CN111653672B - Lattice-matched heterojunction composite film, preparation method and perovskite solar cell - Google Patents

Abstract

The invention discloses a lattice-matched heterojunction composite film, a preparation method and a perovskite solar cell adopting the composite film as an electron transmission layer, wherein the composite film contains nano-scale Bi alkene-SnO₂The heterojunction adopts spin coating and annealing process in air during preparation. The result shows that the energy conversion efficiency of the perovskite solar cell taking the composite film as the electron transport layer is 18.12-19.38 percent and is higher than that of pure SnO₂A perovskite solar cell which is an electron transport layer. Moreover, the perovskite solar cell can still maintain the initial performance of more than 80% in 35-45% humidity air after 800 hours, and has better stability.

Description

Lattice-matched heterojunction composite film, preparation method and perovskite solar cell

Technical Field

The invention relates to a lattice-matched heterojunction thin film material which comprises Bi alkene-stannic oxide (Bi alkene-SnO)₂) A conductive heterojunction structure can be used as an Electron Transport Layer (ETL) for Perovskite Solar Cells (PSCs), and belongs to the field of solar cells.

Background

PSCs have improved the energy conversion efficiency (PCE) from 3.8% to 25.2% in less than ten years, with attractive industrial potential for low cost, simple manufacturing processes, and the like. ETL plays an important role in PSCs devices as an important functional layer of the PSCs devices.

SnO₂Due to the advantages of excellent photoelectric property, energy band matched with a perovskite layer, simple low-temperature annealing preparation process and the like, the material has wide application prospect, is an excellent Electron Transport Material (ETM), and has the characteristics of low light transmittance, low conductivity and the like. Doping is a simple and effective method for improving ETM and has great potential in large-scale industrial applications. Bi alkene has received great attention as a new two-dimensional material due to its semiconductor characteristics and high carrier mobility.

In the prior art, Jun Song et al [ adv. Mater.2018,1803244]Mention of preparation of HTLs of PSCs from antimonene nanosheets, grinding metallic antimony (Sb) to Sb powder, and charging with 100mg mL^-1Mixing was carried out in glass vials of the concentration of sec-butanol. Subsequently, the antimony powder suspension was sonicated at 600W for 2 hours using an ultrasonic probe with an ice bath. The resulting suspension was then subjected to 10000rpm for 10 minutes to produce a semiconducting stibene nanosheet suspension. Coating 30 μ L of the suspension solution on ITO glass, treating at 3000rpm for 30s, and then annealing at 100 ℃ for 2 minutes to obtain a Hole Transport Layer (HTL) of the antimonene nanosheet. However, the HTLs prepared therefrom have no associated heterojunction formation.

In the prior art, Xiao-Feng Wang et al [ J, Mater, Chem, A,2019,7, 565635-]Mention is made of Ti₃C₂To SnO₂ETL of PSCs in colloidal fluids, which convert SnO₂The hydrocolloid was diluted to a concentration of 3 wt%. Then adding titanium carbide (Ti)₃C₂) Mixing the dispersion and adding SnO₂In hydrocolloids, the mixed solution was stirred for 5 minutes before use. Coating 70 mu L of the mixed solution on ITO glass, rotating at 3000rpm for 30s, and annealing at 150 ℃ on a hot bench in air for 30min to prepare Ti₃C₂/SnO₂ETL. However, the device is not suitable for use in a kitchenHowever, the ETL prepared therefrom was not performed in a wider humidity range only under a humidity of 20% when stability test was performed, and stability in a wider humidity environment was not known.

Disclosure of Invention

Based on the problems in the prior art, the invention provides a Bi alkene-SnO with nanoscale₂The heterojunction composite film is used for ETL of the PSCs, the PCE of the obtained PSCs is high, the stability of the obtained PSCs is high in a wide-range humidity environment, the great influence of humidity environment change on the PCE of the PSCs is reduced, the application range of the PSCs is wider, and the durability and practicability of the PSCs are enhanced.

The invention is based on a special hexagonal lattice and rugged single crystal structure of Bi alkene, Bi alkene and SnO₂Combined to form SnO₂Bi-alkene heterojunctions, which differ from the prior art. And, with Bi ene-SnO₂The PSCs with the thin film of ETL can reach the PCE of 19.38 percent at most, and the performance of the film is improved because of Bi alkene-SnO₂The formed lattice-matched heterojunction structure can keep high stability of the performance under the humidity environment of 35% -45%.

Specifically, the lattice-matched heterojunction composite film contains Bi alkene-SnO with nanoscale₂The atomic number percentages of Sn, O and Bi elements of the heterojunction are respectively 23-25%, 73-75% and 1-2%.

Preferably, the Bi alkene is a two-dimensional hexagonal crystal, SnO₂Is three-dimensional nano-particles, proper amount of Bi alkene and SnO₂Combined to form a heterojunction, Bi alkene and SnO₂Form an atomic-scale two-dimensional hexagonal parallel matching interface with lattice matching, and the interface contains Bi₂O₃。

The invention also provides a preparation method of the composite film, which comprises the steps of Bi alkene preparation and Bi alkene-SnO₂Preparation of mixed precursor solution and preparation of Bi alkene-SnO₂And coating the mixed precursor solution on the substrate for annealing. The substrate may be FTO glass, ITO glass, or the like.

Preferably, the preparation method of the composite film specifically comprises the following steps:

1) preparing Bi alkene: with Bi powder, (NH)₄)₂S₂O₈、H₂SO₄(98wt％)、H₂O₂(30 wt%) as raw material, reacting at room temperature for 18-20h, washing with centrifugal water, and ultrasonic dispersing;

2) bi ene-SnO₂Preparation of mixed precursor solution: preparing Bi alkene dispersion solution to make Bi content be 0.08-0.13 wt%, then preparing SnO 2-3 wt%₂Adding 2.65-2.75 wt% Bi alkene dispersion solution into colloidal water solution, and performing ultrasonic treatment at room temperature for 20-40min to obtain Bi alkene-SnO₂Mixing the precursor solution;

3) and (3) annealing: reacting Bi alkene-SnO₂The mixed precursor solution is coated on a substrate, rotated at the rotating speed of 3500-.

