A perovskite solar cell based on a composite hole transport layer and a preparation method thereof

Abstract

The present invention discloses a perovskite solar cell based on a composite hole transport layer and a preparation method thereof, belonging to the technical field of perovskite solar cells. The perovskite solar cell based on the composite hole transport layer comprises an ITO substrate, a composite hole transport layer, a perovskite light-absorbing layer, an electron transport layer and a metal electrode layer stacked in sequence; the preparation material of the composite hole transport layer comprises a heteropolyacid salt and a small molecule hole material; the mass ratio of the heteropolyacid salt to the small molecule hole material is 0.5 to 1.5:1. The present invention utilizes heteropolyacid salts and small molecule hole materials to form a composite hole transport layer, effectively improving the extraction and transport process of hole carriers, reducing non-radiative recombination in the carrier transport process, thereby improving the photoelectric conversion performance of the device. In addition, the good thermal stability of the heteropolyacid salt greatly improves the thermal stability of the device.

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite solar cells, and more particularly relates to a perovskite solar cell based on a composite hole transport layer and a preparation method thereof. Background Art

[0002] Perovskite solar cells, due to their simple fabrication process and high photoelectric conversion efficiency, have attracted extensive research in recent years, bringing new opportunities to the photovoltaic field. However, their current photoelectric conversion efficiency still lags far behind the Shockley-Queisser limit, thus perovskites still hold considerable research potential. Perovskites employ a sandwich structure, where photogenerated charge carriers are transported via different interface layers, with the hole transport layer playing a crucial role in hole transport.

[0003] Currently, commonly used hole transport layers are nickel oxide, small molecule holes, PEDOT:PSS, etc., but these hole materials all have certain problems. For example, there are a large number of O and Ni defect vacancies in nickel oxide, which leads to serious carrier recombination. Small molecule holes have the problem of poor wettability. PEDOT:PSS has the disadvantages of poor device stability due to its hygroscopic properties and corrosion of ITO, which affects the carrier transport of perovskite and causes a decline in device performance. Summary of the Invention

[0004] The purpose of the present invention is to provide a perovskite solar cell based on a composite hole transport layer and a preparation method thereof, so as to solve the problems existing in the above-mentioned prior art and realize the preparation of a perovskite solar cell device with high light conversion efficiency and high thermal stability.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is to provide a perovskite solar cell based on a composite hole transport layer, wherein the raw materials of the composite hole transport layer include a heteropolyacid salt and a small molecule hole material in a mass ratio of 0.5 to 1.5:1.

[0007] Furthermore, the perovskite solar cell includes an ITO substrate, a composite hole transport layer, a perovskite light absorption layer, an electron transport layer and a metal electrode layer stacked in sequence.

[0008] Preferably, the heteropolyacid salt includes one or more of zinc phosphomolybdate, copper phosphomolybdate, tin phosphomolybdate, silver phosphomolybdate and nickel phosphomolybdate.

[0009] Preferably, the small molecule hole material includes one or more of 2PACz, 3PACz, 4PACz, 6PACz, Me-2PACz, Me-3PACz, Me-4PACz, Me-6PACz, MeO-2PACz, MeO-3PACz, MeO-4PACz, MeO-6PAC, V1036, CbzNaph and MTPA-BA.

[0010] Furthermore, the structural formula of the small molecule hole material is as follows:

[0011]

[0012] The existing technology uses heteropoly acid as the hole transport layer and adopts various methods such as spin coating and coating to prepare the corresponding perovskite battery. However, due to the existence of strong acidity, small specific surface area, poor thermal stability and strong oxidizing property of heteropoly acid, NiO x Due to shortcomings such as the reaction, the above-mentioned perovskite solar cell devices based on composite hole transport layers still have low photoelectric conversion efficiency, which affects their application. The present invention prepares a composite hole transport layer by using specific amounts of heteropolyacid salts and small molecule hole-transporting materials, which can effectively solve the above-mentioned problems of the existing technology.

[0013] Preferably, the composite hole transport layer is a composite hole transport layer with a single-layer structure or a composite hole transport layer with a double-layer structure.

[0014] Preferably, the preparation step of the composite hole transport layer comprises: mixing a heteropoly acid salt, a small molecule hole material and a solvent to obtain a mixed solution; spin-coating the mixed solution on an ITO substrate to form a composite hole transport layer with a single-layer structure;

[0015] The preparation steps of the double-layer composite hole transport layer include: firstly spin-coating a first mixed liquid obtained by mixing a heteropolyacid salt and a solvent on an ITO substrate to form a heteropolyacid salt layer, and then spin-coating a second mixed liquid obtained by mixing a small molecule hole material and a solvent on the heteropolyacid salt layer to form a double-layer composite hole transport layer.

[0016] Preferably, the concentrations of the mixed solutions are independently 0.5-2 mg / mL; the concentration of the first mixed solution is 0.5-2 mg / mL; and the concentration of the second mixed solution is 0.5-2 mg / mL.

[0017] The present invention selects a composite hole transport layer containing a specific concentration of heteropolyacid salt and a small molecule hole material to ensure that the heteropolyacid salt or the small molecule hole has good dispersion in the solvent, thereby ensuring good film quality of the hole transport layer after subsequent film formation.

[0018] Preferably, the general formula of the material used for the perovskite light absorbing layer of the perovskite solar cell is ABX3; wherein A is selected from MA + , FA + and Cs + One or more of; B is selected from Pb 2+ and / or Sn 2+ , X is selected from Cl - Br - and I - One or more of .

[0019] Furthermore, the general formula of the material used in the perovskite light absorbing layer of the perovskite solar cell is preferably Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 ) 3. The perovskite light-absorbing layer obtained by the material of the preferred general formula can better cooperate with the composite hole transport layer, playing the role of the composite hole transport layer in extracting holes well in the wide-bandgap perovskite system.

