layer 3 is ABX3, where A is CH3NH3 + (MA + ), NH2=CHNH2 + (FA + )、C4H9NH3 + 、Cs + , Rb + , K + Any one or a mixture of several; B is Pb 2+ , Sn 2+ 、Ge 2+ At least one of the following; X is Cl - Br - , I - Any one or a mixture of the above.

[0010] The dual-functional interface layer 4 is a self-crosslinking dual-functional interface material containing a carbonyl group and a C=S double bond.

[0011] The hole transport layer 5 is made of traditional hole transport materials such as poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) and 2,2",7,7"-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD).

[0012] The material of the metal electrode layer 6 is gold (Au) or silver (Ag).

[0013] The beneficial effects of the present invention are as follows: the present invention adopts a cross-linkable bifunctional interface material containing carbon and C=S double bonds as the interface layer between the perovskite and the hole transport layer, and the carbonyl and C=S double bonds can act as Lewis base sites to passivate the uncoordinated Pb on the perovskite surface. 2+ The dual-functional interface layer can eliminate defects and reduce non-radiative carrier recombination centers. At the same time, it can optimize the energy level arrangement between the perovskite layer and the hole transport layer, improving the extraction and transmission efficiency of photogenerated holes. In addition, during annealing, the vinyl groups on the dual-functional interface material can undergo a cross-linking reaction, thereby forming a protective layer on the perovskite layer, improving the moisture resistance of the interface and the long-term stability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the solar cell structure of the present invention.

[0015] Figure 2 Flow chart of the preparation of the dual-functional interface layer of the present invention.

[0016] Figure 3 Water contact angle test of the perovskite films prepared in Comparative Example 1 and Example 2.

[0017] Figure 4 Performance of the perovskite films prepared in Comparative Example 1 and Example 2 in solar cell applications: (a) JV performance; (b) long-term air stability. DETAILED DESCRIPTION

[0018] The present invention will be further described below with reference to specific embodiments.

[0019] like Figure 1 As shown, the solar cell of the present invention includes, from bottom to top, a transparent conductive substrate 1, an electron transport layer 2, a perovskite light absorption layer 3, a dual-functional interface layer 4, a hole transport layer 5 and a metal electrode 6; a dual-functional interface layer 4 is added between the perovskite light absorption layer 3 and the hole transport layer 5, and the dual-functional interface layer 4 is a type of dual-functional interface material molecule containing a carbonyl group and a C=S double bond and being cross-linkable.

[0020] The preferred material of the transparent conductive substrate 1 is FTO glass.

[0021] The preferred electron transport layer 2 is tin dioxide (SnO2). The electron transport layer solution is prepared as follows: dilute a 15 wt% SnO2 aqueous solution with a mixture of isopropyl alcohol and H2O (v / v = 1) at a dilution ratio of 2.75:1. Stir and filter. The electron transport layer solution is formulated using a ratio well known to those skilled in the art and is not particularly limited.

[0022] The preferred dual-functional interface layer 4 is material (3). The dual-functional interface layer solution is prepared as follows: Material (3) is dissolved in chlorobenzene solvent to form a solution. The selected chlorobenzene can be any chlorobenzene well known to those skilled in the art and is not particularly limited. The concentration of the dual-functional interface material is preferably: 0.4 mg / mL, 0.8 mg / mL, 1.2 mg / mL.

[0023] The preferred chemical formula of the perovskite light absorbing layer 3 is Cs 0.05 ((FA) 0.95 (MA) 0.05 ) 0.95 Pb(I 0.95 Br 0.05 )3. The perovskite precursor solution was prepared as follows: Solution 1: Dissolve 103.92 mg of CsI in 200 μL of DMSO and stir thoroughly. Solution 2: Dissolve 548.6 mg of PbI2, 77.07 mg of PbBr2, 190.12 mg of NH2=CHNH2I (FAI), and 21.84 mg of CH3NH3Br (MABr) in 1 mL of a DMSO and DMF mixture (4:1 volume ratio of DMF to DMSO) and stir thoroughly. Add 34 μL of Solution 1 to Solution 2 and stir thoroughly to obtain the perovskite precursor solution. The perovskite light absorbing layer solution has a composition well known to those skilled in the art and is not particularly limited.

