A method for improving the performance of perovskite solar cells based on a dye interface layer

Abstract

The present invention relates to a method for improving the performance of perovskite solar cells based on a dye interface layer, comprising: (1) attaching a first charge transport layer on a transparent conductive substrate; (2) coating a perovskite precursor solution on the first charge transport layer, then obtaining a perovskite thin film by spin coating, then dripping an antisolvent to promote crystallization, and then performing thermal annealing to obtain a perovskite light-absorbing layer; (3) spin coating a thiophene-quinoline type double heterocyclic azo dye precursor solution on the perovskite light-absorbing layer and then heating and annealing to obtain a dye interface layer; (4) attaching a second charge transport layer on the dye interface layer, and attaching top electrodes on the transparent conductive substrate and the second charge transport layer respectively. By adding a dye interface passivation layer on the perovskite light-absorbing layer in the present invention, the dye exists at the surface and grain boundaries of the perovskite, passivates the grain boundary defects, inhibits the non-radiative recombination at the interface, improves the quality of the perovskite thin film, and enhances the efficiency and stability of the perovskite solar cell.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and particularly relates to a method for improving the performance of perovskite solar cells based on a dye interface layer. Background Art

[0002] Since 2003, organic-inorganic hybrid perovskite materials have received great attention from the photovoltaic research community due to their excellent optoelectronic properties such as high absorption coefficient, long carrier diffusion length, and adjustable bandgap, and have become ideal materials for perovskite solar cells (PSCs) and other photovoltaic applications. In addition, the power conversion efficiency (PCE) of PSCs has rapidly increased from 3.8% to 25.5%, mainly due to their excellent photovoltaic properties and low-cost manufacturing processes, but problems related to internal defects and stability limit the development of PSCs.

[0003] Existing research has proven that during the process of preparing perovskite films by solution method, especially in an air environment, high-density defects will inevitably be generated, especially defects at the perovskite boundaries and surfaces. In addition, during storage, perovskite films will decompose in humid air and a large number of defects will be generated at the surface and grain boundaries. These defects will induce the combination of perovskite with water and oxygen, thereby accelerating the degradation of perovskite. As non-radiative recombination centers, these defects not only reduce the optoelectronic performance but also limit the further improvement of PCE and device stability. Therefore, there is an urgent expectation to alleviate and reduce trap-assisted non-radiative recombination through a good passivation effect, which will help extend the device life and improve the efficiency.

[0004] To address the defect issues of perovskite films, interface modification has been applied to improve the performance and stability of PSCs. Among them, current research mainly focuses on using the special functional groups of interface passivation materials to interact with perovskites to form coordination bonds, thereby effectively passivating surface defects and regulating the carrier recombination behavior of perovskites. Based on this, this study is committed to finding novel and low-cost molecules to achieve the above effects; it is found that dye molecules, due to the nature of chromophores, can be considered special molecules with advanced optical and electronic properties, which can effectively passivate the defects of perovskite films, enhance light absorption performance, and promote charge transfer at the same time. Among many modification methods, depositing an interface modification layer on the perovskite layer stands out because of its simple preparation process and the need not to change the preparation process of the perovskite layer, which plays a key role in improving the performance and stability of devices under atmospheric conditions and is a promising defect passivation method. Based on this, in some research reports, it has been proven that dyes as additives can improve the photovoltaic performance and long-term stability of perovskite films and devices. However, there are few reports on using dye molecules as the interface passivation layer of PSCs. Therefore, preparing an interface layer of dye molecules with high-efficiency passivation effect for PSCs in an air environment is extremely important for the commercial development of preparing high-efficiency and stable PSCs. Summary of the Invention

[0005] Based on the above-mentioned drawbacks and deficiencies existing in the prior art, one of the objectives of the present invention is to at least solve one or more of the above-mentioned problems existing in the prior art. In other words, one of the objectives of the present invention is to provide a method for improving the performance of perovskite solar cells based on a dye interface layer that meets one or more of the foregoing requirements.

