Perovskite solar cell containing crosslinkable hole transport material and preparation method thereof

Abstract

The invention belongs to the technical field of solar cells, and relates to a perovskite solar cell containing a crosslinkable hole transport material and a preparation method of the perovskite solar cell. The cross-linkable hole transport material is doped in the self-assembled molecular layer, and the cross-linkable hole transport material takes carbazole and benzocarbazole as a hole transport structure, phosphoric acid as an anchoring group and R3 as a cross-linking group, so that the prepared hole transport layer can reduce the recombination of photon-generated carriers of the perovskite solar cell and improve the photoelectric conversion efficiency of the perovskite solar cell. And the open-circuit voltage, the filling factor and the photoelectric conversion efficiency of the perovskite solar cell are obviously improved. The photoelectric property of the device is improved, and the device has the characteristics of lower cost and easiness in preparation, and is expected to be widely applied to industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and relates to a perovskite solar cell containing a crosslinkable hole transport material and a preparation method thereof. Background Art

[0002] Energy is the driving force for the progress of human society. While human society is constantly developing, it has also brought problems such as environmental pollution and climate change. In today's era, seeking green, clean, and renewable energy has become a global consensus and urgent need, and solar energy is the most in line with the requirements. A solar cell is a technology that directly converts solar energy into electrical energy using the photovoltaic effect, and perovskite solar cells (PSCs) have received extensive attention due to their adjustable bandgap, high light absorption coefficient, excellent carrier mobility, and low-cost manufacturing process. Perovskite solar cells use a perovskite thin film as a light absorption layer to generate current through the separation and transport of photo-generated charges, achieving energy conversion. Compared with traditional silicon-based solar cells, perovskite solar cells have a higher theoretical photoelectric conversion efficiency and are more suitable for large-scale production and commercial applications. After nearly 15 years of development, the photoelectric conversion efficiency of perovskite solar cells has been continuously improved. Currently, the photoelectric conversion efficiency of perovskite solar cells has exceeded 27%, and its certified PCE reaches 26.95%. However, perovskite solar cells still face some problems, such as the need for further research and improvement in terms of long-term stability and material lifespan.

[0003] In recent years, the crosslinking strategy of crosslinkable organic molecules has received extensive attention due to its great potential in simultaneously improving the intrinsic stability, processing stability, thermal stability, and mechanical stability of perovskites. However, the current application of crosslinkable organic molecules may have the following problems: (1) The performance cannot be balanced. For example, the crosslinking process will change the microstructure and aggregation state of hole transport molecules, resulting in changes in molecular crystallinity. The introduction of some crosslinking agents may significantly reduce the hole mobility, slow down the transport speed of carriers in the hole transport layer, increase the transport resistance, and thus lead to a decrease in the fill factor (FF) of the battery; (2) The crosslinking conditions are harsh. Some require high temperatures above 150°C or ultraviolet irradiation crosslinking, which conflicts with the thermal sensitivity of perovskites. (3) The efficiency upper limit is low. Currently, the highest efficiency of perovskite solar cells using a hole transport layer containing a crosslinking agent is only 23.9%. Compared with the highest certified efficiency of 26.95% of perovskite solar cells without using the crosslinking strategy, there is still a large gap. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a perovskite solar cell containing a crosslinkable hole transport material and a preparation method thereof. The introduction of the crosslinkable hole transport material can promote the crystallization process of the perovskite absorption layer, improve the film-forming quality of the perovskite, and regulate the stress state of the light-absorbing layer to improve the performance of the perovskite solar cell.

[0005] One aspect of the present invention is to provide a perovskite solar cell containing a crosslinkable hole transport material, wherein the hole transport layer of the perovskite solar cell includes a crosslinkable hole transport material, and the crosslinkable hole transport material has a structural formula shown in Formula I:

[0006]

[0007] R 1 、R 2 can independently be selected from one of H, F, Cl, Br, CN, CF3, CCl3, CBr3, (CH2) x CH3, O(CH2) x CH3, or a substituted or unsubstituted phenyl group;

[0008] R 3 is one of;

[0009] wherein, n, x, a, b, and c are independently integers from 0 to 5. Such as any integer among 0, 1, 2, 3, 4, and 5.

