Perovskite solar cell and preparation method thereof

Abstract

The invention provides a perovskite solar cell and a preparation method thereof, an optical excitation polymer layer is arranged between a perovskite light absorption layer and a hole transport layer of the perovskite solar cell, and / or an optical excitation polymer layer is arranged between the perovskite light absorption layer and an electron transport layer of the perovskite solar cell; the photo-excitation polymer layer comprises an electron or hole capturing structure unit, and the photo-excitation polymer layer separates photon-generated carriers through the electron or hole capturing structure unit so as to passivate the perovskite light absorption layer. In the invention, the perovskite solar cell has the advantages of high photoelectric conversion efficiency, good stability, good mechanical performance, good bending performance and good recoverability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solar cells, and particularly relates to a perovskite cell and a preparation method thereof. BACKGROUND

[0002] With the continuous development of human society, the demand for energy is increasing. Traditional energy, such as oil, natural gas, coal and the like, is a non-renewable energy. Not only the storage amount is decreasing, but also it brings a relatively large pollution to the environment. Therefore, it is extremely urgent and important to develop renewable green clean energy. Among them, solar energy is paid more and more attention due to its advantages of inexhaustible and no impact on the environment. Developing clean and pollution-free solar energy with huge reserves has become a hot spot of researchers.

[0003] Organic-inorganic halide perovskite materials have attracted extensive attention in the photovoltaic field due to their excellent photoelectric properties. However, the heavy metal lead contained in the perovskite material is harmful to the environment and human body, which hinders its commercialization process. Tin has the same outer electron structure as lead and a similar ionic radius, can form the same type of three-dimensional perovskite structure, and has a more ideal optical band gap, which is most likely to replace lead-based perovskite and obtain better photovoltaic performance.

[0004] At present, tin-based perovskite solar cells have achieved a record efficiency of more than 14%. However, the research of tin-based perovskite solar cells at the present stage also faces many severe challenges. The most severe challenge is that the tin-based perovskite material itself is easily oxidized to produce Sn vacancies, resulting in serious non-radiative recombination loss and voltage loss. These defects are conducive to the invasion of oxygen and moisture, greatly reducing the photoelectric performance and stability of the device. Secondly, the biggest feature of flexible perovskite solar cells (FPSC) is the bendability and recoverability. The traditional recoverability refers to the deformation of the material under external force and the ability of the object to recover from deformation after the external force is removed. The recoverability of the object is related to the characteristics of the material itself. Therefore, to obtain high recoverability of FPSC, there are some requirements for chemical composition and preparation method. Therefore, it is very important to prepare a perovskite light-absorbing material with low Young's modulus.

[0005] Therefore, it is a technical problem to be solved in the field to develop a perovskite solar cell which can avoid or reduce non-radiative recombination loss and voltage loss, has low Young's modulus, good bendability and recoverability. SUMMARY

[0006] In view of the deficiencies in the prior art, the purpose of the present application is to provide a perovskite solar cell and a preparation method thereof. The perovskite solar cell has high photoelectric conversion efficiency, good stability, and good mechanical properties, bendability and good recoverability.

[0007] To achieve the above object, the present application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a perovskite solar cell, wherein a photoexcited polymer layer is arranged between a perovskite light-absorbing layer and a hole transport layer, and / or a photoexcited polymer layer is arranged between a perovskite light-absorbing layer and an electron transport layer; the photoexcited polymer layer comprises an electron or hole trapping structural unit, and the photoexcited polymer layer separates photo-generated carriers through the electron or hole trapping structural unit to passivate the perovskite light-absorbing layer.

[0009] In the present application, by arranging a photoexcited polymer layer between a hole transport layer and a perovskite light-absorbing layer and / or between an electron transport layer and a perovskite light-absorbing layer, the perovskite solar cell can passivate defects of the perovskite light-absorbing layer, reduce non-radiative recombination loss and voltage loss, and improve conversion efficiency; at the same time, the photoexcited polymer layer can also release stress between interfaces, reduce the Young's modulus of the perovskite light-absorbing layer, and improve the stability and flexibility of the solar cell.

[0010] In the present application, the photoexcited polymer layer further comprises a reducing passivation group; the reducing passivation group comprises a phenolic hydroxyl group.

