A tin-based perovskite solar cell and a preparation method thereof

Abstract

The application provides a tin-based perovskite solar cell and a preparation method thereof. The tin-based perovskite solar cell comprises a substrate, a first carrier transport layer, an interface layer, a tin-containing perovskite light-absorbing layer, a second carrier transport layer and an electrode which are sequentially stacked. The material of the interface layer comprises a conjugated polymer, and the conjugated polymer comprises a spirobifluorene-based conjugated polymer. The interface layer containing the spirobifluorene-based conjugated polymer greatly improves the film forming quality and stability of the perovskite, thereby obtaining a tin-based perovskite solar cell with good photoelectric conversion performance.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a tin-based perovskite solar cell and its preparation method. Background Technology

[0002] With the continuous development of human society, the demand for energy is increasing. Traditional energy sources (such as oil, natural gas, and coal) are non-renewable, with dwindling reserves and significant environmental pollution. Therefore, vigorously developing renewable, green, and clean energy is extremely urgent and important. Solar energy is a typical example of green and clean energy; it is inexhaustible and does not harm the environment. Its application research has received increasing attention, and the development of clean, pollution-free, and abundant solar cells has become a hot topic of research for scientists.

[0003] Organic-inorganic halide perovskite materials have attracted widespread attention in the photovoltaic field due to their excellent photoelectric properties. However, the presence of lead, a heavy metal harmful to the environment and human health, in perovskite materials hinders their commercialization. Tin, with the same outer electron structure and similar ionic radius as lead, can form the same type of three-dimensional perovskite structure and has a more ideal optical band gap, making it the most promising candidate to replace lead-based perovskites and achieve better photovoltaic performance.

[0004] Currently, tin-based perovskite solar cells have achieved record efficiencies exceeding 14%. However, research on tin-based perovskite solar cells also faces numerous severe challenges. For example, tin-based perovskite materials are highly susceptible to oxidation, generating Sn vacancies, leading to severe nonradiative recombination losses and voltage drops. Furthermore, the presence of numerous defects in the perovskite film facilitates corrosion by oxygen and moisture, significantly reducing the device's photoelectric performance, repeatability, and stability. In addition, the Ig content in tin-based perovskite materials... - Furthermore, the organic cations at the A site are highly volatile during the thermal annealing process, making the crystallization process of tin-based perovskite films more difficult to control. This results in poor morphology of the perovskite films, which easily form disordered grains and generate many three-dimensional defects, further reducing the performance and stability of the devices.

[0005] Therefore, how to improve the stability and photoelectric conversion performance of tin-based perovskite materials is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a tin-based perovskite solar cell and its fabrication method. By incorporating an interfacial layer containing a spirodifluorene-based conjugated polymer, the present invention significantly improves the film quality and stability of the perovskite, thereby obtaining a tin-based perovskite solar cell with excellent photoelectric conversion performance.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a tin-based perovskite solar cell, the tin-based perovskite solar cell comprising a substrate, a first carrier transport layer, an interface layer, a tin-containing perovskite light-absorbing layer, a second carrier transport layer and an electrode, which are stacked sequentially. The material of the interface layer includes a conjugated polymer, which comprises structural units as shown in Formula 1: Formula 1; Wherein, the L group is selected from an unsaturated hydrocarbon group, and the X group is selected from at least one of pyridine, pyrimidine, pyridazine, triazine, or tetraazine; The wavy line indicates the connection site between the structural unit and the spirodifluorene group.

[0008] In the interface layer provided by this invention, the aforementioned conjugated polymer containing the structural unit of Formula 1 can generate electron-hole pairs under illumination, wherein electrons in the conduction band migrate to the surface of the tin-containing perovskite light-absorbing layer, thereby greatly suppressing Sn. 2+ The oxidation of the perovskite is also addressed. Simultaneously, the interface layer provided by this invention can further promote multipath carrier transport by utilizing the orthorhombic configuration of the spirodifluorene group, and enhance intersystem crossing through microenvironment engineering, extending the triplet lifetime and thus improving the generation efficiency of electron-hole pairs. Furthermore, the nitrogen-containing six-membered ring substituents in the aforementioned conjugated polymer structure can enhance the crystallinity of the perovskite and passivate surface metal defects, resulting in high photoelectric conversion efficiency and stable performance of the perovskite solar cell.