Preferably, in the preparation method of the composite film, the step 1) of preparing the Bi alkene can adopt a common preparation method, and specifically, the following process can be adopted:

with Bi, (NH)₄)₂S₂O₈、H₂SO₄(98 wt.%) and H₂O₂(30 wt%) as raw material, reacting at 30-40 deg.C for 11-13h, and ultrasonic treating and shaking. Taking 250-400mg Bi powder, and then according to Bi (NH4)₂S₂O₈In a mass ratio of 1:5 (NH4)₂S₂O₈Powder, added to the flask. Adding 8-15mL of H into the flask₂SO₄(98 wt%) then H was added₂SO₄(98 wt.%) with H₂O₂(30 wt%) H with a volume ratio of 5:1₂O₂The solution reacts for 11 to 13 hours at the temperature of between 30 and 40 ℃. Then washing with anhydrous ethanol for at least 3 times to remove unreacted H₂SO₄. The prepared powder was dried in vacuum and stored in a nitrogen glove box. Then, 25-35mg of the prepared powder and 1-2mL of Deionized (DI) water were removed and slowly added to the reagent bottle in a sealed environment. After sonication for 2-4h and shaking for 2-4h, the solution turned grey. Then removing bulk Bi by filtrationTo obtain a dispersion.

Step 2) 2.65-2.75 wt% of Bi alkene dispersion solution accounts for the weight proportion of the mixed precursor solution.

The heterojunction composite thin film structure is based on Bi alkene and SnO with proper content₂The heterojunction formed after mixing improves the interface impedance, reduces the impedance and enhances the carrier transmission. When the light-transmitting material is used as ETL of PSCs, the light-transmitting property can be improved, so that the transmission impedance is reduced, a smooth surface with low hydrophobicity is generated, and the crystal size of the perovskite on the upper layer is increased.

The invention also provides a perovskite solar cell, which comprises a substrate, an ETL, a perovskite active layer, an HTL and a metal electrode, wherein the ETL is based on the composite film or the composite film prepared by the preparation method.

The invention also provides a preparation method of the perovskite solar cell, which comprises the following steps:

1) cleaning a substrate: taking FTO glass as a substrate, washing and drying the FTO glass, and then treating the FTO glass by using UV-ozone;

2) preparing ETL: the ETL prepared according to the invention has a thickness of 50-60 nm;

3) preparing a perovskite active layer: preparing a perovskite active layer on the ETL, wherein the thickness is 565 and 575 nm;

4) preparing an HTL: preparing HTL on the perovskite active layer, wherein the thickness is 180-200 nm;

5) preparing a metal electrode: and preparing a metal electrode on the hole transport layer, wherein the thickness of the metal electrode is 90-110 nm.

Preferably, in the above method for preparing a perovskite solar cell, the perovskite active layer in step 3) may be prepared by a conventional method, specifically, the following process may be adopted;

PbI in a mixed solvent with a volume ratio of DMF (dimethylformamide)/DMSO (dimethyl sulfoxide) of 19:1₂(lead iodide) was spin-coated on the electron transport layer at 1000-2000rpm for 25-35s, followed by annealing at 60-80 ℃ in an inert atmosphere glove box for 1-2 min. When PbI₂After the layer is cooled, it is led to PbI₂Layer injectionAdding 40-60 μ L of FAI (formamidine iodide), MABr (methylamine bromide) and MACl (methylamine chloride) in a mass ratio of 1: (0.10-0.20): (0.20-0.30), and then continuously rotating at the rotation speed of 1000-.

Preferably, in the above-mentioned preparation method of PSCs, the HTL in step 4) may be prepared by a conventional method, specifically, the HTL is formed by coating a precursor of HTL on a perovskite thin film and rotating the perovskite thin film at 3500-4500rpm for 15-25s, and the HTL precursor is an acetonitrile solution containing Spiro-OMeTAD (2,2',7,7' -tetrakis-dimethoxydiphenylamine-spirofluorene) powder, Li-TFSI (bistrifluoromethanesulfonimide) in chlorobenzene, tBP (4-tert-butylpyridine, purity 96%), FK209 (cobalt-based bistrifluoromethanesulfonimide salt), and each content is 85-86mg mL^-1、15-20mg mL^-1、30-40mg mL^-1、7-9mg mL^-1Wherein the content of Li-TFSI relative to acetonitrile in the acetonitrile solution of Li-TFSI is 510-525mg mL^-1(ii) a The content of FK209 in the acetonitrile solution of FK209 relative to acetonitrile is 395-410mg mL^-1。

The PCE of the PSCs is 18.12-19.38%. In addition, it can maintain 80% of the initial performance in air with 35-45% humidity for over 800 hours.

The growth principle of the composite film is as follows: as shown in FIG. 1, when Bi alkene is added to SnO₂In the precursor fluid, Bi-dimensional (2D) hexagonal Bi-ene is disbanded due to strong van der waals interactions between adjacent nanoplates, and OH functional groups are generated around the 2D hexagonal Bi-ene in solution, and SnO₂Dispersed around the Bi alkene. Bi alkene attached to SnO₂The surface promotes the crystallinity of the perovskite layer on the upper layer, so that the crystal grain size of the perovskite layer is increased, and the surface of the perovskite layer is smoother; the bismuth content is in an amount appropriate to react with SnO₂Better combination to enable SnO₂The atomic arrangement of (A) and the atomic arrangement of bismuth present a special atomic-level 2D hexagonal parallel matching interface (hexagonal of Bi alkene and SnO)₂Hexagonal recombination of (a) to form a lattice matching structure), and because the activity of the edge of the 2D Bi alkene is very strong, based on the oxygen contention effectBi alkene and SnO during raw material mixing and annealing₂Generating Bi at the lattice interface₂O₃A parallel channel is formed to facilitate the migration and movement of electron carriers and reduce the electron transport resistance. In addition, an appropriate amount of bismuth content contributes to improvement of light transmittance and absorption of light by the upper perovskite layer.

The invention is to have Bi alkene-SnO₂When the film with the heterojunction structure is used as the ETL of the PSCs, the surface of the ETL is uniform and compact, almost has no pinholes, is rough, and can reduce the reflection of incident light, thereby improving the light transmittance of the ETL, reducing the interface impedance, increasing the crystallinity of an upper perovskite layer, and having higher carrier migration speed; bi ene-SnO₂The film has higher hydrophilicity, and the high hydrophilicity enables the film to more effectively spread the solvent of the perovskite layer, thereby being beneficial to forming a uniform perovskite film; this also makes Bi-ene-SnO-based₂The film PSCs have excellent moisture barrier properties.

The invention is achieved by the use of SnO₂Bi alkene with different contents is introduced into the solution, annealing is carried out in the air by adopting a low-temperature solution method, and the Bi alkene of 2D has adaptivity and is SnO₂In the process of recombination, the atoms between the two are arranged to form a lattice-matched atomic-level 2D hexagonal parallel matching interface, and the formed electron channel accelerates the transition and flow of electrons. Thus, a Bi ene-SnO with a nano-scale is formed₂Heterojunction of Bi ene-SnO₂ETL of composite structure. This ETL allows the perovskite grain size of the upper layer to be further increased and the ETL/perovskite interface to be improved. By optimizing the Bi-based alkene-SnO₂The PCE of ETL, PSCs of (1) is 18.12-19.38%. In addition, it can maintain 80% of the initial performance in air with 35-45% humidity for over 800 hours.

