An electron transport layer, a preparation method therefor and use thereof

Abstract

The application belongs to the technical field of perovskite solar cells, and particularly relates to a graphdiyne (GDY) in-situ grown electron transport layer (ETL), a preparation method thereof and application of the ETL in targeted management of surface oxygen vacancies of tin oxide (SnO2) in a solar cell. The electron transport layer is a SnO2 film with a surface in-situ grown graphdiyne passivation layer. A solar cell is assembled by using the obtained electron transport layer, and the solar cell comprises, from bottom to top, a transparent conductive substrate, an electron transport layer, a perovskite active layer, a perovskite modification layer, a hole transport layer and a metal counter electrode. The method of the application realizes efficient passivation of surface oxygen vacancy defects of SnO2, thereby effectively inhibiting non-radiative recombination, optimizing interface energy level matching degree and significantly improving charge extraction and transport capacity. Meanwhile, defect management of graphdiyne realizes effective adjustment of interface performance and chemical environment between SnO2 and perovskite, and cooperatively realizes optimization of perovskite crystal quality. The preparation method of the application is simple and easy to realize, has high repeatability and effectively improves photoelectric conversion efficiency and stability of the perovskite solar cell.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of perovskite solar cells, and particularly relates to a graphdiyne in-situ grown electron transport layer, a preparation method thereof and application of the graphdiyne in-situ grown electron transport layer to targeted management of surface oxygen vacancies of tin oxide in a solar cell. BACKGROUND

[0002] Due to excellent photoelectric properties, organic-inorganic halide perovskite materials have attracted much attention in the next generation of photovoltaic devices and shown bright application prospects. In recent years, the photoelectric conversion efficiency (PCE) of perovskite solar cells (PSCs) has been rapidly improved from 3.8% to 26.5%. Among them, SnO2 as a high-efficiency electron transport layer plays a key role in the latest breakthroughs in the photoelectric conversion efficiency of the corresponding devices and shows great development potential. Although SnO2 has unique advantages (such as good energy level arrangement, high transmittance, high electron mobility, and easy processing at low temperature), a large number of defects are inevitably formed on the SnO2 surface during thin film preparation and solution spin coating. There are mainly three types of defects on the SnO2 surface: oxygen vacancies (Vo), Sn dangling bonds with unsaturated coordination, and basic end-OH combined with one Sn site and acid bridge-OH combined with two Sn sites.

[0003] The existence of oxygen vacancies reflects the non-stoichiometry of SnO2 thin films, which means the existence of different oxidation state Sn dangling bonds on the surface, which greatly affects the chemical environment and photoelectric properties at the SnO2 / perovskite (PVSK) interface, and further limits the charge transport performance at the interface and the crystal growth of the upper perovskite. At the same time, the oxygen vacancies on the SnO2 surface also significantly affect the electrical and chemical properties of the SnO2 ETL itself. Because the two electron donor levels of the oxygen vacancies are below the minimum value of the conduction band of the SnO2 ETL, they can strongly affect the electron concentration related to the two electron donor levels, so the conductivity of the SnO2 ETL is closely related to the number of oxygen vacancies. In addition, oxygen vacancies usually have positive charge centers, which easily act as electron trapping traps, forming a potential barrier that hinders electron transmission, so the carrier concentration is directly related to the interface non-radiative recombination caused by oxygen vacancies. So far, many effective surface modification strategies and interface engineering techniques have been reported in the literature to improve the interface energy level arrangement and inhibit carrier recombination. Among them, ionic salts or functionalized organic molecules are often used as interface modifiers to passivate the defects on the SnO2 surface. However, these passivation molecules are usually added by spin coating, and their interaction sites with the defects on the SnO2 surface are random, which leads to uncontrollable regulation and modification of the interface environment. Therefore, the in-situ introduction of passivation agents is an important way to overcome this great challenge. SUMMARY

[0004] The application aims to provide a graphdiyne in-situ growth electronic transport layer, a preparation method thereof and an application of the electronic transport layer in targeted management of tin oxide surface oxygen vacancies in a solar cell.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows:

[0006] An electronic transport layer, which is a SnO2 film with a surface in-situ growth graphdiyne passivation layer.