[0010] Preferably, the hole transport layer includes a self-assembled monolayer (SAM) and a crosslinkable hole transport material.

[0011] Preferably, the mass ratio of the crosslinkable hole transport material to SAM is 1:9 to 4:6.

[0012] Preferably, the SAM is one or more of (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid (4PADCB), [4-(9H-carbazol-9-yl)butyl]phosphonic acid (4PACz), (2-(3,6-bis(3-methoxyphenyl)-9H-carbazol-9-yl)ethyl)phosphonic acid (m-PhPACz), [4-(3,6-bis-(bromoammonium)-9H-carbazol-9-yl)butyl]phosphonic acid (BrNH3-4PACz), (4-(9'-phenyl-9H,9'H-[3,3'-bicarbazole]-9-yl)butyl)phosphonic acid (4PABCz), (4-(10H-spiro[acridine-9,9'-fluorene]-10-yl)butyl)phosphonic acid (4PA-spiro), 5-{4-[bis(4-fluorophenyl)amino]phenyl}thiophene-2-carboxylic acid (FTPATC), (4-(3-fluoro-6-methoxy-9H-carbazol-9-yl)butyl)phosphonic acid (MeOF-4PACz), (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz), (2-(3,6-bis(thiophen-2-yl)-9H-carbazol-9-yl)ethyl)phosphonic acid (S-2PACz).

[0013] Preferably, the thickness of the hole transport layer is 2 to 20 nm.

[0014] Preferably, the perovskite solar cell includes a transparent conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, an electron modification layer, and a back electrode stacked in sequence from bottom to top.

[0015] Preferably, the transparent conductive substrate is one or more of indium tin oxide (ITO) transparent conductive glass, fluorine-doped tin oxide (FTO) transparent conductive glass, and aluminum-doped zinc oxide (AZO) transparent conductive glass.

[0016] The perovskite light-absorbing layer includes a perovskite material, which generally refers to a compound with the general formula ABX3, where A is a metal cation (such as cesium ion) or an organic cation (such as methylamine CH3NH3 + ), B is a metal cation (such as Pb 2+ , Sn 2+ ), and X is one or more of halogen anions. The thickness of the perovskite light-absorbing layer is 300 to 800 nm.

[0017] Preferably, the material of the electron transport layer is fullerene or its derivative, which can be exemplified by C 60 , C 60 derivative, [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM), C 70 , C 70 derivative, etc. The thickness of the electron transport layer is 10 to 40 nm.

[0018] Preferably, the material of the electron modification layer is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP). The thickness of the electron modification layer is 3-15 nm.

[0019] Preferably, the back electrode is one or more of Ag, Au, copper-nickel alloy, and carbon-based materials. The thickness of the back electrode is 50-100 nm.

[0020] Another aspect of the present invention lies in providing a method for preparing a perovskite solar cell containing a crosslinkable hole transport material, comprising the following steps:

[0021] Step S1: Pretreat the transparent conductive substrate;

[0022] Step S2: Spin-coat a solution containing a crosslinkable hole transport material on the transparent conductive substrate prepared in Step S1, and perform annealing treatment to obtain a hole transport layer;

[0023] Step S3: Further spin-coat a perovskite precursor solution on the hole transport layer prepared in Step S2, and after annealing treatment, obtain a perovskite absorption layer;

[0024] Step S4: Evaporate and deposit an electron transport layer material, an electron modification layer material, and a back electrode material in sequence on the substrate obtained in Step S3 to obtain an electron transport layer, an electron modification layer, and a back electrode.

[0025] Preferably, the pretreatment in Step S1 includes: cleaning the transparent conductive substrate and drying it with an inert gas, and then treating it with ultraviolet ozone. The inert gas is nitrogen, argon, etc. During the ultraviolet ozone treatment, the strong oxidizing property of O3 is used to clean the residual organic substances on the ITO surface, etc. At the same time, the oxygen vacancies on the ITO surface can be increased, the work function of the ITO surface can be improved, and the surface activity of the ITO conductive glass can be improved, which is beneficial to the preparation of the hole transport layer.

[0026] Preferably, the preparation method of the hole transport layer in Step S2 is as follows: dissolve the crosslinkable hole transport material with a solvent to obtain a solution, and then spin-coat the solution on the transparent conductive substrate and anneal it at 100-150 °C for 10-15 min to obtain the hole transport layer.