Drawings

FIG. 1 is a Bi-ene-SnO-based alloy₂The process flow of the preparation of ETL is schematically shown.

FIG. 2 XRD spectra of sample A, sample C and Bi powder of example 1.

FIG. 3(a) XPS bulk spectra for sample A and sample C of example 1; (b) sn 3d high resolution spectra of sample a and sample C in example 1; (c) high resolution spectra of O1s for sample A and sample C of example 1; (d) high resolution spectrum of Bi 4f for sample C in example 1.

FIG. 4 Transmission Electron microscopy image of example C of example 1

Detailed Description

The following examples are further illustrative of the present invention as to the technical content of the present invention, but the essence of the present invention is not limited to the following examples, and one of ordinary skill in the art can and should understand that any simple changes or substitutions based on the essence of the present invention should fall within the protection scope of the present invention.

Example 1

A preparation method of a lattice-matched heterojunction type composite film specifically comprises the following steps:

1) preparing Bi alkene: with Bi powder, (NH)₄)₂S₂O₈、H₂SO₄(98 wt.%) and H₂O₂(30 wt%) as raw material, reacting at 35 deg.C for 12h, and then subjecting to ultrasonic treatment and oscillation. Taking 300mg of Bi powder, and then according to Bi (NH)₄)₂S₂O₈(NH) in a mass ratio of 1:5₄)₂S₂O₈Powder, added to the flask. Then 10mL of H was added to the flask₂SO₄(98 wt%) then H was added₂SO₄(98 wt%) with H₂O₂(30 wt%) H with a volume ratio of 5:1₂O₂The solution was reacted at 35 ℃ for 12 hours. Then washing with anhydrous ethanol for at least 3 times to remove unreacted H₂SO₄. The prepared powder was dried in vacuum and stored in a nitrogen glove box. Then, 30mg of the prepared powder and 1mL of DI water were removed and slowly added to the reagent bottle in a sealed environment. After 3 hours of sonication and shaking for 3 hours, the solution turned grey. Then, large pieces of Bi that were not peeled off were removed by filtration to obtain a dispersion.

2) Bi ene-SnO₂Preparation of mixed precursor solution: preparing a Bi alkene dispersion solution to enable the content of Bi to be 0.10 wt%, and preparing five parts of 267 wt.% SnO₂The colloid water solution is added in each portion in turn: 0 wt%, 1.38 wt%, 2.65 wt%, 3.3 wt%, 4 wt% of a Bi alkene dispersion solution; respectively configuring sample A, sample B, sample C, sample D and sample E; carrying out ultrasonic treatment on the solution of the sample A and the like for 30min at room temperature;

3) annealing: reacting Bi alkene-SnO₂The mixed precursor solution is coated on FTO glass, rotated for 30s at the rotating speed of 4000rpm, and finally annealed on a hot bench at 150 ℃ for 30 min. Examples prepared based on the foregoing different amounts of the Bi alkene dispersion solution are called Bi alkene-SnO₂In the thin film, sample a was a sample B, C, D, E and a comparative sample, since sample a had a 0 allene content. The surface morphology of the five samples of thin films was studied by Scanning Electron Microscopy (SEM), and it was found that as the content of Bi alkene increased, plaques gradually appeared on the surface of the sample, and the plaques increased as the content of Bi alkene increased. The film components of the sample C are analyzed by an energy spectrometer (EDS) by taking the sample C as a key sample, and Sn, O and Bi are uniformly distributed, so that the condition that the addition of Bi alkene is successfully added into SnO₂A small amount of Bi is introduced. The different material diffraction peaks were obtained by comparing sample a, sample C and Bi powder using X-ray diffraction (XRD), and the diffraction peak of sample C became clear compared to sample a as shown in fig. 2. The peaks at angles 26.4 ° and 33.7 ° are due to SnO in sample A, respectively₂The peaks of (110) and (101) phases of (a). In addition to this, the peaks at angles 27.2 ° and 39.7 ° are respectively attributed to the peaks of the pure Bi powder (012) and (104) phases. These clearly show that the composition of sample C includes SnO2 and Bi crystals. The prepared film of sample C and the film of sample A were analyzed for chemical valence characteristics by X-ray photoelectron spectroscopy (XPS), as shown in FIG. 3. In FIG. 3(a), a Bi 4f peak was observed in the film of sample C, indicating that the addition of Bi alkene successfully introduced a small amount of Bi; in the Sn 3d spectrum of FIG. 3(b), the same peaks at 487.3 eV and 495.3eV were observed for the film of sample C and the film of sample A, respectively, and were attributed to Sn 3d_5/2And Sn 3d_3/2It was confirmed that SnO in the film of sample C₂Successful formation of the phase. In FIG. 3(C), the film of sample C and the film of sample A showed three peaks with binding energies of 530.6, 531.2 and 532.1eV, respectively attributed to the radicals Sn-O, OH and adsorbed oxygenOr a H-O-H bond. In FIG. 3(d), the major deconvolution peaks at 159.0 and 164.3eV for the Bi 4f spectrum of sample C correspond to Bi 4f_{7/ 2}Binding energy of (2) and Bi 4f_{5 / 2}. Furthermore, the lower deconvolution peaks at 160.2 and 165.5 eV here can be derived from partially oxidized Bi, meaning that a trace amount of Bi in sample C is in the +3 oxidation state, i.e., Bi₂O₃. Further, the atomic contents of Sn, O and Bi were respectively 24.17%, 74.50% and 1.33% by XPS measurement.

The lattice structure of the sample C film was further characterized by Transmission Electron Microscopy (TEM) and High Resolution Transmission Electron Microscopy (HRTEM), as shown in fig. 4. In FIG. 4, shown as SnO₂Nano-particles and Bi nano-sheets,

SnO of (1) and (200)₂Quilt

And (110) Bi encapsulation. And the number of the first and second electrodes,

SnO of (2)₂Bi of (110) and Bi are in a parallel relationship, and form a matched heterogeneous crystal lattice structure. Bi and SnO₂The values of (A) and (B) are very close, suggesting that Bi alkene-SnO₂The heterostructure has good electronic connectivity.

These show that the composite film is mainly composed of Bi alkene and SnO₂Form Bi alkene-SnO₂The lattice-matched heterojunction structure contains Sn, O and Bi elements inside.