[0007] A preparation method of the electronic transport layer, which realizes in-situ growth of graphdiyne on the surface of the SnO2 ETL through Glaser-Hay coupling reaction, so that an interface passivation layer is formed on the surface.

[0008] Further, the substrate with the SnO2 film is added into a reaction container, cuprous iodide, acetone, pyridine and N,N,N',N'-tetramethyl ethylenediamine are sequentially added, then a precursor solution is added into the system, and after mixing, the reactor is placed in an argon atmosphere at 50-60 DEG C in the dark (to avoid light irradiation to induce the reaction), and after the reaction, the SnO2 film with a surface in-situ growth graphdiyne passivation layer is obtained after washing.

[0009] The precursor solution is a hexaethynylbenzene (HEB) precursor molecule dissolved in acetone (the concentration is controlled at 0.13-0.67 mg / ml); the amount of the catalyst cuprous iodide in the reaction system is 0.005-0.013 mmol, and the volume ratio of acetone, pyridine and N,N,N',N'-tetramethyl ethylenediamine is 100:1:1-100:1:10.

[0010] The substrate with the SnO2 film is obtained by spin coating SnO2 precursor solution on the substrate.

[0011] The SnO2 film is prepared by diluting SnO2 colloidal solution (15% aqueous colloidal dispersion) with ultrapure water to obtain SnO2:H2O = 1:3-1:5 (v:v), ultrasonic dispersion for 15-30 min, spin coating on the substrate at a speed of 3000-4000 rpm on a film uniformizer for 30-40 s, annealing at 150 DEG C for 15-30 min, and cooling to room temperature.

[0012] The application of the electronic transport layer is in the preparation of an organic-inorganic halide perovskite solar cell.

[0013] An organic-inorganic halide perovskite solar cell, the solar cell comprising, from bottom to top, a transparent conductive substrate, an electron transport layer, a perovskite active layer, a perovskite modification layer, a hole transport layer and a metal counter electrode, the electron transport layer being a SnO2 film with a graphdiyne passivation layer grown in situ on the surface.

[0014] Further, the SnO2 ETL surface is targeted to manage the tin oxide surface oxygen vacancies in the solar cell by in situ growth of graphdiyne, and a passivation channel is successfully constructed at the interface.

[0015] The in situ growth of graphdiyne is achieved by Glaser-Hay coupling reaction on the surface of the SnO2 ETL. The hexaethynylbenzene (HEB) precursor molecule is dissolved in acetone as a precursor solution, and cuprous iodide, acetone, pyridine and N,N,N',N'-tetramethyl ethylenediamine are sequentially added to the reaction bottle containing copper foil and FTO (SnO2). The precursor solution is then slowly added. The reaction is carried out in an argon atmosphere at 60°C in the dark. Due to the strong electronic interaction between the alkyne bond and the oxygen vacancy, the hexaethynylbenzene (HEB) precursor molecule can be anchored on the oxygen vacancy on the surface of SnO2. With the cross-coupling of the precursor molecule, graphdiyne can be directly grown in situ on the SnO2 film. The in situ growth process is monitored according to different reaction times. After the reaction is completed, the product is washed with deionized water, N,N-dimethylformamide (DMF) and acetone several times, and finally a graphdiyne passivation layer (FTO / SnO2 / GDY) is successfully obtained on the SnO2 film.

[0016] A method for preparing the organic-inorganic halide perovskite solar cell, forming a SnO2 electron transport layer on the surface of the substrate, forming a graphdiyne passivation layer in situ on the surface of the transport layer as described above, and then depositing a perovskite precursor solution on the surface of the layer by spin coating to obtain a perovskite active layer film.

[0017] Further, a solution containing phenethylammonium iodide (PEAI) is spin-coated on the surface of the perovskite active layer film to form a perovskite modification layer on the surface of the perovskite active layer film. After formation, a hole transport layer is modified by spin coating, and then aged. After treatment, a metal counter electrode is prepared, and a solar cell is obtained.

[0018] The perovskite precursor solution is prepared by weighing 912.8 mg of PbI2 (1.98 M), 309.6 mg of FAI (1.8 M), 42.5 mg of MACl (0.63 M) and 57.4 mg of CsPbBr3 (0.1 M) in 1000 μL of mixed solvent (DMF:DMSO = 4:1, v:v), and continuously shaking on a vortex shaker for 2 h until the mixture is fully dissolved. A perovskite precursor solution is obtained.

