Thin film, preparation method thereof and application of thin film in trans-structure perovskite solar cell

Abstract

The invention belongs to the technical field of perovskite solar cells, and provides a thin film, a preparation method of the thin film and application of the thin film in a trans-structure perovskite solar cell. The film provided by the invention is prepared from the following raw material components: poly [4-(9H-carbazole-9-yl) butyl phosphonic acid] and an additive, the additive comprises [4-(3, 6-dimethoxy-9H-carbazole-9-yl) phenyl] phosphonic acid, and the mass ratio of poly [4-(9H-carbazole-9-yl) butyl phosphonic acid] to the additive is 2: (1-2). The thin film provided by the invention can be further used for preparing a trans-structure perovskite solar cell, can be used as a modification layer to effectively modify a large-area hole transport layer, and is suitable for preparing a large-scale, large-size, high-conversion-efficiency and high-stability trans-structure perovskite solar cell.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, and more specifically, to thin films, methods for their preparation, and their application in inverted perovskite solar cells. Background Technology

[0002] Perovskite solar cells (PSCs) are a photovoltaic technology with great potential, boasting a theoretical photoelectric conversion efficiency of approximately 33%, making them competitive with traditional crystalline silicon cells. Furthermore, their stability continues to improve. Currently, the industrialization of inverted perovskite solar cells is rapidly progressing, and achieving large-area, high-efficiency cell devices and modules is a key path towards commercial application. Inverted perovskite solar cells typically consist of a hole transport layer, a perovskite absorber layer, an electron transport layer, and electrode materials. NiOx, a common hole transport layer material, significantly impacts efficiency and stability in these devices. Currently, sputtered nickel oxide (NiOx) is a production line-compatible route for depositing the hole transport layer (HTL) in perovskite / silicon tandem solar cells. However, this method of preparing the hole transport layer using sputtered nickel oxide often results in low film crystallinity and structural defects, thus impairing electronic conductivity. Moreover, the inherent energy level mismatch and surface defects of sputtered nickel oxide itself are bottlenecks hindering further improvements in cell performance.

[0003] Methods for preparing hole transport layers based on sputtered nickel oxide suffer from drawbacks such as low intrinsic conductivity, high defect density, energy level mismatch with the perovskite interface, and reactions with perovskite precursors. Introducing an interface layer for modification is one of the main methods to optimize the photovoltaic performance of NiOx-based perovskite solar cells. Generally, self-assembled monolayers (SAMs) are used to modify the NiOx surface, forming a uniform and ordered molecular film on the substrate surface. This effectively improves film quality, alters the surface work function of NiOx, provides a valence band close to that of perovskite, resolves energy level mismatch, and passivates defects, thereby achieving high open-circuit voltage and efficiency, and improving the final photoelectric conversion efficiency and long-term stability. Based on this, most current technical routes revolve around NiOx / SAM hole transport layers. Through uniform and robust anchoring between the NiOx film and the SAM molecular layer, charge extraction is promoted and non-radiative recombination at the interface is suppressed. However, there are still some problems with this interface modification layer: the physicochemical properties of SAM molecules themselves limit the solution processing difficulties, and poor wettability and poor thermal stability lead to serious interface defects and non-radiative recombination; the interface defects and charge transport losses lead to unstable charge transport efficiency, and the lack of energy levels makes it difficult to break through the photoelectric conversion efficiency; in addition, large-area modification layers and scale-up preparation will cause uneven molecular coverage and poor crystal quality, resulting in low photoelectric conversion efficiency of the battery.

[0004] Therefore, there is an urgent need to develop a high-performance hole transport modification material suitable for preparing large-area (e.g., 1200mm*600mm, or larger) hybrid self-assembled molecular hole transport modification layers, which can then be used to prepare inverted perovskite solar cells, thereby promoting the large-scale coating of perovskite solar cells and improving the photoelectric conversion efficiency of the cells. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a thin film, a method for preparing the same, and its application in inverted perovskite solar cells. The thin film provided by this invention can be used as a modification layer for mixing and self-assembly as a hole transport layer, further improving the photoelectric conversion efficiency (e.g., reaching 20.93%) of the inverted perovskite solar cell.