[0009] In summary, by setting an interface layer between the first carrier transport layer and the tin-containing perovskite light-absorbing layer, and by selecting a conjugated polymer with a specific structure as the interface layer material, the photoelectric conversion efficiency and operational stability of tin-based perovskite solar cells are significantly improved.

[0010] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0011] It should be noted that Formula 1 shows the structural unit of the conjugated polymer, where the wavy line represents the connection site between the structural unit and the spirodifluorene group. At the same time, the C atom on the spirodifluorene group is connected to the X group through the L group, and so on, to form the polymer structure of the conjugated polymer.

[0012] In Formula 1, the L group is selected from unsaturated hydrocarbon groups, which may exemplarily include alkenyl and / or alkynyl groups.

[0013] More preferably, the conjugated polymer comprises structural units as shown in Formula 2: Formula 2; Wherein, the X group is selected from at least one of pyridine, pyrimidine, pyridazine, triazine or tetrazine.

[0014] This invention further introduces an alkynyl group, whose π electrons can interact with uncoordinated Pb on the perovskite surface. 2+ Coordinate bonds are formed to fill lead vacancies, thereby reducing nonradiative recombination.

[0015] More preferably, the material of the interface layer comprises at least one of the following conjugated polymers having the following structure: T01 T02 T03 T04 T05 T06.

[0016] This invention, through further rational control of the structure of the above-mentioned conjugated polymer, not only facilitates interfacial electron transfer but also suppresses Sn. 2+ Oxidation can also effectively passivate metal defects on the surface of perovskites, resulting in high photoelectric conversion efficiency and stable performance of tin-based perovskite solar cells.

[0017] In this invention, the above-mentioned conjugated polymer is synthesized using conventional methods; exemplary, the preparation method of the conjugated polymer comprising the structural unit shown in Formula 1 includes the following steps: In a 500 mL Schlenk flask, the spirodifluorenyl compound of formula A and the brominated nitrogen-containing heterocyclic compound of formula B were dissolved in a mixed solvent containing N,N-dimethylformamide and diisopropylamine (volume ratio 1:1), and nitrogen gas was purged for 20-30 min. Subsequently, CuI, tetrakis(triphenylphosphine)palladium, and triphenylphosphine were added to obtain a reaction mixture. The reaction mixture was heated and stirred. The reaction system was then cooled to room temperature, and the precipitate was collected by filtration. The precipitate was then washed with potassium iodide solution (concentration 0.5 g / mL, volume 30 mL, solvent: deionized water), and purified by Soxhlet extraction successively with tetrahydrofuran, dichloromethane, and methanol. Finally, the product was dried overnight at 60 °C to obtain the conjugated polymer. The specific reaction formula is shown below: Preferably, the molar ratio of the spirodifluorenyl compound of Formula A to the brominated nitrogen-containing heterocyclic compound of Formula B is 1:(1.9-2.2), for example, it can be 1:1.9, 1:1.95, 1:2, 1:2.05, 1:2.1, 1:2.15 or 1:2.2, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] Preferably, the molar ratio of the spirodifluorenyl compound of Formula A to CuI is (4-4.5):1, for example, it can be 4:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1 or 4.5:1, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0019] Preferably, the reaction temperature is 90℃-110℃, for example, it can be 90℃, 95℃, 100℃, 105℃ or 110℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Preferably, the reaction time is 72h-96h, for example, it can be 72h, 75h, 78h, 80h, 82h, 85h, 88h, 90h, 92h or 96h, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] The present invention does not impose any special restrictions on the source of the spirodifluorenyl compound with the structure shown in Formula A and the brominated nitrogen-containing heterocyclic compound shown in Formula B, and commercially available products well known to those skilled in the art can be used.

[0022] Preferably, the thickness of the interface layer is 2nm-10nm, for example, it can be 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm or 10nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] This invention, by rationally controlling the thickness range of the interface layer, not only facilitates interfacial electron transfer but also suppresses Sn. 2+ Oxidation can also effectively passivate metal defects on the surface of perovskites, resulting in high photoelectric conversion efficiency and stable performance of tin-based perovskite solar cells.

