CN115568263A

CN115568263A - Preparation method of perovskite active layer in solar cell

Info

Publication number: CN115568263A
Application number: CN202211188723.XA
Authority: CN
Inventors: 张晓丹; 靳璐; 任宁宇; 王鹏阳; 李仁杰; 陈兵兵; 李玉成; 赵颖
Original assignee: Nankai University
Current assignee: Nankai University
Priority date: 2022-09-28
Filing date: 2022-09-28
Publication date: 2023-01-03

Abstract

The invention provides a preparation method of a perovskite active layer in a solar cell, and belongs to the technical field of solar cells. According to the invention, the secondary anti-solvent is introduced in the process of preparing the perovskite thin film by the primary anti-solvent, and the passivation material MAI (methylamine iodide) with the perovskite passivation effect is introduced into the secondary anti-solvent, so that the I vacancy defect caused by volatilization of organic salt in the annealing process after pre-compensation can be realized, and then the passivation treatment is carried out by adopting the traditional surface passivation method, so that the surface defect can be passivated by simultaneously using two passivation materials, and the state density of the surface defect can be further reduced, thereby obviously improving the open-circuit voltage and the filling factor of the battery, increasing the photoelectric conversion efficiency of the battery and improving the performance of a device. The method can realize the surface passivation effect of the perovskite active layer, improve the crystallization kinetics and improve the crystallization quality.

Description

Preparation method of perovskite active layer in solar cell

Technical Field

The invention relates to the technical field of solar cells, in particular to a preparation method of a perovskite active layer in a solar cell.

Background

Perovskite is a novel photovoltaic material, and through the development of a few decades, the highest authenticated conversion efficiency of 25.7% has been achieved, and due to the advantages of adjustable optical band gap, large optical absorption coefficient, long carrier diffusion length, low cost and the like, perovskite becomes a hotspot and focus of researchers. Although the efficiency of the perovskite solar cell is rapidly developed, the instability of the perovskite solar cell under the conditions of moisture, light, heat and the like is still an important factor limiting the further development and the commercial application of the perovskite solar cell. At present, much research is focused on optimizing the perovskite absorption layer (composition, defect passivation, additives), interface management and device packaging, but the stability of perovskite is still not addressed. Recently, researchers have found that introducing long-chain cations into three-dimensional perovskites to form mixed-dimensional perovskite or quasi-two-dimensional perovskites is an effective method for improving device stability. The introduction of the large organic cations can effectively prevent moisture and oxygen from contacting with the inorganic layer, and can also effectively prevent phase separation and inhibit ion migration, thereby achieving the effect of improving the stability of the device.

The structural general formula of the 2D perovskite is (A') _m (A) _n-1 B _n X _3n+1 Wherein A' is a large organic cation connecting the inorganic layers, and n is the number of inorganic frame layers between two organic cations. Due to the excellent chemical adjustability (large organic cations are adjustable, components are adjustable, and n values are adjustable) of the 2D perovskite, the device performance is flexible and adjustable.

At present, the high-efficiency two-dimensional perovskite is mostly prepared by a one-step anti-solvent method. The use of an anti-solvent can facilitate the separation of the solvent from the interior of the film, regulate crystal nucleation and form a high quality film. However, due to the ionic nature of the perovskite lattice, a perovskite thin film treated by a one-step anti-solvent method inevitably suffers from a large number of defects. In addition, residual solvents in the film can produce by-products that affect the purity of the perovskite phase and device performance.

In the preparation process of the perovskite thin film, the growth of perovskite crystals is further promoted through an annealing process, so that a high-quality perovskite absorption layer is obtained. However, the organic components of the perovskite component are thermally unstable, e.g., sustained annealing temperatures in excess of 85 ℃ may volatilize MAI in the component, thereby tending to form a large number of halogen vacancies at the perovskite surface. In addition, the complex solution precursor composition and rapid thermal annealing can also cause the surface of the perovskite light absorption layer to form other types of massive defects, such as I-space, pb/I flip-chip defects or Pb ⁰ Defects, etc., which form electron/hole recombination centers at the interface, seriously affecting the efficiency of the battery. Research shows that the surface defect state density of the perovskite thin film is more than twice of that of a bulk material.