[0020] Preferably, the electron transport layer of the perovskite solar cell comprises an electron transport material layer and a modification layer stacked in sequence; the material used for the electron transport material layer comprises C60; and the material used for the modification layer comprises BCP.

[0021] Preferably, the thickness of the electron transport material layer is 10 to 30 nm; and the thickness of the modified layer is 5 to 20 nm.

[0022] Preferably, the thickness of the composite hole transport layer is 10-30 nm; the thickness of the electron transport layer of the perovskite solar cell is 15-30 nm; the thickness of the modified layer is 5-20 nm; and the thickness of the metal electrode layer of the perovskite solar cell is 80-150 nm.

[0023] Regarding the thickness of the above-mentioned functional layer, its thickness is ensured to be within the above-mentioned specified range to ensure that it plays a good role in promoting the transport of perovskite carriers and suppressing the composite recombination behavior during the carrier transport process.

[0024] Furthermore, the metal materials used for the metal electrode layer of the perovskite solar cell include silver, gold, copper, etc.

[0025] Furthermore, the perovskite solar cell based on the composite hole transport layer is a single-cell device, specifically a full perovskite tandem cell, a perovskite-crystalline silicon tandem cell or a perovskite-organic tandem cell.

[0026] The second technical solution of the present invention is to provide a method for preparing the above-mentioned perovskite solar cell based on the composite hole transport layer, comprising the following steps:

[0027] A composite hole transport layer, a perovskite light absorption layer, an electron transport layer and a metal electrode layer are sequentially stacked on an ITO substrate to obtain the perovskite solar cell based on the composite hole transport layer.

[0028] Furthermore, the configuration of the composite hole transport layer, perovskite light absorption layer, electron transport layer and metal electrode layer includes but is not limited to spin coating, scraping, atomic deposition or thermal evaporation; the spin coating speed is independently 1000-6000 r / min, and the time is independently 20-45 s.

[0029] Furthermore, the composite hole transport layer, perovskite light absorption layer, electron transport layer and metal electrode layer further include an annealing step after the layers are set; the annealing temperature is independently 60 to 150° C., and the time is independently 10 to 30 minutes.

[0030] Whether or not an annealing step is required depends on the inherent properties of the materials used to form the layers.

[0031] The technical mechanism of the present invention is as follows:

[0032] The present invention addresses the problems of poor wettability, severe non-radiative recombination, and severe thermal stability degradation in current perovskite hole transport layer materials. The present invention discloses a perovskite battery based on a heteropolyacid salt composite hole transport layer. The composite hole transport layer of the heteropolyacid salt and small molecule hole material ensures efficient hole extraction and blocks reverse electron transport, reducing carrier recombination. It forms a gentle energy level gradient with the perovskite, reducing energy levels. It also creates a built-in electric field, accelerating the transport of holes to the electrode, thereby effectively improving the hole carrier extraction and transport process, reducing non-radiative recombination in the carrier transport process, and thus improving the device's photoelectric conversion performance. Furthermore, the good thermal stability of the heteropolyacid salt greatly enhances the device's thermal stability.

[0033] The present invention uses zinc phosphomolybdate from a heteropolyacid salt and a small molecule hole material to construct the hole transport layer of the perovskite. The heteropolyacid salt improves the aggregation behavior of the small molecules, optimizes their film-forming behavior during the film formation process, disrupts the ordered arrangement between molecules, increases surface free energy, and thus improves wettability. This can enhance the adhesion between the perovskite and the hole transport layer, thereby improving the poor wettability problem of hole transport layers prepared using small molecule hole materials in the prior art.

[0034] The present invention adopts zinc phosphomolybdate and small molecule hole material in heteropoly acid salt to jointly construct the hole transport layer of perovskite. Compared with heteropoly acid, heteropoly acid salt exists in the form of salt and does not release hydrogen ions like heteropoly acid. Therefore, the acidity of the solution is weaker, thereby effectively solving the problems of heteropoly acid substances such as excessive acidity, small specific surface area, and poor thermal stability.

[0035] The present invention limits the mass ratio of the heteropolyacid salt and the small molecule hole material to 0.5 to 1.5:1. Within this range, good dispersion of the small molecule hole material and the heteropolyacid salt blend system can be achieved, or the small molecule hole material can form a good single-layer self-assembled structure on the heteropolyacid salt hole layer. Exceeding the upper limit of this range will cause the heteropolyacid salt to become turbid and precipitate due to poor solubility, resulting in poor film morphology of the composite layer and a serious decline in battery performance.

[0036] The present invention discloses the following technical effects:

[0037] 1. The present invention uses zinc phosphomolybdate in heteropolyacid salts and small molecule hole materials to jointly construct the hole transport layer of perovskite, which can enhance the adhesion between the perovskite and the hole transport layer and improve the poor wettability of the small molecule hole material.

[0038] 2. The present invention can significantly improve the extraction and transmission rate of hole carriers in perovskite solar cell devices, inhibit the non-radiative recombination of perovskite, and reduce the defect density.

[0039] 3. The present invention can effectively improve the photoelectric conversion efficiency of perovskite solar cell devices by optimizing the carrier transport path, and can improve the thermal stability of perovskite by utilizing the high stability of heteropolyacid salts. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the structure of the perovskite solar cell device described in Example 1 and Example 2;

[0041] Figure 2 Voltage-current density curves of the perovskite solar cell devices prepared in Examples 1 to 4 and Comparative Examples 1 to 6;

[0042] Figure 3 Steady-state fluorescence spectra of the perovskite solar cell devices prepared in Example 1, Example 2, Comparative Example 1 and Comparative Example 2;

[0043] Figure 4 These are the contact angle test results of the perovskite precursor solution and the hole transport layer described in Example 1, Example 2, Comparative Example 1 and Comparative Example 2. DETAILED DESCRIPTION

[0044] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0045] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0046] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0047] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0048] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0049] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in this field and are not the focus of the present invention.