Based on the five samples prepared with different contents, different experimental data were tested, and the best performance was achieved in sample C. The Bi alkene content of sample C made its surface smoother, maximizing the perovskite crystal grain size of the upper layer to 1020 nm. As the content of Bi alkene increased, fine pores began to appear on the surface of the sample, and the crystal particles became smaller. The various sample properties were as follows:

hydrophilicity: example C > example A

Light transmittance: sample C > sample D > sample E > sample B > sample a

Conductivity: example C>Example D>Example E>Example B>Example a, wherein the cause of the change in conductivity was: due to Bi alkene-SnO₂The lattice-matched heterojunction is formed, so that the electron migration is promoted, and the resistance value is reduced.

Example 2

A preparation method of PSCs (polymer dispersed phase) taking a composite film with a lattice matching conductive heterojunction structure as ETL (electron transport layer) specifically comprises the following steps:

1) preparing a substrate: firstly, cutting an FTO glass into a sample with the size of 1.5cm multiplied by 2cm, washing and drying the sample by using a detergent, deionized water, acetone, isopropanol and ethanol in sequence, and then performing ozone cleaning treatment to remove a surface oxide layer and oil stains;

2) preparing ETL: preparation of Bi ene-SnO by the method of example 1₂The composite film is used as ETL, and the thickness of the composite film is 55 nm;

3) preparing a perovskite layer: PbI in DMF/DMSO mixed solvent₂Spin-coat on the ETL at 1400rpm for 30s, then anneal in an Ar glove box at 70 ℃ for 1.5 min. When PbI₂After the layer is cooled, it is led to PbI ₂50 μ L of FAI, MABr and MACl in a mass ratio of 1: 0.15: 0.25 of the mixed solution, continuously rotating at the rotating speed of 1500rpm for 30s, and heating for 15min in the air atmosphere on a hot bench at 150 ℃ to obtain a perovskite layer with the thickness of 570 nm;

4) preparing an HTL: coating an HTL precursor on the perovskite thin film, and rotating at the rotating speed of 4000rpm for 20s to form the HTL, wherein the HTL precursor is acetonitrile solution containing Spiro-OMeTAD powder, Li-TFSI, tBP solution and FK209 in chlorobenzene, and the content of each HTL precursor is 86mg mL^-1、16mg mL^-1、35mg mL^-1、8mg mL^-1Wherein the content of Li-TFSI relative to acetonitrile in the acetonitrile solution of Li-TFSI is 510mg mL^-1(ii) a FK209 in acetonitrile contained FK209 in an amount of 400mg mL relative to acetonitrile^-1The thickness of the prepared HTL is 190 nm;

5) preparing an electrode: and (3) evaporating a layer of gold (Au) electrode on the HTL prepared in the step 4) by using a vacuum film plating machine, wherein the thickness of the prepared electrode is 100 nm.

And (3) carrying out performance analysis on the solar cell:

based on the sample prepared in the step 2), except the sample A, the other samples are Bi alkene-SnO₂Film, in which the PCE of sample C was the highest and the Bi olefin content of sample A was zero, SnO as a control₂A film. The hydrophilicity of the film was analyzed by using the contact angle formed by the drops of ionic water, and it was found that the Bi ene-SnO of sample C₂The contact angle of the film is 30 DEG SnO₂Contact angle of the film was 42 °, Bi ene-SnO of sample C₂The contact angle of the film is less than SnO₂Contact angle of the film, which indicates that Bi ene-SnO of sample C₂The film has high hydrophilicity, and the high hydrophilicity enables the film to have high solvent spreading performance, thereby being beneficial to forming a uniform perovskite film.

Based on several of the foregoing examples, the perovskite crystals based on example C had an average crystal grain size of 1020nm, and the average crystal grain sizes of the remaining examples were: sample D: 970nm, example E: 960nm, sample B: 940nm, sample a: 820nm, illustrating the maximum average grain size for sample C using the present invention.

The test found that the PSCs with sample C as ETL had a PCE of 19.38%, J_scAt 23.82mA cm^-2，V_ocIt was 1.08 and FF was 75.32. In contrast, SnO alone₂The PCE of the ETL film PSCs was only 18.32%, J_scAt 23.28mA cm^-2，V_oc1.06V, FF is only 74.25%. Bi ene-SnO as sample B₂Film ETL PSCs with PCE of only 18.42%, J_scOnly 23.07mA cm^-2，V_ocIt was only 1.07V, and FF was 74.61%. Bi ene-SnO as sample D₂The PCE of the ETL PSCs was only 18.01%, J_scIs only 23.19mA cm^-2，V_ocIt is only 1.05V and FF is only 73.95%. Bi ene-SnO as sample E₂The PCE for the ETL PSCs was only 16.68%, J_sc22.65mA cm only^-2，V_ocIt is only 1.02V and FF is only 72.21%.

To evaluatePerformance of PSCs, SnO, sample A, was measured using a J-V test loop₂PSCs with thin film ETL and Bi ene-SnO with sample C₂The hysteresis characteristics of the PSCs with the film as ETL, sample A and sample C were found to have hysteresis indices of 0.20 and 0.15, respectively. With Bi ene-SnO₂The low hysteresis index of the ETL film PSC further reveals that Bi ene-SnO₂The structure of the thin film effectively accelerates the extraction of electrons.

By performing stability tests on the unencapsulated PSCs at room temperature in air at 45% humidity, it was found that the PSCs of sample C, ETL, have higher stability, and the PCE thereof remains 80% of the initial value even after 800 hours; in contrast, in the same test environment, with SnO₂The PCE of PSCs with thin films of ETL is reduced to below 50% of the initial value, which shows that Bi alkene-SnO₂The structure provides excellent moisture barrier properties to PSCs.

Example 3

A preparation method of a composite film with a lattice matching conductive heterojunction structure specifically comprises the following steps:

1) preparing Bi alkene: with Bi powder, (NH)₄)₂S₂O₈、H₂SO₄(98 wt.%) and H₂O₂(30 wt%) as raw material, reacting at 30 deg.C for 12h, and then subjecting to ultrasonic treatment and shaking. Taking 280mg of Bi powder, and then according to Bi (NH)₄)₂S₂O₈(NH) in a mass ratio of 1:5₄)₂S₂O₈Powder, added to the flask. The flask was then charged with 8mL of H₂SO₄(98 wt%) then H was added₂SO₄(98 wt%) with H₂O₂(30 wt%) H with a volume ratio of 5:1₂O₂The solution was reacted at 30 ℃ for 12 hours. Then washing with anhydrous ethanol for at least 3 times to remove unreacted H₂SO₄. The prepared powder was dried in vacuum and stored in a nitrogen glove box. Then, 30mg of the prepared powder was removed and 1mL of deionized water was slowly added to the reagent bottle in a sealed environment. After sonication for 2h and shaking for 2h, the solution turned grey. Then removing bulk Bi by filtrationTo obtain a dispersion.