[0024] Preferably, the material of the tin-containing perovskite light-absorbing layer has the general structural formula ABX3; wherein A is selected from CH3NH3. + CH(NH2)2 + Cs + or Rb + B is any one or at least two of Sn. 2+and optional Pb 2+ X is selected from Cl - ,Br - Or I - Any one or at least two of them.

[0025] It should be noted that in the aforementioned tin-containing perovskite layer material ABX3, B can be Sn. 2+ It can also be Sn 2+ With Pb 2 + The combination of .

[0026] Preferably, the thickness of the tin-containing perovskite light-absorbing layer is 100nm-400nm, for example, it can be 100nm, 150nm, 200nm, 250nm, 300nm, 350nm or 400nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] Preferably, the first carrier transport layer is an electron transport layer, and the second carrier transport layer is a hole transport layer.

[0028] In this invention, there are no special restrictions on the materials used as electron transport layer and hole transport layer. Conventional electron transport materials and hole transport layer materials that can be used in photovoltaic fields and solar cells are all applicable to this invention.

[0029] Preferably, the material of the electron transport layer includes n-type inorganic semiconductor materials and / or n-type organic semiconductor materials.

[0030] More preferably, the material of the electron transport layer includes C. 60 Any one or at least two of the following: PCBM, BCP, TiO2, SnO2, ZnO, or ZnO-ZnS.

[0031] Preferably, the thickness of the electron transport layer is 10nm-50nm, for example, it can be 10nm, 15nm, 18nm, 20nm, 22nm, 25nm, 28nm, 30nm, 32nm, 35nm, 38nm, 40nm, 45nm, 45nm or 50nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] Preferably, the material of the hole transport layer includes p-type inorganic semiconductor materials and / or p-type organic semiconductor materials.

[0033] More preferably, the hole transport layer is made of 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), NiO x Any one or a combination of at least two of CuI or CuSCN.

[0034] Preferably, the thickness of the hole transport layer is 20nm-300nm, for example, it can be 20nm, 50nm, 80nm, 100nm, 150nm, 200nm, 250nm or 300nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] In this invention, there are no special restrictions on the material used as the substrate; conventional substrate materials that can be used in the photovoltaic field and solar cells are all applicable to this invention.

[0036] Preferably, the substrate material includes any one or a combination of at least two of ITO, FTO, IZO, or AZO.

[0037] Preferably, the thickness of the substrate is 100nm-150nm, for example, it can be 100nm, 110nm, 120nm, 130nm, 140nm or 150nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] In this invention, there are no special restrictions on the materials used as electrodes; conventional electrode materials that can be used in the photovoltaic field and solar cells are all applicable to this invention.

[0039] Preferably, the electrode material includes any one or a combination of at least two of Al, Au, Ag, or carbon-based electrode materials.

[0040] Preferably, the thickness of the electrode is 60nm-100nm, for example, it can be 60nm, 70nm, 80nm, 90nm or 100nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0041] In a second aspect, the present invention provides a method for preparing a tin-based perovskite solar cell as described in the first aspect, the method comprising the following steps: The tin-based perovskite solar cell is obtained by sequentially stacking a substrate, a first carrier transport layer, an interface layer, a tin-containing perovskite light-absorbing layer, a second carrier transport layer, and an electrode. The material of the interface layer includes a conjugated polymer.

[0042] Preferably, the method for preparing the interface layer includes the following steps: coating a conjugated polymer solution on the surface of the first carrier transport layer, and obtaining the interface layer after a first annealing treatment.

[0043] Preferably, the mass concentration of the conjugated polymer in the conjugated polymer solution is 1 mg / mL to 5 mg / mL, for example, it can be 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, 3 mg / mL, 3.5 mg / mL, 4 mg / mL, 4.5 mg / mL or 5 mg / mL, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Preferably, the first solvent in the conjugated polymer solution includes any one or a combination of at least two of water, ethanol, methanol, or acetonitrile.

[0045] Preferably, the temperature of the first annealing treatment is 100℃-150℃, and the time of the first annealing treatment is 10min-20min.