[0027] Further preferably, the preparation method of the hole transport layer in Step S2 is as follows: dissolve SAM and the crosslinkable hole transport material with a solvent to obtain a solution; then spin-coat the solution on the transparent conductive substrate and anneal it at 100-150 °C for 10-15 min to obtain the hole transport layer.

[0028] Preferably, the concentration of SAM is 0.1-1 mg / ml, and the mass ratio of the crosslinkable hole transport material to SAM is 1:9-4:6.

[0029] Preferably, in step S3, the perovskite precursor solution is formed by dissolving a perovskite precursor in a solvent. During the spin coating process, an anti-solvent is added dropwise. The anti-solvent is a solvent that cannot dissolve the perovskite precursor.

[0030] The anti-solvent can be exemplified by one or more of diethyl ether, ethyl acetate, chlorobenzene, anisole, etc. The added dropwise volume of the anti-solvent is 10 - 20 times the volume of the perovskite precursor solution.

[0031] Preferably, the annealing treatment temperature in step S3 is 100 - 130 °C, and the annealing time is 15 - 50 min.

[0032] The solvent in this article refers to one or more of alcohol solvents, ketone solvents, dimethyl sulfoxide, and N,N-dimethylformamide.

[0033] The rotation speed of spin coating in this article is 1000 - 6000 rpm / min, and the spin coating time is 10 - 70 s.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] In the present invention, a crosslinkable hole transport material is doped in the self-assembled molecular layer. The crosslinkable hole transport material has a hole transport structure based on carbazole and benzocarbazole, a phosphoric acid as an anchoring group, and an R 3 group as a crosslinking group; the doped crosslinkable hole transport material has the following advantages:

[0036] (1) The crosslinkable hole transport material can promote the crystallization process of the perovskite absorption layer and improve the film-forming quality of the perovskite: It can be seen from the PL spectrum that after mixing the crosslinkable hole transport material, the PL intensity of the perovskite film is significantly improved, indicating that the grain size of the film becomes larger and non-radiative recombination is inhibited; the scanning electron microscope spectrum (SEM) shows that the grain distribution of the perovskite film is denser and more uniform; the atomic force scanning probe spectrum (AFM) indicates that the surface roughness of the film is reduced and it is smoother and flatter.

[0037] (2) The addition of the crosslinkable hole transport material changes the energy level of the hole transport layer (HTL), forming an energy level arrangement conducive to hole transport: It can be characterized by ultraviolet photoelectron spectroscopy (UPS) that the doped crosslinkable hole transport material has a higher work function and a lower HOMO energy level, and this energy level change helps to improve the performance of the battery.

[0038] (3) The crosslinkable hole transport material can form an interpenetrating network under high-temperature annealing conditions, improve the stability of the hole transport layer, and further enhance the stability of the perovskite solar cell. At the same time, the recombination of photo-generated carriers is reduced, which helps the battery to maintain good performance during long-term use.

[0039] The open-circuit voltage of the perovskite solar cell prepared by the present invention is 1.140 - 1.160, the fill factor is 84 - 86%, and the photoelectric conversion efficiency is 24.5 - 26%. The photoelectric conversion efficiency is significantly better than the highest efficiency of the existing perovskite solar cells using a hole transport layer containing a crosslinking agent.

[0040] The present invention not only improves the photoelectric performance and stability of perovskite solar cell devices, but also has the characteristics of low cost and easy preparation, and is expected to be widely used in industrial production and the field of renewable energy. Description of the Drawings

[0041] Figure 1 The [M-H] mass spectrometry data of (2-methacryloyloxy-3-(9H-carbazol-9-yl)propyl)phosphonic acid prepared in Example 1 - Mass spectrometry data.

[0042] Figure 2 Schematic diagram of the layered structure of the perovskite solar cell prepared in the example.

[0043] Figure 3 J-V curve diagram of the perovskite solar cells of Examples 1-2 and Comparative Example 1 of the present invention.

[0044] Figure 4 In-situ variable-temperature infrared spectrum of Example 1.

[0045] Figure 5 Ultraviolet photoelectron spectroscopy (UPS) secondary electron cut-off edge of the perovskite light-absorbing layer of Examples 1-2 and Comparative Example 1 of the present invention. Figure a is Comparative Example 1, Figure b is Example 1, and Figure c is Example 2.