[0050] Unless otherwise specified, the raw materials used in the following examples and comparative examples of the present invention are all commercially available products, and the sources of the commercially available products do not affect the technical effects of the present invention.

[0051] Unless otherwise specified, the room temperature referred to in the present invention is 25±5°C.

[0052] Example 1

[0053] In step 1, an ITO substrate with a size of 1.5 cm×1.5 cm is used to clean the ITO substrate to remove dust and oil stains on the surface of the substrate. After the substrate is cleaned, ozone UV treatment is used to further remove impurities from the surface of the substrate.

[0054] Step 2, Preparation of a Zinc Phosphomolybdate and Small Molecule Composite Hole Transport Layer: Weigh 1 mg of zinc phosphomolybdate and 1 mg of 4PACz, respectively, and dissolve them in 1 mL of ethanol. Stir overnight at room temperature until complete dissolution is achieved to obtain a precursor solution for the zinc phosphomolybdate and small molecule composite hole transport layer. Use a pipette to measure 50 μL of this zinc phosphomolybdate and small molecule composite hole transport layer precursor solution and spin-coat it onto the ITO substrate obtained in Step 1 at a spin-coating speed of 3000 rpm. Anneal the solution at 100°C for 10 minutes to form a zinc phosphomolybdate and small molecule composite hole transport layer with a thickness of 25 nm.

[0055] Step 3, 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 )3 Preparation of perovskite precursor: Weigh 233.88 mg FAI, 28.55 mg MABr, 22.08 mg CsI, 607.38 mg PbI2, and 140.38 mg PbBr2 and dissolve them in 1 mL of a mixed solvent of DMF and DMSO with a volume ratio of 4:1. Stir at room temperature for more than 4 hours until the solid material is completely dissolved, and filter with a 0.22 μm PTFE filter head for use.

[0056] Step 4, preparation of perovskite light absorbing layer: Preparation of perovskite active layer film in nitrogen glove box, specifically, taking 80 μL of 1.7M Cs 0.0.5 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 A 3-μm perovskite precursor solution was spin-coated onto the resulting composite hole transport layer of zinc phosphomolybdate and small molecules. The perovskite light-absorbing layer was prepared using a step-by-step spin-coating process. 200 μL of chlorobenzene was added dropwise 10 seconds before the end of the step-by-step spin-coating process as an antisolvent for perovskite crystallization. After the spin-coating process, an annealing treatment was performed at 100°C for 10 minutes, forming a 600 nm thick perovskite light-absorbing layer.

[0057] Step 5, preparation of electron transport layer: C60 and BCP are sequentially stacked on the formed perovskite light-absorbing layer by vacuum evaporation to form an electron transport layer. The thickness of C60 is 20 nm, and the thickness of BCP is controlled to be 10 nm.

[0058] Step 6, preparation of a metal electrode layer: a silver electrode layer with a thickness of 120 nm is provided on the formed electron transport layer by vacuum evaporation.

[0059] Example 2

[0060] The difference from Example 1 is that step 2 is different from Example 1, and the other steps are the same as Example 1.

[0061] Specifically:

[0062] In step 1, an ITO substrate with a size of 1.5 cm×1.5 cm is used to clean the ITO substrate to remove dust and oil stains on the surface of the substrate. After the substrate is cleaned, ozone UV treatment is used to further remove impurities from the surface of the substrate.

[0063] Step 2, preparation of a composite hole transport layer of an upper small molecule hole and a lower zinc phosphomolybdate: weigh 1 mg of zinc phosphomolybdate and dissolve it in 1 mL of ethanol, weigh 1 mg of 4PACz and dissolve it in 1 mL of ethanol, stir the two mixed solutions separately at room temperature overnight, and after the two mixed solutions are completely dissolved, a zinc phosphomolybdate precursor solution and a small molecule hole precursor solution can be obtained. Use a pipette to measure 50 μL of the zinc phosphomolybdate precursor solution and spin coat it on the ITO substrate obtained in step 1 at a spin coating speed of 5000 r / min to form a single zinc phosphomolybdate hole transport layer; then measure 30 μL of the small molecule hole precursor solution and spin coat it on the zinc phosphomolybdate single hole transport layer by a dynamic spinning method at a spin coating speed of 5000 r / min, followed by annealing at a temperature of 100 ° C for 10 minutes to form a composite hole transport layer of an upper small molecule hole and a lower zinc phosphomolybdate with a thickness of 30 nm.

[0064] Step 3, 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 )3 Preparation of perovskite precursor: Weigh 233.88 mg FAI, 28.55 mg MABr, 22.08 mg CsI, 607.38 mg PbI2, and 140.38 mg PbBr2 and dissolve them in 1 mL of a mixed solvent of DMF and DMSO with a volume ratio of 4:1. Stir at room temperature for more than 4 hours until the solid material is completely dissolved, and filter with a 0.22 μm PTFE filter head for use.

[0065] Step 4, preparation of perovskite light absorbing layer: Preparation of perovskite active layer film in nitrogen glove box, specifically, taking 80 μL of 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2A 3-μm perovskite precursor solution was spin-coated onto the formed upper layer of small molecule holes and the lower layer of zinc phosphomolybdate composite hole transport layer. The perovskite light-absorbing layer was prepared using a step-by-step spin-coating method. 200 μL of chlorobenzene was added dropwise 10 seconds before the end of the step-by-step spin-coating process as an antisolvent for perovskite crystallization. After the spin-coating process, an annealing treatment was performed at 100°C for 10 minutes to form a 600 nm thick perovskite light-absorbing layer.