[0006] To achieve the above-mentioned invention objective, the present invention adopts the following technical solutions:

[0007] A method for improving the performance of perovskite solar cells based on a dye interface layer, comprising the following steps:

[0008] (1) Attach a first charge transport layer on a transparent conductive substrate;

[0009] (2) Coating a perovskite precursor solution on the first charge transport layer, then obtaining a perovskite film by spin coating, then adding an antisolvent to promote crystallization, and then performing thermal annealing to obtain a perovskite light-absorbing layer;

[0010] (3) Spin-coating a thiophene-quinoline type bisheterocyclic azo dye precursor solution on the perovskite light-absorbing layer and then heating and annealing to obtain a dye interface layer;

[0011] (4) Attach a second charge transport layer on the dye interface layer, and attach top electrodes on the transparent conductive substrate and the second charge transport layer respectively.

[0012] As a preferred embodiment, in the step (3), the thiophene-quinoline type double heterocyclic azo dye precursor solution is a precursor solution obtained by dissolving the thiophene-quinoline type double heterocyclic azo dye in an organic solvent, and the concentration is 1-10 mg / mL.

[0013] As a preferred embodiment, the thiophene-quinoline type double heterocyclic azo dye includes at least one of Dye 1, Dye 2, Dye 3, and Dye 4;

[0014] The molecular structural formula of Dye 1 is:

[0015]

[0016] The molecular structural formula of Dye 2 is:

[0017]

[0018] The molecular structural formula of Dye 3 is:

[0019]

[0020] The molecular structural formula of Dye 4 is:

[0021]

[0022] As a preferred embodiment, the organic solvent includes at least one of chlorobenzene, isopropanol, and toluene.

[0023] As a preferred embodiment, in the step (1), the transparent conductive substrate is ITO conductive glass or FTO conductive glass.

[0024] As a preferred embodiment, in the step (2), the perovskite film is obtained by annealing after one-step spin coating or two-step spin coating.

[0025] Among them, when using one-step spin coating, in the perovskite precursor solution, the components of the perovskite are lead halide (PbX2, where X is one of I, Br, or Cl), formamidinium hydrohalide (FAX), lead halide (PbY2, where Y is one of I, Br, or Cl and is different from X), and methylammonium halide (MAY) mixed in different proportions, and the solvent is anhydrous DMF and anhydrous DMSO;

[0026] When using two-step spin coating, PbI2 is dissolved in the DMF solvent to form a homogeneous solution, and MAI is dissolved in the IPA antisolvent to form a solution.

[0027] As a preferred embodiment, in the step (2), the antisolvent is ethyl acetate (EA), chlorobenzene (CB), or isopropanol (IPA).

[0028] As a preferred solution, in the step (3), the process conditions for heat annealing include: the temperature is 80 - 100 °C, and the time is 40 - 60 min.

[0029] As a preferred solution, the first charge transport layer is an electron transport layer or a hole transport layer. Correspondingly, the second charge transport layer is a hole transport layer or an electron transport layer;

[0030] The electron transport layer is a metal oxide layer, and the metal oxide is selected from one or more of zinc oxide, titanium oxide, aluminum oxide, tin oxide, and fullerene derivatives;

[0031] The hole transport layer is one of spiro-OMeTAD, PEDOT:PSS, PTAA, and P-type transition metal oxides.

[0032] As a preferred solution, in the step (4), the top electrode is obtained by thermal evaporation deposition or spin coating; wherein, the top electrode is a gold, silver, or carbon electrode.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] In the present invention, a thiophene-quinoline type bisheterocyclic azo dye is dissolved in an organic solvent and then spin-coated on the surface of the perovskite light-absorbing layer to form an interfacial modification layer. The dye molecules are distributed on the surface and grain boundaries of the perovskite, making the surface of the perovskite film smoother, reducing surface holes, effectively passivating grain boundaries and surface defects, suppressing non-radiative recombination at the interface, improving the crystallinity of the film, and improving the quality of the perovskite film; at the same time, the light-absorbing performance of the dye itself is beneficial to the optoelectronic performance of the perovskite solar cell, improving the current and efficiency of the device; the interfacial modification layer is also a uniform physical film, reducing the degradation of the perovskite film by moisture in the air, thereby ensuring a significant improvement in the efficiency and stability of the battery device. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic structural diagram of a perovskite solar cell in an embodiment of the present invention, where the thiophene-quinoline type bisheterocyclic azo dye interface layer is in contact with the top electrode and the perovskite light-absorbing layer respectively, and the top electrode is in contact with the transparent conductive substrate and the electron / hole transport layer respectively.

[0036] Figure 2 It is the structural formula and English name of Dye 1, Dye 2, Dye 3, and Dye 4 in the thiophene-quinoline type bisheterocyclic azo dye in an embodiment of the present invention.