[0046] Figure 6 Ultraviolet photoelectron spectroscopy (UPS) valence band maximum (VBM) of the perovskite light-absorbing layer of Examples 1-2 and Comparative Example 1 of the present invention. Figure a is Comparative Example 1, Figure b is Example 1, and Figure c is Example 2.

[0047] Figure 7 Fluorescence spectrum (PL) and delayed fluorescence spectrum (TRPL) of the perovskite light-absorbing layer of Examples 1-2 and Comparative Example 1 of the present invention. Figure a is the PL spectrum, and Figure b is the TRPL spectrum.

[0048] Figure 8 Scanning electron microscope spectrum (SEM) of the perovskite light-absorbing layer of Examples 1-2 and Comparative Example 1 in the examples of the present invention. Figure a is Comparative Example 1, Figure b is Example 1, and Figure c is Example 2.

[0049] Figure 9The atomic force scanning probe spectra (AFM) of the perovskite light-absorbing layers of Examples 1-2 and Comparative Example 1 in the embodiments of the present invention. Figure a shows Comparative Example 1, Figure b shows Example 1, and Figure c shows Example 2. Detailed implementation manners

[0050] The technical solutions of the present invention will be further described and illustrated below through specific examples and drawings. It should be understood that the specific examples described herein are only used to help understand the present invention and are not used for specific limitations of the present invention. Moreover, the drawings used herein are only for better illustrating the disclosed content of the present invention and do not have a limiting effect on the protection scope. If there is no special description, the raw materials used in the embodiments of the present invention are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.

[0051] The reaction process of the crosslinkable hole transport material of the present invention is as follows:

[0052]

[0053] R in the reaction process 1 、R 2 、R 3 、n are defined in the same way as in Formula I.

[0054] The preparation method of the crosslinkable hole transport material includes the following steps:

[0055] S1. Compound 1 and Compound 2 react under the conditions of a base and a polar aprotic solvent. The reaction temperature is 20-100 °C, and the reaction time is 2-24 h to generate Compound 3;

[0056] S2. Compound 3 reacts with triethyl phosphite P(OEt)3 under the conditions of a Lewis acid catalyst and a polar solvent. The reaction temperature is 20-100 °C, and the reaction time is 2-24 h to generate Compound 4;

[0057] S3. Compound 4 and Compound 5 react under the conditions of a basic catalyst and a solvent. The reaction temperature is 20-100 °C, and the reaction time is 2-24 h to generate Compound 6;

[0058] S4. Compound 6 reacts with trimethylsilyl bromide (TMSBr) under the condition of a solvent. The reaction temperature is 20-80 °C, and the reaction time is 1-24 h to generate the crosslinkable hole transport material of Formula I.

[0059] The base in step S1 is one or more of K2CO3, KOH, NaOH, NaH, NEt3, Na2CO3, etc., and the polar aprotic solvent is one or more of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), etc.

[0060] The Lewis acid catalyst in step S2 is one or more of boron trifluoride, zinc chloride, aluminum trichloride, iron trichloride, etc. The polar solvent is one or more of tetrahydrofuran (THF), acetonitrile, methanol, ethanol, isopropanol, etc.

[0061] The basic catalyst in step S3 is one or more of K2CO3, KOH, NaOH, Na2CO3, NEt3, 4-dimethylaminopyridine (DMAP), pyridine, etc., and the solvent is one or more of methanol, dichloromethane, tetrahydrofuran, ethyl acetate, chloroform, etc.

[0062] The solvent in step S4 is one or more of methanol, dichloromethane, tetrahydrofuran, ethyl acetate, chloroform, etc.