[0019] The Spiro-OMeTAD precursor solution uses chlorobenzene as a solvent, 80-100 mg of Spiro-OMeTAD powder, 25-30 μL of a tetrabutylpyridine solution, and 10-20 μL of a lithium bis-trifluoromethanesulfonimide acetonitrile solution, 10-20 μL of a FK209 Co(III) TFSI acetonitrile solution, and the concentration of lithium bis-trifluoromethanesulfonimide in the acetonitrile solution is 520 mg / mL, and the concentration of FK209 Co(III) TFSI is 350 mg / mL.

[0020] Specifically:

[0021] Step (1) The commercially purchased etched FTO glass substrate is ultrasonically treated with glass detergent, deionized water, acetone and isopropyl alcohol for 15 min respectively, then dried with nitrogen, and then plasma treated for 15 min.

[0022] Step (2) The SnO2 solution (15% aqueous colloidal dispersion) is diluted with ultrapure water, spin-coated on the surface of the substrate at a speed of 3700 rpm for 30 s, and then annealed on a heating plate at 150°C for 15 min to prepare the SnO2 electron transport layer.

[0023] Step (3) The pretreated FTO conductive glass sheet with SnO2 film is placed in a three-neck reaction bottle together. Then GDY monomer hexakis(trimethylsilyl ethynyl) benzene (HEB-TMS) is added to a 100 mL reaction bottle for deprotection reaction, dissolved in tetrahydrofuran, and tetrabutylammonium fluoride is added, and stirring is continued for 10 min, and the temperature is always kept below zero during the process. Subsequently, extraction is performed with ethyl acetate and saturated brine, and the obtained solution is dried with anhydrous Na2SO4. Then the solvent is removed in a vacuum rotary evaporator to obtain the graphdiyne precursor HEB, which is then dissolved in acetone as a precursor solution. Next, cuprous iodide, acetone, pyridine and N,N,N',N'-tetramethyl ethylenediamine are added in sequence to the reaction bottle containing FTO (SnO2), and the precursor solution is slowly added. The reaction is carried out in an argon atmosphere at 60°C in the dark, and GDY can be directly grown in situ on the SnO2 film. The in-situ growth process is monitored according to different reaction times. After the reaction is completed, the sample is washed with deionized water, DMF and acetone several times, and finally the in-situ grown GDY passivation layer (FTO / SnO2 / GDY) is successfully obtained on the SnO2 film.

[0024] Step (4): The perovskite precursor solution is deposited by a spin-coating method, in two-step spin-coating procedures, the first step is spin-coating at 1000 rpm for 10 s, and the acceleration per second is 1000 rpm; the second step is spin-coating at 5000 rpm for 30 s, and the acceleration per second is 1000 rpm. 200 μL of ethyl acetate is added dropwise at 15 s before the end of spin-coating to perform anti-solvent treatment, so that the perovskite precursor solution is formed into a film, and then the perovskite active layer film is obtained by annealing at 100 DEG C for 50 min in a glove box.

[0025] Step (5): A phenylethylammonium iodide (PEAI) solution with a concentration of 2 mg / ml is prepared with isopropyl alcohol as a solvent, and the solution is spin-coated on the perovskite active layer at 4000 rpm for 20 s, so that the perovskite modification layer is obtained.

[0026] Step (6): The Sprio-OMeTAD solution is spin-coated on the perovskite active layer prepared in step (5) at a rotation speed of 4000 rpm for 30 s, so that the hole transport layer is obtained, and then the hole transport layer is transferred to an electronic moisture-proof box with a fixed humidity and aged in an air atmosphere for about 15 h.

[0027] Step (7): The perovskite device aged in step (6) is placed in a mask with a suitable size, and a vacuum coating instrument is used to evaporate a 100 nm silver electrode at a rate of 0.1 A under a high vacuum condition of at least 1*10 -7 Pa, so that the prepared perovskite solar cell is obtained.