In recent years, many researchers have used surface passivation strategies to further enhance the performance of 2D perovskites. Cheng just et al (Meng K, wang X, li Z, et al. Self-catalysis of low-dimensional refractory by structural characterization and degradation kinetics [ J]Energy EnvironSci,2021,14 (4): 2357-68.) treatment of two-dimensional perovskite surfaces with a BAI self-passivation strategy, lift (BA) ₂ (MA) ₃ Pb ₄ I ₁₃ (n = 4) device performance to 17% and significantly improved thermal and humidity stability. Bi Dongqin et al (Huang Y, li Y, lim E L, et al. Stable layered 2D peroxide sodium cells with an efficacy of over 19%]JAm Chem Soc,2021,143 (10): 3911-7.) the introduction of GABr at the upper surface to induce surface secondary crystallization and finally the promotion of GA ₂ MA ₄ Pb ₅ I ₁₆ (n = 5) efficiency to 19.3%. Zhang Yuan, etc. (Li K, yue S, li X, et al, high Efficiency Perovskite Solar Cells Employing Quasi-2D Ruddlesden-Popp)er/Dion-Jacobson Heterojunctions[J]Adv Funct Mater,2022,32 (21): 2200024.) using BDAI ₂ A DJ type two-dimensional phase is formed on the surface to passivate an RP type two-dimensional phase, and the heterostructure can improve interface charge separation and reduce the density of surface defect states, so that 18.34% efficiency and 1.24V high open voltage are finally obtained. However, the above method can solve the surface partial defect only by using one passivation material, and when the two materials are used simultaneously for surface passivation, the surface defect state cannot be sufficiently reduced and the surface passivation effect cannot be improved due to incompatibility of the two passivation materials.

Disclosure of Invention

The invention aims to provide a preparation method of a perovskite active layer in a solar cell, which can simultaneously passivate surface defects of the perovskite active layer by two passivation materials, reduce the state density of the surface defects and improve the cell performance.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of a perovskite active layer in a solar cell, which comprises the following steps:

spin-coating a precursor solution of the perovskite active layer on a substrate, sequentially dropwise adding a first anti-solvent and a second anti-solvent in the spin-coating process, and performing surface passivation treatment on the obtained film to obtain the perovskite active layer;

the second anti-solvent comprises a passivation material, and the passivation material comprises methylamine iodine, methylamine chloride, formamidine iodine or guanidine bromide.

Preferably, the first anti-solvent and the second anti-solvent independently comprise isopropanol, ethanol, butanol, chlorobenzene, ethyl acetate, anisole, diethyl ether, toluene or mesitylene.

Preferably, the concentration of the passivation material in the second anti-solvent is 0.5-5 mg/mL.

Preferably, the time for dripping the first anti-solvent is within 10-20 s after the start of the spin coating procedure; the time for dripping the second anti-solvent is within 10-20 s after the first anti-solvent is dripped and 10-20 s before the spin coating procedure is finished.

Preferably, the concentration of the precursor solution of the perovskite active layer is 1.3-1.4 mol/L; the volume ratio of the perovskite active layer precursor solution to the first anti-solvent to the second anti-solvent is (50-60) to (150) to (20-30).

Preferably, the surface passivation material used for the surface passivation treatment comprises methylamine iodine, n-butylamine iodine or choline chloride.

Preferably, the process of the surface passivation treatment comprises the following steps: spin coating the surface passivation material solution on the film, and carrying out annealing treatment; the concentration of the surface passivation material in the surface passivation material solution is 1mg/mL.

Preferably, the substrate is an electron transport layer or a hole transport layer; the electron transport layer is made of tin dioxide, titanium dioxide, zinc oxide, [6,6 ]]-phenyl radical C ₆₁ One or more of methyl butyrate, fullerene and graphene; the material of the hole transport layer is one or more of an inorganic material, an organic material and a self-assembled monomolecular layer material.

Preferably, the perovskite active layer precursor in the perovskite active layer precursor solution comprises ABX ₃ Perovskite type semiconductor material or (A') _m (A) _n-1 B _n X _3n+1 The perovskite semiconductor material comprises a perovskite semiconductor material, wherein A' is a large organic cation, the large organic cation comprises n-butylamine iodine, phenylethylamine iodine or 1,4-butanediamine hydroiodide, A is one or more of methylamine cation, formamidine cation, cs and Rb, B is lead and/or tin, and X is at least one of iodine, bromine and chlorine.

Preferably, the perovskite type of the solar cell is two-dimensional perovskite, three-dimensional perovskite or mixed victorite.

The invention provides a preparation method of a perovskite active layer in a solar cell, which is characterized in that a secondary anti-solvent is introduced in the process of preparing a perovskite film by a primary anti-solvent, and a passivation material MAI (methylamine iodide) with a perovskite passivation effect is introduced into the secondary anti-solvent, so that I vacancy defects caused by volatilization of organic salts in the annealing process after pre-compensation can be realized, and then the traditional surface passivation method is adopted for passivation treatment.

