阅读说明：本技术 A、x位协同调控构建的吸光材料及其制备方法和应用 (A. Light absorption material constructed by X-position cooperative regulation and control as well as preparation method and application thereof ) 是由 黄富强 秦鹏 邵峰 张国庆 于 2020-05-20 设计创作，主要内容包括：本发明涉及A、X位协同调控构建的吸光材料及其制备方法和应用,所述吸光材料为具有立方相结构的卤族钙钛矿,化学式为A-(y)A'-(1-y)BX-(z)X'-(3-z)；其中,A为CH-(3)NH-(3)～(+)；A'为(NH-(2))-(2)CH～(+)、(CH-(3))-(2)NH-(2)～(+)、(CH-(3))-(3)NH～(+)、(CH-(3)CH-(2))NH-(3)～(+)、(CH-(3)CH-(2))-(2)NH-(2)～(+)中的至少一种；B为Sn～(2+)、Sr～(2+)、Ca～(2+)中至少一种和Pb～(2+)、或Pb～(2+)；X为I～(-)；X'为SCN～(-)、BF-(4)～(-)、HCOO～(-)和CN～(-)中的至少一种；0.7≤y＜1.0,2.5≤z＜3.0。(The invention relates to a light absorption material constructed by A, X bit cooperative regulation and control, and a preparation method and application thereof, wherein the light absorption material is halogen perovskite with a cubic phase structure and has a chemical formula A y A' 1‑y BX z X' 3‑z (ii) a Wherein A is CH 3 NH 3 + (ii) a A' is (NH) 2 ) 2 CH + 、(CH 3 ) 2 NH 2 + 、(CH 3 ) 3 NH + 、(CH 3 CH 2 )NH 3 + 、(CH 3 CH 2 ) 2 NH 2 + At least one of; b is Sn 2+ 、Sr 2+ 、Ca 2+ At least one of (1) and Pb 2+ Or Pb 2+ (ii) a X is I ‑ (ii) a X' is SCN ‑ 、BF 4 ‑ 、HCOO ‑ And CN ‑ At least one of; y is more than or equal to 0.7 and less than 1.0, and z is more than or equal to 2.5 and less than 3.0.)

1. A light absorbing material is characterized in that the light absorbing material is halogen perovskite with a cubic phase structure and has a chemical formula A_yA'_1-yBX_zX'_3-z(ii) a Wherein A is CH₃NH₃ ⁺(ii) a A' is (NH)₂)₂CH⁺、(CH₃)₂NH₂ ⁺、(CH₃)₃NH⁺、(CH₃CH₂)NH₃ ⁺、(CH₃CH₂)₂NH₂ ⁺At least one of; b isSn²⁺、Sr²⁺、Ca²⁺At least one of (1) and Pb²⁺Or Pb²⁺(ii) a X is I^-(ii) a X' is SCN^-、BF₄ ^-、HCOO^-And CN^-At least one of; y is more than or equal to 0.7 and less than 1.0, and z is more than or equal to 2.5 and less than 3.0.

2. A method of making a light absorbing material according to claim 1, comprising:

(1) selecting A (X/X '), A' (X/X ') and B (X/X')₂As a precursor, according to a stoichiometric ratio A_yA'_1-yBX_zX'_3-zWeighing, dissolving in a polar organic solvent, and adding an additive according to needs to obtain a precursor solution;

(2) and uniformly coating the precursor solution on the surface of the substrate, and then annealing at 60-140 ℃ to obtain the light absorbing material.

3. The method according to claim 2, wherein the polar organic solvent is at least one selected from the group consisting of N-methylformamide, N-dimethylformamide, N-methylacetamide, N-dimethylacetamide, dimethylsulfoxide, and pyrrolidone.

4. The method according to claim 2 or 3, wherein the additive is selected from at least one of thiosemicarbazide, benzoquinone, and ionic liquids.

5. The method according to any one of claims 2 to 4, wherein the substrate is selected from one of glass, polyimide, silica, quartz, silicon wafer, silicon carbide, sapphire, metal; the substrate surface is also distributed with a conducting layer, and the conducting layer is made of conducting metal oxide, preferably selected from ITO, FTO, AZO, IHO or BZO.