[0028] Working principle:

[0029] The present application realizes the targeted passivation of SnO2 surface defects by controlling the in-situ growth of graphdiyne on the SnO2 ETL surface. The highly active hexaethynylbenzene precursor molecule is first anchored on the oxygen vacancy of SnO2, and as the cross-coupling of the precursor molecule proceeds, effective electron transfer occurs between graphdiyne and SnO2, and the interaction between the alkyne bond and SnO2 induces the ene-yne interconversion, which is conducive to the increase of the overall chemical valence of the surface tin atom and the reduction of the oxygen vacancy trap state. In addition, the in-situ growth of graphdiyne can optimize the surface morphology of tin oxide, regulate the electrical properties and chemical contact at the interface between tin oxide and perovskite, and improve the crystallinity and vertical growth orientation of the upper perovskite. This invention realizes precise electronic layer defect management and interface property regulation, and significantly optimizes the performance of perovskite solar cell devices.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] ​(1) The application is based on the characteristics that graphdiyne can be controllably grown in situ on the surface of any substrate, proposes a new strategy for growing graphdiyne in situ on the surface of SnO2 ETL, and successfully constructs an interface passivation channel.

[0032] (2) The application uses the precursor molecule hexaethynylbenzene to target and anchor on the oxygen vacancy on the surface of SnO2, realizes the in-situ growth of graphdiyne on the surface of SnO2, and effectively manages the oxygen vacancies on the surface of SnO 2 .

[0033] (3) The application ensures the property regulation of the interface between SnO2 and the perovskite layer through in-situ growth and defect management of graphdiyne, and cooperatively realizes the crystallinity optimization of the perovskite layer, which is beneficial to the preparation of high-performance and high-stability perovskite solar cells. At the same time, the application has low production cost and simple preparation method, which is more conducive to actual production. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a schematic diagram for in-situ growth of graphdiyne to target and manage the oxygen vacancies on the surface of tin oxide in a solar cell according to the application;

[0035] Figure 2 It is an SEM and AFM diagram of SnO2 control film and in-situ growth of graphdiyne on the surface of SnO2 ETL according to the application;

[0036] Figure 3 It is an FT-IR spectrum diagram of the interaction between SnO2 and graphdiyne according to the application;

[0037] Figure 4 It is an XPS diagram of SnO2 control film and in-situ growth of graphdiyne on the surface of SnO2 ETL according to the application;

[0038] Figure 5 It is a dark I-V curve diagram and electron mobility of SnO2 control film and in-situ growth of graphdiyne on the surface of SnO2 ETL according to the application;

[0039] Figure 6 It is an SEM diagram of control perovskite film and graphdiyne treated perovskite film according to the application;

[0040] Figure 7 It is a GIWAXS diagram of control perovskite film and graphdiyne treated perovskite film according to the application;

[0041] Figure 8 It is a PL and TRPL spectrum of control and graphdiyne treated perovskite film according to the application;

[0042] Figure 9 It is an energy level arrangement schematic diagram according to the application;

[0043] Figure 10 Perovskite device structure schematic and PCE distribution histogram of the present application;

[0044] Figure 11 J-V curves of forward and reverse scans of the control device and the graphdiyne treated device of the present application;

[0045] Figure 12 Long-term stability test curve of the unpacked control device and the graphdiyne treated device of the present application under N2 atmosphere. DETAILED DESCRIPTION

[0046] The present application is further illustrated by the following examples and figures. However, these examples do not limit the scope of the present application.

[0047] The present application targets the management of SnO2 surface oxygen vacancies in situ growth of graphdiyne, thereby improving the performance and stability of the solar cell. The perovskite solar cell structure is: transparent conductive substrate, electron transport layer, SnO2 modification layer, perovskite active layer, hole transport layer and metal counter electrode. Among them, the transparent conductive substrate uses FTO, the electron transport layer is prepared by spin coating with SnO2 colloidal aqueous solution, the interface between the SnO2 electron transport layer and the perovskite light absorbing layer is modified with graphdiyne to construct a targeted passivation layer, the perovskite light absorbing layer is prepared with organic-inorganic halide perovskite, the hole transport layer is prepared with Spiro-OMeTAD, and the metal Ag electrode is used as the counter electrode.

[0048] In the following examples, the SnO2 precursor solution is prepared by diluting SnO2 colloidal solution (15% aqueous colloidal dispersion) with ultrapure water to obtain SnO2:H2O = 1:3 (v:v), and ultrasonic dispersion for 15 min. Then spin coating on the FTO substrate at a speed of 3700 rpm for 30 s, and annealing at 150℃ for 30 min. After cooling to room temperature, it is transferred to a three-neck reaction bottle filled with argon atmosphere for graphdiyne in situ growth reaction.