[0011] In the present application, the precursor of the photoexcited polymer layer comprises a conjugated polymer; the conjugated polymer has a structure shown in general formula I.

[0012]

[0013] wherein, R1, R2 are each independently selected from a hydroxyl group; R3, R4 are each independently selected from a C6-C18 (for example, can be C6, C8, C10, C12, C14, C16, C18, etc.) arylene group or a C6-C18 (for example, can be C6, C8, C10, C12, C14, C16, C18, etc.) heteroaromatic group; Z1, Z2, Z4, Z5 are each independently selected from an acetylenic group; Z3, Z6 are each independently selected from H or an acetylenic group; the dotted line represents a connection site.

[0014] In the present application, the photoexcited polymer layer uses a conjugated polymer with a specific structure, which generates electron-hole pairs under light irradiation, wherein the electrons in the conduction band migrate to the perovskite surface and continuously transport electrons at the perovskite layer interface, and the phenolic hydroxyl group contained in the conjugated polymer also has strong reducing property, which can effectively inhibit the oxidation of metal ions in the perovskite layer under the double action, reduce non-radiative recombination loss and voltage loss, and improve conversion efficiency; in addition, the conjugated structure of the polymer can also well release stress between interfaces, reduce the Young's modulus of the perovskite light-absorbing layer, and improve the stability of the solar cell.

[0015] Preferably, R3 and R4 are each independently selected from any one of phenylene, biphenylene, or phenylene.

[0016] Preferably, the conjugated polymer comprises at least one of the following compounds;

[0017]

[0018] In this invention, dashed lines represent connection points, as exemplarily shown below.

[0019]

[0020] In this invention, the conjugated polymers are synthesized using conventional methods; exemplarily, the synthetic routes for the aforementioned three polymers are shown below:

[0021]

[0022] Among them, RH is selected from

[0023] Preferably, the precursor further includes compound A and / or a solvent.

[0024] The compound A includes at least one of triethanolamine, lactic acid, sodium sulfite, glycerol, n-butanol, ethylene glycol, or butanethyl alcohol.

[0025] The volume ratio of compound A to solvent is (0.5–2):10, where the specific values ​​of (0.5–2) can be, for example, 0.5, 0.52, 0.54, 0.56, 0.58, 0.6, 0.62, 0.64, 0.66, 0.68, 0.7, 0.72, 0.75, 0.78, 0.8, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95, 0.98, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc.

[0026] In this invention, by adding compound A, the electron-hole pairs generated by the conjugated polymer under illumination can be captured by compound A, which helps to suppress the oxidation of metal ions in the perovskite light-absorbing layer, reduce non-radiative recombination loss and voltage loss, and improve conversion efficiency and stability.

[0027] The solvent includes water and / or ethanol.

[0028] Preferably, the concentration of the conjugated polymer in the precursor is 2–5 mg / mL, for example, it can be 2 mg / mL, 2.2 mg / mL, 2.4 mg / mL, 2.6 mg / mL, 2.8 mg / mL, 3 mg / mL, 3.2 mg / mL, 3.4 mg / mL, 3.6 mg / mL, 3.8 mg / mL, 4 mg / mL, 4.2 mg / mL, 4.4 mg / mL, 4.6 mg / mL, 4.8 mg / mL, 5 mg / mL, etc.

[0029] Preferably, the perovskite light-absorbing layer comprises a tin-based perovskite light-absorbing layer.

[0030] Preferably, the material of the tin-based perovskite light-absorbing layer has the general structural formula ABX3.

[0031] Wherein, A is selected from CH3NH3 + CH(NH2)2 + Cs + or Rb + B is any one or at least two of the following; B is selected from Sn. 2+ X is selected from Cl - ,Br - Or I - Any one or at least two of them.

[0032] The thickness of the tin-based perovskite light-absorbing layer is 150–500 nm, for example, it can be 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, etc.

[0033] The hole transport layer is made of any one or a combination of at least two of the following materials: nickel oxide (NiOx), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), poly(3,4-ethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS), 4-butyl-N,N-diphenylaniline homopolymer (Ploy-TPD), polyvinylcarbazole (PVK), cuprous iodide (CuI), or cuprous thiocyanate (CuSCN).

[0034] The thickness of the hole transport layer is 10–200 nm, for example, it can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, etc.

[0035] In this invention, the hole transport layer comprises a p-type inorganic semiconductor or a p-type organic semiconductor.