[0066] Step 5, preparation of electron transport layer: C60 and BCP are sequentially stacked on the formed perovskite light-absorbing layer by vacuum evaporation to form an electron transport layer. The thickness of C60 is 20 nm, and the thickness of BCP is controlled to be 10 nm.

[0067] Step 6, preparation of a metal electrode layer: a silver electrode layer with a thickness of 120 nm is provided on the formed electron transport layer by vacuum evaporation.

[0068] Example 3

[0069] The difference from Example 1 is that step 2 is different from Example 1, and the other steps are the same as Example 1.

[0070] Specifically:

[0071] In step 1, an ITO substrate with a size of 1.5 cm×1.5 cm is used to clean the ITO substrate to remove dust and oil stains on the surface of the substrate. After the substrate is cleaned, ozone UV treatment is used to further remove impurities from the surface of the substrate.

[0072] Step 2, Preparation of a Zinc Phosphomolybdate and Small Molecule Composite Hole Transport Layer: Weigh 1 mg of zinc phosphomolybdate and 1 mg of Me-2PACz, respectively, and dissolve them in 1 mL of ethanol. Stir overnight at room temperature until complete dissolution is achieved to obtain a precursor solution for the zinc phosphomolybdate and small molecule composite hole transport layer. Use a pipette to measure 50 μL of this zinc phosphomolybdate and small molecule composite hole transport layer precursor solution and spin-coat it onto the ITO substrate obtained in step 1 at a spin-coating speed of 3000 rpm. Anneal the solution at 100°C for 10 minutes to form a zinc phosphomolybdate and small molecule composite hole transport layer with a thickness of 25 nm.

[0073] Step 3, 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2)3 Preparation of perovskite precursor: Weigh 233.88 mg FAI, 28.55 mg MABr, 22.08 mg CsI, 607.38 mg PbI2, and 140.38 mg PbBr2 and dissolve them in 1 mL of a mixed solvent of DMF and DMSO with a volume ratio of 4:1. Stir at room temperature for more than 4 hours until the solid material is completely dissolved, and filter with a 0.22 μm PTFE filter head for use.

[0074] Step 4, preparation of perovskite light absorbing layer: Preparation of perovskite active layer film in nitrogen glove box, specifically, taking 80 μL of 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 A 3-μm perovskite precursor solution was spin-coated onto the formed upper layer of small molecule holes and the lower layer of zinc phosphomolybdate composite hole transport layer. The perovskite light-absorbing layer was prepared using a step-by-step spin-coating method. 200 μL of chlorobenzene was added dropwise 10 seconds before the end of the step-by-step spin-coating process as an antisolvent for perovskite crystallization. After the spin-coating process, an annealing treatment was performed at 100°C for 10 minutes to form a 600 nm thick perovskite light-absorbing layer.

[0075] Step 5, preparation of electron transport layer: C60 and BCP are sequentially stacked on the formed perovskite light-absorbing layer by vacuum evaporation to form an electron transport layer. The thickness of C60 is 20 nm, and the thickness of BCP is controlled to be 10 nm.

[0076] Step 6, preparation of a metal electrode layer: a silver electrode layer with a thickness of 120 nm is provided on the formed electron transport layer by vacuum evaporation.

[0077] Example 4

[0078] The difference from Example 1 is that step 2 is different from Example 1, and the other steps are the same as Example 1.

[0079] Specifically:

[0080] In step 1, an ITO substrate with a size of 1.5 cm×1.5 cm is used to clean the ITO substrate to remove dust and oil stains on the surface of the substrate. After the substrate is cleaned, ozone UV treatment is used to further remove impurities from the surface of the substrate.

[0081] Step 2: Preparation of a Tin Phosphomolybdate and Small Molecule Composite Hole Transport Layer: 1 mg of Tin Phosphomolybdate and 1 mg of 4PACz were weighed separately and dissolved in 1 mL of ethanol. Stirred overnight at room temperature until complete dissolution was achieved to obtain a precursor solution for the Tin Phosphomolybdate and Small Molecule Composite Hole Transport Layer. Using a pipette, 50 μL of this precursor solution was measured and spin-coated onto the ITO substrate obtained in Step 1 at a speed of 3000 rpm. Annealing was then performed at 100°C for 10 minutes to form a 25 nm thick composite hole transport layer of Tin Phosphomolybdate and Small Molecule Composite Hole Transport Layer.

[0082] Step 3, 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 )3 Preparation of perovskite precursor: Weigh 233.88 mg FAI, 28.55 mg MABr, 22.08 mg CsI, 607.38 mg PbI2, and 140.38 mg PbBr2 and dissolve them in 1 mL of a mixed solvent of DMF and DMSO with a volume ratio of 4:1. Stir at room temperature for more than 4 hours until the solid material is completely dissolved, and filter with a 0.22 μm PTFE filter head for use.

[0083] Step 4, preparation of perovskite light absorbing layer: Preparation of perovskite active layer film in nitrogen glove box, specifically, taking 80 μL of 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 A 3-μm perovskite precursor solution was spin-coated onto the formed upper layer of small molecule holes and the lower layer of zinc phosphomolybdate composite hole transport layer. The perovskite light-absorbing layer was prepared using a step-by-step spin-coating method. 200 μL of chlorobenzene was added dropwise 10 seconds before the end of the step-by-step spin-coating process as an antisolvent for perovskite crystallization. After the spin-coating process, an annealing treatment was performed at 100°C for 10 minutes to form a 600 nm thick perovskite light-absorbing layer.

