Application of three-dimensional aromatic materials, perovskite solar cells and preparation methods thereof

Abstract

The present invention provides the application of three-dimensional aromatic materials, perovskite solar cells and their preparation methods, belonging to the technical field of solar cell materials. The three-dimensional aromatic material is triphenylamine tricarboxylic acid, tetrakis(4-carboxyphenyl)methane or trinitro triphenylamine, which is used as a dopant for the perovskite active layer. The preparation method of the perovskite solar cell is as follows: deposit a NiO x film on the surface of the conductive substrate to obtain a hole transport layer; under nitrogen protection, spin-coat the perovskite precursor solution doped with the three-dimensional aromatic material on the hole transport layer to form a perovskite film, thereby obtaining a perovskite active layer; continue to deposit a phenethylamine iodide salt film to obtain a modification layer; then deposit a PCBM film to obtain an electron transport layer; and evaporate a metal electrode to obtain a perovskite solar cell. By using the three-dimensional aromatic material as a dopant for the perovskite active layer, the present invention improves the hysteresis performance and environmental stability of the perovskite solar cell and increases the photoelectric conversion efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cell materials, and particularly relates to the application of three-dimensional aromatic materials, perovskite solar cells and their preparation methods. Background Art

[0002] Perovskite materials are a general term for a class of materials with a calcium titanate crystal structure, which is usually abbreviated as ABX3. Due to their excellent optoelectronic properties, ideal optical band gaps and good thermal stability, they are widely used in the light absorption layer of solar cells, also known as the perovskite active layer; the all-solid-state solar cells prepared based on perovskite materials are called perovskite solar cells, abbreviated as PSCs. PSCs combine the advantages of direct band gap, high absorption coefficient, low exciton binding energy, high carrier mobility, long carrier lifetime and diffusion distance, and high defect tolerance, and have the advantages of simple preparation process, low cost and high photoelectric conversion efficiency. However, at present, the commercial application of PSCs still faces certain challenges, mainly manifested as insufficient long-term stability and hysteresis effect.

[0003] One of the key functional layers affecting the stability of PSCs is the perovskite active layer. The perovskite active layer is mainly a perovskite polycrystalline thin film grown by solution method, which is enriched with defects on the surface and grain boundaries, easily leading to non-radiative recombination of carriers and affecting the device efficiency and stability; in addition, the perovskite active layer is sensitive to environmental factors such as humidity and temperature, which will cause irreversible decomposition of the layer material, thereby reducing the interlayer stability and damaging the contact between layers, having a negative impact on the overall stability of the device, and ultimately resulting in a significant attenuation of the lifespan of PSCs.

[0004] The hysteresis effect refers to the phenomenon that when measuring the current-voltage (J-V) characteristics of perovskite solar cells, the curves obtained from forward scanning and reverse scanning do not coincide, showing a hysteresis phenomenon. The main reasons are as follows: the mismatch between the perovskite lattice and the nickel oxide lattice of the hole transport layer; the rapid growth process leads to residual strain in the perovskite thin film; and there are voids between grains, which further leads to ion migration and causes the hysteresis effect. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide the application of three-dimensional aromatic materials, perovskite solar cells and their preparation methods, aiming to solve at least one of the technical problems in the background art.

[0006] The present invention is implemented as follows:

[0007] The first aspect of the present invention provides the application of three-dimensional aromatic materials. The three-dimensional aromatic materials have a space rotationally symmetric structure and include at least three carboxylic phenyl groups or three nitro phenyl groups; the three-dimensional aromatic materials are triphenylamine tricarboxylic acid, trinitro triphenylamine or tetrakis(4-carboxyphenyl)methane;

[0008] The three-dimensional aromatic material is used as a dopant for the perovskite active layer;

[0009] The structural formula of the triphenylamine tricarboxylic acid is as follows:

[0010] ;

[0011] The structural formula of the tetrakis(4-carboxyphenyl)methane is as follows:

[0012] ;

[0013] The structural formula of the trinitrotriphenylamine is as follows:

[0014] .

[0015] In a second aspect of the present invention, a perovskite solar cell is provided, which includes a conductive substrate, a hole transport layer, a perovskite active layer, a modification layer, an electron transport layer, and a metal electrode stacked in sequence from bottom to top; the three-dimensional aromatic material is doped in the perovskite active layer;

[0016] The three-dimensional aromatic material is doped in the perovskite precursor solution, and the doping amount is 1 mg / mL to 4 mg / mL. It is deposited on the hole transport layer to form a perovskite thin film, and the perovskite active layer is prepared.

[0017] Preferably, the conductive substrate is made of conductive glass;

[0018] The material of the hole transport layer is NiO x ,

[0019] The material of the modification layer is phenethylamine iodide salt dissolved in isopropyl alcohol;

[0020] The material of the electron transport layer is 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]-C-61 dissolved in chlorobenzene;

[0021] The metal electrode is made of gold, silver, or copper.