[0036] Preferably, the material of the electron transport layer includes any one or a combination of at least two of fullerenes and their derivatives, titanium dioxide, tin dioxide, zinc oxide, or zinc oxide doped with zinc sulfide.

[0037] In this invention, the fullerene comprises C 60 .

[0038] The thickness of the electron transport layer is 10–40 nm, for example, it can be 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm, 40 nm, etc.

[0039] In this invention, the electron transport layer comprises an n-type inorganic semiconductor or an n-type organic semiconductor.

[0040] A hole blocking layer is also provided between the electron transport layer and the electrode; the thickness of the hole blocking layer is 2 to 15 nm, for example, it can be 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, etc.

[0041] In this invention, the hole-blocking layer is made of materials including, but not limited to, 2,9-dimethyl-4,7-biphenyl-1,10-o-phenanthroline (BCP).

[0042] In this invention, the perovskite solar cell further includes a substrate and electrodes.

[0043] The substrate includes a flexible substrate and / or indium tin oxide conductive glass (ITO conductive glass).

[0044] In this invention, the flexible substrate is made of at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or colorless polyimide (CPI).

[0045] The thickness of the substrate is 2 to 3 μm, for example, it can be 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3 μm, etc.

[0046] In this invention, a composite substrate of a flexible substrate and indium tin oxide (ITO) conductive glass is preferred; in the composite substrate, the thickness of the flexible substrate is 2 to 2.8 μm, and the thickness of the indium tin oxide conductive glass is 100 to 200 nm, for example, it can be 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, etc.

[0047] The electrodes include metal electrodes and / or carbon electrodes.

[0048] The metal electrode includes any one or a combination of at least two of the following: aluminum electrode, gold electrode, silver electrode, or copper electrode.

[0049] The thickness of the metal electrode is 40-150 nm, for example, it can be 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, etc.

[0050] The carbon electrode includes a low-temperature carbon electrode.

[0051] The thickness of the carbon electrode is 5 to 25 μm, for example, it can be 5 μm, 8 μm, 10 μm, 12 μm, 14 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, etc.

[0052] In this invention, the perovskite solar cell includes a conventional perovskite solar cell or an inverted perovskite solar cell; that is, the perovskite solar cell includes a substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and an electrode stacked sequentially; or, the perovskite solar cell includes a substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and an electrode stacked sequentially; a photoexcitation polymer layer is independently disposed between the perovskite light-absorbing layer and the hole transport layer, and between the perovskite light-absorbing layer and the electron transport layer.

[0053] In a second aspect, the present invention provides a method for preparing a perovskite solar cell according to the first aspect, the method comprising the following steps:

[0054] A precursor for coating a photoexcited polymer layer is coated on the surface of a substrate and then annealed to obtain the photoexcited polymer layer.

[0055] In this invention, the substrate includes at least one of a hole transport layer, an electron transport layer, or a perovskite light-absorbing layer.

[0056] In this invention, the specific selection of the substrate is determined according to the structure of the perovskite solar cell and the position of the photoexcited polymer layer; for example, the perovskite solar cell includes a substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer and an electrode stacked in sequence, and the photoexcited polymer layer is disposed between the hole transport layer and the perovskite light-absorbing layer. In this case, the substrate is the hole transport layer.

[0057] The coating rotation speed is 1000-3000 rpm, for example, 1000 rpm, 1200 rpm, 1500 rpm, 1800 rpm, 2000 rpm, 2200 rpm, 2400 rpm, 2600 rpm, 2800 rpm, 3000 rpm, etc.; the time is 40-80 s, for example, 40 s, 45 s, 50 s, 55 s, 60 s, 65 s, 70 s, 75 s, 80 s, etc.

[0058] The annealing temperature is 90–150°C, for example, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, etc.; the time is 10–20 min, for example, 10 min, 11 min, 12 min, 13 min, 14 min, 16 min, 18 min, 20 min, etc.

[0059] In this invention, the hole transport layer is prepared using conventional methods, including but not limited to: depositing a hole transport layer precursor on the surface of a substrate (or perovskite light-absorbing layer), annealing, and obtaining the hole transport layer.