6. A perovskite thin film solar cell, comprising: a conductive substrate, and an electron transport layer, a light absorption layer, a hole transport layer and a counter electrode which are sequentially formed on the surface of the conductive substrate, the light absorption layer prepared from the light absorption material of claim 1; preferably, the thickness of the light absorption layer is 300 to 800 nm.

7. The perovskite thin-film solar cell according to claim 6 or claim, wherein the material of the electron transport layer is selected from one of titanium oxide, tin oxide, zinc oxide, fullerene and derivatives thereof; the thickness of the electron transmission layer is 50-150 nm.

8. The perovskite thin-film solar cell according to claim 6 or 7, wherein the hole transport layer is made of one material selected from the group consisting of spiro-MeOTAD, PTAA, small molecules with a push-pull conjugated structure, and conductive polymers; the thickness of the hole transport layer is 50-100 nm.

9. The perovskite thin-film solar cell according to any one of claims 6 to 8, wherein the material of the counter electrode is selected from one of gold, silver, conductive metal oxides.

Technical Field

The invention relates to a light absorption material with a A, X-site synergistically regulated and constructed perovskite structure, a preparation method and application thereof, and belongs to the field of solar cell energy sources, wherein the perovskite structure is stabilized to realize the unification of high efficiency and high stability of a perovskite solar cell.

Background

With the increasing severity of global energy and environmental issues, china has promoted new energy industries, including solar energy, as the national strategic industry. The solar photovoltaic technology converts abundant solar energy into electric energy by utilizing a photovoltaic principle, and becomes one of the most potential ways for solving the energy crisis of human beings. The metal halide perovskite is a photovoltaic material with great application prospect due to excellent light absorption and carrier transmission performance, rich raw materials and low cost. Through the development of 10 years, the laboratory certification efficiency of the single-junction organic-inorganic hybrid perovskite solar cell is over 25 percent, and exceeds the level of traditional thin-film solar cells with the development of copper indium gallium selenide, cadmium telluride and the like for decades. Wherein methylamine lead iodine perovskite is tetragonal phase at room temperature, and above 56 deg.C phase transformation from tetragonal phase to cubic phase occurs, but ABX represented by methylamine lead iodine₃The intrinsic stability of the organic-inorganic hybrid perovskite is poor, and the ion migration and structural phase change in the material are easy to occur under the influence of illumination, temperature and the like; the material is easy to degrade under the action of water/oxygen, and the service life of the device is limited. The unification of high efficiency and high stability is a major challenge facing the further commercial application of perovskite photovoltaic materials.

Disclosure of Invention

Therefore, the invention aims to provide a perovskite light absorption layer constructed by utilizing A, X-site cooperative regulation and control, a preparation method thereof and application thereof in a thin-film solar cell, so that the stability of the conventional perovskite solar cell is improved.

In one aspect, the present invention provides a light absorbing material that is a halogen perovskite having a cubic phase structure and having a chemical formula A_yA'_1-yBX_zX'_3-z(ii) a Wherein A is CH₃NH₃ ⁺(ii) a A' is (NH)₂)₂CH⁺、(CH₃)₂NH₂ ⁺、(CH₃)₃NH⁺、(CH₃CH₂)NH₃ ⁺、(CH₃CH₂)₂NH₂ ⁺At least one of; b is Sn²⁺、Sr²⁺、Ca²⁺At least one of (1) and Pb²⁺Or Pb²⁺(ii) a X is I^-(ii) a X' is SCN^-、BF₄ ^-、HCOO^-And CN^-At least one of; y is more than or equal to 0.7 and less than 1.0, and z is more than or equal to 2.5 and less than 3.0.

In the method, the influence of the size effect of A-site ions and X-site ions on an organic-inorganic hybrid perovskite framework is utilized, the phase transformation from a tetragonal phase to a cubic phase at room temperature is induced through the cooperative regulation and control among ions, the distortion and the distortion of crystal lattices are improved, and the construction of a stable perovskite structure is finally realized. Specifically, SCN is introduced into X' in the invention^-、BF₄ ^-、HCOO^-And CN^-Simultaneously with the A' position (NH)₂)₂CH⁺、(CH₃)₂NH₂ ⁺、(CH₃)₃NH⁺、(CH₃CH₂)NH₃ ⁺、(CH₃CH₂)₂NH₂ ⁺And when large-size cations are equal, cubic phase perovskite with smaller lattice stress is formed. The smaller lattice stress can inhibit the non-radiative recombination of the material and improve the service life of the charge separation state. And meanwhile, the stable frame structure is beneficial to improving the thermal stability of the material.Therefore, the synchronous improvement of the photoelectric conversion efficiency and the stability is finally obtained.