2) Bi ene-SnO₂Preparation of mixed precursor solution: preparing a Bi-alkene dispersion solution to ensure that the content of Bi is 0.08 wt%, and preparing five parts of SnO with the content of 2.5 wt%₂The colloid water solution is added in each portion in turn: 0 wt%, 1.35 wt%, 2.68 wt%, 3.35 wt%, 4.06 wt% of a Bi alkene dispersion solution; respectively configuring sample A, sample B, sample C, sample D and sample E; carrying out ultrasonic treatment on the solution of the sample A and the like for 20min at room temperature;

3) annealing: reacting Bi alkene-SnO₂The mixed precursor solution is coated on FTO glass, rotated for 20s at the rotating speed of 4000rpm, and finally annealed on a hot bench at 150 ℃ for 20 min.

Based on the samples prepared by the process, the following samples are obtained in sequence: A. b, C, D, E, wherein sample A has zero Bi olefin content, so sample A can be compared to several other samples, and the properties of the samples are as follows:

hydrophilicity: example C > example A

Light transmittance: sample C > sample D > sample E > sample B > sample a

Conductivity: example C>Example D>Example E>Example B>Example a, wherein the cause of the change in conductivity was: due to Bi alkene-SnO₂The lattice-matched heterojunction is formed, so that the electron migration is promoted, and the resistance value is reduced.

Example 4

A preparation method of PSCs (polymer dispersed Cs) taking lattice-matched heterojunction type composite films as ETLs (electron transfer layers) specifically comprises the following steps:

1) preparing a substrate: firstly, taking ITO glass, shearing a sample with the thickness of 1.5cm multiplied by 2cm, washing and drying the sample by using a detergent, deionized water, acetone, isopropanol and ethanol in sequence, and then carrying out UV-ozone cleaning treatment to remove a surface oxide layer and oil stains;

2) preparing ETL: an ETL was prepared using the method of example 3, with a thickness of 50 nm;

3) preparing a perovskite layer: PbI in DMF/DMSO mixed solvent₂Spin-coating on ETL at 1000rpm for 25s, then N at 60 deg.C₂Annealing in a glove box for 1 min. When PbI₂After the layer is cooledTo PbI₂And injecting 40 mu L of FAI, MABr and MACl into the layer according to the mass ratio of 1: 0.12: 0.25 of the mixed solution, continuously rotating at the rotating speed of 1000rpm for 25s, and heating for 13min in the air atmosphere on a hot bench at the temperature of 130 ℃ to obtain a perovskite layer with the thickness of 560 nm;

4) preparing an HTL: coating an HTL precursor on the perovskite thin film, and rotating at 3500rpm for 15s to form the HTL, wherein the HTL precursor is an acetonitrile solution containing Spiro-OMeTAD powder, Li-TFSI, tBP and FK209 in chlorobenzene, and the contents of the HTL precursor and the acetonitrile solution are respectively 85mg mL^-1、15mg mL^-1、30mg mL^-1、7mg mL^-1Wherein the content of Li-TFSI relative to acetonitrile in the acetonitrile solution of Li-TFSI is 510mg mL^-1(ii) a FK209 in acetonitrile contained 395mg mL of FK209 relative to acetonitrile^-1The thickness of the prepared HTL is 195 nm;

5) preparing an electrode: and (4) evaporating an Au electrode on the HTL prepared in the step 4) by using a vacuum film plating machine, wherein the thickness of the prepared electrode is 100 nm.

Based on the sample prepared in the step 2), the samples except the sample A are called Bi alkene-SnO₂Film in which the properties of sample C were the best compared to the other samples, sample A having zero Bi olefin content and referred to as SnO as a comparative sample₂A film. The Bi alkene-SnO of sample C is found by testing₂Film ETL of PSCs with a PCE of 18.75%, J_scIs 23.61mA cm^-2，V_ocIt was 1.06 and FF was 74.92. In contrast, with SnO₂The PCE of the ETL film PSCs was only 17.35%, J_scAt 22.78mA cm^-2，V_oc1.04V and FF of only 73.23%. Bi ene-SnO as sample B₂Film ETL PSCs with PCE of only 17.56%, J_scOnly 22.97mA cm^-2，V_ocIt was only 1.04V and FF was 73.50%. Bi ene-SnO as sample D₂The PCE for the ETL PSCs was only 16.83%, J_scOnly 22.46mA cm^-2，V_ocIt is only 1.03V, and FF is only 72.75%. Bi ene-SnO as sample E₂The PCE for ETL's PSCs was only 16.09%, J_scOnly 22.17mA cm^-2，V_oc1.02V only and 71.15 FF only％。

By performing stability tests on the unencapsulated PSCs in air at 45% humidity at room temperature, the PSCs of sample C, ETL, were found to have higher stability, even after 800 hours, with the PCE remaining 80% of the initial value; in contrast, in the same test environment, with SnO₂The PCE of PSCs with thin films of ETL is reduced to below 50% of the initial value, which shows that Bi alkene-SnO₂The structure makes the PSCs have excellent moisture resistance.

Example 5

A preparation method of a composite film with a lattice matching conductive heterojunction structure specifically comprises the following steps:

1) preparing Bi alkene: with Bi powder, (NH)₄)₂S₂O₈、H₂SO₄(98 wt.%) and H₂O₂(30 wt%) as raw material, reacting at 40 deg.C for 12h, and then subjecting to ultrasonic treatment and shaking. Taking 350mg of Bi powder, and then according to Bi (NH)₄)₂S₂O₈(NH) in a mass ratio of 1:5₄)₂S₂O₈Powder, added to the flask. The flask was then charged with 12mL of H₂SO₄(98 wt%) then H was added₂SO₄(98 wt.%) with H₂O₂(30 wt%) H with a volume ratio of 5:1₂O₂The solution was reacted at 40 ℃ for 12 hours. Then washing with anhydrous ethanol for at least 3 times to remove unreacted H₂SO₄. The prepared powder was dried in vacuum and stored in a nitrogen glove box. Then, 30mg of the prepared powder and 1mL of DI water were removed and slowly added to the reagent bottle in a sealed environment. After sonication for 2.5h and shaking for 3.5h, the solution turned grey. Then, large pieces of Bi that were not peeled off were removed by filtration to obtain a dispersion.

2) Bi ene-SnO₂Preparation of mixed precursor solution: preparing a Bi-alkene dispersion solution to enable the content of Bi to be 0.09 wt%, and preparing five parts of SnO with the content of 2.75 wt%₂The colloid water solution is added in each portion in turn: 0 wt%, 1.4 wt%, 2.7 wt%, 3.4 wt%, 4.05 wt% of a Bi alkene dispersion solution; respectively arranged as sample A, sample B, sample C, sample D,Sample E; carrying out ultrasonic treatment on the solution of the sample A and the like for 40min at room temperature;

3) and (3) annealing: reacting Bi alkene-SnO₂The mixed precursor solution is coated on FTO glass, rotated for 40s at the rotating speed of 3000rpm, and finally annealed on a hot bench at the temperature of 170 ℃ for 35 min.