[0063] The crosslinkable hole transport material used in Example 1 is (2-methacryloyloxy-3-(9H-carbazol-9-yl)propyl)phosphonic acid, which is prepared through the following steps:

[0064] S1. 10 mmol of carbazole and 10 mmol of epibromohydrin are reacted overnight at room temperature under the conditions of 20 mmol of KOH and 20 mL of DMF, extracted with dichloromethane, the solvent is evaporated to dryness, and separated by column chromatography to obtain 9-(oxiran-2-ylmethyl)-9H-carbazole;

[0065] S2. 8 mmol of 9-(oxiran-2-ylmethyl)-9H-carbazole reacts with 6 mmol of triethyl phosphite P(OEt)3 under the conditions of 8 mmol of ZnCl2 and 10 mL of THF, reacts overnight at room temperature, extracted with dichloromethane, the solvent is evaporated to dryness, and separated by column chromatography to obtain diethyl 3-(9H-carbazol-9-yl)-2-hydroxypropylphosphonate;

[0066] S3. 3 mmol of diethyl 3-(9H-carbazol-9-yl)-2-hydroxypropylphosphonate and 5 mmol of methylacrylic anhydride react under the conditions of 5 mmol of NEt3, 0.3 mmol of DMAP, and 10 mL of DCM, react overnight at room temperature, extracted with dichloromethane, the solvent is evaporated to dryness, and separated by column chromatography to obtain diethyl (2-methacryloyloxy-3-(9H-carbazol-9-yl)propyl)phosphonate;

[0067] S4. Under argon protection, 2 mmol of diethyl (2-methacryloyloxy-3-(9H-carbazol-9-yl)propyl)phosphonate reacts with 8 mmol of trimethylsilyl bromide (TMSBr) in 10 mL of DCM at room temperature overnight. After the reaction is completed, 1 mL of methanol is added, and then a large amount of distilled water is added to precipitate a solid. After filtration and drying, the crosslinkable hole transport material (2-methacryloyloxy-3-(9H-carbazol-9-yl)propyl)phosphonic acid is obtained.

[0068] The reaction process is as follows:

[0069]

[0070] [M-H] of the product prepared in Example 1 - The mass spectrometry data is as Figure 1 shown. The calculated molecular mass of C 19 H 19 NO5P is 372.1006, and the actually observed peak is 372.1033. The theoretical value is very close to the measured value, indicating that the product obtained by this preparation method is the calculated molecular formula.

[0071] The crosslinkable hole transport material used in Example 2 is (2-methacryloyloxy-3-(7H-dibenzo[c,g]carbazol-7-yl)propyl)phosphonic acid, which can be prepared by a similar procedure.

[0072] Example 1

[0073] The perovskite solar cell of this example is as Figure 2 shown, including an ITO conductive glass, a hole transport layer containing (2-methacryloyloxy-3-(9H-carbazol-9-yl)propyl)phosphonic acid, a perovskite light-absorbing layer, a C 60 electron transport layer, a BCP electron modification layer, and a silver metal electrode stacked in sequence from bottom to top.

[0074] The preparation method of the perovskite solar cell of this example is as follows:

[0075] Step S1: The ITO conductive glass is ultrasonically treated in ultrapure water with detergent, deionized water, acetone, and isopropanol for 30 min in sequence. The cleaned ITO conductive glass is dried with argon, and then treated with ultraviolet ozone for 30 min to obtain a clean ITO conductive glass substrate.

[0076] Step S2: Dissolve 0.64 mg of 4PADCB and 0.16 mg of (2-methacryloyloxy-3-(9H-carbazol-9-yl)propyl)phosphonic acid in 1 ml of ethanol solvent to obtain a solution; then spin-coat 80 μl of the mixed solution on the ITO conductive glass substrate at a spin-coating speed of 3000 rpm for 30 s, and anneal at 140 °C for 15 min to obtain the SAM hole transport layer with a thickness of 5 nm.

[0077] Step S3: Dissolve 0.82147 g of PbI2, 0.27698 g of formamidinium hydroiodide FAI, 0.00368 g of MABr, 0.0127 g of PbBr2, 0.01811 g of MACl, 0.004 g of PbCl2 and 0.02247 g of CsI in a mixed solvent of 833.33 μL of DMF and 166.67 μL of DMSO, stir at room temperature for 4 h to obtain a perovskite precursor solution. Take 55 μL of the perovskite precursor solution and drop it onto the SAM substrate obtained in Step S2, spin-coat at a speed of 3000 rpm for 30 s, and drop 670 μL of ethyl ether antisolvent at the 16th s. Anneal the ITO substrate coated with perovskite at 100 °C for 30 min to obtain the perovskite light-absorbing layer with a thickness of 600 nm.