For A_yA'_1-yBX_zX'_3-zIn other words, although it is theoretically possible that y and z are 0 < y < 1 and 0 < z < 3, it is found in the course of further studies by the present inventors that: if the values of y and z are too low, the resulting material is prone to form a low dimensional structure, which is not conducive to charge transport. If the values of y and z are too high, the resulting material tends to form a tetragonal phase rather than a cubic phase perovskite structure. That is, when y is more than or equal to 0.7 and less than 1.0 and z is more than or equal to 2.5 and less than 3.0, the three-dimensional structure cubic phase perovskite can be formed, and the requirements on photoelectric properties and stability are met, so that the three-dimensional structure cubic phase perovskite can be used for perovskite thin-film solar cells.

In another aspect, the present invention provides a method for preparing the light absorbing material, including:

(1) selecting A (X/X '), A' (X/X ') and B (X/X')₂As a precursor, according to a stoichiometric ratio A_yA'_1-yBX_zX'_3-zWeighing, dissolving in a polar organic solvent, and adding an additive according to needs to obtain a precursor solution;

(2) and uniformly coating the precursor solution on the surface of the substrate, and then annealing at 60-140 ℃ to obtain the light absorbing material.

Preferably, the polar organic solvent is at least one selected from the group consisting of N-methylformamide, N-dimethylformamide, N-methylacetamide, N-dimethylacetamide, dimethylsulfoxide, and pyrrolidone.

Preferably, the additive is at least one selected from thiosemicarbazide, benzoquinone and ionic liquid.

Preferably, the substrate is selected from one of glass, polyimide, silicon dioxide, quartz, silicon wafer, silicon carbide, sapphire and metal; the substrate surface is also distributed with a conducting layer, and the conducting layer is made of conducting metal oxide, preferably selected from ITO, FTO, AZO, IHO or BZO.

In yet another aspect, the present invention also provides a perovskite thin film solar cell, comprising: the light absorption layer is made of the light absorption material, and the hole transmission layer and the counter electrode are sequentially formed on the surface of the conductive substrate; preferably, the thickness of the light absorption layer is 300 to 800 nm.

Preferably, the material of the electron transport layer is selected from one of titanium oxide, tin oxide, zinc oxide, fullerene and derivatives thereof; the thickness of the electron transmission layer is 50-150 nm.

Preferably, the material of the hole transport layer is selected from one of spiro-MeOTAD, PTAA, small molecules with a push-pull conjugated structure and conductive polymers; the thickness of the hole transport layer is 50-100 nm.

Preferably, the material of the counter electrode is selected from one of gold, silver and conductive metal oxide.

Has the advantages that:

the perovskite thin-film solar cell obtained in the invention has the advantages of low cost, high photoelectric conversion efficiency, good thermal stability and great application value.

Drawings

FIG. 1 is A prepared in example 1_yA'_1-yBX_zX'_3-zCubic phase perovskite material and ABX in comparative example 1₃X-ray diffraction patterns of (a);

FIG. 2 is A prepared on a quartz substrate in example 1_yA'_1-yBX_zX'_3-zFilms and ABX in comparative example 1₃Ultraviolet-visible absorption spectrum of (a);

FIG. 3A is a graph showing a crystal layer A prepared on a quartz substrate in example 1_yA'_1-yBX_zX'_3-zFilms and ABX in comparative example 1₃Scanning electron microscope images of the film surface;

fig. 4 is a schematic structural diagram of a perovskite thin-film solar cell prepared by the invention.

Detailed Description

The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.

In the present disclosure, the structure of the thin film solar cell may sequentially include a conductive substrate (or called conductive substrate), an electron transport layer, a perovskite light absorption layer, a hole transport layer, and a counter electrode.