[0024] The preferred hole transport layer 5 is a mixture of 2,2",7,7"-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), lithium bis(trifluoromethanesulfonyl imide), and 4-tert-butylpyridine. The hole transport layer solution is prepared as follows: 72.3 mg of Spiro-OMeTAD is dissolved in 1 mL of chlorobenzene, followed by the addition of 17.5 μL of Li-TFSI solution (520 mg of Li-TFSI dissolved in 1 mL of acetonitrile) and 28.8 μL of tBP. The mixture is stirred and filtered. The hole transport layer solution has a ratio well known to those skilled in the art and is not particularly limited.

[0025] The preferred metal electrode 6 is gold (Au).

[0026] Comparative Example 1 In this example, an electron transport layer is provided on the transparent conductive substrate. The electron transport layer is prepared by spin-coating the electron transport layer solution onto the transparent conductive substrate at 3000 rpm for 30 seconds and annealing at 150°C for 30 minutes to obtain the electron transport layer. The electron transport layer preparation method is well known to those skilled in the art and is not particularly limited.

[0027] A perovskite light-absorbing layer is disposed on the electron transport layer. The perovskite light-absorbing layer is prepared by spin-coating a perovskite precursor solution at a low speed (1300 rpm for 10 seconds) and then at a high speed (5000 rpm for 45 seconds) onto the electron transport layer. 200 μL of chlorobenzene is then added dropwise 15 seconds before the end of the high-speed spin coating. After the spin coating, the solution is annealed at 110°C for 1 hour to obtain the perovskite light-absorbing layer. The perovskite layer preparation method is well known to those skilled in the art and is not particularly limited.

[0028] A hole transport layer is disposed on the perovskite light-absorbing layer. The hole transport layer is prepared by spin-coating a hole transport layer solution onto the perovskite light-absorbing layer at 3000 rpm for 30 seconds to obtain the hole transport layer. The hole transport layer can be any hole transport layer known to those skilled in the art and is not particularly limited.

[0029] A metal electrode is disposed on the hole transport layer; the thickness of the metal electrode layer is preferably 500 nm. The metal electrode layer can be any electrode layer known to those skilled in the art without any particular limitation.

[0030] Example 1 The preparation method of the electron transport layer in this example is consistent with that in Comparative Example 1.

[0031] The concentration of the dual-functional interface material (3) used in this example is 0.4 mg / mL.

[0032] The perovskite light absorbing layer and the dual-functional interface layer are prepared as follows: Figure 2 As shown, the perovskite precursor was first spin-coated at a low speed (1300 rpm, 10s), and then spin-coated onto the electron transport layer at a high speed (5000 rpm, 45s). 200 μL of the dual-functional interface material solution was added as an anti-solvent 15s before the end of the high-speed spin coating. After the spin coating was completed, annealing was performed at 110 °C for 1h to obtain the perovskite layer and the dual-functional interface layer.

[0033] The preparation method of the hole transport layer and the metal electrode in this example is consistent with that in Comparative Example 1.

[0034] Example 2 The preparation method of the electron transport layer in this example is consistent with that in Comparative Example 1.

[0035] The concentration of the dual-functional interface material (3) used in this example is 0.8 mg / mL.

[0036] The perovskite light absorbing layer and the dual-functional interface layer are prepared as follows: Figure 2As shown, the perovskite precursor was first spin-coated at a low speed (1300 rpm, 10s), and then spin-coated onto the electron transport layer at a high speed (5000 rpm, 45s). 200 μL of the dual-functional interface material solution was added as an anti-solvent 15s before the end of the high-speed spin coating. After the spin coating was completed, annealing was performed at 110 °C for 1h to obtain the perovskite layer and the dual-functional interface layer.

[0037] The preparation method of the hole transport layer and the metal electrode in this example is consistent with that in Comparative Example 1.

[0038] Example 3 The preparation method of the electron transport layer in this example is consistent with that in Comparative Example 1.

[0039] The concentration of the dual-functional interface material (3) used in this example is 1.2 mg / mL.

[0040] The perovskite light absorbing layer and the dual-functional interface layer are prepared as follows: Figure 2 As shown, the perovskite precursor was first spin-coated at a low speed (1300 rpm, 10s), and then spin-coated onto the electron transport layer at a high speed (5000 rpm, 45s). 200 μL of the dual-functional interface material solution was added as an anti-solvent 15s before the end of the high-speed spin coating. After the spin coating was completed, annealing was performed at 110 °C for 1h to obtain the perovskite layer and the dual-functional interface layer.