The method has the advantages that: 1) The density of surface defect states can be reduced by nearly 2 times on the basis of traditional surface post-treatment passivation; 2) The secondary anti-solvent is dripped, so that the solvent in the thin film can be further extracted, the residual organic solvent in the thin film can be reduced, the phase transformation is more sufficient, the crystallization kinetics is improved, the crystallization quality of the thin film is improved, the open-circuit voltage and the filling factor of the battery are improved, and the perovskite solar battery with higher efficiency is obtained; 3) The energy level difference between the light emitting diode and the hole transport layer can be reduced, and the extraction and the transport of holes are facilitated.

For the two-dimensional perovskite, the use of the secondary anti-solvent can optimize n value distribution, so that small n values only exist on the upper surface of the two-dimensional perovskite, the lower part of the two-dimensional perovskite is mainly a 3D-like phase, and the two-dimensional perovskite can be effectively improved in efficiency and stability due to the phase structure distribution.

The method is simple to operate and easy to implement, is suitable for the perovskite solar cell (comprising the solar cell with narrow band gap of 1.1-1.3 eV, normal band gap of 1.4-1.6 eV and wide band gap of 1.6-1.8 eV) prepared by the one-step anti-solvent solution method, and is also suitable for the perovskite/crystalline silicon two-end laminated solar cell prepared by the one-step anti-solvent solution method.

Drawings

FIG. 1 is a flow chart of the present invention for preparing a perovskite active layer;

FIG. 2 is a structural diagram of an N-I-P type two-dimensional perovskite solar cell in example 1 and comparative example 1;

FIG. 3 is a schematic diagram of a P-I-N type wide bandgap perovskite solar cell in example 3 and comparative example 2;

fig. 4 is a structural diagram of a perovskite/silicon heterojunction tandem solar cell device in example 4, wherein a silicon heterojunction bottom cell is a double-sided textured structure;

FIG. 5 is a J-V diagram of an N-I-P type two-dimensional perovskite cell in comparative example 1;

FIG. 6 is a J-V plot of a 3mg/mL MAI/IPA secondary anti-solvent optimized N-I-P type two-dimensional perovskite battery of example 1;

FIG. 7 is a J-V plot of a 3mg/mL MACl/IPA secondary anti-solvent optimized N-I-P type two-dimensional perovskite cell of example 2;

FIG. 8 is a J-V diagram of a P-I-N type wide band gap perovskite cell of comparative example 2;

FIG. 9 is a J-V plot of a 3mg/mL MAI/IPA secondary anti-solvent optimized P-I-N type wide bandgap perovskite cell of example 3;

FIG. 10 is a J-V diagram of a wide bandgap perovskite/silicon heterojunction tandem solar cell optimized for 3mg/mL MAI/IPA secondary anti-solvent in example 4, wherein the silicon heterojunction bottom cell has a double-sided texturing structure;

FIG. 11 is a charge defect state density N obtained by the Space Charge Limited Current (SCLC) method for perovskite devices of comparative example 1 and example 1 _t Comparing the graph, wherein the device structure is Glass/ITO/SnO ₂ Perovskite absorption layer/passivation layer/PCBM/BCP/Ag.

Detailed Description

In the present invention, unless otherwise specified, all the materials or reagents required are commercially available products well known to those skilled in the art.

In the invention, the perovskite type of the solar cell is preferably two-dimensional perovskite, three-dimensional perovskite or mixed victorite; the cell structure of the solar cell is preferably P-I-N type or N-I-P type; the preferred band gap is 1.10-1.80 eV; the structure of the solar cell is preferably planar or mesoporous. The perovskite used by the solar cell is an organic-inorganic hybrid perovskite material, an inorganic perovskite material or a wide band gap perovskite-crystalline silicon two-end laminated material. The area of the solar cell is not specially limited, and the solar cell can be adjusted according to actual requirements.

The invention has no special limitation on the layer structure and the preparation method of the solar cell, and the perovskite solar cell with the corresponding layer structure is prepared according to the method well known in the field; in the present invention, the perovskite solar cell preferably has a structure including an underlying substrate, a transparent conductive layer, a hole transport layer, a perovskite active layer, an electron transport layer, and a metal electrode layer.

The material of the base substrate and the transparent conductive layer is not particularly limited in the present invention, and any corresponding material known in the art may be used. The treatment process of the base substrate and the transparent conductive layer is not particularly limited in the present invention, and may be performed according to a method well known in the art.

In the present invention, the material of the metal electrode layer is preferably one or more of gold (Au), silver (Ag), copper (Cu), aluminum (Al), and a carbon material; the carbon material is not particularly limited in the present invention, and any corresponding material known in the art may be used; the metal electrode layer is preferably prepared by a thermal evaporation method or a screen printing method.