[0084] Step 5, preparation of electron transport layer: C60 and BCP are sequentially stacked on the formed perovskite light-absorbing layer by vacuum evaporation to form an electron transport layer. The thickness of C60 is 20 nm, and the thickness of BCP is controlled to be 10 nm.

[0085] Step 6, preparation of a metal electrode layer: a silver electrode layer with a thickness of 120 nm is provided on the formed electron transport layer by vacuum evaporation.

[0086] Comparative Example 1

[0087] The difference from Example 2 is that the small molecule holes in the composite hole transport layer are omitted, and the rest is the same as Example 2.

[0088] Specifically:

[0089] In step 1, an ITO substrate with a size of 1.5 cm×1.5 cm is used to clean the ITO substrate to remove dust and oil stains on the surface of the substrate. After the substrate is cleaned, ozone UV treatment is used to further remove impurities from the surface of the substrate.

[0090] Step 2, Preparation of a Zinc Phosphomolybdate Single Hole Transport Layer: Weigh 1 mg of zinc phosphomolybdate and dissolve it in 1 mL of ethanol. Stir overnight at room temperature until the solution is complete to obtain a zinc phosphomolybdate precursor solution. Use a pipette to measure 50 μL of the zinc phosphomolybdate precursor solution and spin-coat it onto the ITO substrate obtained in Step 1 at a spin-coating speed of 5000 rpm to form a zinc phosphomolybdate single hole transport layer. Then, anneal the layer at 100°C for 10 minutes to form a zinc phosphomolybdate single hole transport layer with a thickness of 15 nm.

[0091] Step 3, 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 )3 Preparation of perovskite precursor: Weigh 233.88 mg FAI, 28.55 mg MABr, 22.08 mg CsI, 607.38 mg PbI2, and 140.38 mg PbBr2 and dissolve them in 1 mL of a mixed solvent of DMF and DMSO with a volume ratio of 4:1. Stir at room temperature for more than 4 hours until the solid material is completely dissolved, and filter with a 0.22 μm PTFE filter head for use.

[0092] Step 4, preparation of perovskite light absorbing layer: Preparation of perovskite active layer film in nitrogen glove box, specifically, taking 80 μL of 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 A 3-μm perovskite precursor solution was spin-coated onto the formed zinc phosphomolybdate single hole transport layer. The perovskite light-absorbing layer was prepared using a step-by-step spin-coating method. 200 μL of chlorobenzene was added dropwise 10 seconds before the end of the step-by-step spin-coating process as an antisolvent for perovskite crystallization. After the spin-coating process, an annealing treatment was performed at 100°C for 10 minutes to form a 600 nm thick perovskite light-absorbing layer.

[0093] Step 5, preparation of electron transport layer: C60 and BCP are sequentially stacked on the formed perovskite light-absorbing layer by vacuum evaporation to form an electron transport layer. The thickness of C60 is 20 nm, and the thickness of BCP is controlled to be 10 nm.

[0094] Step 6, preparation of a metal electrode layer: a silver electrode layer with a thickness of 120 nm is provided on the formed electron transport layer by vacuum evaporation.

[0095] Comparative Example 2

[0096] The difference from Example 2 is that zinc phosphomolybdate in the composite hole transport layer is omitted, and the rest is the same as Example 2.

[0097] Specifically:

[0098] In step 1, an ITO substrate with a size of 1.5 cm×1.5 cm is used to clean the ITO substrate to remove dust and oil stains on the surface of the substrate. After the substrate is cleaned, ozone UV treatment is used to further remove impurities from the surface of the substrate.

[0099] Step 2, Preparation of a Small-Molecule Hole Transport Layer: Weigh 1 mg of 4PACz and dissolve it in 1 mL of ethanol. Stir at room temperature overnight. Once completely dissolved, a small-molecule hole precursor solution is obtained. Measure 30 μL of this small-molecule hole precursor solution and spin-coat it onto the ITO substrate obtained in Step 1 using a dynamic spin coating method at a speed of 5000 rpm. Anneal the substrate at 100°C for 10 minutes to form a small-molecule hole transport layer with a thickness of 5 nm.

[0100] Step 3, 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 )3 Preparation of perovskite precursor: Weigh 233.88 mg FAI, 28.55 mg MABr, 22.08 mg CsI, 607.38 mg PbI2, and 140.38 mg PbBr2 and dissolve them in 1 mL of a mixed solvent of DMF and DMSO with a volume ratio of 4:1. Stir at room temperature for more than 4 hours until the solid material is completely dissolved, and filter with a 0.22 μm PTFE filter head for use.

[0101] Step 4, preparation of perovskite light absorbing layer: Preparation of perovskite active layer film in nitrogen glove box, specifically, taking 80 μL of 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8Br 0.2 A 3-μm perovskite precursor solution was spin-coated onto the formed small-molecule hole single hole transport layer. The perovskite light-absorbing layer was prepared using a step-by-step spin-coating method. 200 μL of chlorobenzene was added dropwise 10 seconds before the end of the step-by-step spin-coating process as an antisolvent for perovskite crystallization. After the spin-coating process, an annealing treatment was performed at 100°C for 10 minutes to form a 600 nm thick perovskite light-absorbing layer.

[0102] Step 5, preparation of electron transport layer: C60 and BCP are sequentially stacked on the formed perovskite light-absorbing layer by vacuum evaporation to form an electron transport layer. The thickness of C60 is 20 nm, and the thickness of BCP is controlled to be 10 nm.

[0103] Step 6, preparation of a metal electrode layer: a silver electrode layer with a thickness of 120 nm is provided on the formed electron transport layer by vacuum evaporation.

[0104] Comparative Example 3

[0105] The difference from Example 1 is that step 2 is different from Example 1, and the other steps are the same as Example 1.