[0006] A first aspect of the present invention provides a thin film.

[0007] Specifically, a film, the raw material components of which include: poly[4-(9H-carbazole-9-yl)butylphosphonic acid] (Ploy-4PACz) and additives; The additive is [4-(3,6-dimethoxy-9H-carbazole-9-yl)phenyl]phosphonic acid (MeO-PhPACz). The mass ratio of the poly[4-(9H-carbazole-9-yl)butylphosphonic acid] (Ploy-4PACz) to the additive is 2:1-2.

[0008] This invention utilizes the π-π conjugation between poly[4-(9H-carbazole-9-yl)butylphosphonic acid] (Ploy-4PACz) and [4-(3,6-dimethoxy-9H-carbazole-9-yl)phenyl]phosphonic acid (MeO-PhPACz) additives to construct a film with a layered structure. Furthermore, the film effectively optimizes the distribution of SAM molecules by anchoring its own phosphate groups to the unadsorbed sites of SAM. In addition, the fully aromatic configuration is crucial for promoting the formation of a dense and highly ordered hole transport layer (HSL) and improving hole extraction / transport efficiency. This invention, through the optimized combination of two raw material components, can further serve as a modification layer for inverted perovskite solar cells. The hybrid self-assembled molecular hole transport modification layer has high configurational entropy, thus exhibiting high thermodynamic stability. In addition, it can adjust the surface energy of the overall interface, thereby improving the processing window and wettability. By modifying the hole transport layer, it fills the holes that are not adsorbed to the substrate by the single SAM and adjusts its energy level structure to adapt to the perovskite active layer. Through the bi-group anchoring effect, it significantly improves the carrier extraction and transport at the interface between the inorganic charge hole transport layer and the perovskite active layer, increases the interfacial compatibility with the perovskite active layer, promotes the growth of uniform perovskite thin films, and thus improves the photoelectric conversion efficiency of inverted perovskite solar cells.

[0009] Preferably, the mass ratio of poly[4-(9H-carbazole-9-yl)butylphosphonic acid] (Ploy-4PACz) to the additive is 2:1.

[0010] A second aspect of the present invention provides a method for preparing a thin film.

[0011] A method for preparing a thin film includes the following steps: First, the poly[4-(9H-carbazole-9-yl)butylphosphonic acid] is dissolved in an organic solvent, and then the additive is added to obtain a mixed self-assembled molecular solution. Then, the mixed self-assembled molecular solution is successively coated and annealed to obtain the film.

[0012] The preparation method provided by this invention has mild reaction conditions, is easy to control, and has few operation steps, making it applicable to pilot-scale production.

[0013] Preferably, after adding the additive, the mixture is heated and stirred at 40-60°C for 3-10 hours. Heating and stirring facilitate dissolution.

[0014] More preferably, after adding the additive, the mixture is stirred at 50-55°C for 5-10 hours.

[0015] Preferably, the organic solvent includes methanol and / or chloroform.

[0016] More preferably, the organic solvent is methanol and chloroform in a volume ratio of (1-2):(1-2).

[0017] More preferably, the organic solvent is methanol and chloroform in a volume ratio of 1:1.

[0018] Preferably, the coating method is one of slot coating, blade coating, or spraying.

[0019] Preferably, the coating involves applying the mixed self-assembled molecular solution onto the substrate surface.

[0020] Preferably, the annealing temperature is 90-120°C, and / or the annealing time is 5-20 minutes.

[0021] A third aspect of the present invention provides an application of a thin film.

[0022] Application of a thin film in the fabrication of inverted perovskite solar cells.

[0023] A fourth aspect of the present invention provides an inverted perovskite solar cell.

[0024] An inverted perovskite solar cell includes a substrate, a hole transport layer, a modification layer, a perovskite absorber layer (perovskite active layer), an interface passivation layer, an electron transport layer, and a metal electrode, which are sequentially stacked; the modification layer is the thin film.

[0025] Preferably, the substrate is a fluorine-doped tin oxide (FTO) glass substrate or an indium tin oxide (ITO) glass substrate.