In the embodiment of the invention, the specific structure of the N-I-P type two-dimensional perovskite solar cell sequentially comprises from top to bottom: silver electrode, spiro-OMeTAD hole transport layer, perovskite active layer, snO ₂ An electron transport layer and ITO transparent conductive glass; the specific structure of the P-I-N type wide band gap perovskite solar cell sequentially comprises from top to bottom: the composite material comprises an Ag electrode, a BCP buffer layer, a PCBM electron transport layer, a perovskite active layer, a NiOx + Poly-TPD hole transport layer and ITO transparent conductive glass; P-I-N type wide band gap perovskite and double-sided textured silicon heterojunction are combined to prepare the perovskite/silicon heterojunction laminated solar cell, and the effective area of the cell is 0.5003cm ² From top to bottom in proper order: front metal grid line electrode silver, transparent conductive film IZO and buffer layer SnO ₂ Electron transport layer C ₆₀ A perovskite active layer, a Poly-TPD/NiOx double-hole transport layer,The solar cell comprises a connecting layer ITO, a silicon heterojunction bottom cell electron selection layer a-Si: H (N), a passivation layer a-Si: H (i), a silicon substrate N-Si, a passivation layer a-Si: H (i), a hole selection layer a-Si: H (p), ITO and back electrode silver.

In the present invention, the substrate is preferably an electron transport layer or a hole transport layer; the electron transport layer is made of tin dioxide, titanium dioxide, zinc oxide, [6,6 ]]-phenyl radical C ₆₁ Butyric acid methyl ester (PCBM), fullerene (C) ₆₀ ) And one or more of graphene, when the materials corresponding to the electron transport layer are more than two of the above materials, the proportion of different materials is not particularly limited, and any proportion can be adopted. In the present invention, the material of the hole transport layer is preferably one or more of an inorganic material, an organic material, and a self-assembled monolayer material; the inorganic material is preferably poly [ bis (4-phenyl) (2,4,6-trimethylphenyl) amine](PTAA), nickel oxide (NiOx) or cuprous thiocyanate (CuSCN), the organic material preferably being 2,2,7,7-tetrakis (N, N-di-p-tolyl) amino-9,9-spirobifluorene (Spiro-TTB) or 2,2',7,7' -tetrakis [ N, N-bis (4-methoxyphenyl) amino]-9,9' -spirobifluorene (Spiro-OMeTAD); the self-assembled monomolecular layer material is preferably (2- (9H-carbazol-9-yl) ethyl) phosphonic acid (2 PACz), [2- (3,6-dimethoxy-9H-carbazol-9-yl) ethyl]Phosphonic acid (MeO-2 PACz), [4- (3,6-dimethyl-9H-carbazol-9-yl) butyl]One or more of phosphoric acid (Me-4 PACz). When the materials of the hole transport layer are more than the above materials, the invention has no special limitation on the mixture ratio of different types of hole transport layers and can adjust the hole transport layer according to actual requirements. The electron transport layer and the hole transport layer may be prepared according to a process known in the art without any particular limitation.

In the invention, the perovskite active layer precursor in the perovskite active layer precursor solution comprises ABX ₃ Perovskite type semiconductor material or (A') _m (A) _n-1 B _n X _3n+1 A' is a large organic cation preferably comprising n-butylamine iodide, phenethylamine iodide or 1,4-butanediamine hydroiodide, and A is one or more of methylamine cation, formamidine cation, cs and RbB is lead and/or tin, and X is at least one of iodine, bromine and chlorine. The invention is directed to the ABX ₃ Type or (A') _m (A) _n-1 B _n X _3n+1 The specific type of perovskite semiconductor material is not particularly limited, and perovskite semiconductor materials composed of the above elements well known in the art may be used.

In the present invention, the concentration of the perovskite active layer precursor solution is preferably 1.3 to 1.4mol/L.

The preparation process of the perovskite active layer precursor solution, the solvent used by the preparation process and the specific composition of the perovskite active layer precursor solution are not particularly limited, and the corresponding perovskite active layer precursor solution can be prepared according to the process well known in the art.

The spin coating rate and time are not particularly limited in the present invention, and may be performed according to the procedures well known in the art, and in the embodiment of the present invention, the spin coating is specifically performed at 3000rpm for 40s, or at 5000rpm for 50s.

In the present invention, the first anti-solvent and the second anti-solvent preferably independently comprise isopropanol, ethanol, butanol, chlorobenzene, ethyl acetate, anisole, diethyl ether, toluene or mesitylene.

In the present invention, it is preferable to adjust the kind of the second anti-solvent in accordance with the perovskite structure, and it is preferable to use an alcohol as the second anti-solvent for a two-dimensional perovskite, and it is preferable to set the kind of the second anti-solvent to be different from that of the first anti-solvent for a three-dimensional perovskite.