[0060] In this invention, the substrate further includes a washing step before use; the washing includes ultrasonically cleaning the substrate sequentially with detergent, deionized water, acetone and anhydrous ethanol, and then drying it with a nitrogen gun; wherein the ultrasonic cleaning power is 50-150Hz and the ultrasonic cleaning time is 10-20min.

[0061] In this invention, the method for depositing the hole transport layer precursor includes spin coating; the spin coating speed is 4000-6000 rpm and the time is 20-40 s; the annealing temperature for obtaining the hole transport layer is 300-500℃ and the time is 30-50 min.

[0062] The perovskite light-absorbing layer is prepared using conventional methods, including but not limited to: depositing a perovskite precursor on the surface of a substrate and annealing it to obtain the perovskite light-absorbing layer; the substrate is determined according to the structure of the perovskite solar cell and includes a photoexcited polymer layer, a hole transport layer, or an electron transport layer.

[0063] In this invention, the method for depositing perovskite precursors includes spin coating, wherein the spin coating speed is 4000-6000 rpm and the time is 60-100 s; the annealing temperature is 60-100℃ and the time is 5-20 min.

[0064] In this invention, while coating the perovskite precursor onto the substrate surface, the process also includes a step of coating an anti-solvent. The time for coating the anti-solvent is more than half of the total time for coating the perovskite precursor onto the substrate surface. The anti-solvent includes, but is not limited to, chlorobenzene.

[0065] In this invention, the solvent for the perovskite precursor includes at least one of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), γ-butyrolactone (GBL), 1,3-dimethyl-2-imidazolinone (DMI), dimethylacetamide (DMAC), N,N-dimethylpropenylurea (DMPU), acetonitrile (ACN), or 2-mercaptoethanol (2-ME).

[0066] In this invention, the electron transport layer can be prepared using conventional methods, including but not limited to: preparing the electron transport layer on the surface of a perovskite light-absorbing layer (or substrate) by vapor deposition.

[0067] In this invention, the vacuum degree of the vapor deposition is (3~6)×10⁻⁶. -4 Pa, with a vapor deposition rate of 0.05–0.25 A / s.

[0068] The preparation method further includes: preparing a hole blocking layer on the surface of the electron transport layer by vapor deposition.

[0069] In this invention, the vacuum degree for obtaining the hole-blocking layer by vapor deposition is (3~6)×10⁻⁶. -4 Pa, with a vapor deposition rate of 0.1–0.3 A / s.

[0070] In this invention, the electrode can be prepared using conventional methods, including but not limited to: preparing the electrode on the surface of the electron transport layer (or hole transport layer) by vapor deposition.

[0071] In this invention, the vacuum degree of the electrode evaporation is (0.5~2)×10⁻⁶. -4 Pa, evaporation rate is 0.5~2A / s.

[0072] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0073] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0074] The perovskite solar cell provided by this invention, by setting a photoexcitation polymer layer with a specific structure between the hole transport layer and the perovskite light-absorbing layer and / or between the perovskite light-absorbing layer and the electron transport layer, can suppress the oxidation of metal ions in the perovskite light-absorbing layer, passivate its defects, reduce non-radiative recombination loss and voltage loss, and improve conversion efficiency; at the same time, it can also release the stress between the interfaces, reduce the Young's modulus of the perovskite light-absorbing layer, and improve the stability of the cell. Attached Figure Description

[0075] Figure 1 The ultraviolet absorption spectra of the perovskite light-absorbing layer of the flexible tin-based perovskite solar cells provided in Examples 1-3 and Comparative Example 1 are shown below.

[0076] Figure 2 The fluorescence spectra of the perovskite light-absorbing layer of the flexible tin-based perovskite solar cells provided in Examples 1-3 and Comparative Example 1;

[0077] Figure 3 The PCE variation graphs of the flexible tin-based perovskite solar cells provided in Examples 1-3 and Comparative Example 1 over time;

[0078] Figure 4 The PCE variation graphs of the flexible tin-based perovskite solar cells provided in Examples 1-3 and Comparative Example 1, with a bending radius of 5 mm, show the changes in the number of bending cycles. Detailed Implementation

[0079] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0080] The materials used in this invention are as follows:

[0081] Conjugated polymer PE-1: The preparation method includes the following steps:

[0082] 0.5 mmol 1 mmol of 1,4-diethynylbenzene, 20 mg of tetrakis(triphenylphosphine)palladium (Pd(PPh3)4), and 10 mg of cuprous iodide (CuI) were dissolved in a mixture of 4 mL of N,N-dimethylformamide (DMF) and 4 mL of triethanolamine (TEA). The reaction mixture was then heated to 90 °C and stirred under a nitrogen atmosphere for 72 h. After cooling to room temperature, the solid was collected by filtration and washed three times successively with distilled water, tetrahydrofuran, and ethanol. The solid was then extracted with a mixed solvent of ethanol, water, and tetrahydrofuran (volume ratio 1:1:1) in a Soxhlet extractor for 48 h and dried in a vacuum oven at 80 °C for 24 h to obtain PE-1.

[0083] Conjugated polymer PE-2: The difference between the preparation method described above and PE-1 is that 1,4-diethynylbenzene is replaced with an equimolar amount of 4,4'-diethynylbiphenyl.

[0084] Conjugated polymer PE-3: The difference between the preparation method described above and PE-1 is that 1,4-diethynylbenzene is replaced with an equimolar amount of 1,3,5-triethynylbenzene.

[0085] Tin-based perovskite precursor: 0.85 M DMSO solution of elemental iodine was reacted with excess Sn for 12 h to obtain SnI2 solution; 1 mL of SnI2 solution was filtered through a 0.45 μm PTFE filter, and then 0.7225 mmol FAI, 0.1225 mmol PEABr, and 0.085 mmol SnF2 were mixed with the above SnI2 solution and stirred for 2 h. Finally, the resulting solution was filtered again through a 0.45 μm PTFE filter to obtain tin-based perovskite precursor solution.

[0086] Example 1

[0087] This embodiment provides a flexible tin-based perovskite solar cell, comprising a substrate, a hole transport layer, a photoexcited polymer layer, a tin-based perovskite light-absorbing layer, an electron transport layer, and electrodes stacked sequentially; the fabrication method of the flexible tin-based perovskite solar cell includes the following steps:

[0088] (1) The PEN / ITO substrate was ultrasonically cleaned sequentially with detergent, deionized water, acetone and anhydrous ethanol, and then dried with a nitrogen gun for later use. The ultrasonic cleaning power was 100 Hz and the ultrasonic cleaning time was 15 min. The thickness of the PEN substrate was 2.5 μm and the thickness of the ITO substrate was 140 nm.

[0089] (2) Mix 125 mg Ni(OCOCH3)2·4H2O, 5 mL anhydrous ethanol, and 30 μL diethanolamine at room temperature and stir for 2 h to obtain NiO.x Precursor solution; then NiO x The precursor solution was spin-coated onto the surface of ITO conductive glass at 5000 rpm for 30 s, and then annealed at 400℃ for 40 min to form a NiO layer with a thickness of 20 nm. x Hole transport layer.

[0090] (3) Spin-coat the precursor of the photoexcited polymer layer onto the surface of the hole transport layer obtained in step (2), wherein the precursor of the polymer layer includes conjugated polymer PE-1, triethanolamine and water; the concentration of conjugated polymer PE-1 is 2.5 mg / mL, the volume ratio of triethanolamine to water is 1:10, the spin coating speed is 2000 rpm and the time is 60 s; then anneal at 120 °C for 15 min in a glove box to obtain a photoexcited polymer layer with a thickness of 3 nm.

[0091] (4) Take 18 μL of tin-based perovskite precursor solution and spin coat it onto the surface of the polymer layer obtained in step (3) at a speed of 5000 rpm. The total spin coating time is 80 s. At the 50th s, spin coat 800 μL of anti-solvent chlorobenzene. At this time, the perovskite film can be observed to turn dark brown. Then, anneal at 80 °C for 10 min. The film turns dark black, and a tin-based perovskite light-absorbing layer with a thickness of 200 nm is obtained.

[0092] (5) C60 is deposited on the surface of the tin-based perovskite light-absorbing layer obtained in step (4) by vacuum evaporation, wherein the evaporation is carried out at a vacuum degree of 5×10 -4 The process was carried out under Pa conditions at an evaporation rate of 0.15 A / s, resulting in an electron transport layer with a thickness of 20 nm.

[0093] (6) BCP is deposited on the surface of the electron transport layer obtained in step (5) by vacuum evaporation, wherein the evaporation is carried out at a vacuum degree of 5×10 -4 The evaporation was carried out under Pa conditions at a rate of 0.2 A / s, resulting in a hole-blocking layer with a thickness of 8 nm.