In an alternative embodiment, the conductive base may be composed of a substrate and a conductive layer. The material of the substrate is not limited, and various known substrates, such as a rigid substrate made of glass, quartz, or the like, and/or a flexible substrate made of polyimide, plastic, or the like, can be used. The conductive layer is deposited on the substrate and can be metal oxide such as FTO, ITO and the like. The deposition method adopts the existing vacuum coating technology, such as magnetron sputtering and the like.

An electron transport layer is deposited on the conductive substrate. The material of the electron transport layer can be titanium oxide, tin oxide, zinc oxide, fullerene and derivatives thereof. The preparation method of the electron transport layer can adopt a liquid phase coating process (spin coating, spray coating, screen printing and the like) and/or a vacuum coating technology (atomic layer deposition, electrochemical deposition, magnetron sputtering and the like) and the like for preparation. The thickness of the electron transport layer can be 50-150 nm.

And preparing a light absorption layer on the electron transport layer. Wherein the light absorption layer is cubic phase A_yA'_1-yBX_zX'_3-zThe halogen perovskite film is prepared into the light absorption layer with a stable cubic phase structure by utilizing A, X bit cooperative regulation and control. Wherein A may be CH₃NH₃ ⁺(ii) a A' is (NH)₂)₂CH⁺、(CH₃)₂NH₂ ⁺、(CH₃)₃NH⁺、(CH₃CH₂)NH₃ ⁺、(CH₃CH₂)₂NH₂ ⁺One of (1); b is Pb²⁺Or Pb²⁺And Sn²⁺、Sr²⁺、Ca²⁺Mixing the two materials; x is I^-(ii) a X' is SCN^-、BF₄ ^-、HCOO^-、CN^-One kind of (1).

In one embodiment of the invention, the liquid phase coating technology is combined with annealing crystallization to prepare A_yA'_1-yBX_zX'_3-zPerovskite light absorption layers (for short, y is more than or equal to 0.7 and less than 1.0, and z is more than or equal to 2.5 and less than 3.0). The following exemplarily illustrates a method of preparing the light absorbing layer.

Choose to useA(X/X')、A'(X/X')、B(X/X')₂As a precursor, dissolving in a polar organic solvent, and selecting corresponding additives according to needs to form a stable source solution, namely a precursor solution. Wherein, the meaning of "X/X '" is X or/and X'. The polar organic solvent may include, but is not limited to, one or more of N-methylformamide, N-dimethylformamide, N-methylacetamide, N-dimethylacetamide, dimethyl argon sulfone, and pyrrolidone. Wherein, the additive comprises one of thiosemicarbazide, benzoquinone and ionic liquid. The addition of additives facilitates perovskite crystallization. Preferably, the ionic liquid is selected from one of methylamine acetate, 1-butyl-3-methylimidazolium tetrafluoroborate and 1-hexyl-3-methylimidazolium bistrifluoromethylsulphonimide salt. The addition amount of the additive is 0-8% of the total molar amount of the precursor.

And preparing a precursor film on the surface of the conductive substrate/electron transport layer by using the precursor solution through liquid phase coating processes such as a spin coating method, a screen printing method, an ink-jet printing method, a drawing method, a slit coating method and the like.

And (3) carrying out crystallization annealing treatment (annealing treatment for short) on the precursor thin film to obtain the cubic phase perovskite thin film (light absorption layer). Wherein, the temperature of the crystallization annealing treatment can be 60-140 ℃, and the time can be 0.3-1 hour. Wherein the atmosphere of the crystallization annealing comprises a nitrogen atmosphere, an argon atmosphere, a dry air atmosphere and/or an air atmosphere and the like. The thickness of the light absorption layer can be 300-800 nm.

The precursor film may be pretreated as desired prior to the crystallization annealing treatment. Wherein the pretreatment comprises: the method comprises the following steps of nonpolar solvent auxiliary treatment, vacuum auxiliary treatment, gas phase auxiliary treatment and the like, and aims to regulate and control the crystal size of perovskite and the surface appearance of a thin film. The steps and parameters of the nonpolar solvent auxiliary treatment comprise: coating a small amount of non-polar solvents such as chlorobenzene, cyclohexane and the like on the surface of the precursor film; the steps and parameters of the vacuum assisted process include: placing the precursor film in a vacuum chamber with 5-30 Pa for 5-30 s; the steps and parameters of the gas-phase auxiliary treatment comprise: and placing the precursor film in organic amine halide steam for 10-30 min.