[0046] Specifically, the temperature of the first annealing treatment can be, for example, 100℃, 110℃, 120℃, 130℃, 140℃, or 150℃; the time of the first annealing treatment can be, for example, 10min, 12min, 15min, 18min, or 20min, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] Preferably, the method for preparing the tin-containing perovskite light-absorbing layer includes: A tin-containing perovskite precursor solution is provided, wherein the tin-containing perovskite precursor solution comprises a combination of ABX3 perovskite material and a second solvent; wherein A is selected from CH3NH3. + CH(NH2)2 + Cs + or Rb + B is any one or at least two of Sn. 2+ and optional Pb 2+ X is selected from Cl - ,Br - Or I - Any one or at least two of them.

[0048] The tin-containing perovskite precursor solution is coated onto the interface layer to form a thin film, and the thin film is subjected to a second annealing treatment to obtain the tin-containing perovskite light-absorbing layer.

[0049] Preferably, the solvent in the tin-containing perovskite precursor solution includes any one or a combination of at least two 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).

[0050] Preferably, the temperature of the second annealing treatment is 60℃-100℃, and the time of the second annealing treatment is 5min-30min.

[0051] Specifically, the temperature of the second annealing treatment can be, for example, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, or 100℃; the time of the second annealing treatment can be 5min, 8min, 10min, 12min, 15min, 18min, 20min, 22min, 25min, or 30min, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0052] Preferably, the first carrier transport layer is an electron transport layer, and the second carrier transport layer is a hole transport layer.

[0053] Preferably, the preparation method of the electron transport layer and hole transport layer is not particularly limited. Methods known in the art for forming electron transport layers and hole transport layers, such as coating and vapor deposition, are all applicable to the present invention.

[0054] Preferably, the electrode is prepared by vapor deposition.

[0055] 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.

[0056] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a tin-based perovskite solar cell, wherein the conjugated polymer comprising the structural unit of Formula 1 is capable of generating electron-hole pairs under illumination, wherein electrons in the conduction band migrate to the surface of the tin-containing perovskite light-absorbing layer, thereby significantly suppressing Sn. 2+The oxidation of the perovskite is also addressed. Simultaneously, the interface layer provided by this invention can further promote multipath carrier transport by utilizing the orthorhombic configuration of the spirodifluorene group, and enhance intersystem crossing through microenvironment engineering, extending the triplet lifetime and thus improving the generation efficiency of electron-hole pairs. Furthermore, the nitrogen-containing six-membered ring substituents in the aforementioned conjugated polymer structure can enhance the crystallinity of the perovskite and passivate surface metal defects, resulting in high photoelectric conversion efficiency and stable performance of the perovskite solar cell.

[0057] In summary, by setting an interface layer between the first carrier transport layer and the tin-containing perovskite light-absorbing layer, and by selecting a conjugated polymer with a specific structure as the interface layer material, the photoelectric conversion efficiency and operational stability of tin-based perovskite solar cells are significantly improved. Attached Figure Description

[0058] Figure 1 The current-voltage curves are for the tin-based perovskite solar cells provided in Example 1 and Comparative Example 1, respectively. Detailed Implementation

[0059] The technical solution of the present invention will be further described below with reference to specific embodiments and accompanying drawings. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be considered as specific limitations thereof.

[0060] The conjugated polymer materials used in this invention are as follows: Conjugated polymer T01 ( The preparation method of ) includes the following steps: In a 500 mL Schlenk flask, 2,2′,7,7′-tetraethynyl-9,9′-spirodifluorene (1.69 mmol, 700 mg) and 2,5-dibromopyridine (3.39 mmol) were dissolved in a mixed solvent containing N,N-dimethylformamide and diisopropylamine (200 mL, 1:1 v / v), and nitrogen was purged for 25 min. Then, CuI (0.407 mmol, 77.5 mg), tetrakis(triphenylphosphine)palladium (0.2 mmol, 231.1 mg), and triphenylphosphine (1.36 mmol, 356 mg) were added to obtain a reaction mixture. The reaction mixture was heated to 100 °C and stirred for 96 h. The reaction system was then cooled to room temperature, and the precipitate was collected by filtration. The precipitated solid was then washed with potassium iodide solution (0.5 g / mL, 30 mL, deionized water) and purified by Soxhlet extraction with tetrahydrofuran, dichloromethane, and methanol in sequence. Finally, the product was dried at 60 °C overnight to obtain the conjugated polymer T01.