[0026] Preferably, the hole transport layer is a NiOx transport layer.

[0027] Preferably, the raw material of the perovskite absorber layer (perovskite active layer) includes at least one of cesium iodide, lead iodide, lead bromide, and cesium bromide.

[0028] Preferably, the raw material for the interface passivation layer includes at least one of phenylethyl ammonium iodide, benzylamine iodide, and butylamine iodide.

[0029] Preferably, the raw material of the electron transport layer includes one of C60, SnO2, and methyl [6,6]-phenyl-C61-butyrate (PCBM).

[0030] Preferably, the metal electrode comprises one of copper, silver, and gold.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows: The film provided by this invention uses poly[4-(9H-carbazole-9-yl)butylphosphonic acid] (Ploy-4PACz) and additives as the main raw material components; the additives include [4-(3,6-dimethoxy-9H-carbazole-9-yl)phenyl]phosphonic acid (MeO-PhPACz), wherein the mass ratio of poly[4-(9H-carbazole-9-yl)butylphosphonic acid] (Ploy-4PACz) to additives is 2:1-2. This invention utilizes the π-π conjugation between a specific ratio of poly[4-(9H-carbazole-9-yl)butylphosphonic acid] (Ploy-4PACz) and [4-(3,6-dimethoxy-9H-carbazole-9-yl)phenyl]phosphonic acid (MeO-PhPACz) additives to construct a film with a layered structure. Furthermore, it effectively optimizes the distribution of SAM molecules by anchoring its own phosphate groups to the unadsorbed sites of SAM. In addition, the fully aromatic configuration is crucial for promoting the formation of a dense and highly ordered hole transport layer (HSL) and improving hole extraction / transport efficiency. The thin film provided by this invention can be further used to fabricate inverted perovskite solar cells. As a modifying layer, it effectively modifies large-area hole transport layers, filling holes not adsorbed onto the substrate by single SAMs and adjusting their energy level structure to adapt to the perovskite active layer. Through bifunctional anchoring, it significantly improves carrier extraction and transport at the interface between the inorganic charge-hole transport layer and the perovskite active layer, increasing interfacial compatibility with the perovskite active layer and promoting uniform perovskite film growth. This makes it suitable for fabricating large-scale, large-size inverted perovskite solar cells with high photoelectric conversion efficiency and long-term stability. Furthermore, the raw materials used in this invention are inexpensive, low-risk, and widely available. Attached Figure Description

[0032] Figure 1 This is a structural diagram of the inverted perovskite solar cell obtained by Application Example 1 of the present invention. Detailed Implementation

[0033] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0034] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0035] Example 1 A method for preparing a thin film includes the following steps: (1) Dissolve 40 mg of Ploy-4PACz and 20 mg of MeO-PhPACz (the weight ratio of Ploy-4PACz to MeO-PhPACz is 2:1) in a mixed solution of 200 mL of methanol and 200 mL of chloroform, heat and stir at 50 °C for 6 hours to obtain a mixed self-assembled molecular solution (referred to as mixed SAM solution). (2) The mixed self-assembled molecular solution was uniformly coated onto the glass substrate by slit coating. After flash evaporation for 50 seconds, it was annealed at 100°C for 10 minutes to obtain a thin film.

[0036] Example 2 A method for preparing a thin film differs from Example 1 in that 40 mg of Ploy-4PACz and 20 mg of MeO-PhPACz are replaced with 30 mg of Ploy-4PACz and 30 mg of MeO-PhPACz (the weight ratio of Ploy-4PACz to MeO-PhPACz is 1:1).

[0037] Comparative Example 1 A method for preparing a thin film differs from Example 1 in that 40 mg of Ploy-4PACz and 20 mg of MeO-PhPACz are replaced with 60 mg of MeO-PhPACz.

[0038] Comparative Example 2 A method for preparing a thin film, differing from Example 1, is provided in that 40 mg of Ploy-4PACz and 20 mg of MeO-PhPACz are replaced with 60 mg of Ploy-4PACz.