[0022] Preferably, the thickness of the hole transport layer is 10 nm to 30 nm; the thickness of the perovskite active layer is 500 nm to 700 nm; the thickness of the metal electrode is 150 nm to 200 nm.

[0023] In a third aspect of the present invention, a method for preparing the above perovskite solar cell is provided, including the following steps:

[0024] Provide a conductive substrate;

[0025] Deposit a NiO x thin film on the surface of the conductive substrate to obtain the hole transport layer;

[0026] The three-dimensional aromatic material is doped in the perovskite precursor solution, and the doping amount is 1 mg / mL to 4 mg / mL. Under the protection of nitrogen, the perovskite precursor solution is spin-coated on the hole transport layer by spin coating, and then heated and cooled in sequence to form a perovskite thin film, thereby obtaining the perovskite active layer;

[0027] A phenyl ethylamine iodide salt film is deposited on the surface of the perovskite active layer to obtain the modification layer;

[0028] A 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]-C-61 (PCBM) film is deposited on the surface of the modification layer to obtain the electron transport layer;

[0029] A metal electrode is evaporated on the electron transport layer to obtain a perovskite solar cell.

[0030] Preferably, when preparing the perovskite active layer, the total spin coating time is 30 s to 45 s, 150 mL to 250 mL of chlorobenzene is added dropwise at 10 s to 15 s, and after spin coating, the conductive substrate is placed on a hot stage and heated at 100 °C to 150 °C for 30 min to 60 min.

[0031] Preferably, the preparation steps of the hole transport layer include:

[0032] NiO x The NiO nanoparticles are dissolved in deionized water, and its concentration is 5 mg / mL to 30 mg / mL. After shaking evenly, a NiO x solution is formed;

[0033] The NiO x solution is spin-coated on the conductive substrate by spin coating, the spin coating rate is 2000 rpm to 5000 rpm, the spin coating time is 30 s to 40 s, and then heat treatment is carried out at 120 °C to 150 °C for 10 min to 30 min to obtain the hole transport layer.

[0034] Preferably, the preparation steps of the modification layer include: dissolving phenyl ethylamine iodide salt in an isopropanol solution to prepare a 1 mg / mL to 5 mg / mL phenyl ethylamine iodide salt solution; obtaining the modification layer by spin coating the phenyl ethylamine iodide salt solution on the surface of the perovskite active layer, the spin coating rate is 3000 rpm to 6000 rpm, and the spin coating time is 30 s to 50 s.

[0035] Preferably, the preparation steps of the electron transport layer include: dissolving 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]-C-61 in chlorobenzene at a concentration range of 18 mg / mL to 25 mg / mL, heating and stirring evenly at 40 °C to 60 °C to obtain a PCBM solution; spin-coating the PCBM solution on the surface of the modification layer at a rotation speed of 2000 rpm to 2500 rpm, and then treating at 80 °C to 90 °C for 20 min to 40 min to obtain the electron transport layer.

[0036] Preferably, the metal electrode is formed by vacuum thermal evaporation, and the evaporation rate is 0.5 Å / s to 5.0 Å / s.

[0037] Compared with the prior art, the present invention uses triphenylamine tricarboxylic acid (TATA), tetrakis(4-carboxyphenyl)methane (TCPM), and trinitro triphenylamine (TNHA) as dopants for the perovskite active layer, improving the hysteresis performance and environmental stability of the perovskite solar cell, and increasing the photoelectric conversion efficiency.

[0038] The present invention provides a dopant with a spatially rotationally symmetric structure and including polycarboxyphenyl or polynitrophenyl, which can regulate the nucleation and growth kinetic processes of perovskite grains, improve the film-forming quality of the perovskite thin film. The prepared perovskite active layer has high crystallization quality, the grain size reaches the micron level, and has good light absorption performance.

[0039] At the same time, TATA, TCPM, and TNHA located at the grain boundaries of the perovskite active layer can multi-dimensionally adhere to the grains, passivate interface defects, and inhibit the migration of ions at the interface. Therefore, the performance of the perovskite solar cell is effectively improved, the photoelectric conversion efficiency is increased, and there is no obvious hysteresis effect.

[0040] In addition, the application of TATA, TCPM, and TNHA materials can also improve the barrier ability of the perovskite solar cell to water vapor in the air, thereby improving the stability and service life of the battery. After the unencapsulated perovskite solar cell is placed in high-humidity air for 240 hours, it still maintains a photoelectric conversion efficiency of more than 83%. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a schematic structural diagram of the perovskite solar cell of the present invention;

[0042] Figure 2 is the nuclear magnetic resonance hydrogen spectrum of the dopants and FAPbI3 perovskite containing the dopants in Example 1, Example 8, and Example 12;

[0043] Figure 3 is the SEM image of the FAPbI3 perovskite thin films prepared in Comparative Example 1, Example 1, Example 8, and Example 12;

[0044] Figure 4 X-ray diffraction patterns of the FAPbI3 perovskite thin films prepared in Comparative Example 1, Example 1, Example 8, and Example 12;

[0045] Figure 5 Transient fluorescence spectra of the FAPbI3 perovskite thin films prepared in Comparative Example 1, Example 1, Example 8, and Example 12;

[0046] Figure 6 Partial Fourier transform infrared spectra of the FAPbI3 perovskite thin films prepared in Comparative Example 1, Example 1, Example 8, and Example 12;

[0047] Figure 7 Forward and reverse scan current density-voltage curves of the FAPbI3 perovskite solar cells prepared in Example 1, Example 8, and Example 12.