[0049] Example 1

[0050] As Figure 1 The process schematic of in situ growth of GDY on the surface of SnO2 thin film and targeted passivation of SnO2 surface oxygen vacancies is shown.

[0051] Step (1) The etched FTO glass substrate purchased commercially is treated with glass detergent, deionized water, acetone and isopropanol for 15 min each, then blown dry with nitrogen, and then plasma treated for 15 min;

[0052] Step (2): Sn02electron transport layer was prepared by diluting Sn02solution (15% hydrocolloid dispersion) with ultrapure water, spin-coating on the surface of the substrate at a rotation speed of 3700 rpm for 30 s, and then annealing on a hot plate at 150°C for 15 min;

[0053] Step (3): The FTO conductive glass sheet with the Sn02thin film was placed in a three-necked reaction bottle for storage. Then 10 mg of monomer hexakis(trimethylsilyl ethynyl) benzene (HEB-TMS) of GDY was added to 100 mL of the reaction bottle for deprotection reaction, dissolved in 20 mL of tetrahydrofuran, and 0.3 mL of tetrabutylammonium fluoride was added at the same time. The stirring was continued for 10 min, and the temperature was always kept below zero during the process. Subsequently, extraction was performed with an appropriate amount of ethyl acetate and saturated brine, and the obtained solution was dried with anhydrous Na2S04. Then the solvent was removed in a vacuum rotary evaporator to obtain the graphdiyne precursor HEB, which was then dissolved in 30 mL of acetone as a precursor solution. Next, 1 mg of cuprous iodide, 100 mL of acetone, 1 mL of pyridine, and 10 mL of N,N,N',N'-tetramethyl ethylenediamine were sequentially added to the reaction bottle containing FTO (Sn02), and the precursor solution was slowly added. The reaction was carried out in an argon atmosphere at 60°C in the dark, and GDY was directly grown in situ on the Sn02thin film. The reaction time was controlled for 1 h, and the in-situ growth process was monitored. After the reaction was completed, the in-situ grown GDY passivation layer (FTO / Sn02 / GDY) was successfully obtained on the Sn02thin film after washing with deionized water, DMF, and acetone.

[0054] Step (4): The perovskite precursor solution (912.8 mg of Pbl2 (1.98 M), 309.6 mg of FAI (1.8 M), 42.5 mg of MACl (0.63 M), and 57.4 mg of CsPbBr3 (0.1 M) were mixed in 1000 μL of mixed solvent (DMF:DMSO = 4:1, v:v)) was deposited by spin-coating method, and two-step spin-coating procedure was used, the first step was spin-coating at a speed of 1000 rpm for 10 s with an acceleration of 1000 rpm per second, and the second step was spin-coating at a speed of 5000 rpm for 30 s with an acceleration of 1000 rpm per second. 200 μL of ethyl acetate was added 15 s before the end of spin-coating for anti-solvent treatment, and the perovskite precursor solution was formed into a film. Subsequent annealing at 100°C for 50 min in the glove box resulted in a perovskite active layer thin film;

[0055] Step (5): A phenethylammonium iodide (PEAI) solution with a concentration of 2 mg / ml was prepared using isopropanol as the solvent. The solution was spin-coated on the perovskite active layer at a speed of 4000 rpm for 20 s to obtain a perovskite modification layer.

[0056] Step (6): The Spiro-OMeTAD solution was spin-coated on the perovskite active layer prepared in step (5) at a speed of 4000 rpm for 30 s to obtain a hole transport layer, and then transferred to an electronic moisture-proof box with fixed humidity for aging in air for about 15 h;

[0057] Step (7): The perovskite film after aging was placed in a mask with appropriate specifications, and MoO3 and Ag were deposited on the surface of the hole transport layer by thermal evaporation using a vacuum coating instrument under a high vacuum condition of at least 1 x 10 -7 Pa to obtain a prepared perovskite solar cell.