[0039] Comparative Example 3 A method for preparing a thin film, which differs from Example 1 in that 40 mg of Ploy-4PACz and 20 mg of MeO-PhPACz are replaced with 45 mg of Ploy-4PACz and 15 mg of MeO-PhPACz (the weight ratio of Ploy-4PACz to MeO-PhPACz is 3:1).

[0040] Comparative Example 4 A method for preparing a thin film, which differs from Example 1, is to replace 40 mg of Ploy-4PACz and 20 mg of MeO-PhPACz with 15 mg of Ploy-4PACz and 45 mg of MeO-PhPACz (the weight ratio of Ploy-4PACz to MeO-PhPACz is 1:3).

[0041] Comparative Example 5 A method for preparing a thin film differs from Example 1 in that MeO-PhPACz is replaced with an equal weight of MeO-4PACz (4-(3,6-dimethoxy-9H-carbazole-9-yl)butylphosphonic acid).

[0042] Comparative Example 6 A method for preparing a thin film differs from Example 1 in that MeO-PhPACz is replaced with an equal weight of MeO-2PACz (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid).

[0043] Application Example 1 An inverted perovskite solar cell, such as Figure 1 As shown, an inverted perovskite solar cell, consisting of a substrate, a hole transport layer, a modification layer, a perovskite absorber layer (perovskite active layer), an interface passivation layer, an electron transport layer, and a metal electrode stacked sequentially, comprises the following steps: (1) Substrate cleaning: A 1200mm*600mm transparent conductive glass (fluorine-doped tin oxide) was used as the substrate. The substrate was ultrasonically cleaned with deionized water and ultrasonically cleaned twice with ethanol for 10 minutes each time to obtain a clean substrate.

[0044] (2) NiOx layer (hole transport layer): After sputtering nickel oxide on a clean substrate, it is annealed and cooled.

[0045] (3) Preparation of the modification layer: The film prepared using the raw materials and preparation method of Example 1 is the modification layer.

[0046] (4) Perovskite absorber layer (perovskite active layer): Cesium iodide, lead iodide, formamidinium iodide compound, methylamine chloride compound, lead bromide, and cesium bromide were mixed and dissolved in DMF / DMSO. After stirring at room temperature, a molar concentration of 1.2 mol / L (CsPbI3) was obtained. 0.1 (FAPbI3) 0.9 Perovskite solution; Take 400 mL of perovskite solution and prepare a perovskite film with a thickness of about 300 nm using a slit coating process. After flash evaporation for 50 seconds, anneal at 120 °C for 10 minutes.

[0047] (5) Interface passivation layer: 400 mL of 0.8 mg / mL phenylethyl ammonium iodide (PEAI) passivation layer solution was prepared, and a thin film was prepared by slit coating process and annealed at 80 °C for 10 minutes.

[0048] (6) Electron transport layer: Vacuum deposition is used to coat electrons at a depth of 0.3 A s. -1 A 30 nm thick C60 layer was deposited on the perovskite active layer at a rate of 0.05 A s⁻¹. -12,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) with a thickness of 5 nm was deposited on C60 at a rate of [missing information].

[0049] (7) Metal electrode: A copper electrode with a thickness of 100 nm was deposited on the electron transport layer by vacuum evaporation to obtain an inverted perovskite solar cell.

[0050] Comparative Application Examples 1-6 Comparative Application Examples 1-6 provide inverted perovskite solar cells. The only difference between their preparation methods and those of Application Example 1 is that the modification layer in step (3) is replaced with the thin film prepared in Comparative Examples 1-6.

[0051] Product effectiveness test 1. Testing Method The inverted perovskite solar cells fabricated in various application examples and comparative application examples were subjected to relevant performance tests. The short-circuit current density (Jsc), open-circuit voltage (Voc), and photoelectric conversion efficiency (Eff) were all measured under standard test conditions (AM1.5, 25℃, 1000 W / m²). 2 The result was measured below.

[0052] Open-circuit voltage (Voc): The voltage value on the JV curve when the current is zero.

[0053] Short-circuit current density (Jsc): The current density value of the JV curve when the voltage is zero.

[0054] Fill factor: A parameter that measures the degree of "squareness" of the JV curve.

[0055] Photoelectric conversion efficiency (Eff): The ultimate efficiency indicator of a device.