[0037] Figure 3Scanning electron microscope (SEM) images of the perovskite film surface in Example 1 of the present invention: (a) unmodified with thiophene-quinoline type double heterocyclic azo dye, (b) modified with thiophene-quinoline type double heterocyclic azo dye as an additive, and (c) modified as an interfacial layer.

[0038] Figure 4 X-ray diffraction analysis (XRD) patterns of the perovskite film before and after modification of the thiophene-quinoline type double heterocyclic azo dye as an additive and an interfacial layer in Example 1 of the present invention.

[0039] Figure 5 UV-visible absorption spectra (UV-Vis) of the perovskite film before and after modification of the thiophene-quinoline type double heterocyclic azo dye as an additive and an interfacial layer in Example 1 of the present invention.

[0040] Figure 6 Current density-voltage (J-V) characteristic curves of the perovskite solar cell before and after modification of the thiophene-quinoline type double heterocyclic azo dye as an additive and an interfacial layer in Example 1 of the present invention.

[0041] Figure 7 Evolution diagram of the energy conversion efficiency of the perovskite solar cell before and after modification of the thiophene-quinoline type double heterocyclic azo dye as an additive and an interfacial layer in Example 1 of the present invention when stored in air for 2000 hours. Detailed implementation manners

[0042] To more clearly illustrate the embodiments of the present invention, the specific implementation manners of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings and other implementation manners can be obtained.

[0043] The perovskite solar cell structure of the present invention is as Figure 1 shown. From bottom to top, it is successively a transparent conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a thiophene-quinoline type double heterocyclic azo dye interfacial modification layer, a hole transport layer, and a top electrode, or successively: a transparent conductive substrate, a hole transport layer, a perovskite light-absorbing layer, a thiophene-quinoline type double heterocyclic azo dye interfacial modification layer, an electron transport layer, and a top electrode; wherein, the function of the electron transport layer is to conduct electrons and at the same time avoid direct contact between the bottom substrate and the perovskite light-absorbing layer.

[0044] Example 1:

[0045] The preparation method of the perovskite solar cell in this example includes the following steps:

[0046] First, clean the FTO glass substrate with deionized water and acetone successively for 30 min. Dry the cleaned glass substrate on a heating stage with the heating temperature of 100 °C, and perform re-cleaning with ultraviolet ozone before use, with the ultraviolet ozone treatment time of 45 min.

[0047] Subsequently, dilute 750 mg and 1500 mg of titanium diisopropoxide bis(acetylacetonate) in 10 mL of ethanol respectively to form titanium dioxide (TiO2) precursor solutions with different concentrations. Spin-coat the 75 mg / mL solution on the FTO substrate at 2000 rpm for 20 s, then perform thermal annealing at 150 °C for 30 min. After cooling to room temperature, spin-coat the high-concentration 150 mg / mL solution on the low-concentration TiO2 film at 4000 rpm for 20 s, and then keep it at 450 °C for 30 min.

[0048] Preparation of perovskite precursor solution: Dissolve MAI and PbI2 in a mixed solvent of DMF and DMSO (volume ratio is about 4:1) at a molar ratio of 1:1, and stir in the dark at 60 °C for 30 min.

[0049] Then, spin-coat the prepared perovskite precursor solution on the TiO2 / FTO glass substrate by a one-step method. The parameters for stepwise spin-coating are 2000 rpm for 10 s and 4000 rpm for 30 s. Rapidly drop about 245 μL of ethyl acetate (EA) anti-solvent at the center of the substrate 15 s before the end of spin-coating to induce rapid crystallization, and then place the prepared perovskite film on a heating stage and heat it at 100 °C for 30 min to complete the perovskite crystallization process.

[0050] After the above process cools to room temperature, dissolve 2 mg of thiophene-quinoline type bisheterocyclic azo dye (Dye 1) in 1 mL of chlorobenzene solvent to form a uniform 2 mg / mL solution, stir for more than 30 min, spin-coat it on the perovskite light-absorbing layer at 3000 rpm for 30 s, and then heat it at 80 °C for 1 h.