[0048] Illustration: 1 - Conductive substrate; 2 - Hole transport layer; 3 - Perovskite active layer; 4 - Modifying layer, 5 - Electron transport layer, 6 - Metal electrode. Detailed implementation manners

[0049] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific implementation cases described herein are only used to explain the present invention and are not used to limit the present invention.

[0050] As Figure 1 shown, the perovskite solar cell includes a conductive substrate 1, a hole transport layer 2, a perovskite active layer 3, a modifying layer 4, an electron transport layer 5, and a metal electrode 6 stacked in sequence from bottom to top.

[0051] The perovskite active layer 3 is doped with a three-dimensional aromatic material, and the three-dimensional aromatic material is triphenylamine tricarboxylic acid or tetrakis(4-carboxyphenyl)methane or trinitro triphenylamine;

[0052] Among them, the structural formula of triphenylamine tricarboxylic acid (TATA) is as follows:

[0053] ;

[0054] The structural formula of tetrakis(4-carboxyphenyl)methane (TCPM) is as follows:

[0055] ;

[0056] The structural formula of trinitro triphenylamine (TNHA) is as follows:

[0057] .

[0058] A method for preparing a perovskite solar cell, comprising steps S1 to S6.

[0059] S1. Provide a conductive substrate;

[0060] Using indium tin oxide (ITO) conductive glass or fluorine-doped tin oxide (FTO) conductive glass as the conductive substrate, the laser-etched conductive substrate is successively ultrasonically cleaned with deionized water, acetone, and ethanol for 15 minutes each, then dried with nitrogen, and finally treated with ozone plasma for 10 minutes.

[0061] S2. Deposit a NiO x thin film on the surface of the conductive substrate to obtain a hole transport layer;

[0062] First, add sodium hydroxide to a 0.2 M aqueous solution of Ni(NO3)2·6H2O until the pH value of the solution is 10, stir for about 30 minutes to obtain a precipitate;

[0063] Then, filter the precipitate by suction and wash it twice, and transfer it to a drying oven at about 80°C for drying for about 8 hours;

[0064] Place the dried powder in a muffle furnace and calcine it at about 270°C for 2 hours to obtain black NiO x nanoparticles;

[0065] Dissolve the NiO x nanoparticles in deionized water at a concentration of 5 mg / mL to 30 mg / mL, and shake evenly to form a NiO x solution;

[0066] Then, use the spin-coating method to spin-coat the NiO x solution on the conductive substrate at a spin-coating rate of 2000 rpm to 5000 rpm and a spin-coating time of 30 s to 40 s;

[0067] Finally, heat-treat at a temperature of 120°C to 150°C for 10 min to 30 min, and the thickness of the formed hole transport layer is 10 nm to 30 nm.

[0068] S3. Deposit a perovskite thin film on the surface of the hole transport layer to obtain a perovskite active layer;

[0069] Dope triphenylamine tricarboxylic acid, tetrakis(4-carboxyphenyl)methane, or trinitro triphenylamine in the perovskite precursor solution, with the doping amount being 1 mg / mL to 4 mg / mL, and the concentration of this doping amount being based on the solvent in the perovskite precursor solution; in specific implementations, the perovskite material can be any perovskite material allowed in the art. The following examples use the YPbX3 material for illustration, where Y is at least one of Cs, NH2CH=NH2 (FA), and CH3NH3 (MA), and X is at least one of Br and I;

[0070] Under nitrogen protection, spin-coat the perovskite precursor solution on the hole transport layer by spin coating. The total spin coating time is 30 s to 45 s, and 150 mL to 250 mL of chlorobenzene is dropped at 10 s to 15 s. After spin coating, place the conductive substrate on a hot stage and heat it at 100 °C to 150 °C for 30 min to 60 min. After cooling, a perovskite thin film is formed to obtain the perovskite active layer;

[0071] In specific implementations, the perovskite precursor solution is prepared by a conventional solvent method, and the specific reaction parameters and steps can be adjusted according to actual needs and are not specifically limited here.

[0072] S4. Deposit a phenethylamine iodide salt film on the surface of the perovskite active layer to obtain the modification layer;

[0073] Phenethylamine iodide salt can passivate the surface defects of the perovskite thin film, hinder the ion leakage of the perovskite layer, and improve the quality of the perovskite thin film and the stability of the perovskite solar cell;

[0074] Specifically, dissolve phenethylamine iodide salt in an isopropanol solution to prepare a 1 mg / mL to 5 mg / mL phenethylamine iodide salt solution, and spin coat the phenethylamine iodide salt solution on the surface of the perovskite active layer by spin coating to obtain the modification layer. The spin coating rate is 3000 rpm to 6000 rpm, and the spin coating time is 30 s to 50 s.