[0041] The preparation method of the hole transport layer and the metal electrode in this example is consistent with that in Comparative Example 1.

[0042] The perovskite films prepared in Comparative Example 1 and Example 2 were tested at room temperature (25±2° C.) and a humidity of 50±5%.

[0043] Figure 3 Using the static contact angle method, deionized water droplets (approximately 2 μL) were added to the surfaces of the perovskite film samples prepared in Comparative Example 1 and Example 2. The instrument automatically captured the droplet profile and calculated the contact angle. The first water contact angle was recorded starting at 0 min, and subsequent water contact angles were recorded at 4-min intervals until 12 min. The water contact angle of the perovskite film in Example 2 was significantly higher than that of the perovskite film in Comparative Example 1. Therefore, the cross-linkable bifunctional interface material containing carbonyl and C=S groups can enhance the hydrophobicity of the perovskite film, thereby effectively preventing corrosion of the perovskite layer by water vapor in the air.

[0044] The solar cells prepared in Comparative Example 1 and Example 2 were subjected to photoelectric performance tests and stability tests under a standard sunlight.

[0045] Figure 4(a) JV performance of the perovskite films prepared in Comparative Example 1 and Example 2 in solar cells. The cell based on the perovskite film prepared in Example 2 was subjected to a standard simulated sunlight (100 mW cm -2 ) achieved a photoelectric conversion efficiency of 20.74% (J sc = 24.51 mA cm -2 , V oc = 1.12 V, FF = 0.81), which is significantly higher than the cell performance based on the perovskite film of Comparative Example 1 (PCE = 21.43%, J sc = 24.36 mA cm -2 , V oc = 1.11V, FF = 0.79). Figure 4 (b) Long-term environmental stability testing of the perovskite solar cells prepared in Comparative Example 1 and Example 2. After exposure to ambient air (room temperature, 50-85% relative humidity) for 60 days, the perovskite thin film prepared in Example 2 maintained 89% of its initial efficiency, while the perovskite thin film prepared in the comparative example maintained only 77% of its initial efficiency. Therefore, perovskite solar cells based on a cross-linkable dual-functional interface material containing carbonyl and C=S groups exhibit superior photovoltaic performance and long-term stability.

[0046] The above description is merely an illustration of the present invention and is not intended to limit the scope of protection of the present invention. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A solar cell having a self-crosslinkable dual-functional interface layer containing carbonyl and C=S groups, comprising, from bottom to top, a transparent conductive substrate 1, an electron transport layer 2, a perovskite light absorption layer 3, a dual-functional interface layer 4, a hole transport layer 5, and a metal electrode 6; characterized in that: A dual-function interface layer 4 is provided between the perovskite light-absorbing layer 3 and the hole transport layer 5 .

2. The solar cell comprising a self-crosslinkable dual-functional interface layer containing carbonyl and C=S according to claim 1, characterized in that: The dual-functional interface layer 4 is a self-crosslinking interface material containing carbonyl and C=S.

3. The self-crosslinkable interface material containing carbonyl and C=S according to claim 2, characterized in that: The interface material is one of the following materials: 。 4. The solar cell comprising a self-crosslinkable dual-functional interface layer containing carbonyl and C=S according to claim 1, characterized in that: The material of the electron transport layer 2 is a traditional electron transport material such as tin dioxide (SnO2) or titanium dioxide (TiO2).

5. The solar cell comprising a self-crosslinkable dual-functional interface layer containing carbonyl and C=S according to claim 1, characterized in that: The chemical structure of the perovskite light absorbing layer 3 is generally: ABX3, where A is CH3NH3 + (MA + ), NH2=CHNH2 + (FA + )、C4H9NH3 + 、Cs + , Rb + , K + Any one or a mixture of several; B is Pb 2+ , Sn 2+ 、Ge 2+ At least one of the following; X is Cl - Br - , I - Any one or a mixture of the above.

6. The solar cell comprising a self-crosslinkable dual-functional interface layer containing carbonyl and C=S according to claim 1, characterized in that: The material of the metal electrode 6 is gold or silver.

7. The solar cell comprising a self-crosslinkable dual-functional interface layer containing carbonyl and C=S according to claim 1, characterized in that: The hole transport layer 5 is made of conventional hole transport materials such as poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) and 2,2",7,7"-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD).

8. Use of a self-assembled hole transport material containing a bidentate passivation unit according to any one of claims 1 to 7, characterized in that: Application in perovskite-based solar cells.

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