[0094] (7) Gold is deposited on the surface of the hole-blocking layer obtained in step (6), and the vacuum degree in the evaporation chamber is 1.0 × 10⁻⁶. -4 Pa; evaporation rate is A metal electrode with a thickness of 80 nm is obtained, thus obtaining the flexible tin-based perovskite solar cell.

[0095] Example 2

[0096] This embodiment provides a flexible tin-based perovskite solar cell, which differs from Embodiment 1 only in that the material of the photoexcitation polymer layer is a conjugated polymer PE-2. In the preparation method, step (3) replaces the conjugated polymer PE-1 with a conjugated polymer PE-2 of equal concentration. Other raw materials, dosages and preparation methods are the same as in Embodiment 1.

[0097] Example 3

[0098] This embodiment provides a flexible tin-based perovskite solar cell, which differs from Embodiment 1 only in that the conjugated polymer in the precursor of the photoexcitation polymer layer is PE-3, and in the preparation method, step (3) replaces the conjugated polymer PE-1 with the same concentration of conjugated polymer PE-3. Other raw materials, amounts and preparation methods are the same as in Embodiment 1.

[0099] Example 4

[0100] This embodiment provides a flexible tin-based perovskite solar cell, which differs from Embodiment 1 only in that the concentration of the conjugated polymer PE-1 in the precursor of the photoexcitation polymer layer is 3 mg / mL, the total volume of triethanolamine and water remains unchanged, and the volume ratio is 0.8:10. Other raw materials, dosages, and preparation methods are the same as in Embodiment 1.

[0101] Example 5

[0102] This embodiment provides a flexible tin-based perovskite solar cell, which differs from Embodiment 1 only in that the concentration of the conjugated polymer PE-1 in the precursor of the photoexcitation polymer layer is 4 mg / mL, the total volume of triethanolamine and water remains unchanged, and the volume ratio is 1.6:10. Other raw materials, dosages, and preparation methods are the same as in Embodiment 1.

[0103] Example 6

[0104] This embodiment provides a flexible tin-based perovskite solar cell, which differs from Example 1 only in that the mass of the conjugated polymer PE-1 is reduced so that its concentration is 0.8 mg / mL. The other raw materials, amounts and preparation methods are the same as in Example 1.

[0105] Example 7

[0106] This embodiment provides a flexible tin-based perovskite solar cell, which differs from Example 1 only in that the mass of the conjugated polymer PE-1 is increased so that its concentration is 7 mg / mL. The other raw materials, amounts and preparation methods are the same as in Example 1.

[0107] Example 8

[0108] This embodiment provides a flexible tin-based perovskite solar cell, which differs from Example 1 only in that the total volume of triethanolamine and water remains unchanged, with a volume ratio of 4:10. All other raw materials, amounts, and preparation methods are the same as in Example 1.

[0109] Example 9

[0110] This embodiment provides a flexible tin-based perovskite solar cell, which differs from Embodiment 1 only in that the total volume of triethanolamine and water remains unchanged, with a volume ratio of 0.2:10. All other raw materials, amounts, and preparation methods are the same as in Embodiment 1.

[0111] Example 10

[0112] This embodiment provides a flexible tin-based perovskite solar cell, which differs from Example 1 only in that the total volume of triethanolamine and water remains unchanged, and triethanolamine is not used. All other raw materials, amounts, and preparation methods are the same as in Example 1.

[0113] Example 11

[0114] This embodiment provides a flexible tin-based perovskite solar cell, which differs from Embodiment 1 only in that the photoexcitation polymer layer is disposed between the tin-based perovskite light-absorbing layer and the electron transport layer, and the preparation method is the same as Embodiment 1 except that the order of steps (3) and (4) is reversed.

[0115] Comparative Example 1

[0116] This comparative example provides a flexible tin-based perovskite solar cell, which differs from Example 1 only in that the flexible tin-based perovskite solar cell does not have a photoexcitation polymer layer; in the preparation method, step (3) is not performed, and the other raw materials, amounts and preparation methods are the same as in Example 1.