[0051] Then, spin-coat 60 μL of spiro-OMeTAD solution on the top of the thiophene-quinoline type bisheterocyclic azo dye interface layer at a speed of 3000 rpm within 30 s. The spiro-OMeTAD solution consists of 72.3 mg of spiro-OMeTAD, 28.8 μL of 4-tert-butylpyridine (TBP), and 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) solution (520 mg of Li-TSFI dissolved in 1 mL of anhydrous acetonitrile (ACN)).

[0052] Finally, deposit a silver electrode by thermal evaporation, and the thickness of the silver electrode is about 80 nm.

[0053] Figure 3 It shows the influence of thienoquinoline-based heterocyclic azo dye (Dye 1) as an additive and on the perovskite light-absorbing layer before and after interface layer modification on the morphology of the perovskite film. It can be seen from the SEM images of the perovskite that after modification with the thienoquinoline-based heterocyclic azo dye additive, the perovskite crystal grains are regulated, the size is relatively reduced, but the crystal grains become uniform, the compactness of the perovskite film is also improved, and the quality of the perovskite film is improved; in contrast, after modification with the thienoquinoline-based heterocyclic azo dye interface layer, the size of the perovskite crystal grains does not change much, the surface of the perovskite film is smoother and flatter, and the pores are also significantly reduced, which also improves the quality of the perovskite film.

[0054] Figure 4 It is about the influence of thienoquinoline-based heterocyclic azo dye (Dye 1) as an additive and on the perovskite light-absorbing layer before and after interface layer modification on the crystallization performance of the perovskite. It can be seen from the XRD pattern of the perovskite that after being used as an additive and interface layer modification, the XRD peak positions remain the original values, ensuring that the crystal structure of the perovskite remains unchanged. The intensity of the (110) peak of the perovskite after modification is significantly enhanced, which is consistent with the reduction of pores confirmed in the SEM image and the improvement of the quality of the perovskite film.

[0055] Figure 5 It shows the influence of thienoquinoline-based heterocyclic azo dye (Dye 1) as an additive and on the perovskite film before and after interface layer modification on the light absorption performance of the perovskite film. It can be seen from the ultraviolet-visible absorption spectrum that after modification with the dye additive and interface layer, the light absorption ability of the perovskite film increases significantly in the range of 400 - 600 nm, which is very helpful for enhancing the current of the perovskite solar cell. Compared with the absorbance of the perovskite film after additive modification, the absorbance of the perovskite film after interface layer modification is stronger, which also corresponds to the size of the perovskite crystal grains in the SEM image.

[0056] Example 2:

[0057] The preparation method of the perovskite solar cell in this example includes the following steps:

[0058] First, clean the ITO glass substrate with deionized water and acetone in turn for 20 min. Dry the cleaned glass substrate on a heating table, the heating temperature of the heating table is 100 °C, and perform re-cleaning with ultraviolet ozone before use, and the ultraviolet ozone treatment time is 45 min.

[0059] Subsequently, 0.2 mL of SnO2 colloidal solution was diluted in 1.2 mL of deionized water (mass fraction 2.14 wt%), and then spin-coated on the pre-cleaned ITO glass at a speed of 4000 rpm for 30 s. After spin-coating, it was thermally annealed at 150 °C for 30 min. When the glass substrate cooled to room temperature, the ITO glass substrate was placed in ultraviolet ozone for 15 min again.

[0060] Subsequently, a perovskite precursor solution was prepared: lead iodide (PbI2), formamidinium hydroiodide (FAI), lead chloride (PbCl2), and methylammonium iodide (MAI) were used as perovskite precursors, and their concentrations were 1.3 M, 1 M, 0.3 M, and 0.3 M in sequence. Then, (FA a MA 1-a )Pb(I b Cl 1-b )3 perovskite precursor solution was prepared in a mixed solvent of anhydrous DMF and anhydrous DMSO (volume ratio 5:1).

[0061] Then, the prepared perovskite precursor solution was spin-coated on the SnO2 / ITO glass substrate by a one-step method. The parameters for stepwise spin-coating were spin-coating at 2500 rpm for 15 s and 5000 rpm for 25 s. Twelve seconds before the end of spin-coating, approximately 245 μL of chlorobenzene (CB) antisolvent was quickly dropped onto the center of the substrate. Then, the prepared perovskite film was placed on a heating stage and heated at 150 °C for 30 min to complete the perovskite crystallization process.