[0061] Conjugated polymer T04 ( The only difference between it and conjugated polymer T01 is that the raw material 2,5-dibromopyridine is replaced with an equimolar amount of 2,5-dibromopyrazine in the preparation method. Other raw materials, amounts and step parameters are the same as those of conjugated polymer T01.

[0062] Conjugated polymer T05 ( The only difference between it and conjugated polymer T01 is that the raw material 2,5-dibromopyridine is replaced with an equimolar amount of 3,6-dibromo-1,2,4-triazine in the preparation method. Other raw materials, amounts and step parameters are the same as those of conjugated polymer T01.

[0063] Conjugated polymer T06 ( The only difference between it and conjugated polymer T01 is that the raw material 2,5-dibromopyridine is replaced with an equimolar amount of 3,6-dibromo-1,2,4,5-tetraazine in the preparation method. Other raw materials, dosages and step parameters are the same as those of conjugated polymer T01.

[0064] Example 1 This embodiment provides a tin-based perovskite solar cell, comprising a substrate, an electron transport layer, an interface layer, a tin-containing perovskite light-absorbing layer, a hole transport layer, and an electrode, which are stacked sequentially.

[0065] The interface layer is made of conjugated polymer T01, and the structure of conjugated polymer T01 is shown below: T01.

[0066] This embodiment also provides a method for preparing the above-mentioned tin-based perovskite solar cell, the method comprising the following steps: (1) The transparent conductive glass substrate was ultrasonically cleaned in sequence 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, the ultrasonic cleaning time was 15 min, the thickness of the transparent conductive glass substrate was 2.5 μm, and the thickness of ITO was 140 nm.

[0067] (2) Under air conditions, at a rotation speed of 4000 rpm, SnO2 nanocolloid solution (concentration of 3.67%) was spin-coated onto the surface of ITO conductive glass for 30 s. Then, it was annealed on a hot plate at 150 °C for 30 min to obtain an electron transport layer with a thickness of 25 nm.

[0068] (3) Spin-coat an aqueous solution containing conjugated polymer T01 onto the surface of the electron transport layer obtained in step (2), wherein the concentration of conjugated polymer T01 is 3 mg / mL, 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 an interface layer with a thickness of 5 nm.

[0069] (4) 0.85 M iodine dispersed in dimethyl sulfoxide (DMSO) was reacted with excess Sn for 12 h to obtain SnI2 solution. 1 mL of this solution was filtered through a 0.45 μm PTFE filter. Then, 0.7225 mmol FAI (CH(NH2)2I), 0.1225 mmol PEABr (phenylethylamine bromide) and 0.085 mmol SnF2 were mixed with the above solution and stirred for 2 h. Finally, the resulting solution was filtered through a 0.45 μm PTFE filter again to obtain tin-based perovskite precursor solution.

[0070] Take 80 μL of the above tin-based perovskite precursor solution and spin-coat it onto the surface of the above interface layer at a speed of 5000 rpm for 80 s. At the 50th s, spin-coat 100 μL of the anti-solvent chlorobenzene. At this time, the perovskite film can be observed to turn dark brown. Then, anneal it at 80 °C for 10 min. The film turns dark black, and a tin-containing perovskite light-absorbing layer with a thickness of 200 nm is obtained.

[0071] (5) In a glove box, a Spiro-OMeTAD solution (concentration of 72.3 mg / mL) was spin-coated onto the surface of the tin-containing perovskite light-absorbing layer at a spin speed of 3000 rpm for 30 s to obtain a hole transport layer with a thickness of 150 nm.

[0072] (6) Gold electrodes are deposited on the surface of the hole transport layer obtained in step (5), and the vacuum degree in the evaporation chamber is 1.0 × 10⁻⁶. -4 Pa; the evaporation rate is 1 Å / s, and a gold electrode with a thickness of 100 nm is obtained, which is the tin-based perovskite solar cell.