Preparing a hole transport layer on the basis of the conductive substrate/the electron transport layer/the perovskite light absorption layer. The hole transport layer can be prepared using liquid phase coating techniques (spin coating, spray coating, screen printing, etc.). The material of the hole transport layer can be selected from spiro-MeOTAD, PTAA, small molecules with a push-pull conjugated structure or a conductive polymer film and the like. The thickness of the hole transport layer can be 50-100 nm.

And depositing a counter electrode by using a vacuum evaporation and/or magnetron sputtering mode and the like to finish the preparation of the thin-film solar cell. The material of the counter electrode can be selected from gold, silver, metal oxide or the like.

In the invention, after the thin-film solar cell is assembled, a standard light source (standard solar simulator AM1.5100mW/cm) is utilized²) And testing parameters such as current, voltage and the like of the battery. Through tests, the photoelectric conversion efficiency of the thin-film solar cell exceeds 19.5%; and carrying out rapid attenuation test on the unpackaged device under the conditions of 50% of ambient humidity and 85 ℃ of ambient temperature. Tests show that the efficiency attenuation of the thin-film solar cell is lower than 20% after the thin-film solar cell is placed in the environment for 7 days.

The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.

Example 1

(1) Will PbI₂(0.70～0.90mmol)、Pb(SCN)₂(0.10～0.30mmol)、CH₃NH₃I (0.70-0.95 mmol) and (CH)₃)₂NH₂Dissolving the I (0.05-0.30 mmol) in a mixed solvent of dimethyl sulfoxide and pyrrolidone (volume ratio is 8:1) to obtain a yellow transparent solution (namely a precursor solution);

(2) coating the precursor solution into a film by a liquid phase method, and then carrying out surface treatment on 0.5-2.0 mL of cyclohexane solution to obtain a precursor film;

(3) and (3) putting the precursor film in a nitrogen atmosphere, and carrying out annealing treatment (crystallization) on a hot bench at 70-110 ℃ for 0.5 hour to obtain the perovskite film (light absorption layer). The obtained light absorbing layer has a chemical formula of (CH)₃NH₃)_0.70～0.95((CH₃)₂NH₂)_{0.30～ 0.05}PbI_2.40～2.80SCN_0.60～0.20And a thickness of about 500 nm.

The perovskite thin film obtained in example 1 was subjected to an X-ray diffraction test, as shown in FIG. 1, indicating the formation of a pure cubic perovskite phase.

The cubic phase perovskite thin film prepared on the quartz substrate in this example 1 is subjected to an ultraviolet-visible spectrum test, as shown in fig. 2, and the forbidden band width thereof meets the requirements of a solar cell.

The perovskite thin film obtained in the embodiment 1 is subjected to surface scanning electron microscope test, and as shown in fig. 3, the obtained thin film has a uniform and flat surface and high crystallinity.

The structure of the solar cell based on the perovskite thin film is shown in FIG. 4, and the preparation process of the solar cell comprises the following steps: the preparation process of the light absorption layer is as above, and the device structure is FTO conductive glass substrate/TiO₂perovskite/spiro-MeOTAD/Au. Wherein the TiO is₂The coating is prepared by adopting a spin coating process, and the thickness is about 60 nm; the Spiro-MeOTAD is prepared by adopting a spin-coating process, and the thickness is about 80 nm; the Au electrode is prepared by adopting a vacuum evaporation process, and the thickness is about 100 nm. After parameter optimization, the photoelectric conversion efficiency of the obtained solar cell reaches 21.2%. And carrying out rapid attenuation test on the unpackaged device under the conditions of 50% of ambient humidity and 85 ℃ of ambient temperature. The photoelectric conversion efficiency of the solar cell decayed by 17.0% (from 21.2% to 17.6%) after being left in the above-described environment for 7 days.