[0075] S5. Deposit a PCBM film on the surface of the modification layer to obtain the electron transport layer;

[0076] Specifically, dissolve 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]-C-61 (PCBM) in chlorobenzene, with its concentration range being 18 mg / mL to 25 mg / mL, heat and stir at 40 °C to 60 °C for about 12 hours to prepare a PCBM solution; spin coat the PCBM solution on the surface of the modification layer at a rotation speed of 2000 rpm to 2500 rpm, and then treat it at 80 °C to 90 °C for 20 min to 40 min to obtain the electron transport layer.

[0077] S6. Evaporate a metal electrode on the electron transport layer to obtain a perovskite solar cell;

[0078] The metal electrode is any one of gold, silver or copper, and is formed into a film by vacuum thermal evaporation method, and the evaporation rate is 0.5 Å / s to 5.0 Å / s.

[0079] In the present invention, a functional symmetric small molecule organic compound with a three-dimensional structure is doped into the perovskite active layer to improve the quality of the perovskite thin film, thereby enhancing the stability of the perovskite solar cell device and suppressing the hysteresis effect.

[0080] Compared with common symmetric small molecules such as biphenyl dicarboxylic acid (BCLA) and phthalic acid (PPA) at present, the present invention uses triphenylamine tricarboxylic acid material (TATA), tetrakis(4-carboxyphenyl)methane material (TCPM), and trinitro triphenylamine (TNHA) with a space rotation symmetric structure and multiple carboxylic / nitric acid groups as dopants to realize the regulation of perovskite crystal growth and defect passivation in a large range in three dimensions, inhibit ion migration and improve its stability. The present invention makes full use of the unique nano-scale size and controllable 3D stereoscopic molecular configuration of the dopant, and uses the nano-scaffold formed by its self-assembly as a template to precisely regulate the nucleation and crystallization growth behavior of perovskite at the nano-scale, improve the microstructure, and enhance the crystallinity and stability; in addition, TATA and TCPM have multiple carboxylic acid groups, and TNHA has multiple nitric acid groups, which can effectively passivate the perovskite crystal defects in the 3D direction, inhibit ion migration, form an electroactive tight connection between grains, and effectively release the tensile strain of perovskite grains in all directions. On the premise of ensuring sufficient photoelectric conversion efficiency of the perovskite solar cell, the hysteresis performance and environmental stability of the perovskite solar cell device are improved.

[0081] Example 1

[0082] This Example 1 is a preparation method of a FAPbI3 perovskite solar cell based on TATA doping, and its steps include:

[0083] S1. Using indium tin oxide (ITO) conductive glass as the conductive substrate, the laser-etched conductive substrate is ultrasonically cleaned with deionized water, acetone, and ethanol for 15 minutes in sequence, then dried with nitrogen, and finally treated with ozone plasma for 10 minutes;

[0084] S2. Add sodium hydroxide to a 0.2 M aqueous solution of Ni(NO3)2·6H2O to make the pH value of the solution 10, stir for 30 minutes to obtain a precipitate; then, filter the precipitate and wash it twice, transfer it to a drying oven and dry it at 80 °C for 8 hours; place the dried powder in a muffle furnace and calcine it at 270 °C for 2 hours to obtain black NiO x nano-particles; dissolve the NiO x nano-particles in deionized water, with a concentration of 20 mg / mL, and oscillate evenly to form NiO xA solution was then spin-coated on a conductive substrate at a spin-coating rate of 4000 rpm for 30 s, and then heat-treated at 140 °C for 130 min. The formed hole transport layer had a thickness of about 20 nm;

[0085] S3. Prepare a FAPbI3 perovskite precursor solution doped with TATA, and then deposit a FAPbI3 perovskite active layer on the surface of the hole transport layer; specifically:

[0086] (1) Dissolve 1.6 mol of PbI2 and 1.6 mol of FAI in 1 mL of a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), where the volume ratio of DMF to DMSO is 4:1, stir at room temperature for about 20 h, and then add 2 mg of TATA to obtain a perovskite precursor solution;

[0087] (2) Under nitrogen protection and at a temperature of 15 °C to 25 °C, spin-coat the perovskite precursor solution on the hole transport layer at a speed of 4000 rpm for a total spin-coating time of 30 s. Add 200 mL of chlorobenzene at 10 s. After spin-coating, place the substrate on a hot stage and heat at 150 °C for 30 min; after cooling, a FAPbI3 perovskite thin film is formed to obtain a perovskite active layer with a thickness of about 600 nm;

[0088] S4. Dissolve phenethylamine iodide salt in isopropanol at a concentration of 2 mg / mL, and spin-coat it on the surface of the perovskite active layer at 4000 rpm for 40 s to obtain a modification layer;

[0089] S5. Dissolve 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]-C-61 (PCBM) in chlorobenzene to prepare a PCBM solution with a concentration of 23 mg / mL, and heat and stir at 60 °C for 12 h; spin-coat the PCBM solution on the phenethylamine iodide salt modification layer at a speed of 2000 rpm, and then treat it at 90 °C for 30 min to obtain an electron transport layer;

[0090] S6. Evaporate a silver electrode on the electron transport layer at a rate of 2.0 Å / s. The thickness of the silver electrode thin film is about 150 nm to obtain a TATA-doped FAPbI3 perovskite solar cell.