[0073] Example 2 The difference between this embodiment and Embodiment 1 is that the material of the interface layer is a conjugated polymer TO4, and the structure of the conjugated polymer TO4 is shown below: T04; In the preparation method, step (3) replaces the conjugated polymer T01 with the same mass concentration of the conjugated polymer T04. Other raw materials, dosages and preparation methods are the same as in Example 1.

[0074] Example 3 The difference between this embodiment and Embodiment 1 is that the material of the interface layer is a conjugated polymer T05, and the structure of the conjugated polymer T05 is shown below: T05; In the preparation method, step (3) replaces the conjugated polymer T01 with the same mass concentration of the conjugated polymer T05. Other raw materials, dosages and preparation methods are the same as in Example 1.

[0075] Example 4 The difference between this embodiment and Embodiment 1 is that the material of the interface layer is a conjugated polymer T06, and the structure of the conjugated polymer T06 is shown below: T06; In the preparation method, step (3) replaces the conjugated polymer T01 with the same mass concentration of the conjugated polymer T06. Other raw materials, dosages and preparation methods are the same as in Example 1.

[0076] Example 5 The difference between this embodiment and Example 1 is that in the preparation method, the mass concentration of the conjugated polymer T01 in step (3) is adjusted to 1 mg / mL, while the other raw materials, dosages and preparation methods are the same as in Example 1.

[0077] Example 6 The difference between this embodiment and Example 1 is that in the preparation method, the mass concentration of the conjugated polymer T01 in step (3) is adjusted to 5 mg / mL, while the other raw materials, dosages and preparation methods are the same as in Example 1.

[0078] Example 7 The difference between this embodiment and Example 1 is that in the preparation method, the mass concentration of the conjugated polymer TO1 in step (3) is adjusted to 0.5 mg / mL, while the other raw materials, dosages and preparation methods are the same as in Example 1.

[0079] Example 8 The difference between this embodiment and Example 1 is that in the preparation method, the mass concentration of the conjugated polymer T01 in step (3) is adjusted to 6 mg / mL, while the other raw materials, dosages and preparation methods are the same as in Example 1.

[0080] Comparative Example 1 The difference between this comparative example and Example 1 is that no interface layer is set, and the preparation process of the interface layer is omitted in the preparation method. Otherwise, they are the same as Example 1.

[0081] Comparative Example 2 The difference between this comparative example and Example 1 is that the material of the interface layer is 2,2',7,7'-tetra(diphenylamino)-9,9'-spirobifluorene, and the structure of 2,2',7,7'-tetra(diphenylamino)-9,9'-spirobifluorene is shown below: ; In the preparation method, step (3) replaces the conjugated polymer T01 with 2,2',7,7'-tetra(diphenylamino)-9,9'-spirobisfluorene of equal mass concentration. Other raw materials, dosages and preparation methods are the same as in Example 1.

[0082] Test conditions The performance of the tin-based perovskite solar cells provided in the above embodiments and comparative examples was tested under the following conditions: Measurements were performed using a solar energy simulation testing system. The light source of the system was a 500W xenon lamp solar spectrum simulator, calibrated with a standard silicon cell KG-5, at a solar intensity of 100mW / cm². 2 Measurements were performed under the following conditions. A continuously varying voltage (-0.5V to 1.2V) was applied across the perovskite solar cell under test, and the output current of the perovskite solar cell was measured (using a Keithley 2400 tester). The product of the two measurements yielded the JV test curve, which showed the photoelectric conversion efficiency of the perovskite solar cell under different conditions.

[0083] (1) Open circuit voltage (Voc): The maximum voltage applied across the perovskite solar cell after irradiation by the solar simulation test system is the open circuit voltage (Voc).

[0084] (2) Current density (Jsc): The current when the potential difference between the positive and negative electrodes of a perovskite solar cell is 0.

[0085] (3) Fill factor (FF): FF = (I max ×V max ) / (Jsc×Voc)×100, where, I max and V max These are the current and voltage values ​​of a perovskite solar cell at its maximum power point.

[0086] (4) Photoelectric conversion efficiency (PCE): PCE=(Jsc×Voc×FF) / P in ×100%; where P in The incident power of the solar energy simulation test system.

[0087] The test results are shown in Table 1.