[0062] After the above process cooled to room temperature, 1 mg of thiophene-quinoline type bisheterocyclic azo dye (Dye 2) was dissolved in 1 mL of isopropanol solvent to form a uniform solution of 1 mg / mL, stirred for 40 min, spin-coated on the perovskite light-absorbing layer at 4000 rpm for 30 s, and then heated at 85 °C for 1 h.

[0063] 75 μL of spiro-OMeTAD solution was spin-coated on top of the thiophene-quinoline type bisheterocyclic azo dye interface layer at a speed of 4000 rpm within 30 s. The spiro-OMeTAD solution consisted of 70 mg of spiro-OMeTAD, 20 μL of TBP, 50 μL of FK-209, and 500 μL of chlorobenzene.

[0064] Finally, a silver electrode was deposited by thermal evaporation, and the thickness of the silver electrode was approximately 90 nm.

[0065] The morphology and structure of the perovskite surface before and after modification with Dye 2 were analyzed, and the results obtained were similar to those of Example 1. Compared with the cells assembled with unmodified perovskite, the perovskite solar cells assembled with perovskite modified with a thiophene-quinoline type bis-heterocyclic azo dye (Dye 2) have higher energy conversion efficiency and stability.

[0066] Example 3:

[0067] The preparation method of the perovskite solar cell of this example includes the following steps:

[0068] First, clean the ITO glass substrate with deionized water and acetone in sequence for 20 min. Dry the cleaned glass substrate on a heating table, the heating temperature of the heating table is 100 °C, and perform re-cleaning with ultraviolet ozone before use, and the ultraviolet ozone treatment time is 45 min.

[0069] Then mix PEDOT:PSS and isopropanol according to a volume ratio of 20:1, perform ultrasonic treatment for later use. After the above perovskite annealing process cools to room temperature, perform dynamic spin-coating of PEDOT:PSS. At this time, the spin-coating is carried out in two steps: spin-coating at 2000 rpm for 10 s and spin-coating at 5000 rpm for 30 s. After spin-coating PEDOT:PSS, perform heat treatment at 120 °C for 1 h.

[0070] Prepare a perovskite precursor solution: Dissolve MAI and PbI2 in a mixed solvent of DMF and DMSO (volume ratio is about 19:1) at a molar ratio of 1:1 to form a perovskite precursor solution, and stir in the dark at 60 °C for 30 min.

[0071] Next, spin-coat the prepared perovskite precursor solution on the PEDOT:PSS / ITO glass substrate by a one-step method. The parameters of stepwise spin-coating are spin-coating at 2000 rpm for 15 s and spin-coating at 3000 rpm for 30 s. About 245 μL of IPA anti-solvent is quickly dropped onto the center of the substrate 17 s before the end of spin-coating, and then the prepared perovskite thin film is placed on a heating table and heated at 100 °C for 30 min to complete the perovskite crystallization process.

[0072] After the above process cools to room temperature, dissolve 10 mg of the thiophene-quinoline type bis-heterocyclic azo dye (Dye 3) in 1 mL of toluene solvent to form a uniform solution of 10 mg / mL, stir for more than 30 min, spin-coat on the perovskite light-absorbing layer, spin-coat at 5000 rpm for 30 s, and then heat at 100 °C for 40 min.

[0073] Then, the electron transport layer material was replaced with PCBM (a fullerene derivative), and its preparation method was as follows: PCBM was formulated into a 20 mg / mL solution with chlorobenzene as the solvent, stirred at 50 °C for more than 24 h, and filtered before use. In addition, a 0.5 mg / mL BCP solution was formulated with isopropanol as the solvent. First, the PCBM solution was spin-coated at 2000 rpm for 30 s, and then the BCP solution was spin-coated at 5000 rpm for 30 s. The electron transport layer material was prepared by a two-step spin-coating method.

[0074] Finally, a gold electrode was deposited by thermal evaporation, and the thickness of the gold electrode was about 80 nm.

[0075] The final experimental results were similar to those of Example 1. The perovskite solar cell prepared by modifying with the thiophene-quinoline type bisheterocyclic azo dye (Dye 3) had higher energy conversion efficiency and stability than the unmodified device.

[0076] Example 4:

[0077] The preparation method of the perovskite solar cell in this example includes the following steps:

[0078] First, the ITO conductive substrate was cleaned. The ITO glass substrate was cleaned with deionized water and acetone for 30 min in sequence. The cleaned glass substrate was dried on a heating stage, the heating temperature of the heating stage was 100 °C, and it was further cleaned by ultraviolet ozone before use, and the ultraviolet ozone treatment time was 45 min.