[0091] Example 2

[0092] This Example 2 is a preparation method of a formamidinium methylammonium cesium lead iodide perovskite solar cell doped with TATA. The difference from Example 1 is only the perovskite material in the perovskite precursor solution of the perovskite active layer, and its molecular formula is FA 0.78 MA 0.18 Cs 0.04 PbI3. The preparation steps of the perovskite precursor solution specifically include:

[0093] Dissolve 1.6 mol of PbI2, 1.6 mol of CH(NH2)2I (FAI), 0.075 mol of CsI, 0.15 mol of CH3NH3I (MAI) and 0.1875 mol of CH3NH3Cl (MACl) in 1 mL of a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), where the volume ratio of DMF to DMSO is 4:1. Stir at room temperature for about 20 h, and then add 2 mg of TATA and stir evenly to obtain a TATA-doped perovskite precursor solution. During the preparation process, the chlorine element in MACl will escape as chlorine gas.

[0094] Other steps and parameters are the same as those in Example 1.

[0095] Example 3

[0096] This Example 3 is a preparation method of a formamidinium methylammonium cesium lead iodide bromide perovskite solar cell based on TATA doping. The difference from Example 1 is only the perovskite material in the perovskite precursor solution of the perovskite active layer, and its molecular formula is FA 0.78 MA 0.18 Cs 0.04 PbI 2.88 Br 0.12 , and the preparation steps of the perovskite precursor solution specifically include:

[0097] Dissolve 1.6 mol of PbI2, 1.6 mol of CH(NH2)2I (FAI), 0.075 mol of CsI, 0.15 mol of CH3NH3Br (MABr) and 0.1875 mol of CH3NH3Cl (MACl) in 1 mL of a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), where the volume ratio of DMF to DMSO is 4:1. Stir at room temperature for about 20 h, and then add 2 mg of TATA and stir evenly to obtain a TATA-doped perovskite precursor solution.

[0098] Other steps and parameters are the same as those in Example 1.

[0099] Example 4

[0100] This Example 4 is a preparation method of a MAPbI3 perovskite solar cell based on TATA doping. The difference from Example 1 is only the perovskite material in the perovskite active layer, and its molecular formula is MAPbI3. The preparation steps of the perovskite precursor solution specifically include:

[0101] 1.6 mol of PbI2 and 1.6 mol of CH3NH3I (MAI) were dissolved in 1 mL of a solvent mixture of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), where the volume ratio of DMF to DMSO was 4:1. The mixture was stirred at room temperature for about 20 h, and then 2 mg of TATA was added and stirred evenly to obtain a TATA-doped perovskite precursor solution.

[0102] Other steps and parameters were the same as those in Example 1.

[0103] Example 5

[0104] This Example 5 is a preparation method of a TATA-doped FAPbI3 perovskite solar cell. The difference from Example 1 is only that the dosage of the TATA dopant was adjusted to 1 mg, and other steps and parameters were the same as those in Example 1.

[0105] Example 6

[0106] This Example 6 is a preparation method of a TATA-doped FAPbI3 perovskite solar cell. The difference from Example 1 is only that the dosage of the TATA dopant was adjusted to 3 mg, and other steps and parameters were the same as those in Example 1.

[0107] Example 7

[0108] This Example 7 is a preparation method of a TATA-doped FAPbI3 perovskite solar cell. The difference from Example 1 is only that the dosage of the TATA dopant was adjusted to 4 mg, and other steps and parameters were the same as those in Example 1.

[0109] Example 8

[0110] This Example 8 is a preparation method of a TCPM-doped FAPbI3 perovskite solar cell. The difference from Example 1 is only that the TATA dopant was replaced with a TCPM dopant, and other steps and parameters were the same as those in Example 1.

[0111] Example 9

[0112] This Example 9 is a preparation method of a TCPM-doped formamidinium methylammonium cesium lead iodide perovskite solar cell. The difference from Example 2 is only that the TATA dopant was replaced with a TCPM dopant, and other steps and parameters were the same as those in Example 2.

[0113] Example 10

[0114] This Example 10 is a preparation method of a TCPM-doped formamidinium methylammonium cesium lead iodide bromide perovskite solar cell. The difference from Example 3 is only that the TATA dopant was replaced with a TCPM dopant, and other steps and parameters were the same as those in Example 3.

[0115] Example 11

[0116] Example 11 is a preparation method of a TCPM-doped MAPbI3 perovskite solar cell, which is only different from Example 4 in that the TATA dopant is replaced by a TCPM dopant, and other steps and parameters are the same as those in Example 4.