[0117] Comparative Example 2

[0118] This comparative example provides a flexible tin-based perovskite solar cell, which differs from Example 1 only in that the conjugated polymer PE-1 is replaced with a conjugated polymer. The other raw materials, dosages, and preparation methods are the same as in Example 1.

[0119] Performance testing

[0120] (1) The ultraviolet absorption and fluorescence spectra of the tin-based perovskite absorber layers obtained in Examples 1-3 and Comparative Example 1 were tested, and the results are as follows: Figure 1 (ultraviolet absorption spectrum) and Figure 2 (Fluorescence spectrum) as shown; by Figure 1It can be seen that the conjugated polymer causes a slight red shift in the ultraviolet absorption peak of the tin-based perovskite absorbing layer, indicating that the polymer effectively promotes the crystallization of the tin-based perovskite absorbing layer, resulting in a larger size of the final perovskite. Simultaneously, the fluorescence spectrum of the polymer-treated perovskite absorbing layer (e.g., ...) Figure 2 The emission peak of Sn was significantly enhanced, further demonstrating that the polymer can continuously donate electrons and effectively suppress Sn. 2+ Oxidation reduces p-type self-doping in tin-based perovskites, passivates surface defects in perovskite films, and reduces non-radiative recombination.

[0121] (2) The open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (FF), and photoelectric conversion efficiency (PCE) of the flexible tin-based perovskite solar cells provided in Examples 1 to 11 and Comparative Examples 1 and 2 were tested. The test results are shown in Table 1.

[0122] Furthermore, taking the flexible tin-based perovskite solar cells provided in Examples 1-3 and Comparative Example 1 as examples, the PCE variation curves of the flexible tin-based perovskite solar cells as time progresses are as follows: Figure 3 As shown, without a polymer layer, the PCE of flexible tin-based perovskite solar cells decays rapidly over time; however, the PCE of the flexible tin-based perovskite solar cell provided by this invention does not decrease significantly over time, and can still maintain more than 90% of its initial value after 1000 hours. This further demonstrates the rapid transfer of interface electrons from the polymer to the perovskite interface, effectively suppressing Sn... 2+ Oxidation reduces battery stability.

[0123] (3) Taking the flexible tin-based perovskite solar cells provided in Examples 1-3 and Comparative Example 1 as examples, the PCE change over time was tested when the bending radius was 5 mm. The results are as follows: Figure 4 As shown; by Figure 4 It is known that the flexible tin-based perovskite solar cell provided by the present invention has significantly improved mechanical properties, good bendability and recovery performance. After 3000 bends, the PCE can still reach more than 90% of the initial PCE. This is because the conjugated structure of the polymer can effectively release the stress between the interfaces, reduce the Young's modulus of the perovskite film, and improve the flexibility of the cell.

[0124] Table 1

[0125] Voc (V) Jsc(mA / cm 2 )]]> FF (%) PCE (%) Example 1 0.72 21.3 75.1 11.5 Example 2 0.73 21.2 74.9 11.6 Example 3 0.73 21.0 75.0 11.5 Example 4 0.74 21.4 74.5 11.8 Example 5 0.73 21.5 74.8 11.7 Example 6 0.68 20.2 73.4 10.1 Example 7 0.69 20.4 73 10.3 Example 8 0.71 19.9 72.3 10.2 Example 9 0.72 19.8 72.5 10.3 Example 10 0.68 19.7 72.3 9.7 Example 11 0.73 21.1 74.9 11.5 Comparative Example 1 0.62 20.3 72.3 9.1 Comparative Example 2 0.61 20.5 72.0 9.0

[0126] As shown in Table 1, the flexible tin-based perovskite solar cell provided by this invention, by setting a photoexcitation polymer layer between the hole transport layer and / or electron transport layer and the tin-based perovskite light-absorbing layer, can suppress the oxidation of divalent tin, reduce non-radiative recombination loss and voltage loss, and improve conversion efficiency; at the same time, it can also release the stress between the interfaces, reduce the Young's modulus of the perovskite light-absorbing layer, and improve the stability of the cell; the conversion efficiency of the flexible tin-based perovskite solar cell is 9.7-11.8%; after 1000h, the PCE can still maintain more than 90% of the initial value, showing good stability; after 3000 bending cycles, the PCE can still reach more than 90% of the initial PCE, showing good flexibility.