Example 2

(1) Will PbI₂(1.0mmol)、CH₃NH₃I(0.70～0.90mmol)、CH₃NH₃BF₄(0.05-0.15 mmol) and (CH)₃)₂NH₂I (0.05-0.15 mmol) and ionic liquid (0.02-0.05 mmol) solutionDissolving in a mixed solvent (10:1) of dimethyl sulfoxide and N, N-dimethylformamide to obtain a yellow transparent solution;

(2) coating the yellow transparent solution into a film through a liquid phase to obtain a precursor film;

(3) and directly placing the obtained precursor film on a hot stage at 70-110 ℃ in a nitrogen atmosphere for annealing treatment for 0.5 hour to obtain the cubic phase perovskite film. The obtained light absorbing layer has a chemical formula of (CH)₃NH₃)_0.85～0.95((CH₃)₂NH₂)_{0.15～ 0.05}PbI_2.85～2.95(BF₄)_0.15～0.05And the thickness is about 600 nm.

The material selection and preparation process of other layers of the solar cell in this example 2 refer to example 1, and the photoelectric conversion efficiency of the obtained solar cell reaches 20.0%, and the efficiency of the solar cell is reduced by 18% (from 20.0% to 16.4%) after the solar cell is placed in the above environment for 7 days. The results of solar cell testing based on this perovskite thin film are similar to example 1.

Example 3

(1) Will PbI₂(1.0mmol)、CH₃NH₃I(0.60～0.80mmol)、CH₃NH₃BF₄(0.10 to 0.20mmol) and (CH)₃CH₂)NH₃Dissolving the I (0.10-0.20 mmol) in a mixed solvent (5:1) of dimethyl sulfoxide and N, N-dimethylformamide to obtain a yellow transparent solution;

(2) coating the yellow transparent solution into a film through a liquid phase, and placing the film in methylamine steam for 10min to obtain a precursor film;

(3) and directly placing the obtained precursor film on a hot table at 70-110 ℃ in dry air for annealing treatment for 0.5 hour to obtain the cubic phase perovskite film. The obtained light absorbing layer has a chemical formula of (CH)₃NH₃)_0.80～0.90(CH₃CH₂NH₃)_{0.20～ 0.10}PbI_2.80～2.90(BF₄)_0.20～0.10And the thickness is about 700 nm.

In this embodiment 3, the solar cell structure is FTO conductive glass substrate/SnO₂CalciumTitanium ore/spiro-MeOTAD/Au. Wherein SnO₂The film is prepared by adopting an atomic layer deposition process, and the thickness is about 30 nm; the Spiro-MeOTAD is prepared by adopting a spin-coating process, and the thickness is about 80 nm; the Au electrode is prepared by adopting a vacuum evaporation process, and the thickness is about 100 nm. The photoelectric conversion efficiency of the obtained solar cell reaches 19.9%, and the efficiency of the solar cell is reduced by 16% (from 19.9% to 16.7%) after the solar cell is placed in the environment for 7 days. The results of solar cell testing based on this perovskite thin film are similar to example 1.

Example 4

(1) Will PbI₂(0.70～0.90mmol)、SnI₂(0.10～0.30mmol)、CH₃NH₃I(0.60～0.80mmol)、CH₃NH₃SCN (0.10-0.20 mmol) and (CH)₃CH₂)NH₃Dissolving I (0.10-0.20 mmol) in dimethyl sulfoxide to obtain a yellow transparent solution;

(2) coating the yellow transparent solution into a film through a liquid phase to obtain a precursor film;

(3) and directly placing the obtained precursor film on a hot stage at 70-120 ℃ in an argon atmosphere for annealing for 1.0 hour to obtain the cubic phase perovskite film. The obtained light absorbing layer has a chemical formula of (CH)₃NH₃)_0.80～0.90(CH₃CH₂NH₃)_{0.20～ 0.10}Pb_0.70～0.90Sn_0.30～0.10I_2.80～2.90(SCN)_0.20～0.10And the thickness is about 600 nm.

The material selection and preparation process of other layers of the solar cell in the embodiment 4 are shown in the embodiment 3, the photoelectric conversion efficiency of the obtained solar cell reaches 19.6%, and the efficiency of the solar cell is reduced by 20% (from 19.6% to 15.7%) after the solar cell is placed in the environment for 7 days. The results of solar cell testing based on this perovskite thin film are similar to example 1.