[0117] Example 12

[0118] Example 12 is a preparation method of a TNHA-doped FAPbI3 perovskite solar cell, which is only different from Example 1 in that the TATA dopant is replaced by a TNHA dopant, and other steps and parameters are the same as those in Example 1.

[0119] Example 13

[0120] Example 13 is a preparation method of a TNHA-doped formamidinium methylammonium cesium lead iodide perovskite solar cell, which is only different from Example 2 in that the TATA dopant is replaced by a TNHA dopant, and other steps and parameters are the same as those in Example 2.

[0121] Example 14

[0122] Example 14 is a preparation method of a TNHA-doped formamidinium methylammonium cesium lead iodide bromide perovskite solar cell, which is only different from Example 3 in that the TATA dopant is replaced by a TNHA dopant, and other steps and parameters are the same as those in Example 3.

[0123] Example 15

[0124] Example 15 is a preparation method of a TNHA-doped MAPbI3 perovskite solar cell, which is only different from Example 4 in that the TATA dopant is replaced by a TNHA dopant, and other steps and parameters are the same as those in Example 4.

[0125] Comparative Example 1

[0126] Comparative Example 1 is a preparation method of an undoped FAPbI3 perovskite solar cell, which is only different from Example 1 in that there is no dopant in the perovskite precursor solution in the perovskite active layer, and other steps and parameters are the same as those in Example 1.

[0127] Comparative Example 2

[0128] Comparative Example 2 is a preparation method of an FAPbI3 perovskite solar cell without a modification layer, which is only different from Example 1 in that S4 is deleted, and there is no modification layer made of phenethylamine iodide salt; the electron transport layer is directly prepared on the perovskite active layer, and other steps and parameters are the same as those in Example 1.

[0129] Comparative Example 3

[0130] The difference between this Comparative Example 3 and Example 1 is only that TATA is used as the organic interfacial layer instead of the dopant of the perovskite active layer, and the other steps and parameters are the same as those in Example 1.

[0131] The specific steps of S3 in this Comparative Example 3 are as follows:

[0132] (1) Dissolve 2 mg of TATA in 1 mL of ethanol solution, coat it on the hole transport layer, and then perform annealing treatment at 120 °C for 20 min to obtain the TATA organic interfacial layer;

[0133] (2) Dissolve 1.6 mol of PbI2 and 1.6 mol of FAI in 1 mL of a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), where the volume ratio of DMF to DMSO is 4:1, and stir at room temperature for about 20 h to obtain the perovskite precursor solution; under nitrogen protection, spin-coat the perovskite precursor solution on the TATA organic interfacial layer at a speed of 4000 rpm at a temperature of 15 °C to 25 °C, with a total spin-coating time of 30 s. Add 200 mL of chlorobenzene at 10 s. After spin-coating, place the substrate on a hot stage and heat it at 150 °C for 30 min; after cooling, form the FAPbI3 perovskite thin film to obtain the perovskite active layer, and its thickness is about 600 nm.

[0134] Figure 2 1H NMR spectra of the dopants and FAPbI3 perovskite containing the dopants in Example 1, Example 8, and Example 12. In Figure 2 TATA-PVK, TCPM-PVK, and TNHA-PVK are FAPbI3 perovskite thin films containing the corresponding dopants prepared in Example 1, Example 8, and Example 12, respectively; as can be seen from Figure 2 it, compared with TATA, TCPM, and TNHA, the chemical shift of H element occurs in the 1H NMR spectra of TATA-PVK, TCPM-PVK, and TNHA-PVK, indicating that TATA, TCPM, and TNHA all interact with PbI2.

[0135] Figure 3 SEM images of the FAPbI3 perovskite thin films prepared in Comparative Example 1, Example 1, Example 8, and Example 12; in Figure 3 PVK is the FAPbI3 perovskite thin film without dopant prepared in Comparative Example 1, and TATA-PVK, TCPM-PVK, and TNHA-PVK are FAPbI3 perovskite thin films containing the corresponding dopants prepared in Example 1, Example 8, and Example 12, respectively. As can be seen from Figure 3It can be seen that the perovskite films doped with TATA, TCPM, and TNHA have larger grains, and the grains are dense and void-free.

[0136] Figure 4 XRD patterns of the FAPbI3 perovskite films prepared in Comparative Example 1, Example 1, Example 8, and Example 12; from Figure 4 it can be seen that the crystals doped with TATA, TCPM, or TNHA have better crystal orientation and crystallinity.

[0137] Figure 5 Transient fluorescence spectra of the FAPbI3 perovskite films prepared in Comparative Example 1, Example 1, Example 8, and Example 12; from Figure 5 it can be seen that the perovskite films doped with TATA, TCPM, and TNHA have longer carrier lifetimes.

[0138] Figure 6 Partial Fourier transform infrared spectra of the FAPbI3 perovskite films prepared in Example 1, Example 8, and Example 12; from Figure 6 it can be seen that in Example 1, Example 8, and Example 12, the C=N vibration peaks shift from 1709 to 1711, 1711.1, and 1710.6 respectively, indicating that the doped TATA, TCPM, TNHA, and FA all interact with each other.