[0106] Specifically:

[0107] In step 1, an ITO substrate with a size of 1.5 cm×1.5 cm is used to clean the ITO substrate to remove dust and oil stains on the surface of the substrate. After the substrate is cleaned, ozone UV treatment is used to further remove impurities from the surface of the substrate.

[0108] Step 2: Preparation of a zinc phosphomolybdate and small molecule composite hole transport layer: Weigh 2 mg of zinc phosphomolybdate and 1 mg of 4PACz separately, blend and dissolve in 1 mL of ethanol. Stir overnight at room temperature until complete dissolution is complete to obtain a precursor solution for the zinc phosphomolybdate and small molecule composite hole transport layer. Use a pipette to measure 50 μL of this zinc phosphomolybdate and small molecule composite hole transport layer precursor solution and spin-coat it onto the ITO substrate obtained in step 1 at a spin-coating speed of 3000 rpm. Anneal the solution at 100°C for 10 minutes to form a zinc phosphomolybdate and small molecule composite hole transport layer with a thickness of 30 nm.

[0109] Step 3, 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2)3 Preparation of perovskite precursor: Weigh 233.88 mg FAI, 28.55 mg MABr, 22.08 mg CsI, 607.38 mg PbI2, and 140.38 mg PbBr2 and dissolve them in 1 mL of a mixed solvent of DMF and DMSO with a volume ratio of 4:1. Stir at room temperature for more than 4 hours until the solid material is completely dissolved, and filter with a 0.22 μm PTFE filter head for use.

[0110] Step 4, preparation of perovskite light absorbing layer: Preparation of perovskite active layer film in nitrogen glove box, specifically, taking 80 μL of 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 A 3-μm perovskite precursor solution was spin-coated onto the formed upper layer of small molecule holes and the lower layer of zinc phosphomolybdate composite hole transport layer. The perovskite light-absorbing layer was prepared using a step-by-step spin-coating method. 200 μL of chlorobenzene was added dropwise 10 seconds before the end of the step-by-step spin-coating process as an antisolvent for perovskite crystallization. After the spin-coating process, an annealing treatment was performed at 100°C for 10 minutes to form a 600 nm thick perovskite light-absorbing layer.

[0111] Step 5, preparation of electron transport layer: C60 and BCP are sequentially stacked on the formed perovskite light-absorbing layer by vacuum evaporation to form an electron transport layer. The thickness of C60 is 20 nm, and the thickness of BCP is controlled to be 10 nm.

[0112] Step 6, preparation of a metal electrode layer: a silver electrode layer with a thickness of 120 nm is provided on the formed electron transport layer by vacuum evaporation.

[0113] Comparative Example 4

[0114] The difference from Example 1 is that step 2 is different from Example 1, and the other steps are the same as Example 1.

[0115] Specifically:

[0116] In step 1, an ITO substrate with a size of 1.5 cm×1.5 cm is used to clean the ITO substrate to remove dust and oil stains on the surface of the substrate. After the substrate is cleaned, ozone UV treatment is used to further remove impurities from the surface of the substrate.

[0117] Step 2: Preparation of a zinc phosphomolybdate and small molecule composite hole transport layer: Weigh 1 mg of zinc phosphomolybdate and 2 mg of 4PACz, respectively, and dissolve them in 1 mL of ethanol. Stir overnight at room temperature until complete dissolution is achieved to obtain a precursor solution for the zinc phosphomolybdate and small molecule composite hole transport layer. Use a pipette to measure 50 μL of this zinc phosphomolybdate and small molecule composite hole transport layer precursor solution and spin-coat it onto the ITO substrate obtained in step 1 at a spin-coating speed of 3000 rpm. Anneal the solution at 100°C for 10 minutes to form a zinc phosphomolybdate and small molecule composite hole transport layer with a thickness of 30 nm.

[0118] Step 3, 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 )3 Preparation of perovskite precursor: Weigh 233.88 mg FAI, 28.55 mg MABr, 22.08 mg CsI, 607.38 mg PbI2, and 140.38 mg PbBr2 and dissolve them in 1 mL of a mixed solvent of DMF and DMSO with a volume ratio of 4:1. Stir at room temperature for more than 4 hours until the solid material is completely dissolved, and filter with a 0.22 μm PTFE filter head for use.

[0119] Step 4, preparation of perovskite light absorbing layer: Preparation of perovskite active layer film in nitrogen glove box, specifically, taking 80 μL of 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 A 3-μm perovskite precursor solution was spin-coated onto the formed upper layer of small molecule holes and the lower layer of zinc phosphomolybdate composite hole transport layer. The perovskite light-absorbing layer was prepared using a step-by-step spin-coating method. 200 μL of chlorobenzene was added dropwise 10 seconds before the end of the step-by-step spin-coating process as an antisolvent for perovskite crystallization. After the spin-coating process, an annealing treatment was performed at 100°C for 10 minutes to form a 600 nm thick perovskite light-absorbing layer.

[0120] Step 5, preparation of electron transport layer: C60 and BCP are sequentially stacked on the formed perovskite light-absorbing layer by vacuum evaporation to form an electron transport layer. The thickness of C60 is 20 nm, and the thickness of BCP is controlled to be 10 nm.

[0121] Step 6, preparation of a metal electrode layer: a silver electrode layer with a thickness of 120 nm is provided on the formed electron transport layer by vacuum evaporation.

[0122] Comparative Example 5

[0123] The difference from Example 1 is that step 2 is different from Example 1, and the other steps are the same as Example 1.

[0124] Specifically:

[0125] In step 1, an ITO substrate with a size of 1.5 cm×1.5 cm is used to clean the ITO substrate to remove dust and oil stains on the surface of the substrate. After the substrate is cleaned, ozone UV treatment is used to further remove impurities from the surface of the substrate.