In the invention, the time for dripping the first anti-solvent is within 10-20 s after the start of the spin coating process, and more preferably 15s; the time for dropping the second anti-solvent is within 10 to 20 seconds after the first anti-solvent is dropped and 10 to 20 seconds before the spin coating process is finished, and more preferably 15 seconds after the first anti-solvent is dropped.

In the invention, the second antisolvent comprises a passivation material, wherein the passivation material is methylamine iodine, methylamine chloride, formamidine iodine or guanidine bromide; the concentration of the passivating material in the second anti-solvent is preferably 0.5 to 5mg/mL, more preferably 3mg/mL.

In the present invention, the ratio of the perovskite active layer precursor solution to the first antisolvent to the second antisolvent is preferably (50-60): 150 (20-30).

After the second anti-solvent is dripped, annealing the obtained product to form a film preferably after the spin coating is finished; the specific process of the annealing is not particularly limited in the invention, and the annealing can be carried out according to the process well known in the art; in the embodiment of the invention, annealing is carried out for 10min at 100 ℃.

In the invention, the surface passivation material used for the surface passivation treatment comprises methylamine iodine, n-butylamine iodine or choline chloride; the process of the surface passivation treatment preferably comprises: and spin-coating the surface passivation material solution on the film, and carrying out annealing treatment to form a passivation layer on the film so as to obtain the perovskite active layer. In the present invention, the concentration of the surface passivation in the surface passivation solution is preferably 1mg/mL. The process of spin-coating the surface passivation material solution is not particularly limited, and may be performed according to a process well known in the art, and in an embodiment of the present invention, the spin-coating is performed at 5000rpm for 30 seconds. The specific process of the annealing treatment is not particularly limited in the invention, and the annealing treatment can be carried out according to the process well known in the field; in the embodiment of the invention, annealing is carried out for 10min at 100 ℃.

After the secondary anti-solvent is used, the band gap of the film is not changed, and the surface of the film is more n-type, so that the energy level difference between the film and a hole transport layer is favorably reduced, and the extraction and the transmission of holes are improved. In the embodiment of the present invention, since the second anti-solvent used is IPA (isopropyl alcohol), and MAI has lower solubility in IPA than FAI (formamidine iodide), relatively more MAI remains on the surface after the IPA anti-solvent is used. And the large organic cations in the MAI and two-dimensional perovskite will preferentially react with PbI ₂ And the reaction occurs, and the potential barrier of the two-dimensional perovskite crystal is relatively small, so that more two-dimensional phases can be formed on the surface after IPA treatment, and more three-dimensional-like phases exist in the body region, thereby being beneficial to obtaining a two-dimensional device with higher efficiency.

FIG. 1 is a flow chart of perovskite active layer preparation according to an embodiment of the present invention, a perovskite two-dimensional precursor solution is spin-coated on a substrate, ethyl acetate antisolvent is dropped after 15s of spin-coating, methylamine iodide/isopropanol antisolvent is dropped as a secondary antisolvent when the total time of spin-coating is 30s, and annealing and surface post-treatment are sequentially performed to obtain the perovskite active layer.

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Comparative example 1

The solar cell structure of the comparative example is an N-I-P type two-dimensional perovskite solar cell, and is prepared by adopting a one-step anti-solvent method, the specific structure is shown in figure 2, and the solar cell structure sequentially comprises the following components from top to bottom: silver electrode, spiro-OMeTAD hole transport layer, perovskite active layer, snO ₂ An electron transport layer and ITO transparent conductive glass.

The preparation method comprises the following steps:

1) Using glass as a substrate, depositing a transparent conductive ITO layer on the upper surface of the glass substrate, sequentially ultrasonically cleaning the obtained ITO glass substrate by using a Hill glass cleaning agent, deionized water, acetone and isopropanol, and using N ₂ After drying, carrying out ultraviolet ozone treatment on the ITO substrate for 20min to obtain an ITO substrate;

2) In the air, nano SnO with the mass fraction of 2.67 percent ₂ Spin-coating the aqueous solution on an ITO substrate at 4000r/min for 30s, annealing at 80 ℃ for 30min to form an electron transport layer, cooling to room temperature, and transferring to a glove box;

3) 0.16mmol of BDAI ₂ (1,4-butanediamine hydroiodide), 0.2mmol MAI (methylamine iodide) + FAI (formamidine iodide), 0.8mmol PbI ₂ (lead iodide), 0.28mmol of MACl (methylamine chloride) and 0.08mmol of PbCl ₂ (lead chloride) was dissolved in 1mL of DMF (N, N-dimethylformamide) and 99.1. Mu.L of NMP (N-methylpyrrolidone) was added to obtain a two-dimensional precursor solution (concentration 1.3 mol/L); taking 50 mu L of the two-dimensional precursor solution, spin-coating for 40s at the rotating speed of 3000rpm, wherein the solution is dropwise added for 25s before the end of spin-coating150 mu L of ethyl acetate anti-solvent, after the spin coating is finished, annealing for 10min at 100 ℃ in an air atmosphere with 30-40% relative humidity, and cooling to room temperature to form a perovskite thin film;