[0139] Figure 7 Current density-voltage curves of the FAPbI3 perovskite solar cells prepared in Example 1, Example 8, and Example 12 during forward and reverse scans; from Figure 7 it can be seen that the curves of the perovskite solar cells prepared based on TATA, TCPM, and TNHA during forward and reverse scans basically coincide, that is, they have a low hysteresis effect.

[0140] The test method for the performance of perovskite solar cells is specifically as follows: under standard simulated sunlight (AM1.5G, 100 mW / cm 2 ), the current density-voltage (J-V) characteristic curves of perovskite solar cell devices are tested; performance parameters such as open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency are obtained from the J-V characteristic curves;

[0141] The coincidence degree of the J-V characteristic curves of the forward scan (Forward Scanning, FS) from low voltage to high voltage and the reverse scan (Reverse Scanning, RS) from high voltage to low voltage characterizes the hysteresis effect of the device, which is an important evaluation index for device performance and is quantified using the hysteresis coefficient. The hysteresis coefficient HI (%) of the present invention = 100% × (PCE RS -PCEFS ) / PCE RS ; PCE RS , PCE FS are the photoelectric conversion efficiencies of reverse scanning and forward scanning, respectively; the smaller the hysteresis coefficient, the smaller the hysteresis effect of the device.

[0142] The performance test results of the perovskite solar cells prepared in Examples 1 to 15 and Comparative Examples 1 to 3 were compared, as shown in Table 1.

[0143] Table 1

[0144]

[0145] In Table 1, V OC is the open-circuit voltage, with the unit of V; J SC is the short-circuit current density, with the unit of mA / cm 2 ; FF is the fill factor; PCE is the photoelectric conversion efficiency.

[0146] It can be seen from Table 1 that in the present invention, triphenylamine tricarboxylic acid (TATA), tetrakis(4-carboxyphenyl)methane (TCPM), and trinitro triphenylamine (TNHA) are used as dopants for the perovskite active layer respectively, which improves the hysteresis performance and environmental stability of the perovskite solar cell device and increases the photoelectric conversion efficiency.

[0147] In addition, it can be seen from Examples 1 to 4, Examples 8 to 11, and Examples 12 to 15 that the dopants of the present invention have a wide range of applications and are suitable for various types of perovskite materials.

[0148] Comparing Examples 1, 5 to 7, it can be known that as the amount of dopant increases, the photoelectric conversion efficiency of the prepared perovskite solar cell first increases and then decreases, and the hysteresis coefficient increases. The reason is that excessive dopant affects the carrier transport and extraction of the film; therefore, the amount of dopant is set to 1 mg / ml to 4 mg / ml, preferably 1 mg / ml to 3 mg / ml, and the optimal amount is 2 mg / ml.

[0149] Comparing Examples 1, 8, 12 with Comparative Example 1, it can be known that compared with the perovskite solar cell without dopant, after doping with TATA, TCPM, and TNHA, the performance of the prepared perovskite solar cell is better than that of the undoped perovskite solar cell.

[0150] Comparing Example 1 with Comparative Example 2, it can be known that the performance of the perovskite solar cell prepared without the modification layer is lower than that of the cell with the modification layer. The reason is that the modification layer helps to improve the stability and carrier extraction of the perovskite solar cell.

[0151] It can be seen from the comparison between Example 1 and Comparative Example 3 that when triphenylamine tricarboxylic acid (TATA) is used as the organic interfacial layer, the photoelectric conversion efficiency of the fabricated solar cell is also very excellent. However, it is still lower than that of Example 1, and its hysteresis performance has not been effectively improved, and the hysteresis coefficient is much higher than that of Example 1.

[0152] The perovskite solar cells fabricated in Comparative Examples 1 to 3 and Examples 1 to 15 without encapsulation were placed in air (humidity not less than 70%), and the change in the photoelectric conversion efficiency PCE was tested as the placement time increased, and its retention rate was calculated. The PCE retention rate = (PCE0 - PCE n ) / PCE0; PCE0 and PCE n are the photoelectric conversion efficiencies of the perovskite solar cell device at the initial stage and after being placed in air for n hours without encapsulation, respectively. The results are shown in Table 2; the greater the PCE retention rate, the higher the barrier ability of the device to water vapor and the stronger the stability.

[0153] Table 2

[0154]

[0155] It can be seen from Table 2 that as the placement time increases, due to the erosion of the perovskite solar cell device by moisture in the external environment, the photoelectric conversion efficiency decreases. After being placed for 240 h, the perovskite solar cell fabricated by the present invention can still maintain a PCE of more than 83%, and after being placed for 480 h, it can still maintain a PCE of about more than 70%. This shows that adding a dopant material to the perovskite active layer of the present invention can effectively improve the barrier ability of the perovskite solar cell device to water vapor in the air. Compared with Example 1, the perovskite solar cells fabricated in Comparative Example 1 without a dopant and Comparative Example 2 without a modification layer have a significantly reduced barrier ability to water vapor in the air. It can be seen from the comparison between Example 1 and Comparative Example 3 that the barrier ability of the solar cell fabricated with triphenylamine tricarboxylic acid (TATA) as the organic interfacial layer to water vapor in the air is weaker than that of the solar cell fabricated with TATA as the dopant.