[0126] Step 2: Preparation of a zinc phosphomolybdate and small molecule composite hole transport layer: Weigh 0.5 mg of zinc phosphomolybdate and 1 mg of 4PACz separately, blend and dissolve in 1 mL of ethanol. Stir overnight at room temperature until complete dissolution is complete to obtain a precursor solution of the zinc phosphomolybdate and small molecule composite hole transport layer. Use a pipette to measure 50 μL of this zinc phosphomolybdate and small molecule composite hole transport layer precursor solution and spin-coat it onto the ITO substrate obtained in step 1 at a spin-coating speed of 3000 rpm. Then, anneal at 100°C for 10 minutes to form a zinc phosphomolybdate and small molecule composite hole transport layer with a thickness of 20 nm.

[0127] Step 3, 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 )3 Preparation of perovskite precursor: Weigh 233.88 mg FAI, 28.55 mg MABr, 22.08 mg CsI, 607.38 mg PbI2, and 140.38 mg PbBr2 and dissolve them in 1 mL of a mixed solvent of DMF and DMSO with a volume ratio of 4:1. Stir at room temperature for more than 4 hours until the solid material is completely dissolved, and filter with a 0.22 μm PTFE filter head for use.

[0128] Step 4, preparation of perovskite light absorbing layer: Preparation of perovskite active layer film in nitrogen glove box, specifically, taking 80 μL of 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2A 3-μm perovskite precursor solution was spin-coated onto the formed upper layer of small molecule holes and the lower layer of zinc phosphomolybdate composite hole transport layer. The perovskite light-absorbing layer was prepared using a step-by-step spin-coating method. 200 μL of chlorobenzene was added dropwise 10 seconds before the end of the step-by-step spin-coating process as an antisolvent for perovskite crystallization. After the spin-coating process, an annealing treatment was performed at 100°C for 10 minutes to form a 600 nm thick perovskite light-absorbing layer.

[0129] Step 5, preparation of electron transport layer: C60 and BCP are sequentially stacked on the formed perovskite light-absorbing layer by vacuum evaporation to form an electron transport layer. The thickness of C60 is 20 nm, and the thickness of BCP is controlled to be 10 nm.

[0130] Step 6, preparation of a metal electrode layer: a silver electrode layer with a thickness of 120 nm is provided on the formed electron transport layer by vacuum evaporation.

[0131] Comparative Example 6

[0132] The difference from Example 1 is that step 2 is different from Example 1, and the other steps are the same as Example 1.

[0133] Specifically:

[0134] In step 1, an ITO substrate with a size of 1.5 cm×1.5 cm is used to clean the ITO substrate to remove dust and oil stains on the surface of the substrate. After the substrate is cleaned, ozone UV treatment is used to further remove impurities from the surface of the substrate.

[0135] Step 2: Preparation of a zinc phosphomolybdate and small molecule composite hole transport layer: 1 mg of zinc phosphomolybdate and 0.5 mg of 4PACz were weighed separately and dissolved in 1 mL of ethanol. Stirred overnight at room temperature until complete dissolution was achieved to obtain a precursor solution for the zinc phosphomolybdate and small molecule composite hole transport layer. Using a pipette, 50 μL of this zinc phosphomolybdate and small molecule composite hole transport layer precursor solution was spin-coated onto the ITO substrate obtained in step 1 at a spin-coating speed of 3000 rpm. Annealing was then performed at 100°C for 10 minutes to form a zinc phosphomolybdate and small molecule composite hole transport layer with a thickness of 22 nm.

[0136] Step 3, 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2)3 Preparation of perovskite precursor: Weigh 233.88 mg FAI, 28.55 mg MABr, 22.08 mg CsI, 607.38 mg PbI2, and 140.38 mg PbBr2 and dissolve them in 1 mL of a mixed solvent of DMF and DMSO with a volume ratio of 4:1. Stir at room temperature for more than 4 hours until the solid material is completely dissolved, and filter with a 0.22 μm PTFE filter head for use.

[0137] Step 4, preparation of perovskite light absorbing layer: Preparation of perovskite active layer film in nitrogen glove box, specifically, taking 80 μL of 1.7M Cs 0.05 FA 0.8 MA 0.15 Pb(I 0.8 Br 0.2 A 3-μm perovskite precursor solution was spin-coated onto the formed upper layer of small molecule holes and the lower layer of zinc phosphomolybdate composite hole transport layer. The perovskite light-absorbing layer was prepared using a step-by-step spin-coating method. 200 μL of chlorobenzene was added dropwise 10 seconds before the end of the step-by-step spin-coating process as an antisolvent for perovskite crystallization. After the spin-coating process, an annealing treatment was performed at 100°C for 10 minutes to form a 600 nm thick perovskite light-absorbing layer.

[0138] Step 5, preparation of electron transport layer: C60 and BCP are sequentially stacked on the formed perovskite light-absorbing layer by vacuum evaporation to form an electron transport layer. The thickness of C60 is 20 nm, and the thickness of BCP is controlled to be 10 nm.

[0139] Step 6, preparation of a metal electrode layer: a silver electrode layer with a thickness of 120 nm is provided on the formed electron transport layer by vacuum evaporation.

[0140] Performance testing:

[0141] The photoelectric conversion efficiency of the perovskite solar cell devices prepared in Examples 1 to 4 and Comparative Examples 1 to 6 was tested using an AAA-level steady-state solar simulation and a corresponding IV test system. The test results of each Example and Comparative Example are based on the optimal device performance and average device performance of 6 groups of devices. The specific open circuit voltage (V OC ), short-circuit current density (J SC ), fill factor (FF), and photoelectric conversion efficiency (PCE) test results are shown in Table 1.