[0079] PTAA was used as the hole transport layer. First, the hole transport layer was spin-coated to construct an inverted perovskite solar cell device.

[0080] PTAA was dissolved in toluene solution and then ultrasonicated (concentration: 2 mg / mL). Then, PTAA was dynamically spin-coated on the ITO substrate, that is, first spin-coated at 5000 rpm for 30 s, and after spin-coating PTAA, it was heat-treated at 100 °C for 10 min.

[0081] Preparation of perovskite precursor solution: Dissolve 552 mg of PbI2 in a mixed solvent of 1 mL of DMF and DMSO (volume ratio about 4:1) to form a PbI2:DMF solution, stir it in the dark at 70 °C for 30 min, dissolve 12 mg of MAI in 1 mL of IPA solution to form a MAI:IPA solution, and stir it at 20 °C for 10 min. Then spin-coat the prepared PbI2:DMF solution on a PTAA / ITO glass substrate, with the spin-coating parameters of 4500 rpm for 30 s, and then heat it at 70 °C for 15 min; then spin-coat the MAI:IPA solution on the PbI2 film for two-step spin-coating, with the spin-coating parameters of 0 rpm for 30 s and 4000 rpm for 30 s, and then place the prepared perovskite film on a heating table to complete the annealing crystallization process, with the heating table temperature of 100 °C and the heating time of 60 min.

[0082] After the above process is cooled to room temperature, dissolve 1 mg of thiophene-quinoline type heterocyclic azo dye (dye 4) in 1 mL of chlorobenzene solvent to form a 1 mg / mL uniform solution, stir it for more than 30 min, spin-coat it on the perovskite light-absorbing layer, spin-coat it at 2000 rpm for 30 s, and then heat it at 90 °C for 50 min.

[0083] Then the electron transport layer is PCBM (a fullerene derivative), and its preparation method is as follows: Prepare a 20 mg / mL solution of PCBM with chlorobenzene as the solvent, stir it at 60 °C for more than 24 h, and filter it before use. In addition, prepare a 0.5 mg / mL BCP solution with isopropanol as the solvent. First, spin-coat the PCBM solution at 2000 rpm for 30 s, and then spin-coat the BCP solution at 5000 rpm for 30 s, and use a two-step spin-coating method to fabricate the electron transport layer material.

[0084] Finally, spin-coat the carbon paste on the electron transport layer, and obtain the carbon electrode after drying in vacuum at room temperature.

[0085] The final experimental results are similar to those of Example 1, and the perovskite solar cells prepared by modifying with thiophene-quinoline type heterocyclic azo dye (dye 4) have higher conversion efficiency and stability.

[0086] Comparative Example 1:

[0087] To prove the effectiveness of the application of the present invention, unmodified perovskite was prepared using a similar process for assembling the battery. The specific steps are as follows:

[0088] First, wash the FTO glass substrate with deionized water and acetone in turn for 30 min. Dry the washed glass substrate on a heating table, with the heating temperature of the heating table being 100 °C, and perform re-cleaning with ultraviolet ozone before use, and the ultraviolet ozone treatment time is 45 min.

[0089] Subsequently, 750 mg and 1500 mg of titanium diisopropoxybis(acetylacetonate) were respectively diluted in 10 mL of ethanol to form titanium dioxide (TiO2) precursor solutions with different concentrations. The 75 mg / mL solution was spin-coated on the FTO substrate at 2000 rpm for 20 s, then thermally annealed at 150 °C for 30 min. After cooling to room temperature, the high-concentration 150 mg / mL solution was spin-coated on the low-concentration TiO2 film at 4000 rpm for 20 s, and then kept at 450 °C for 30 min.

[0090] Preparation of perovskite precursor solution: MAI and PbI2 were dissolved in a mixed solvent of DMF and DMSO (volume ratio approximately 4:1) at a molar ratio of 1:1, and stirred in the dark at 60 °C for 30 min.

[0091] Then, the prepared perovskite precursor solution was spin-coated on the TiO2 / FTO glass substrate in two steps. The spin-coating parameters for the two-step method were 2000 rpm for 10 s and 4000 rpm for 30 s. About 245 μL of EA antisolvent was quickly dropped onto the center of the substrate 15 s before the end of spin-coating. Then, the prepared perovskite film was placed on a heating stage and heated at 100 °C for 30 min to complete the perovskite crystallization process.