Based on the samples prepared by the process, samples are obtained in sequence: A. b, C, D, E, wherein sample A has zero Bi olefin content, so sample A can be compared to several other samples, and the properties of the samples are as follows:

hydrophilicity: example C > example A

Light transmittance: sample C > sample D > sample E > sample B > sample a

Conductivity: example C>Example D>Example E>Example B>Example a, wherein the cause of the change in conductivity was: due to Bi alkene-SnO₂A lattice-matched heterojunction is formed, and electron migration is promoted, so that the resistance value is reduced.

Example 6

A preparation method of PSCs (polymer dispersed Cs) taking lattice-matched heterojunction type composite films as ETLs (electron transfer layers) specifically comprises the following steps:

1) preparing a substrate: firstly, cutting an FTO glass into a sample with the size of 1.5cm multiplied by 2cm, washing and drying the sample by using a detergent, deionized water, acetone, isopropanol and ethanol in sequence, and then performing UV-ozone cleaning treatment to remove a surface oxide layer and oil stains;

2) preparing ETL: an ETL was prepared using the method of example 5, with a thickness of 60 nm;

3) preparing a perovskite layer: will PbI₂Dissolving the powder in DMF/DMSO mixed solvent to obtain mixed solution, spin-coating the mixed solution on ETL at 2000rpm for 35s, and annealing at 80 deg.C in Ar glove box for 1min to obtain PbI₂And (3) a layer. When PbI₂After the layer is cooled, it is led to PbI₂And injecting 60 mu L of FAI, MABr and MACl into the layer according to the mass ratio of 1: 0.11: 0.26, continuously rotating at 2000rpm for 35s, and heating at 170 deg.C in air atmosphere for 17min to obtain perovskite layer with thickness of 570 nm; .

4) Preparing an HTL: coating an HTL precursor on a perovskite thin filmThen, the mixture was rotated at 4500rpm for 25 seconds to form HTL, and the precursor of HTL was a solution containing Spiro-OMeTAD powder, Li-TFSI in acetonitrile, tBP in acetonitrile, and FK209 in chlorobenzene, and the contents of each were 86mg mL^-1、20mg mL^-1、40mg mL^-1、9mg mL^-1Wherein the content of Li-TFSI in the acetonitrile solution of Li-TFSI is 525mg mL relative to acetonitrile^-1(ii) a FK209 in acetonitrile contained 410mg mL of FK209 relative to acetonitrile^-1The thickness of the prepared HTL is 200 nm;

5) preparing an electrode: and (3) evaporating an Au electrode on the hole transport layer prepared in the step 4) by using a vacuum coating machine, wherein the thickness of the prepared electrode is 100 nm.

Based on the sample prepared in the step 2), the samples except the sample A are called Bi alkene-SnO₂Film in which the properties of sample C were the best compared to the other samples, sample A having zero Bi olefin content and referred to as SnO as a comparative sample₂A film. The Bi alkene-SnO of sample C is found by testing₂Film as ETL PSCs with a PCE of 19.12%, J_scIs 23.35mA cm^-2，V_ocIt was 1.09 and FF was 75.11. In contrast, with SnO₂The PCE for the ETL film of PSCs was only 18.22%, J_scIs 23.92mA cm^-2，V_oc1.04V and FF of only 73.23%. Bi ene-SnO as sample B₂Film ETL PSCs with PCE of only 17.56%, J_scOnly 22.97mA cm^-2，V_ocIt was only 1.04V and FF was 73.50%. Bi ene-SnO as sample D₂The PCE for the ETL PSCs was only 16.83%, J_scOnly 22.46mA cm^-2，V_ocIt is only 1.03V and FF is only 72.75%. Bi ene-SnO as sample E₂The PCE of the ETL PSCs was only 16.09%, J_scOnly 22.19mA cm^-2，V_ocIt is only 1.02V and FF is only 71.15%.

By performing stability tests on the unencapsulated PSCs at room temperature in air at 35% humidity, it was found that the PSCs of sample C, ETL, have higher stability, and the PCE thereof remains 80% of the initial value even after 800 hours; in contrast, in the same test environment, with SnO₂The PCE of PSCs with thin films of ETL is reduced to below 50% of the initial value, which shows that Bi alkene-SnO₂The structure makes the PSCs have excellent moisture resistance.

Example 7

A preparation method of a composite film with a lattice matching conductive heterojunction structure specifically comprises the following steps:

1) preparing Bi alkene: with Bi powder, (NH)₄)₂S₂O₈、H₂SO₄(98 wt.%) and H₂O₂(30 wt%) as raw material, reacting at 32 deg.C for 12h, and then subjecting to ultrasonic treatment and shaking. 380mg of Bi powder is taken, and then Bi (NH) is added₄)₂S₂O₈(NH) in a mass ratio of 1:5₄)₂S₂O₈Powder, added to the flask. The flask was then charged with 13mL of H₂SO₄(98 wt%) then H was added₂SO₄(98 wt.%) with H₂O₂(30 wt%) H with a volume ratio of 5:1₂O₂The solution was reacted at 32 ℃ for 12 hours. Then washing with anhydrous ethanol for at least 3 times to remove unreacted H₂SO₄. The prepared powder was dried in vacuum and stored in a nitrogen glove box. Then, 30mg of the prepared powder and 1mL of DI water were removed and slowly added to the reagent bottle in a sealed environment. After sonication for 3h and shaking for 3.5h, the solution turned grey. Then, large pieces of Bi that were not peeled off were removed by filtration to obtain a dispersion.

2) Bi ene-SnO₂Preparation of mixed precursor solution: preparing a Bi-alkene dispersion solution to enable the content of Bi to be 0.09 wt%, and preparing five parts of SnO with the content of 2.80 wt%₂The colloid water solution is added in each portion in turn: 0 wt%, 1.42 wt%, 2.73 wt%, 3.38 wt%, 4.04 wt% of a Bi alkene dispersion solution; respectively configuring sample A, sample B, sample C, sample D and sample E; carrying out ultrasonic treatment on the solution of the sample A and the like for 40min at room temperature;

3) annealing: reacting Bi alkene-SnO₂The mixed precursor solution is coated on FTO glass, rotated for 30s at the rotating speed of 5000rpm, and finally annealed on a thermal platform at 130 ℃ for 40 min.