[0056] 2. Test Results Table 1. Performance test results of inverted perovskite solar cells fabricated in various application examples and comparative application examples.

[0057] As shown in the table above, Application Examples 1-2 of the present invention can produce a large-area modification layer of 1200mm*600mm, and the photoelectric conversion efficiency of the obtained inverted perovskite solar cells reaches 17.60-21.56%. Among them, Application Example 1 of the present invention shows the most significant performance improvement compared with Comparative Application Examples 1-6, with a photoelectric conversion efficiency of 21.56%.

[0058] In contrast, Application Example 1 uses only MeO-PhPACz, and the single modification layer may form an uneven coverage on the perovskite surface, leading to poor local contact and thus relatively low efficiency.

[0059] In contrast, Application Example 2 uses only Ploy-4PACz, and the single modification layer may form an uneven coverage on the perovskite surface, leading to poor local contact and thus relatively low efficiency.

[0060] Comparative Application Examples 3 and 4 show that the photoelectric conversion efficiency decreased because the ratio of Ploy-4PACz to MeO-PhPACz was changed. This is because the improper ratio of Ploy-4PACz to MeO-PhPACz leads to competition on the substrate, resulting in a lower hole extraction rate, which in turn leads to a decrease in open-circuit voltage and low photoelectric conversion efficiency.

[0061] In contrast to application example 5, since MeO-PhPACz was replaced with Meo-4PACz, the hole mobility of the two materials is different. The modified layer after MeO-4PACz participated in the mixing formed a poor charge extraction channel at the interface, which increased charge accumulation and recombination loss. The fill factor is very sensitive to the charge extraction rate, so it was significantly reduced, and the photoelectric conversion efficiency dropped to 18.04%.

[0062] In contrast to application example 6, since MeO-PhPACz was replaced with Meo-2PACz, the hole mobility of the two materials is different. The modified layer after MeO-2PACz participated in the mixing formed a poor charge extraction channel at the interface, which increased charge accumulation and recombination loss. The fill factor is very sensitive to the charge extraction rate, so it was significantly reduced, and the photoelectric conversion efficiency dropped to 18.19%.

Claims

1. A thin film, characterized in that, The raw material components of the film include: poly[4-(9H-carbazole-9-yl)butylphosphonic acid] and additives; the additives include [4-(3,6-dimethoxy-9H-carbazole-9-yl)phenyl]phosphonic acid; The mass ratio of the poly[4-(9H-carbazole-9-yl)butylphosphonic acid] to the additive is 2:1-2.

2. The thin film according to claim 1, characterized in that, The mass ratio of poly[4-(9H-carbazole-9-yl)butylphosphonic acid] to additives is 2:

1.

3. The method for preparing the thin film according to claim 1 or 2, characterized in that, Includes the following steps: First, the poly[4-(9H-carbazole-9-yl)butylphosphonic acid] is dissolved in an organic solvent, and then the additive is added to obtain a mixed self-assembled molecular solution. Then, the mixed self-assembled molecular solution is successively coated and annealed to obtain the film.

4. The preparation method according to claim 3, characterized in that, The organic solvents include methanol and / or chloroform.

5. The preparation method according to claim 3, characterized in that, After adding the additive, stir at 40-60℃ for 3-10 hours.

6. The preparation method according to claim 3, characterized in that, The annealing temperature is 90-120°C, and / or the annealing time is 5-20 minutes.

7. The application of the thin film according to claim 1 or 2 in the preparation of inverted perovskite solar cells.

8. A reverse-structure perovskite solar cell, characterized in that, It includes a substrate, a hole transport layer, a modification layer, a perovskite absorber layer, an interface passivation layer, an electron transport layer, and a metal electrode, which are stacked sequentially; the modification layer is the thin film described in claim 1 or 2.

9. The inverted perovskite solar cell according to claim 8, characterized in that, The hole transport layer is a NiOx transport layer.

10. The inverted perovskite solar cell according to claim 8, characterized in that, The raw material for the perovskite absorber layer includes at least one of cesium iodide, lead iodide, lead bromide, and cesium bromide.

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