[0058] Control group 1

[0059] Step (1): The commercially purchased etched FTO glass substrate was treated with glass detergent, deionized water, acetone and isopropanol for 15 min respectively, then blown dry with nitrogen, and then treated with plasma for 15 min;

[0060] Step (2): The SnO2 solution (15% aqueous colloidal dispersion) was diluted with ultrapure water, and then spin-coated on the substrate surface at a speed of 3700 rpm for 30 s, and then annealed on a heating plate at 150°C for 15 min to obtain a SnO2 electron transport layer;

[0061] Step (3): The perovskite precursor solution (912.8 mg PbI2(1.98 M), 309.6 mg FAI (1.8 M), 42.5 mg MACl (0.63 M) and 57.4 mg CsPbBr3(0.1 M) were mixed in 1000 μL of mixed solvent (DMF:DMSO = 4:1, v:v)) was deposited by spin coating, and the spin coating speed was 1000 rpm for the first step, the duration was 10 s, and the acceleration per second was 1000 rpm; the spin coating speed was 5000 rpm for the second step, the duration was 30 s, and the acceleration per second was 1000 rpm. 200 μL of ethyl acetate was added 15 s before the end of spin coating for anti-solvent treatment to form a perovskite precursor solution film, and then annealed at 100°C in a glove box for 50 min to obtain a perovskite active layer film;

[0062] Step (4): A phenethylammonium iodide (PEAI) solution with a concentration of 2 mg / ml was prepared with isopropanol as the solvent, and the solution was spin-coated on the perovskite active layer at a speed of 4000 rpm for 20 s to obtain a perovskite modification layer;

[0063] Step (5): Spin-coat the Spiro-OMeTAD solution on the prepared perovskite active layer at a speed of 4000 rpm for 30 seconds to obtain a hole transport layer, and transfer the layer to an electronic moisture-proof box with a fixed humidity and age it in air for about 15 hours;

[0064] Step (6): Place the aged perovskite film into a mask with suitable specifications and use a vacuum coating machine to coat the film at a depth of at least 1×10 -7 Under the high vacuum conditions of Pa, MoO3 and Ag are deposited on the upper surface of the hole transport layer by thermal evaporation to obtain the prepared perovskite solar cell.

[0065] Step (7): Perform performance testing using the above examples and control examples.

[0066] Depend on Figure 2 Scanning electron microscopy (SEM) images show that before the in-situ growth of GDY, the SnO2ETL presents an uneven film state on the FTO surface, and pinhole-like pores can be clearly observed. The GDY film grows evenly on the SnO2 surface and tends to be in the uneven area of ​​the surface, indicating that the in-situ growth of GDY successfully achieves the pinhole filling and surface flatness optimization of the SnO2 film. The morphology of the in-situ growth of GDY on the SnO2 film surface was further explored by atomic force microscopy (AFM). The GDY film is evenly distributed on the SnO2 surface, which is consistent with the SEM results, further confirming the effective realization of the in-situ growth of GDY. More importantly, compared with the surface roughness of the original SnO2 film of 1.57nm, the roughness value of the SnO2 film after GDY passivation is significantly reduced to 0.84nm, which will be beneficial to the spreading of the perovskite precursor solution and the nucleation and growth of perovskite.

[0067] During the growth of GDY, we first tracked the intermolecular interactions between GDY and SnO2 by Fourier transform infrared spectroscopy (FT-IR), e.g. Figure 3 As shown: In SnO2 / HEB, at 3090cm -1 A distinct stretching vibration peak of olefinic hydrogen (=CH) appears at 948 cm-1. This is due to the strong electronic interaction between HEB and SnO2, which transfers part of the charge of HEB to SnO2, thereby causing some acetylenic bonds to break and transform into olefinic bonds. After the in-situ growth of GDY is completed, the interaction between it and SnO2 is further tracked by infrared spectroscopy. Compared with pure GDY, the infrared results of SnO2 / GDY show that the peak at 948 cm-1 is larger than that of pure GDY. -1 A new chemical bond C-O appears at 500 cm-1, indicating that the alkyne bond C in GDY forms a covalent bond with the O in SnO2. -1The nearby O-Sn-O bond also underwent a significant blue shift. The above results all indicate that the presence of the alkyne bond leads to a strong electronic interaction between GDY and SnO2, and the alkyne bond C can target and bind to the O atom on SnO2, resulting in charge transfer between molecules.