Based on the samples prepared by the process, samples are obtained in sequence: A. b, C, D, E, wherein sample A has zero Bi olefin content, so sample A can be compared to several other samples, and the properties of the samples are as follows:

hydrophilicity: example C > example A

Light transmittance: sample C > sample D > sample E > sample B > sample a

Conductivity: example C>Sample D>Example E>Example B>Example a, wherein the cause of the change in conductivity was: due to Bi alkene-SnO₂The lattice-matched heterojunction is formed, so that the electron migration is promoted, and the resistance value is reduced.

Example 8

A preparation method of PSCs (polymer dispersed Cs) taking lattice-matched heterojunction type composite films as ETLs (electron transfer layers) specifically comprises the following steps:

1) preparing a substrate: firstly, cutting an FTO glass into a sample with the size of 1.5cm multiplied by 2cm, washing and drying the sample by using a detergent, deionized water, acetone, isopropanol and ethanol in sequence, and then performing UV-ozone cleaning treatment to remove a surface oxide layer and oil stains;

2) preparing ETL: an ETL was prepared using the method of example 7, with a thickness of 55 nm;

3) preparing a perovskite layer: PbI in DMF/DMSO mixed solvent₂Spin-coating on ETL at 1800rpm for 34s, then at 80 ℃ under N₂Annealing in a glove box for 1 min. When PbI₂After the layer is cooled, it is led to PbI₂And injecting 60 mu L of FAI, MABr and MACl into the layer according to the mass ratio of 1: 0.17: 0.22, continuously rotating at 1800rpm for 33s, and heating at 160 deg.C in air atmosphere on hot stage for 16min to obtain perovskite layer with thickness of 565 nm; .

4) Preparing an HTL: coating an HTL precursor on the perovskite thin film, and rotating the perovskite thin film at the rotating speed of 4400rpm for 23s to form the HTL, wherein the HTL precursor is acetonitrile solution containing Spiro-OMeTAD powder, Li-TFSI, tBP solution and FK209 in chlorobenzene, and the content of each HTL precursor is 85.8mg mL^-1、20mg mL^-1、35mg mL^-1、9mg mL^-1Wherein the content of Li-TFSI relative to acetonitrile in the acetonitrile solution of Li-TFSI is 525mg mL^-1(ii) a FK209 in acetonitrile contained 410mg mL of FK209 relative to acetonitrile^-1The thickness of the prepared HTL is 195 nm;

5) preparing an electrode: and (3) evaporating an Au electrode on the hole transport layer prepared in the step 4) by using a vacuum coating machine, wherein the thickness of the prepared electrode is 95 nm.

Based on the sample prepared in the step 2), the samples except the sample A are called Bi alkene-SnO₂Film in which the properties of sample C were the best compared to the other samples, sample A having zero Bi olefin content and referred to as SnO as a comparative sample₂A film. The Bi alkene-SnO of sample C is found by testing₂Film ETL of PSCs with a PCE of 18.28%, J_scAt 22.44mA cm^-2，V_oc1.05 and FF 74.27. In contrast, with SnO₂The PCE of the ETL film PSCs was only 17.12%, J_scIs 22.70mA cm^-2，V_oc1.04V and FF of only 72.53%. Bi ene-SnO as sample B₂Film ETL PSCs with PCE of only 17.49%, J_scOnly 23.78mA cm^-2，V_ocIt is only 1.02V and FF is only 72.11%. Bi ene-SnO as sample D₂The PCE for the ETL PSCs was only 16.73%, J_scOnly 23.15mA cm^-2，V_ocIt is only 1.01V and FF is only 71.55%. Bi ene-SnO as sample E₂The PCE for ETL of PSCs was only 15.89%, J_scOnly 22.43mA cm^-2，V_ocIt is only 1.01V and FF is only 70.15%.

By performing stability tests on the unencapsulated PSCs in 45% humidity air at room temperature, it was found that the PSCs of sample C, ETL, have higher stability, and even after 800 hours, their PCE remained 80% of the initial value; in contrast, in the same test environment, with SnO₂The PCE of PSCs with ETL thin film is reduced to below 50% of the initial value, which shows that Bi alkene-SnO₂The structure makes the PSCs have excellent moisture resistance.

Example 9

A preparation method of a composite film with a lattice matching conductive heterojunction structure specifically comprises the following steps:

1) preparing Bi alkene: with Bi powder, (NH)₄)₂S₂O₈、H₂SO₄(98 wt.%) and H₂O₂(30 wt%) as raw material, reacting at 37 deg.C for 12h, and then subjecting to ultrasonic treatment and shaking. Taking 400mg of Bi powder, and then according to Bi (NH)₄)₂S₂O₈(NH) in a mass ratio of 1:5₄)₂S₂O₈Powder, added to the flask. The flask was then charged with 15mL of H₂SO₄(98 wt%) then H was added₂SO₄(98 wt.%) with H₂O₂(30 wt%) H with a volume ratio of 5:1₂O₂The solution was reacted at 37 ℃ for 12 hours. Then washing with anhydrous ethanol for at least 3 times to remove unreacted H₂SO₄. The prepared powder was dried in vacuum and stored in a nitrogen glove box. Then, 30mg of the prepared powder and 1mL of DI water were removed and slowly added to the reagent bottle in a sealed environment. After sonication for 4h and shaking for 4h, the solution turned grey. Then, large pieces of Bi that were not peeled off were removed by filtration to obtain a dispersion.

2) Bi ene-SnO₂Preparation of mixed precursor solution: preparing a Bi-olefin dispersion solution to ensure that the content of Bi is 0.13 wt%, and preparing five parts of SnO with the content of 3.00 wt%₂The colloid water solution is added in each portion in turn: 0 wt%, 1.45 wt%, 2.75 wt%, 3.4 wt%, 4.1 wt% of a Bi alkene dispersion solution; respectively configuring sample A, sample B, sample C, sample D and sample E; carrying out ultrasonic treatment on the solution of the sample A and the like for 40min at room temperature;

3) annealing: reacting Bi alkene-SnO₂The mixed precursor solution is coated on FTO glass, rotated at 3500rpm for 35s, and finally annealed on a hot bench at 140 ℃ for 45 min.

Based on the samples prepared by the process, samples are obtained in sequence: A. b, C, D, E, wherein sample A has zero Bi olefin content, so sample A can be compared to several other samples, and the properties of the samples are as follows:

hydrophilicity: example C > example A

Light transmittance: sample C > sample D > sample E > sample B > sample a

Conductivity: example C>Example D>Example E>Example B>Example a, wherein the cause of the change in conductivity was: due to Bi alkene-SnO₂The lattice-matched heterojunction is formed, so that the electron migration is promoted, and the resistance value is reduced.