[0078] Step S4: Evaporate 25 nm of C 60 onto the perovskite absorption layer obtained in Step S3 by vacuum thermal evaporation technology to obtain the perovskite electron transport layer.

[0079] Step S5: Evaporate 6 nm of BCP onto the perovskite electron transport layer obtained in Step S4 by vacuum thermal evaporation technology to obtain the perovskite electron transport modification layer.

[0080] Step S6: Evaporate 80 nm of silver as the electrode onto the electron transport modification layer obtained in Step S5 by vacuum thermal evaporation technology to obtain the perovskite solar cell.

[0081] Example 2

[0082] The perovskite solar cell of this example is as Figure 2 shown, including an ITO conductive glass, a hole transport layer containing (2-methacryloyloxy-3-((7H-dibenzo[c,g]carbazol-7-yl))propyl)phosphonic acid, a perovskite light-absorbing layer, C 60 electron transport layer, BCP electron modification layer, and metal silver electrode stacked in sequence from bottom to top.

[0083] The difference between the preparation method of the perovskite solar cell in this example and that in Example 1 is that step S2 in Example 2 is as follows: 0.64 mg of 4PADCB and 0.16 mg of (2-methacryloyloxy-3-(7H-dibenzo[c,g]carbazol-7-yl)propyl)phosphonic acid are respectively dissolved in 1 ml of ethanol solvent to obtain a solution, and then 80 μl of the mixed solution is spin-coated on an ITO conductive glass substrate at a spin-coating speed of 3000 rpm for 30 s, and annealed at 140 °C for 15 min to obtain a SAM hole transport layer with a thickness of 5 nm. Other steps are the same as those in Example 1.

[0084] Comparative Example 1

[0085] The difference between the preparation method of the perovskite solar cell in Comparative Example 1 and that in Example 1 is that step S2 in Comparative Example 1 is as follows: 0.80 mg of 4PADCB is dissolved in 1 ml of ethanol solvent to obtain a solution; then 80 μl of the mixed solution is spin-coated on an ITO conductive glass substrate at a spin-coating speed of 3000 rpm for 30 s, and annealed at 100 °C for 10 min to obtain a hole transport layer. Others are the same as those in Example 1.

[0086] Comparative Example 2

[0087] The difference between the preparation method of the perovskite solar cell in Comparative Example 2 and that in Example 1 is that step S2 in Comparative Example 1 is as follows: 0.80 mg of (2-methacryloyloxy-3-(9H-carbazol-9-yl)propyl)phosphonic acid is dissolved in 1 ml of ethanol solvent to obtain a solution; then 80 μl of the mixed solution is spin-coated on an ITO conductive glass substrate at a spin-coating speed of 3000 rpm for 30 s, and annealed at 140 °C for 15 min to obtain a hole transport layer. Others are the same as those in Example 1.

[0088] Comparative Example 3

[0089] The difference between the preparation method of the perovskite solar cell in Comparative Example 3 and that in Example 2 is that step S2 in Comparative Example 3 is as follows: 0.80 mg of (2-methacryloyloxy-3-(7H-dibenzo[c,g]carbazol-7-yl)propyl)phosphonic acid is dissolved in 1 ml of ethanol solvent to obtain a solution, and then 80 μl of the mixed solution is spin-coated on an ITO conductive glass substrate at a spin-coating speed of 3000 rpm for 30 s, and annealed at 140 °C for 15 min to obtain a SAM hole transport layer. Others are the same as those in Example 2.

[0090] Under standard test conditions (AM 1.5G illumination), the photoelectric conversion efficiency, open-circuit voltage, short-circuit current, and fill factor of the perovskite solar cells prepared in Examples 1-2 and Comparative Examples 1-3 are shown in Table 1.

