Perovskite solar cell taking alcohol-soluble tungsten oxide as electron transport layer, alcohol-soluble tungsten oxide and preparation method thereof

Abstract

The invention belongs to the technical field of solar energy, and particularly relates to a perovskite solar cell with alcohol-soluble tungsten oxide as an electron transport layer, alcohol-soluble tungsten oxide and a preparation method thereof.The structure of the solar cell comprises a transparent anode, a hole transport layer, a perovskite absorption layer, a first electron transport layer and a second electron transport layer which are sequentially stacked from bottom to top, the first electron transport layer is prepared from an alcohol-soluble tungsten oxide dispersion liquid through spin coating, printing and slit coating processes, and the second electron transport layer is made of one of SnO2, ZnO, TiO2, C60, PC61BM, ZnSO4, CdS and CdSe. The tungsten-based organic derivative generates nanoscale tungsten oxide under the conditions of high temperature and high pressure, and the nanoscale tungsten oxide can be well dissolved in an alcohol organic solution to serve as electron transport layer spin-coating liquid, so that the blank that tungsten oxide cannot be effectively coated on perovskite is filled up.

Description

Technical Field

[0001] The invention belongs to the technical field of solar energy, and in particular relates to a perovskite solar cell using alcohol-soluble tungsten oxide as an electron transport layer, alcohol-soluble tungsten oxide and a preparation method thereof. Background Art

[0002] With the continuous development of science and technology, perovskite solar cells have gradually attracted widespread attention as an emerging technology. In perovskite solar cells, commonly used inorganic electron transport materials mainly include TiO2 and SnO2, which are usually dispersed in water and widely used in formal device structures. However, the application of these materials in trans structures is limited, mainly because water can destroy the perovskite structure, thereby narrowing their scope of use in the field of perovskite solar cells.

[0003] Tungsten oxide nanomaterials are widely used in the field of perovskite solar cells because they have a suitable energy level match with perovskite, high electron mobility, and are easy to synthesize and low in cost. Conventional tungsten oxide is made into an aqueous solution of ammonium tungstate, which is then spin-coated on the transparent electrodes of ITO (tin-doped indium oxide) and FTO (Fluorine-doped Tin Oxide). After calcination and annealing, a tungsten oxide film is formed. However, since it is an aqueous solution, it cannot be used on trans devices. Because in trans devices, the electron transport layer material is spin-coated on the perovskite coating, the water in the ammonium tungstate aqueous solution will destroy the perovskite coating, causing the perovskite to dissociate. Summary of the invention

[0004] The purpose of the present invention is to provide a perovskite solar cell with alcohol-soluble tungsten oxide as an electron transport layer, an alcohol-soluble tungsten oxide and a preparation method thereof, so as to solve the problem of limited application of tungsten oxide nanomaterials in inverse perovskite solar cells in the prior art.

[0005] The technical solution of the present invention is as follows:

[0006] A perovskite solar cell using alcohol-soluble tungsten oxide as an electron transport layer comprises a transparent anode, a hole transport layer, a perovskite absorption layer, a first electron transport layer, a second electron transport layer, and a cathode layer stacked in sequence from bottom to top, wherein the first electron transport layer is prepared by spin coating, printing, and slit coating of an alcohol-soluble tungsten oxide dispersion, and the second electron transport layer is made of SnO2, ZnO, TiO2, C 60 , PC 61 One of BM, ZnSO4, CdS, and CdSe.

[0007] A method for preparing alcohol-soluble tungsten oxide comprises the following steps:

[0008] S1. Mixing the tungsten precursor and the first solvent at 0-10° C. and stirring evenly to form a first reaction system;

[0009] S2. The hydrogen peroxide solution and the first reaction system are added dropwise at a uniform rate and mixed, and the mixture is reacted for 0.5-24 hours to obtain a transparent tungsten precursor solution;

[0010] S3. Mix the tungsten precursor, the ligand and a certain amount of ethylene glycol to make the molar concentration of the tungsten element 0.05-0.5 mol / L, place it in a hydrothermal reactor, the temperature is 100-200°C, react for 0.5-24h, and obtain a mother solution of tungsten oxide nanoparticles;

[0011] S4. The mother solution of tungsten oxide nanoparticles is dialyzed into water through a dialysis bag with a molecular weight of 1000-50000, and then freeze-dried into a powder to obtain alcohol-soluble tungsten oxide nanoparticles;

[0012] S5. Dispersing the tungsten oxide nanoparticles in an organic alcohol solvent to obtain an alcohol-soluble tungsten oxide dispersion.

[0013] Furthermore, the tungsten precursor described in S1 is tungsten powder, one of sodium tungstate and its hydrate, ammonium tungstate and its hydrate, lithium tungstate, potassium tungstate or cesium tungstate; the first solvent described in S1 is one of water, methanol and ethanol.

[0014] Furthermore, the hydrogen peroxide described in S2 is a 10-30 wt % hydrogen peroxide aqueous solution.

[0015] Furthermore, in terms of the amount of substance, the ratio of the tungsten precursor to hydrogen peroxide is 1:(1-10).

[0016] Furthermore, the ligand described in S3 is one or more of ethanolamine, acetic acid, glycolic acid, PEG200, PEG400, and PVP.

[0017] An alcohol-soluble tungsten oxide comprises an inorganic tungsten oxide and an organic ligand on the surface of the inorganic tungsten oxide.

[0018] Furthermore, the weight of the organic ligand accounts for 3%-20% of the whole.

[0019] Furthermore, the alcohol-soluble tungsten oxide has a particle size of 3-10 nm, a band gap of 2.5-3.5 eV, and an empty electron mobility of 0.1-20 cm 2 V -1 s -1 .