[0142] Table 1 Performance test results of perovskite solar cell devices prepared in Examples 1 to 4 and Comparative Examples 1 to 6

[0143]

[0144] As can be seen from Table 1, the performance of the perovskite solar cell device provided with the composite hole transport layer of zinc phosphomolybdate and small molecule hole material of the present invention is better than that of the perovskite solar cell device composed of a single zinc phosphomolybdate or small molecule hole material, which is mainly manifested in the improvement of fill factor and voltage. This shows that the composite hole transport layer composed of zinc phosphomolybdate and small molecule hole material has greatly improved the adhesion between the hole transport layer and the perovskite light absorbing layer, and has better contact between the interfaces, providing a better channel for the transmission of internal carriers and suppressing non-radiative recombination. The corresponding IV test curve is shown in FIG. Figure 2 shown.

[0145] Figure 2 The voltage-current density curves of the perovskite solar cell devices prepared in Examples 1 to 4 and Comparative Examples 1 to 6 are shown in FIG. Figure 2 It can be seen that the device performance of Examples 1 to 4 is better than that of Comparative Examples 1 to 6, among which the best performance is Example 3 (composite hole transport layer of Me-2PACz and zinc phosphomolybdate), wherein J SC =22.56mA / cm 2 , V OC =1.14V, FF=82.85%, PCE=21.37%. In addition, the performance of Example 4 (4PACz and tin phosphomolybdate composite transport layer) is J SC =22.37mA / cm 2 , V OC =1.13V, FF=81.82%, and PCE=20.62%, demonstrating the universality of heteropolyacid salt-small molecule hole transport layers. Furthermore, device performance based on different concentrations of zinc phosphomolybdate and 4PACz showed that the composite hole transport layer composed of 1mg zinc phosphomolybdate and 1mg 4PACz performed best.

[0146] Figure 3 Steady-state fluorescence spectra of the perovskite solar cell devices prepared in Example 1, Example 2, Comparative Example 1 and Comparative Example 2. Steady-state fluorescence spectra were used to investigate the transport of hole carriers. Figure 3 As can be seen, Examples 1 and 2 exhibit lower fluorescence intensities than Comparative Examples 1 and 2, indicating that the internal defect density is low and carrier transport and recombination are suppressed. This shows that the composite hole transport layer of the present invention can effectively improve carrier transport, thereby improving device performance.

[0147] Figure 4The contact angle test results of the perovskite solution and the hole transport layer described in Example 1, Example 2, Comparative Example 1, and Comparative Example 2 are shown. The wettability of the perovskite precursor was tested using the contact angle test. Example 1 exhibited the smallest contact angle of 19.75°. The contact angles of Example 2, Comparative Example 1, and Comparative Example 2 were 35.67°, 23.74°, and 40.32°, respectively. The contact angle of the single hole transport layer based on small molecule holes was the largest, indicating poor wettability. The above results show that zinc phosphomolybdate can improve the wettability of small molecule holes, thereby improving device performance.

[0148] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0149] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A perovskite solar cell based on a composite hole transport layer, characterized in that: The raw materials of the composite hole transport layer include heteropoly acid salt and small molecule hole material in a mass ratio of 0.5 to 1.5:1; The heteropoly acid salt is one or more of zinc phosphomolybdate, copper phosphomolybdate, tin phosphomolybdate, silver phosphomolybdate and nickel phosphomolybdate; The small molecule hole material is 2PACz and / or 4PACz; The composite hole transport layer is a single-layer composite hole transport layer or a double-layer composite hole transport layer; the preparation steps of the single-layer composite hole transport layer include: mixing a heteropolyacid salt, a small molecule hole material and a solvent to obtain a mixed solution; and spin-coating the mixed solution on an ITO substrate to form a single-layer composite hole transport layer; the preparation steps of the double-layer composite hole transport layer include: first spin-coating a first mixed solution obtained by mixing a heteropolyacid salt and a solvent on the ITO substrate to form a heteropolyacid salt layer, and then spin-coating a second mixed solution obtained by mixing a small molecule hole material and a solvent on the heteropolyacid salt layer to form a double-layer composite hole transport layer; The electron transport layer of the perovskite solar cell comprises an electron transport material layer and a modification layer stacked in sequence; the material used in the electron transport material layer comprises C60; the material used in the modification layer comprises BCP; The thickness of the electron transport material layer is 10~30nm; the thickness of the modified layer is 5~20nm; the thickness of the composite hole transport layer is 10~30nm; the thickness of the electron transport layer of the perovskite solar cell is 15~30nm; and the thickness of the metal electrode layer of the perovskite solar cell is 80~150nm.

2. The perovskite solar cell based on a composite hole transport layer according to claim 1, characterized in that: The concentration of the mixed solution is 0.5-2 mg / mL; and / or the concentration of the first mixed solution is 0.5-2 mg / mL; and / or the concentration of the second mixed solution is 0.5-2 mg / mL.

3. The perovskite solar cell based on a composite hole transport layer according to claim 1, characterized in that: The general formula of the material used for the perovskite light absorption layer of the perovskite solar cell is ABX3; wherein A is selected from MA + , FA + and Cs + One or more of; B is selected from Pb 2+ and / or Sn 2+ ; X is selected from Cl - Br - and I - One or more of .

4. The method for preparing a perovskite solar cell based on a composite hole transport layer according to any one of claims 1 to 3, characterized in that: The steps include: A composite hole transport layer, a perovskite light absorption layer, an electron transport layer and a metal electrode layer are sequentially stacked on an ITO substrate to obtain the perovskite solar cell based on the composite hole transport layer.

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