[0091] Table 1 Performance data of perovskite solar cells in Examples 1-2 and Comparative Examples 1-3

[0092]

[0093] The effective area of the perovskite solar cells in the comparative examples and examples is 0.06 cm 2 . It can be seen from the J-V curve graph and Table 1 that the PCE of the perovskite solar cell without the mixed crosslinkable SAM in the 4PADCB hole transport layer is 24.37%, V oc is 1.131 V, J sc is 25.86 mA cm -2 , and the fill factor FF is 83.26%. When the crosslinkable SAM is mixed in the hole transport layer, the PCE of the perovskite solar cell is significantly improved. For Example 1, it is 25.73%, V oc is 1.150 V, J sc is 26.24 mA cm -2 , and the fill factor FF is 85.27%; for Example 2, it is 25.67%, V oc is 1.152 V, J sc is 25.98 mA cm -2 , and the fill factor FF is 85.79%. It is worth mentioning that when these two crosslinkable SAMs are used alone as the hole transport layer, their performance is average, and the PCEs are 10.89% and 22.88% respectively, V oc is 0.978 V and 1.129 V, J sc is 23.14 mA cm -2 and 25.54 mA cm -2 , and the FFs are 48.09% and 79.31% respectively. This indicates that after the crosslinkable SAM and 4PADCB are mixed, the device voltage, current and fill factor can be improved, thereby improving the device efficiency.

[0094] The crosslinking process of the SAM in Example 1 was detected by in-situ infrared spectroscopy. As Figure 4 shown, when the temperature is increased, the stretching vibration peak of the carbon-carbon double bond near 1637 cm -1 weakens, indicating that the SAM is partially crosslinked. The energy level changes of the perovskite light-absorbing layer in the comparative examples and examples were characterized by ultraviolet photoelectron spectroscopy. As Figure 5 shown, where Figure 5 a is the secondary electron cut-off edge of Comparative Example 1, Figure 5 b and 5c are the secondary electron cut-off edges of Example 1 and Example 2, indicating that the examples have a higher work function. Figure 6 a is the valence band maximum (VBM) of Comparative Example 1, Figure 6b and 6c are the maximum valence band values of Examples 1-2, from which it is deduced that the Examples have lower HOMO energy levels. This indicates that the addition of the crosslinkable SAM changes the energy levels of the HTL, forming an energy level arrangement that promotes holes. As Figure 7 shown in a, the PL intensity of the perovskite film with the crosslinkable SAM mixed in the hole transport layer is significantly enhanced, indicating that the addition of the crosslinkable SAM improves the film-forming quality of the perovskite film, increases the film grain size, and inhibits non-radiative recombination. As Figure 7 shown in b, the average lifetime of the perovskite film of Comparative Example 1 is 819 ns, while the lifetimes of the perovskite films with the crosslinkable SAM mixed in the hole transport layer increase to 1033 and 1301 ns. As Figure 8 shown, through scanning electron microscopy (SEM), it can be observed that the grain size distribution of the perovskite film of Comparative Example 1 is uneven, and the surface is uneven, with obvious grain boundaries visible. When the crosslinkable SAM is mixed in the hole transport layer, the perovskite film undergoes a more obvious morphological change, showing a denser and more uniform grain distribution. This indicates that after the SAM with crosslinking groups crosslinks, it can change the crystallization behavior of the upper perovskite, making it more conducive to growing perovskite films with larger and more uniform grain sizes. As Figure 9 shown, the surface roughness (R q ) of the perovskite film was measured by atomic force microscopy (AFM). The R q of Comparative Example 1 was measured to be 28.3 nm, while the surface roughness of Examples 1 and 2 decreased significantly, and their R q were 26.4 nm and 24.3 nm respectively. The test results of AFM show that mixing the crosslinkable SAM in the hole transport layer makes the perovskite film smoother and flatter.

[0095] All aspects, embodiments, and features of the present invention should be considered illustrative in all respects and do not limit the present invention. The scope of the present invention is only defined by the claims. Without departing from the spirit and scope of the claimed invention, those skilled in the art will understand other embodiments, modifications, and uses.

[0096] In the preparation method of the present invention, the order of each step is not limited to the listed order. For those of ordinary skill in the art, without creative efforts, the sequential changes of each step are also within the protection scope of the present invention. In addition, two or more steps or actions can be carried out simultaneously.

[0097] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the present invention and do not limit the implementation of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar ways to substitute. It is not necessary and impossible to list all embodiments here. And these obvious changes or variations derived from the essence of the present invention still fall within the protection scope of the present invention. Interpreting them as any additional restrictions is contrary to the spirit of the present invention.