[0092] 60 μL of spiro-OMeTAD solution was spin-coated on the top of the perovskite film at a speed of 3000 rpm within 30 s. The spiro-OMeTAD solution consists of 72.3 mg of spiro-OMeTAD, 28.8 μL of 4-tert-butylpyridine (TBP), and 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) solution (520 mg of Li-TSFI dissolved in 1 mL of anhydrous acetonitrile (ACN)).

[0093] Finally, a silver electrode was deposited by thermal evaporation, and the thickness of the silver electrode was approximately 80 nm.

[0094] The final experimental results show that compared with the perovskite modified with thiophene-quinoline type bisheterocyclic azo dye (Dye 1) in Example 1, the perovskite crystallization in this comparative example has a more uneven surface and more surface pores. The photoelectric conversion efficiency and stability in air of the fabricated battery devices are much lower than those obtained by modifying the interface layer with thiophene-quinoline type bisheterocyclic azo dye.

[0095] Comparative Example 2:

[0096] To prove the effectiveness of the application of the present invention, perovskite modified with Dye 1 additive was prepared using a similar process to assemble a battery. The specific steps are as follows:

[0097] First, wash the FTO glass substrate with deionized water and acetone successively for 30 min. Dry the cleaned glass substrate on a heating stage, with the heating temperature of the heating stage being 100 °C, and perform re-cleaning with ultraviolet ozone before use, with the ultraviolet ozone treatment time being 45 min.

[0098] Subsequently, dilute 750 mg and 1500 mg of titanium diisopropoxide bis(acetylacetonate) in 10 mL of ethanol respectively to form titanium dioxide (TiO2) precursor solutions with different concentrations. Spin-coat the 75 mg / mL solution on the FTO substrate at 2000 rpm for 20 s, then perform thermal annealing at 150 °C for 30 min. After cooling to room temperature, spin-coat the high-concentration 150 mg / mL solution on the low-concentration TiO2 film at 4000 rpm for 20 s, and then keep it at 450 °C for 30 min.

[0099] Preparation of perovskite precursor solution: Dissolve MAI and PbI2 in a mixed solvent of DMF and DMSO (volume ratio approximately 4:1) at a molar ratio of 1:1, and stir in the dark at 60 °C for 30 min. At the same time, dissolve 0.1 mg of 1 molecule of thiophene-quinoline-based bisheterocyclic azo dye in 1 mL of EA antisolvent to prepare a homogeneous solution for use as the antisolvent.

[0100] Then, spin-coat the prepared perovskite precursor solution on the TiO2 / FTO glass substrate in two steps. The spin-coating parameters for the two-step method are 2000 rpm for 10 s and 4000 rpm for 30 s. Rapidly drop the above-mentioned approximately 245 μL of EA mixed antisolvent onto the center of the substrate 15 s before the end of spin-coating, and then place the prepared perovskite film on a heating stage and heat it at 100 °C for 30 min to complete the perovskite crystallization process.

[0101] Spin-coat 60 μL of spiro-OMeTAD solution on the top of the perovskite film at a speed of 3000 rpm within 30 s. The spiro-OMeTAD solution consists of 72.3 mg of spiro-OMeTAD, 28.8 μL of 4-tert-butylpyridine (TBP), and 17.5 μL of lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) solution (520 mg of Li-TSFI dissolved in 1 mL of anhydrous acetonitrile (ACN)).

[0102] Finally, deposit a silver electrode by thermal evaporation, with the thickness of the silver electrode being approximately 80 nm.

[0103] As Figure 6As shown, the photoelectric conversion efficiency of the perovskite assembled battery without dye modification is 16.47%. However, after the interface layer of the perovskite assembled perovskite solar cell is modified with thiophene-quinoline type heterocyclic azo dye (Dye 1), the photoelectric conversion efficiency reaches 20.08%. At the same time, the photoelectric conversion efficiency of the battery after dye additive modification also reaches a high efficiency of 18.66%. As Figure 7 shown, the perovskite assembled perovskite solar cell with the additive and interface layer of thiophene-quinoline type heterocyclic azo dye (Dye 1) has better stability. After being stored in air for 2000 hours, they all remain above 80% of the initial efficiency, while the stability of the unmodified battery is only 20% of the original efficiency.