Example 10

A preparation method of PSCs (polymer dispersed phase) taking a composite film with a lattice matching conductive heterojunction structure as ETL (electron transport layer) specifically comprises the following steps:

1) preparing a substrate: firstly, cutting an FTO glass into a sample with the size of 1.5cm multiplied by 2cm, washing and drying the sample by using a detergent, deionized water, acetone, isopropanol and ethanol in sequence, and then performing UV-ozone cleaning treatment to remove a surface oxide layer and oil stains;

2) preparing ETL: an ETL was prepared using the method of example 9, with a thickness of 60 nm;

3) preparing a perovskite layer: PbI in DMF/DMSO mixed solvent₂Spin-coating on ETL at 1700rpm for 32s, then N at 80 deg.C₂Annealing in a glove box for 1 min. When PbI₂After the layer is cooled, towards PbI₂And injecting 60 mu L of FAI, MABr and MACl into the layer according to the mass ratio of 1: 0.19: 0.30, continuously rotating at 1700rpm for 31s, and heating at 150 deg.C in air atmosphere for 15min to obtain perovskite layer with thickness of 570 nm; .

4) Preparing an HTL: an HTL precursor is coated on the perovskite thin film and then rotated for 23s at the rotating speed of 4200rpm to form the HTL, and the HTL precursor is an acetonitrile solution containing Spiro-OMeTAD powder, Li-TFSI, tBP and FK209 in chlorobenzene, and the contents of the HTL precursor, the Spiro-OMeTAD powder, the acetonitrile solution of Li-TFSI, the tBP solution and the acetonitrile solution of FK209 are respectively 85.5mg mL^-1、19mg mL^-1、35mg mL^-1、8mg mL^-1Wherein the content of Li-TFSI in acetonitrile solution of Li-TFSI is 520mg mL relative to the acetonitrile^-1(ii) a FK209 in acetonitrile contained FK209 in an amount of 405mg mL relative to acetonitrile^-1The thickness of the prepared HTL is 195 nm;

5) preparing an electrode: and (3) evaporating a layer of silver (Ag) electrode on the hole transport layer prepared in the step 4) through a vacuum coating machine, wherein the thickness of the prepared electrode is 90 nm.

Based on the foregoing steps2) The samples obtained, except for sample A, are designated Bi ene-SnO₂Film in which the properties of sample C were the best compared to the other samples, sample A having zero Bi olefin content and referred to as SnO as a comparative sample₂A film. The Bi alkene-SnO of sample C is found by testing₂Film as ETL PSCs with a PCE of 18.65%, J_scIs 23.92mA cm^-2，V_oc1.05 and FF 74.27. In contrast, with SnO₂The PCE of the ETL film PSCs was only 17.12%, J_scIs 22.70mA cm^-2，V_oc1.04V and FF of only 72.53%. Bi ene-SnO as sample B₂Film ETL PSCs with PCE of only 17.49%, J_scOnly 23.78mA cm^-2，V_ocIt is only 1.02V and FF is only 72.11%. Bi ene-SnO as sample D₂The PCE for the ETL PSCs was only 16.73%, J_scOnly 23.15mA cm^-2，V_ocIt is only 1.01V and FF is only 71.55%. Bi ene-SnO as sample E₂The PCE of the ETL PSCs was only 16.21%, J_scOnly 22.88mA cm^-2，V_ocIt is only 1.01V and FF is only 70.15%.

By performing stability tests on the unencapsulated PSCs in 45% humidity air at room temperature, it was found that the PSCs of sample C, ETL, have higher stability, and even after 800 hours, their PCE remained 80% of the initial value; in contrast, in the same test environment, with SnO₂The PCE of PSCs with thin films of ETL is reduced to below 50% of the initial value, which shows that Bi alkene-SnO₂The structure makes the PSCs have excellent moisture resistance.

By adopting the method of the invention, Bi alkene and SnO₂The lattice-matched conductive heterojunction structure is designed as a main component by adopting mixing, shaking and annealing modes, and can be applied to ETL of PSCs (polymer dispersed capacitors) to improve the moisture resistance of the battery and PCE (prestressed concrete) of the battery.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents or improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (7)

1. A lattice-matched heterojunction composite film containing nano-sized Bi alkene-SnO₂A heterojunction of said Bi ene-SnO₂In the heterojunction, the atomic number percentages of Sn, O and Bi elements are respectively 23-25%, 73-75% and 1-2%; the Bi alkene is a two-dimensional atomic-scale lamellar layer, SnO₂Being three-dimensional nanoparticles, Bi alkenes and SnO₂Form lattice-matched two-dimensional hexagonal parallel matching interface in atomic level.

2. A method for preparing the composite film as claimed in claim 1, which comprises preparing Bi alkene, Bi alkene-SnO₂Preparation of mixed precursor solution and preparation of Bi alkene-SnO₂And coating the mixed precursor solution on the substrate for annealing.

3. The method for preparing a composite film according to claim 2, comprising the steps of:

1) preparing Bi alkene: with Bi powder, (NH)₄)₂S₂O₈、H₂SO₄、H₂O₂Reacting the raw materials at room temperature for 18-20h, then centrifugally washing, ultrasonically treating, and drying in vacuum at 55-65 ℃ for 11-13h to obtain dilute Bi;

2) bi alkene-SnO₂Preparation of mixed precursor solution: preparing a Bi alkene dispersion solution so that the content of Bi is 0.08-0.13 wt%; preparing 2-3 wt% of SnO₂Adding 2.65-2.75 wt% Bi alkene dispersion solution into colloidal water solution, and performing ultrasonic treatment at room temperature for 20-40 min;

3) annealing: reacting Bi alkene-SnO₂The mixed precursor solution is coated on a substrate, rotated at the rotating speed of 3500-.

4. Use of the composite film according to claim 1 or the composite film obtained by the production method according to any one of claims 2 to 3 as an electron transport medium.

5. The use according to claim 4, wherein the composite thin film is used in an electron transport layer of a perovskite solar cell.

6. A perovskite solar cell comprising a substrate, an electron transport layer, a perovskite active layer, a hole transport layer, a metal electrode, characterized in that the electron transport layer is based on the composite thin film according to claim 1 or obtained by the production method according to any one of claims 2 to 3.

7. The method of fabricating the perovskite solar cell as claimed in claim 6, comprising the steps of:

1) cleaning a substrate: taking FTO glass as a substrate, washing and drying the FTO glass, and then treating the FTO glass by using UV-ozone;

2) preparing an electron transport layer: preparing an electron transport layer on a substrate, wherein the thickness of the electron transport layer is 50-60 nm;

3) preparing a perovskite active layer: preparing a perovskite active layer on the electron transport layer, wherein the thickness is 565 and 575 nm;

4) preparing a hole transport layer: preparing a hole transport layer on the perovskite active layer, wherein the thickness of the hole transport layer is 180-200 nm;

5) preparing a metal electrode: and preparing a metal electrode on the hole transport layer, wherein the thickness of the metal electrode is 90-110 nm.

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