[0068] The interaction between GDY and SnO2 and the effect of GDY on oxygen vacancy management were further studied by X-ray photoelectron spectroscopy (XPS). Figure 4 As shown, the C1s spectrum of the original GDY shows that at 284.4 eV (sp 2 There are four sub-peaks at 284.9eV (sp-C), 286.2eV (CO) and 288.4eV (C=O). In the C1s spectrum of SnO2 / GDY film, there are four sub-peaks at 284.5eV (sp 2 -C), 285.0eV (sp-C), 286.3eV (CO), 288.2eV (C=O) and 289.4eV (π-π* transition). The π-π* transition peak at 289.4eV means the existence of delocalized π electrons, revealing the electronic interaction between GDY and SnO2. Especially for the original GDY structure, I sp-C / sp2-C =2. When GDY is in situ introduced into the SnO2 surface, I sp-C with I sp2-C The ratio of GDY to SnO2 decreased to 1.86, indicating that some alkyne bonds were broken by intermolecular interactions, which is consistent with the infrared results. In order to further study the effect of GDY on the passivation of oxygen vacancies on the SnO2 surface, the Sn3d and O1s XPS fine spectra were analyzed in detail. With the introduction of GDY, the Sn 3d spectrum shifted to a higher binding energy by 0.32 eV. 5 / 2 Detailed analysis of the XPS spectrum revealed that the I Sn4+ / I Sn2+ The ratio is 2.05, while in SnO2 / GDY film this ratio is significantly increased to 7.69. This result shows that the electron transfer between SnO2 and the alkyne bond induces the chemical valence state of the nearby Sn to change, and the coordination-unsaturated Sn 2+ Effectively converted to Sn 4+ , thereby significantly reducing the concentration of oxygen vacancies. In addition, the XPS spectrum of O 1s contains three peaks, and the binding energies correspond to lattice oxygen (O lattice ), vacancy oxygen (O vacancy ) and chemically adsorbed oxygen (O chemical ). With the passivation of GDY, the lattice oxygen (O-Sn 4+ ) signal intensity increased significantly, and the signal intensity of vacancy oxygen decreased significantly (O-Sn 2+ It is worth mentioning that lattice oxygen and vacancy oxygen (IO 2- / IO vacancy ) This ratio is 1.77 in pristine SnO2 and significantly increases to 2.72 after in-situ passivation with GDY, indicating that oxygen vacancies are well suppressed due to the strong electronic interaction between GDY and SnO2.

[0069] like Figure 5 As shown in the figure, a pure electronic device with glass / FTO / ETL / Al structure was constructed, and the conductivity and electron mobility of SnO2 and SnO2 / GDY ETL were tested by space charge limited current method (SCLC). After in-situ growth of GDY, the electron mobility increased from 1.56×10 -4 cm 2 ·V -1 ·s -1 Increased to 4.40×10 -4 cm 2 ·V -1 ·s -1 Meanwhile, the dark IV curves recorded under light-shielding conditions show that the conductivity of the SnO2 / GDY-based ETL is significantly increased. The above results indicate that GDY significantly optimizes the charge extraction and transport at the SnO2 interface, which is due to the effective suppression of oxygen vacancies on the SnO2 surface, which enhances its electrical properties.

[0070] Figure 6 SEM images of perovskite films deposited on SnO2 without GDY passivation and after in-situ GDY passivation are shown. Compared to the pristine perovskite film, the SnO2 / GDY-based perovskite film is smoother and has more uniform grain size. The average grain size of the pristine perovskite film is approximately 1.15 μm, while the average grain size of the SnO2 / GDY-based perovskite film increases to 1.22 μm.

[0071] The effects of SnO2 surface properties on the orientation and crystallinity of the upper perovskite crystals were studied by grazing incidence wide-angle X-ray scattering (GIWAXS) tests. Figure 7 As shown, SnO2-based and SnO2 / GDY-based perovskite films at q = 10nm -1 The characteristic signal of α-FAPbI3 is shown in Figure 2. The peak intensity of the α-phase signal of the perovskite film based on the GDY optimized substrate is significantly increased. z The GDY passivation layer creates an optimal interface for the perovskite film to grow vertically, which in turn facilitates charge extraction and transport at the SnO2 / perovskite interface.