[0104] Compared with the performance of the perovskite film, the modification with the thiophene-quinoline type heterocyclic azo dye additive is slightly lower than that with the thiophene-quinoline type heterocyclic azo dye interface modification. This results in the photoelectric conversion efficiency and the stability in air of the fabricated battery device being lower than those of the battery with the interface layer of the thiophene-quinoline type heterocyclic azo dye added.

[0105] The above further proves the effectiveness of the present invention. After the perovskite is modified with the thiophene-quinoline type heterocyclic azo dye, the pores and defects on the surface of the perovskite film are reduced, the non-radiative recombination between the perovskite interfaces is inhibited, and the energy levels of the perovskite are regulated. Moreover, the surface of the perovskite film modified with the thiophene-quinoline type heterocyclic azo dye is more hydrophobic, thus achieving the effects of improving the efficiency of the perovskite solar cell and enhancing the stability of the perovskite solar cell in the environment. The present invention provides a favorable guidance for the development of multifunctional dye interface modification engineering and highly efficient and stable solar cells.

[0106] In view of the large number of embodiments of the present invention and the huge amount of experimental data of each embodiment, it is not suitable to list them one by one here. However, the contents to be verified and the final conclusions obtained by each embodiment are similar.

[0107] The above is only a detailed description of the preferred embodiments and principles of the present invention. For those of ordinary skill in the art, according to the idea provided by the present invention, there will be changes in the specific implementation manners, and these changes should also be regarded as the protection scope of the present invention.

Claims

1. A method for improving the performance of perovskite solar cells based on a dye interface layer, characterized in that, It includes the following steps: (1) Attach a first charge transport layer on a transparent conductive substrate; (2) Coating a perovskite precursor solution on the first charge transport layer, then obtaining a perovskite thin film by spin-coating, then dropping an antisolvent to promote crystallization, and then performing thermal annealing to obtain a perovskite light-absorbing layer; (3) Spin-coating a thiophene-quinoline type bisheterocyclic azo dye precursor solution on the perovskite light-absorbing layer and then heating and annealing to obtain a dye interface layer; (4) Attach a second charge transport layer on the dye interface layer, and attach a top electrode on the transparent conductive substrate and the second charge transport layer respectively.

2. The method according to claim 1, characterized in that, In the step (3), the thiophene-quinoline type bisheterocyclic azo dye precursor solution is a precursor solution obtained by dissolving a thiophene-quinoline type bisheterocyclic azo dye in an organic solvent, and the concentration is 1-10 mg / mL.

3. The method according to claim 2, wherein The thiophene-quinoline type bisheterocyclic azo dye includes at least one of Dye 1, Dye 2, Dye 3, and Dye 4; The molecular structural formula of Dye 1 is: The molecular structural formula of Dye 2 is: The molecular structural formula of Dye 3 is: The molecular structural formula of Dye 4 is: 。 4. The method according to claim 3, wherein The organic solvent includes at least one of chlorobenzene, isopropanol, and toluene.

5. The method according to any one of claims 1-4, characterized in that, In the step (1), the transparent conductive substrate is ITO conductive glass or FTO conductive glass.

6. The method according to any one of claims 1-4, characterized in that In the step (2), the perovskite thin film is obtained by annealing after one-step spin-coating or two-step spin-coating.

7. The method according to any one of claims 1-4, characterized in that, In the step (2), the antisolvent is ethyl acetate, chlorobenzene or isopropanol.

8. The method according to any one of claims 1-4, characterized in that, In the step (3), the process conditions for heating and annealing include: the temperature is 80-100 °C, and the time is 40-60 min.

9. The method according to any one of claims 1 to 4, characterized in that The first charge transport layer is an electron transport layer or a hole transport layer. Correspondingly, the second charge transport layer is a hole transport layer or an electron transport layer; The electron transport layer is a metal oxide layer, and the metal oxide is selected from one or more of zinc oxide, titanium oxide, aluminum oxide, tin oxide, and fullerene derivatives; The hole transport layer is one of spiro-OMeTAD, PEDOT:PSS, PTAA, and P-type transition metal oxides.

10. The method according to any one of claims 1-4, characterized in that, In the step (4), the top electrode is obtained by thermal evaporation deposition or spin-coating; wherein, the top electrode is a gold, silver or carbon electrode.

Images