Claims

1. A perovskite solar cell containing a crosslinkable hole transport material, characterized in that, The hole transport layer of the perovskite solar cell includes a crosslinkable hole transport material, and the crosslinkable hole transport material has the structural formula shown in Formula I: R 1 、R 2 may be independently selected from one of H, F, Cl, Br, CN, CF3, CCl3, CBr3, (CH2) x CH3, O(CH2) x CH3, and a substituted or unsubstituted phenyl; R 3 one of in; Wherein, n, x, a, and b are independently integers from 0 to 5.

2. The perovskite solar cell according to claim 1, wherein The hole transport layer includes SAM and the crosslinkable hole transport material.

3. The perovskite solar cell according to claim 2, wherein The mass ratio of the crosslinkable hole transport material to SAM is 1:9 to 4:

6.

4. The perovskite solar cell according to claim 2 or 3, characterized in that, The SAM is one or more of (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid, [4-(9H-carbazol-9-yl)butyl]phosphonic acid, (2-(3,6-bis(3-methoxyphenyl)-9H-carbazol-9-yl)ethyl)phosphonic acid, [4-(3,6-bis-(bromoammonium)-9H-carbazol-9-yl)butyl]phosphonic acid, (4-(9'-phenyl-9H,9'H-[3,3'-bicarbazole]-9-yl)butyl)phosphonic acid, (4-(10H-spiro[acridine-9,9'-fluorene]-10-yl)butyl)phosphonic acid, 5-{4-[bis(4-fluorophenyl)amino]phenyl}thiophene-2-carboxylic acid, (4-(3-fluoro-6-methoxy-9H-carbazol-9-yl)butyl)phosphonic acid, (2-(9H-carbazol-9-yl)ethyl)phosphonic acid, (2-(3,6-di(thiophen-2-yl)-9H-carbazol-9-yl)ethyl)phosphonic acid.

5. The perovskite solar cell according to claim 1, characterized in that, The perovskite solar cell includes a transparent conductive substrate, a hole transport layer, a perovskite light absorption layer, an electron transport layer, an electron modification layer, and a back electrode stacked in sequence from bottom to top.

6. The perovskite solar cell according to claim 5, characterized in that, The transparent conductive substrate is one or more of indium tin oxide transparent conductive glass, fluorine-doped tin oxide transparent conductive glass, and aluminum-doped zinc oxide transparent conductive glass; And / or, the material of the electron transport layer is fullerene or its derivative, and the thickness of the electron transport layer is 10 to 40 nm; And / or, the material of the electron modification layer is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, and the thickness of the electron modification layer is 3 to 15 nm; And / or, the back electrode is one or more of Ag, Au, copper-nickel alloy, and carbon-based materials, and the thickness of the back electrode is 50 to 100 nm.

7. The preparation method of a perovskite solar cell containing a crosslinkable hole transport material according to claim 1, characterized in that Including the following steps: Step S1: Pretreat the transparent conductive substrate; Step S2: Spin-coat a solution containing the crosslinkable hole transport material on the transparent conductive substrate prepared in Step S1, and perform annealing treatment to obtain a hole transport layer; Step S3: Further spin-coat a perovskite precursor solution on the hole transport layer prepared in Step S2, and perform annealing treatment to obtain a perovskite absorption layer; Step S4: Evaporate the electron transport layer material, the electron modification layer material, and the back electrode material in sequence on the substrate obtained in Step S3 to obtain an electron transport layer, an electron modification layer, and a back electrode.

8. The preparation method according to claim 7, characterized in that, The preparation method of the hole transport layer in Step S2 includes: dissolving the crosslinkable hole transport material with a solvent to obtain a solution, then spin-coating the solution on the transparent conductive substrate, and annealing at 100 to 150 °C for 10 to 15 min to obtain the hole transport layer.

9. The preparation method according to claim 7, characterized in that, The preparation method of the hole transport layer in step S2 includes: dissolving SAM and a crosslinkable hole transport material in a solvent to obtain a solution; then spin-coating the solution on a transparent conductive substrate and annealing at 100-150 °C for 10-15 min to obtain the hole transport layer.

10. The preparation method according to claim 7, characterized in that, In step S3, the perovskite precursor solution is formed by dissolving a perovskite precursor in a solvent. During the spin-coating process, an anti-solvent is added dropwise, and the anti-solvent is a solvent that cannot dissolve the perovskite precursor. And / or, the annealing treatment temperature in step S3 is 100-130 °C, and the annealing time is 15-50 min.

Images