[0072] The influence of GDY passivation on the interface charge transport dynamics was studied by steady-state fluorescence (PL) and transient fluorescence (TRPL) tests. The results show that the charge extraction and transfer process of the FTO / SnO2 / GDY / perovskite film is faster (see Figure 8 ).

[0073] Through ultraviolet photoelectron spectroscopy (UPS) analysis, it is found that the construction of graphdiyne passivation layer can optimize the device energy level arrangement and promote the transport of carriers (see Figure 9 ).

[0074] Further, through device performance test, that is, spin-coating an electron transport layer, in-situ growth of a GDY passivation layer, a perovskite active layer, a perovskite modification layer, a hole transport layer and a metal counter electrode on a transparent conductive substrate, a perovskite solar cell device is formed, and the device performance and stability test are carried out under simulated sunlight.

[0075] As can be seen from Figure 10 and Figure 11 , the in-situ growth of GDY can effectively passivate the oxygen vacancies on the surface of SnO2, which can significantly reduce the hysteresis effect of the device, and the average photoelectric conversion efficiency is increased from 23.01% of the reference device to 24.78%; and compared with the control device, the long-term stability of the GDY-based device is significantly improved (see Figure 12 ).

[0076] The above only describes the embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent flow transformation made by using the content of the specification and drawings, or directly or indirectly applied to other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An electron transport layer, characterized in that: The electron transport layer is a SnO2 film with an in-situ growth of graphyne passivation layer on the surface; The in-situ growth of graphyne is achieved on the surface of the tin oxide electron transport layer through a Glaser-Hay coupling reaction, so that an interfacial passivation layer is formed with the surface thereof; a substrate with a SnO2 film is added to a reaction vessel, and cuprous iodide, acetone, pyridine and N,N,N',N'-tetramethylethylenediamine are added in sequence, and then a precursor solution is added to the system. After mixing, the reactor is placed in an argon atmosphere at 50-60°C in the dark for reaction, and after the reaction, the SnO2 film with the graphyne passivation layer in situ grown on the surface is obtained by washing; The precursor solution is a hexaethynylbenzene (HEB) precursor molecule dissolved in acetone, with the concentration controlled at 0.13-0.67 mg / mL; the amount of cuprous iodide catalyst used in the reaction system is 0.005-0.013 mmol, and the volume ratio of acetone, pyridine and N,N,N',N'-tetramethylethylenediamine is 100:1:1-100:1:

10.

2. The method for preparing an electron transport layer according to claim 1, wherein: The substrate with the SnO2 thin film is obtained by spin coating a SnO2 precursor solution on the substrate.

3. The method for preparing an electron transport layer according to claim 2, wherein: The SnO2 thin film is prepared by diluting a SnO2 colloidal solution with ultrapure water to obtain a SnO2:H2O volume ratio of 1:3-1:5, and ultrasonically dispersing it for 15-30 minutes to obtain a SnO2 precursor solution; then, the solution is spin-coated onto a substrate on a homogenizer at a speed of 3000-4000 rpm for 30-40 seconds, and annealed at 150°C for 15-30 minutes. The solution is cooled to room temperature and then used. The SnO2 colloidal solution is a 15% aqueous colloidal dispersion.

4. An application of the electron transport layer according to claim 1, characterized in that: Application of the electron transport layer in the preparation of organic and inorganic halide perovskite solar cells.

5. An organic-inorganic halide perovskite solar cell, comprising, arranged in order from bottom to top, a transparent conductive substrate, an electron transport layer, a perovskite active layer, a perovskite modification layer, a hole transport layer, and a metal counter electrode, characterized in that: The electron transport layer is a SnO2 film with an in-situ grown graphyne passivation layer on the surface as claimed in claim 1.

6. A method for preparing an organic-inorganic halide perovskite solar cell according to claim 5, characterized in that: Forming a SnO2 electron transport layer on the surface of the substrate, forming an in-situ grown graphyne passivation layer on the surface of the transport layer according to claim 1; then modifying the perovskite precursor solution on the surface of the layer by spin coating deposition to obtain a perovskite active layer film; A solution containing phenylethylammonium iodide (PEAI) is further spin-coated on the surface of the perovskite active layer film formed above to form a perovskite modification layer on the surface of the perovskite active layer film; after formation, the hole transport layer is modified by spin coating, aged, and a metal counter electrode is prepared after treatment to obtain a solar cell.

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