4) Dissolving 1mg of BAI (n-butylamine iodine) in 1mL of isopropanol, taking 50 mu L of the obtained solution, spin-coating for 30s at the rotating speed of 5000rpm, annealing on a heating table at 100 ℃ for 10min, and forming a passivation layer on the perovskite thin film to obtain a perovskite active layer;

5) Dissolving 72.3mg of Spiro-OMeTAD in 1mL of chlorobenzene, and spin-coating 40 mu L of the obtained solution at the rotating speed of 4000rpm for 30s to form a hole transport layer;

6) And thermally evaporating a silver electrode on the hole transport layer to obtain the N-I-P type two-dimensional perovskite solar cell.

Comparative example 2

The specific structure of the P-I-N type wide band gap perovskite solar cell provided by the comparative example is shown in fig. 3, and comprises the following components in sequence from top to bottom: ag electrode, BCP buffer layer, PCBM electron transport layer, perovskite active layer, niOx + Poly-TPD hole transport layer and ITO transparent conductive glass.

The preparation method comprises the following steps:

1) Using glass as a substrate, depositing a transparent conductive ITO layer on the upper surface of the glass plate, sequentially ultrasonically cleaning the obtained ITO glass substrate by using a Hill glass cleaning agent, deionized water, acetone and isopropanol, and using N ₂ After drying, carrying out ultraviolet ozone treatment on the obtained ITO substrate for 20min to obtain an ITO substrate;

2) Spin-coating 25mg/mLNiOx aqueous solution on the ITO substrate in the air for 30s, then annealing at 120 ℃ for 20min, cooling to room temperature, and transferring to a glove box; spin-coating 0.5mg/mL of a Poly-TPD chlorobenzene solution at the rotating speed of 5000rpm for 30s to form a double-hole transport layer;

3) 74.3mg CsI (cesium iodide), 174.2mg FAI, 466.1mg PbI ₂ And 102.3mg of PbBr ₂ Dissolving in 1mL of mixed solvent of DMF and DMSO (DMF: DMSO volume ratio = 3:1) to obtain wide band gap precursor solution (concentration is 1.4 mol/L), and the band gap is 1.67eV; taking 60 mu L of the wide band gap precursor solution, spin-coating at the rotating speed of 5000rpm for 50s, dripping 150 mu L of ethyl acetate anti-solvent at the reciprocal 25s, and spin-coatingAfter the coating is finished, annealing for 30min in a glove box at 100 ℃; after cooling to room temperature, dissolving 1mg of choline chloride in 1mL of isopropanol, taking 50 mu L of the obtained solution, spin-coating for 30s at the rotating speed of 5000rpm, and carrying out annealing treatment on a heating table at 100 ℃ for 10min to form a passivation layer so as to obtain a perovskite active layer;

4) Dissolving 20mg of PCBM in 1mL of chlorobenzene, and spin-coating 40 mu L of the obtained solution at the rotating speed of 4000rpm for 30s to form an electron transport layer;

5) Preparing a BCP saturated solution with the concentration of 0.5mg/mL (isopropanol is used as a solvent), taking 60 mu L of the obtained solution, and spin-coating for 30s at the rotating speed of 6000rpm to form a buffer layer;

6) And thermally evaporating a silver electrode on the buffer layer to obtain the P-I-N type wide band gap perovskite solar cell.

Example 1

The only difference from comparative example 1 is: dissolving 3mg of MAI (methylamine iodide) in 1mL of IPA (isopropanol), stirring and dissolving at normal temperature to obtain an MAI/IPA anti-solvent serving as a second anti-solvent;

in the step 3: taking 50 mu L of the two-dimensional precursor solution, carrying out spin coating for 40s at the rotating speed of 3000rpm, wherein 150 mu L of ethyl acetate anti-solvent is dropwise added at the inverse number of 25s before the spin coating is finished, 20 mu L of MAI/IPA anti-solvent is dropwise added at the inverse number of 10s before the spin coating is finished, annealing is carried out for 10min at 100 ℃ in an air atmosphere with 30-40% relative humidity after the spin coating is finished, and cooling is carried out to room temperature to form a perovskite film;

the rest is the same as in comparative example 1.

Example 2

The only difference from example 1 is: MAI (methylamine iodide) was replaced with MACl (methylamine chloride).