Example 5

(1) Will PbI₂(1.0mmol)、CH₃NH₃I(0.60～0.80mmol)、CH₃NH₃(HCOO) (0.10-0.20 mmol) and (NH)₂)₂CHI (0.10-0.20 mmol) and thiosemicarbazide (0.02-0.05 mmol) in waterObtaining a yellow transparent solution in a mixed solvent (9:1) of dimethyl sulfoxide and pyrrolidone;

(2) coating the yellow transparent solution into a film through a liquid phase to obtain a precursor film;

(3) and (3) pretreating the obtained precursor film in vacuum, and then annealing for 0.8 hour on a hot table at the temperature of 80-120 ℃ in a dry air atmosphere to obtain the cubic phase perovskite film. The obtained light absorbing layer has a chemical formula of (CH)₃NH₃)_0.80～0.90((NH₂)₂CH)_0.20～0.10PbI_2.80～2.90(HCOO)_0.20～0.10And a thickness of about 500 nm.

The solar cell in this example 5 has the structure of FTO conductive glass substrate/TiO₂Perovskite/push-pull conjugated structure small molecule/Au. Wherein the TiO is₂The thickness is about 60 nm; the push-pull conjugated structure micromolecules are prepared by adopting a spin-coating process, and the thickness is about 40 nm; the Au electrode is prepared by adopting a vacuum evaporation process, and the thickness is about 100 nm. The photoelectric conversion efficiency of the obtained solar cell reaches 20.4%, and the efficiency of the solar cell is reduced by 18% (from 20.4% to 16.7%) after the solar cell is placed in the environment for 7 days. The results of solar cell testing based on this perovskite thin film are similar to example 1.

Example 6

(1) Will PbI₂(0.75～0.90mmol)、Pb(HCOO)₂(0.10～0.25mmol)、CH₃NH₃I (0.80-0.90 mmol) and (NH)₂)₂Dissolving CHI (0.10-0.20 mmol) and 1-butyl-3-methylimidazolium tetrafluoroborate (0.02-0.05 mmol) in dimethyl sulfoxide to obtain a yellow transparent solution;

(2) coating the yellow transparent solution into a film through a liquid phase, and placing the film in a vacuum chamber with 20Pa for 5-20 s to obtain a precursor film;

(3) and directly placing the obtained precursor film on a hot stage at 70-120 ℃ in a nitrogen atmosphere for annealing treatment for 0.5 hour to obtain the cubic phase perovskite film. The obtained light absorbing layer has a chemical formula of (CH)₃NH₃)_0.80～0.90((NH₂)₂CH)_{0.20～ 0.10}PbI_2.50～2.80(HCOO)_0.50～0.20And the thickness is about 600 nm.

Referring to example 5, the photoelectric conversion efficiency of the solar cell obtained in example 6 is 20.6%, and the efficiency of the solar cell is reduced by 15% (from 20.6% to 17.5%) after being placed in the above environment for 7 days. The results of solar cell testing based on this perovskite thin film are similar to example 1.

Comparative example 1

(1) Will PbI₂(1.0mmol) and CH₃NH₃Dissolving I (1.0mmol) in a mixed solvent of dimethyl sulfoxide and pyrrolidone (volume ratio is 8:1) to obtain a yellow transparent solution (namely a precursor solution);

(2) coating the precursor solution into a film by a liquid phase method, and then carrying out surface treatment on 0.5-2.0 mL of cyclohexane solution to obtain a precursor film;

(3) and (3) putting the precursor film in a nitrogen atmosphere, and carrying out annealing treatment (crystallization) on a hot bench at 70-110 ℃ for 0.5 hour to obtain the perovskite film (light absorption layer). The obtained light absorbing layer has a chemical formula of (CH)₃NH₃)PbI₃And a thickness of about 500 nm.

Referring to example 1, the photoelectric conversion efficiency of the solar cell obtained by selecting materials and preparing the other layers of the solar cell in comparative example 1 is 19.2%, but the efficiency of the solar cell is reduced by 65% (from 19.2% to 6.7%) after the solar cell is placed in the environment for 7 days.