[0088] Table 1 From Table 1 and Figure 1As can be seen, compared with the tin-based perovskite solar cell without an interface layer in Comparative Example 1, the tin-based perovskite solar cells of Examples 1 to 6 of this invention, after treatment, have significantly improved open-circuit voltage, short-circuit current, fill factor and photoelectric conversion efficiency.

[0089] Comparing Examples 5 to 8, it can be seen that when the mass concentration of the conjugated polymer is low (Example 7), the number of electron-hole pairs generated in the formed interface layer under illumination is reduced, resulting in a decrease in the number of electrons migrating from the conduction band to the surface of the tin-containing perovskite light-absorbing layer, thereby suppressing Sn. 2+ The oxidation effect is not significant, and the content of nitrogen-containing six-membered rings in the interface layer is also reduced accordingly, failing to effectively passivate the metal defects on the perovskite surface. Both of these factors contribute to a decrease in the photoelectric conversion efficiency of tin-based perovskite solar cells. When the mass concentration of the conjugated polymer is high (Example 8), the thickness of the interface layer increases, hindering carrier conduction and thus reducing the photoelectric conversion efficiency of tin-based perovskite solar cells.

[0090] Comparing Example 1 and Comparative Example 2, it can be seen that the molecules containing spirobisfluorene structure and diphenylamino in Comparative Example 2 only slightly improve the photoelectric conversion efficiency of tin-based perovskite solar cells. This is mainly because the conjugated polymer structure provided by the present invention contains more binding sites, which can significantly improve the passivation effect.

[0091] 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 tin-based perovskite solar cell, characterized in that, The tin-based perovskite solar cell includes a substrate, a first carrier transport layer, an interface layer, a tin-containing perovskite light-absorbing layer, a second carrier transport layer, and an electrode, which are stacked sequentially. The material of the interface layer includes a conjugated polymer, which comprises structural units as shown in Formula 1: Formula 1; Wherein, the L group is selected from an unsaturated hydrocarbon group, and the X group is selected from at least one of pyridine, pyrimidine, pyridazine, triazine, or tetraazine; The wavy line indicates the connection site between the structural unit and the spirodifluorene group.

2. The tin-based perovskite solar cell according to claim 1, characterized in that, The conjugated polymer comprises structural units as shown in Formula 2: Formula 2; Wherein, the X group is selected from at least one of pyridine, pyrimidine, pyridazine, triazine or tetrazine.

3. The tin-based perovskite solar cell according to claim 1 or 2, characterized in that, The material of the interface layer includes at least one of the following conjugated polymers having the following structure: T01 T02 T03 T04 T05 T06。 4. The tin-based perovskite solar cell according to claim 1, characterized in that, The thickness of the interface layer is 2nm-10nm.

5. The tin-based perovskite solar cell according to claim 1, characterized in that, The general structural formula of the material of the tin-containing 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 Sn. 2+ and optional Pb 2+ X is selected from Cl - ,Br - Or I - Any one or at least two of them; And / or, the thickness of the tin-containing perovskite light-absorbing layer is 100nm-400nm.

6. The tin-based perovskite solar cell according to claim 1, characterized in that, The first carrier transport layer is an electron transport layer, and the second carrier transport layer is a hole transport layer.

7. A method for preparing a tin-based perovskite solar cell according to any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: The tin-based perovskite solar cell is obtained by sequentially stacking a substrate, a first carrier transport layer, an interface layer, a tin-containing perovskite light-absorbing layer, a second carrier transport layer, and an electrode. The material of the interface layer includes a conjugated polymer.

8. The preparation method according to claim 7, characterized in that, The method for preparing the interface layer includes the following steps: A conjugated polymer solution is coated on the surface of the first carrier transport layer, and the interface layer is obtained after a first annealing treatment.

9. The preparation method according to claim 8, characterized in that, The mass concentration of the conjugated polymer in the conjugated polymer solution is 1 mg / mL-5 mg / mL; And / or, the temperature of the first annealing treatment is 100℃-150℃, and the time of the first annealing treatment is 10min-20min.

10. The preparation method according to claim 7, characterized in that, The first carrier transport layer is an electron transport layer, and the second carrier transport layer is a hole transport layer.

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