Example 3

The only difference from comparative example 2 is: dissolving 3mg of MAI in 1mL of isopropanol, stirring and dissolving at normal temperature to obtain an MAI/IPA anti-solvent serving as a second anti-solvent;

step 3, taking 60 mu L of the wide-bandgap precursor solution, carrying out spin coating for 50s at the rotating speed of 5000rpm, dropwise adding 150 mu L of ethyl acetate antisolvent in 25s from the last, dropwise adding 20 mu L of the MAI/IPA antisolvent in 10s from the last, and annealing for 30min at 100 ℃ in a glove box after the spin coating is finished;

the rest is the same as in comparative example 2.

Example 4

The embodiment provides a P-I-N type wide band gap perovskite and double-sided textured silicon heterojunction combined perovskite/silicon heterojunction laminated solar cell, and the effective area of the cell is 0.5003cm ² The concrete structure is as shown in fig. 4, and comprises from top to bottom in sequence: front metal grid line electrode silver, transparent conductive film IZO and buffer layer SnO ₂ Electron transport layer C ₆₀ The solar cell comprises a perovskite active layer, a Poly-TPD/NiOx double-hole transport layer, a connecting layer ITO, a silicon heterojunction bottom cell electron selection layer a-Si: H (N), a passivation layer a-Si: H (i), a silicon substrate N-Si, a passivation layer a-Si: H (i), a hole selection layer a-Si: H (p), ITO and back electrode silver.

The preparation method comprises the following steps:

preparing ITO with the thickness of 20nm as a connecting layer on the front surface of a commercial silicon heterojunction cell substrate by adopting a sputtering deposition technology;

sputtering NiOx as a hole transport layer; spin-coating 0.5mg/mL of a Poly-TPD chlorobenzene solution at the rotating speed of 5000rpm for 30s to form a double-hole transport layer;

the preparation process of perovskite layer PVSK is the same as in example 3;

thermal evaporation of 20nm C on top of the perovskite layer ₆₀ As an electron transport layer;

deposition of 30nm SnO by thermal atomic layer deposition techniques ₂ A buffer layer;

at SnO ₂ IZO with the thickness of 85nm is sputtered on the buffer layer;

and thermally evaporating the metal silver electrodes at two ends to obtain the perovskite/silicon heterojunction laminated solar cell.

Performance testing

1) At a standard solar intensity (AM 1.5, 100 mW/cm) ² ) The photoelectric properties of the solar cells prepared in comparative examples 1 to 2 and examples 1 to 4 were tested under irradiation, and the results are shown in fig. 5 to 10;

FIG. 5 is a J-V diagram of an N-I-P type two-dimensional perovskite cell in comparative example 1, and as shown in FIG. 5, the cell has an open-circuit voltage of 1.09V, a fill factor of 73.94%, and a short-circuit current density of 21.04mA/cm ² The photoelectric conversion efficiency was 16.89%.

FIG. 6 is a J-V diagram of the N-I-P type two-dimensional perovskite cell after the optimization of 3mg/mL MAI/IPA secondary anti-solvent in example 1, as shown in FIG. 6, the open-circuit voltage of the device is increased to 1.16V after the treatment of the secondary anti-solvent, the filling factor is increased to 78.88%, and the short-circuit current density is 21.37mA/cm ² And finally, the photoelectric conversion efficiency reaches 19.55%.

FIG. 7 is a J-V diagram of the N-I-P type two-dimensional perovskite cell after the optimization of 3mg/mL MACl/IPA secondary anti-solvent in example 2, as shown in FIG. 7, the open-circuit voltage of the device is increased to 1.12V after the treatment of the secondary anti-solvent, the filling factor is increased to 77.36%, and the short-circuit current density is 21.22mA/cm ² And finally, the photoelectric conversion efficiency reaches 18.34%.

FIG. 8 is a J-V diagram of a P-I-N type wide band gap perovskite cell in comparative example 2, and as shown in FIG. 8, the cell has an open-circuit voltage of 1.09V, a fill factor of 80.22%, and a short-circuit current density of 19.78mA/cm ² The photoelectric conversion efficiency was 17.36%.

FIG. 9 is a J-V diagram of a P-I-N type wide band gap perovskite cell optimized with 3mg/mL MAI/IPA secondary anti-solvent in example 3, as shown in the figure, the open-circuit voltage of the device is increased to 1.12V after the secondary anti-solvent treatment, the filling factor is increased to 82.23%, and the short-circuit current density is 20.98mA/cm ² And finally, the photoelectric conversion efficiency reaches 19.32%.