[0127] As can be seen from the comparison of Examples 1-3 with Comparative Examples 1 and 2, when no polymer layer is provided or the conjugated polymer is not specific to this invention, the conversion efficiency of flexible tin-based perovskite solar cells decreases, the stability and flexibility deteriorate, and the degradation is rapid.

[0128] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A perovskite solar cell, characterized in that, A photoexcited polymer layer is disposed between the perovskite light-absorbing layer and the hole transport layer of the perovskite solar cell, and / or a photoexcited polymer layer is disposed between the perovskite light-absorbing layer and the electron transport layer of the perovskite solar cell. The photoexcited polymer layer includes electron or hole trapping structural units, which separate photogenerated carriers to passivate the perovskite light-absorbing layer.

2. The perovskite solar cell according to claim 1, characterized in that, The photoexcited polymer layer also includes reducing passivation groups; The reducing passivating group includes a phenolic hydroxyl group.

3. The perovskite solar cell according to claim 1, characterized in that, The precursor of the photoexcited polymer layer includes a conjugated polymer; The conjugated polymer has the structure shown in general formula I; R1 and R2 are each independently selected from hydroxyl groups; R3 and R4 are each independently selected from C6-C18 arylene or C6-C18 metaarylene; Z1, Z2, Z4, and Z5 are each independently selected from ethynyl groups; Z3 and Z6 are each independently selected from H or ethynyl groups. Dashed lines indicate connection points.

4. The perovskite solar cell according to claim 3, characterized in that, R3 and R4 are each independently selected from any one of phenylene, biphenylene, or phenylene.

5. The perovskite solar cell according to claim 3, characterized in that, The conjugated polymer includes at least one of the following compounds; 6. The perovskite solar cell according to claim 3, characterized in that, The precursor also includes compound A and / or a solvent.

7. The perovskite solar cell according to claim 6, characterized in that, The compound A includes at least one of triethanolamine, lactic acid, sodium sulfite, glycerol, n-butanol, ethylene glycol, or butanethyl alcohol; The solvent includes water and / or ethanol.

8. The perovskite solar cell according to claim 6, characterized in that, The precursor also includes compound A and a solvent, wherein the volume ratio of compound A to solvent is (0.5–2):

10.

9. The perovskite solar cell according to claim 3, characterized in that, The concentration of the conjugated polymer in the precursor is 2–5 mg / mL.

10. The perovskite solar cell according to claim 1, characterized in that, The perovskite light-absorbing layer includes a tin-based perovskite light-absorbing layer; The general structural formula of the perovskite light-absorbing layer is ABX3; Wherein, A is selected from CH3NH3 + CH(NH2)2 + Cs + or Rb + B is any one or at least two of the following; B is selected from Sn. 2+ X is selected from Cl - ,Br - Or I - Any one or at least two of them; The thickness of the perovskite light-absorbing layer is 150–500 nm.

11. The perovskite solar cell according to claim 1, characterized in that, The hole transport layer material includes any one or a combination of at least two of the following: nickel oxide, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene, poly(3,4-ethylenedioxythiophene:polystyrene sulfonate), 4-butyl-N,N-diphenylaniline homopolymer, polyvinylcarbazole, cuprous iodide, or cuprous thiocyanate. The thickness of the hole transport layer is 10–200 nm.

12. The perovskite solar cell according to claim 1, characterized in that, The electron transport layer is made of any one or a combination of at least two of the following: fullerenes and their derivatives, titanium dioxide, tin dioxide, zinc oxide, or zinc oxide doped with zinc sulfide. The thickness of the electron transport layer is 10–40 nm; A hole blocking layer is also disposed between the electron transport layer and the electrode; the thickness of the hole blocking layer is 2-15 nm.

13. The perovskite solar cell according to claim 1, characterized in that, The perovskite solar cell also includes a substrate and electrodes.

14. A method for preparing a perovskite solar cell according to any one of claims 1 to 13, characterized in that, The preparation method includes the following steps: A precursor for coating a photoexcited polymer layer onto a substrate surface is annealed to obtain the photoexcited polymer layer. The substrate includes at least one of a hole transport layer, an electron transport layer, or a perovskite light-absorbing layer.

15. The preparation method according to claim 14, characterized in that, The coating rotation speed is 1000-3000 rpm, and the time is 40-80 s; The annealing temperature is 90–150°C, and the time is 10–20 min.

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