[0156] The above-described embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. Application of three-dimensional aromatic materials, characterized in that, The three-dimensional aromatic material is tetrakis(4-carboxyphenyl)methane; the three-dimensional aromatic material is used as a dopant for the perovskite active layer; The structural formula of the tetrakis(4-carboxyphenyl)methane is as follows: ； The three-dimensional aromatic material is doped in the perovskite precursor solution, and the doping amount is 1 mg / mL to 4 mg / mL; A phenylethylamine iodide salt film is deposited on the surface of the perovskite active layer to obtain a modified layer.

2. A perovskite solar cell, characterized in that The perovskite solar cell comprises a conductive substrate, a hole transport layer, a perovskite active layer, a modification layer, an electron transport layer and a metal electrode stacked in sequence from bottom to top; The perovskite active layer is doped with the three-dimensional aromatic material according to claim 1; The three-dimensional aromatic material is doped in a perovskite precursor solution at a doping amount of 1 mg / mL to 4 mg / mL, and is deposited on a hole transport layer to form a perovskite film, thereby obtaining the perovskite active layer.

3. The perovskite solar cell according to claim 2, characterized in that: The conductive substrate is made of conductive glass; The hole transport layer is made of NiO x , The material of the modification layer is phenylethylamine iodide dissolved in isopropanol; The material of the electron transport layer is 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]-C-61 dissolved in chlorobenzene; The metal electrode is made of gold, silver or copper.

4. The perovskite solar cell according to claim 2, characterized in that: The thickness of the hole transport layer is 10nm~30nm; the thickness of the perovskite active layer is 500nm~700nm; and the thickness of the metal electrode is 150nm~200nm.

5. A method for preparing a perovskite solar cell, characterized in that: Used to prepare the perovskite solar cell according to any one of claims 2 to 4; the preparation method comprises the following steps: providing a conductive substrate; Deposition of NiO on the surface of conductive substrate x Thin film, preparing hole transport layer; The three-dimensional aromatic material is doped in a perovskite precursor solution at a doping amount of 1 mg / mL to 4 mg / mL. Under nitrogen protection, the perovskite precursor solution is spin-coated on the hole transport layer by a spin coating method, and then heated and cooled in sequence to form a perovskite film to obtain the perovskite active layer. Depositing a phenylethylamine iodide salt film on the surface of the perovskite active layer to obtain the modified layer; Depositing a 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]-C-61 thin film on the surface of the modified layer to obtain the electron transport layer; A metal electrode is evaporated on the electron transport layer to prepare a perovskite solar cell.

6. The method for preparing a perovskite solar cell according to claim 5, characterized in that: When preparing the perovskite active layer, the total spin coating time is 30s to 45s, 150mL to 250mL of chlorobenzene is added dropwise at 10s to 15s, and after spin coating, the conductive substrate is placed on a hot stage and heated at 100°C to 150°C for 30min to 60min.

7. The method for preparing a perovskite solar cell according to claim 5, characterized in that: The preparation steps of the hole transport layer include: NiO x The nanoparticles were dissolved in deionized water at a concentration of 5 mg / mL to 30 mg / mL and vibrated to form NiO x Solution; NiO was spin-coated x The solution is spin-coated on a conductive substrate at a spin-coating rate of 2000 rpm to 5000 rpm for 30 s to 40 s, and then heat-treated at 120° C. to 150° C. for 10 min to 30 min to obtain a hole transport layer.

8. The method for preparing a perovskite solar cell according to claim 5, characterized in that: The preparation step of the modification layer includes: dissolving phenethylamine iodide salt in isopropanol solution to prepare 1 mg / mL~5 mg / mL phenethylamine iodide salt solution, and spin coating the phenethylamine iodide salt solution on the surface of the perovskite active layer by spin coating to obtain the modification layer, the spin coating rate is 3000rpm~6000rpm, and the spin coating time is 30s~50s.

9. The method for preparing a perovskite solar cell according to claim 5, characterized in that: The preparation steps of the electron transport layer include: dissolving 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]-C-61 in chlorobenzene with a concentration range of 18 mg / mL to 25 mg / mL, heating and stirring at 40°C to 60°C to obtain a PCBM solution; spin coating the PCBM solution on the surface of the modified layer at a speed of 2000rpm to 2500rpm, and then treating at 80°C to 90°C for 20min to 40min to obtain the electron transport layer.

10. The method for preparing a perovskite solar cell according to claim 5, characterized in that: The metal electrode is formed into a film by a vacuum thermal evaporation method, and the evaporation rate is 0.5Å / s~5.0Å / s.

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