FIG. 10 is a J-V diagram of a wide band gap perovskite/silicon heterojunction tandem solar cell optimized by 3mg/mL MAI/IPA secondary anti-solvent in example 4, wherein the silicon heterojunction bottom cell has a double-sided texturing structure, as shown in FIG. 10, the photoelectric conversion efficiency of the cell is 23.02%, and the short-circuit current density is 17.11mA/cm ² The fill factor is 76.47% and the open circuit voltage is 1.76V.

2) The perovskite devices obtained in comparative example 1 and example 1 are characterized by charge defect state density N by Space Charge Limited Current (SCLC) technology _t And the perovskite device without any surface passivation is taken as a reference, the obtained result is shown in figure 11, and the device structure is Glass/ITO/SnO ₂ Perovskite absorption layer/passivation layer/PCBM/BCP/Ag. FIG. 11 shows the conventional surface treatment used in comparative example 1 and the secondary reaction used in example 1The effect of solvent in combination with conventional surface passivation on the density of corresponding charge defect states. As can be seen from FIG. 11, the perovskite device without any surface passivation (specifically prepared by the same method as in comparative example 1, but without the surface treatment with n-butylamine iodine in step 4) had a defect state density of 4.0X 10 ¹⁶ cm ^-3 The defect state density after the surface passivation is reduced to 2.04X 10 in the comparative example 1 ¹⁶ cm ^-3 The defect state density is further reduced to 1.06X 10 after the second anti-solvent treatment combined with the surface passivation in example 1 ¹⁶ cm ^-3 It is demonstrated that the method of the present invention can reduce the density of surface defect states by nearly 2 times based on the passivation of the conventional surface post-treatment.

According to the embodiment, the secondary anti-solvent containing the passivation material is dripped, and then surface passivation treatment is carried out, so that the surface defects of the perovskite can be reduced to the greatest extent, the crystallization quality of the perovskite thin film can be improved, the open-circuit voltage and the filling factor of the two-dimensional perovskite and the wide-band-gap perovskite are obviously improved, the efficiency of the battery based on the two-end laminated battery of the wide-band-gap perovskite base/crystalline silicon is obviously improved, and the method is simple and easy to implement.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a perovskite active layer in a solar cell comprises the following steps:

spin-coating a perovskite active layer precursor solution on a substrate, sequentially dropwise adding a first anti-solvent and a second anti-solvent in the spin-coating process, and performing surface passivation treatment on the obtained film to obtain a perovskite active layer;

2. The method of claim 1, wherein the first and second anti-solvents independently comprise isopropanol, ethanol, butanol, chlorobenzene, ethyl acetate, anisole, diethyl ether, toluene, or mesitylene.

3. The method of claim 1, wherein the concentration of the passivating material in the second antisolvent is from 0.5 to 5mg/mL.

4. The production method according to claim 1, 2 or 3, wherein the time for dropping the first antisolvent is within 10 to 20 seconds after the start of the spin coating process; the time for dripping the second anti-solvent is within 10-20 s after the first anti-solvent is dripped and 10-20 s before the spin coating procedure is finished.

5. The production method according to claim 1, wherein the concentration of the perovskite active layer precursor solution is 1.3 to 1.4mol/L; the volume ratio of the perovskite active layer precursor solution to the first anti-solvent to the second anti-solvent is (50-60) to (150) to (20-30).

6. The preparation method of claim 1, wherein the surface passivation material used for the surface passivation treatment comprises methylamine iodine, n-butylamine iodine or choline chloride.

7. The production method according to claim 1 or 6, wherein the surface passivation treatment process includes: spin-coating the surface passivation material solution on the film, and annealing; the concentration of the surface passivation material in the surface passivation material solution is 1mg/mL.

8. The production method according to claim 1, wherein the substrate is an electron transport layer or a hole transport layer; the electron transport layer is made of tin dioxide, titanium dioxide, zinc oxide, [6,6 ]]-phenyl radical C ₆₁ One or more of methyl butyrate, fullerene and graphene; the hole transport layerThe material of (2) is one or more of an inorganic material, an organic material and a self-assembled monomolecular layer material.

9. The production method according to claim 1, wherein the perovskite active layer precursor in the perovskite active layer precursor solution comprises ABX ₃ Perovskite type semiconductor material or (A') _m (A) _n-1 B _n X _3n+1 The perovskite semiconductor material comprises a perovskite semiconductor material, wherein A' is a large organic cation, the large organic cation comprises n-butylamine iodine, phenylethylamine iodine or 1,4-butanediamine hydroiodide, A is one or more of methylamine cation, formamidine cation, cs and Rb, B is lead and/or tin, and X is at least one of iodine, bromine and chlorine.

10. The production method according to claim 1, characterized in that the perovskite type of the solar cell is a two-dimensional perovskite, a three-dimensional perovskite, or a mixed victorite.