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention proposes an innovative perovskite solar cell structure, especially in the inverted perovskite solar cell, for the first time introduces a two-layer electron transport layer design. The first electron transport layer uses tungsten oxide nanomaterials, and the second electron transport layer has a variety of options, including SnO2, ZnO, TiO2, C 60 or PC 61 BM and other materials. This design not only effectively solves the problem of large energy barrier between perovskite and electron transport layer, but also reduces the energy barrier between electron transport layers and realizes ohmic contact.

[0022] In addition, the tungsten oxide alcohol solution prepared by the present invention successfully fills the gap that tungsten oxide cannot be effectively coated on perovskite, bringing new material selection and application possibilities to the field of perovskite solar cells. Alcohol-soluble tungsten oxide nanomaterials can form a dense film on the perovskite film, which helps to optimize the tiny gaps in the perovskite film, thereby reducing the series resistance. At the same time, the annealing temperature of the tungsten oxide film is low, only 80°C, which ensures that the structure of the perovskite will not be destroyed during the processing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of a double electron transport layer device of the present application.

[0024] Figure 2 This is a TEM image (Transmission Electron Microscope image) of tungsten oxide nanoparticles. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be further described below through the accompanying drawings and embodiments.

[0026] like Figure 1 As shown, the present invention provides a perovskite solar cell structure, which includes, from bottom to top, a transparent anode, a hole transport layer, a perovskite absorption layer, a first electron transport layer, a second electron transport layer, and a cathode layer.

[0027] The first electron transport layer is prepared by spin coating, printing, and slit coating of the alcohol-soluble tungsten oxide dispersion in the present application. The second electron transport layer material can be but is not limited to SnO2, ZnO, TiO2, C 60 , PC 61 BM, ZnSO4, CdS, CdSe (tin dioxide, zinc oxide, titanium oxide, fullerene / carbon 60, [6,6]-phenyl-C61-butyric acid methyl ester, zinc sulfate, cadmium sulfide, cadmium selenide) electron transport layer materials.

[0028] A method for preparing an alcohol-soluble tungsten oxide nanomaterial comprises the following steps:

[0029] S1. Mixing the tungsten precursor and the first solvent at 0-10° C. and stirring evenly to form a first reaction system;

[0030] S2. The hydrogen peroxide solution and the first reaction system are added dropwise at a uniform rate and mixed, and the mixture is reacted for 0.5-24 hours to obtain a transparent tungsten precursor solution;

[0031] S3. Mix the tungsten precursor, the ligand and a certain amount of ethylene glycol so that the mass concentration of the tungsten element is 0.05-0.5 mol / L, and place them in a hydrothermal reactor at a temperature of 100-200°C for 0.5-24 hours to obtain a mother solution of tungsten oxide nanoparticles;

[0032] S4. The mother solution of tungsten oxide nanoparticles is dialyzed into water through a dialysis bag with a molecular weight of 1000-50000, and then freeze-dried into powder to obtain alcohol-soluble tungsten oxide nanoparticles.

[0033] S5. The tungsten oxide nanoparticles can be dispersed in an organic alcohol solvent to obtain an alcohol-soluble tungsten oxide dispersion. The organic alcohol solvent can be selected from but not limited to one or more mixed solvents of ethanol, methanol, isopropanol, n-butanol, and isobutanol.

[0034] like Figure 2 As shown, the present invention also provides an alcohol-soluble tungsten oxide, and its structure is as follows: tungsten oxide nanoparticles include tungsten oxide inorganic matter and organic ligands on the surface of tungsten oxide. It is calculated that its band gap ranges from 2.5 to 3.5 eV. The particle size of the nanoparticles is 3 to 10 nm. The surface of the nanoparticles carries some organic ligands, which include but are not limited to: ethanolamine, acetic acid, glycolic acid, PEG200 (polyethylene 200), PEG400 (polyethylene 400), PVP (polyvinyl pyrrolidone) One or more. These ligands mainly play the role of dispersing WO3 into alcohol organic solvents. In terms of the amount of substance, n(O) / n(W) in the nanomaterial of the present application is between 3 and 2.9.

[0035] The tungsten oxide synthesis method in this application belongs to the hydrothermal reaction synthesis method, and its principle is based on the organic derivatives of tungsten under high temperature and high pressure conditions to generate nano-scale tungsten oxide, and can be well dissolved in alcohol organic solutions, acting as an electron transport layer spin coating liquid. In order to allow the tungsten precursor (tungsten powder, ammonium tungstate) to form a homogeneous solution in ethylene glycol, this application reacts the tungsten precursor with hydrogen peroxide to generate polyperoxytungstic acid, and then reacts with alcohols to generate tungstate derivatives, which can be well dissolved in ethylene glycol. In order to obtain tungsten oxide nanomaterials, this application uses a hydrothermal synthesis reaction to treat the ethylene glycol solution of tungstate derivatives, and successfully obtains 3-10nm tungsten oxide nanomaterials.

[0036] The particle size of the tungsten oxide nanomaterial in the present application is determined by the temperature and reaction time during the hydrothermal reaction. Generally speaking, the higher the temperature and the longer the time, the larger the particle size of the nanomaterial will be. The photoelectric performance of the nanomaterial is related to the particle size, and the device performance of 5-10nm tungsten oxide is the best.

[0037] Embodiment 1

[0038] S1. At 5°C, mix 1g of tungsten powder with 40ml of ethanol and stir evenly to form a first reaction system;

[0039] S2. 40 ml of 30 wt% hydrogen peroxide was added to the first reaction system at a drip rate of 40 ml / h and reacted for 12 h to obtain a transparent tungsten precursor solution;

[0040] S3. Mix 40 ml of tungsten precursor with 1 ml of ethanolamine and 40 ml of ethylene glycol, place in a hydrothermal reactor, and react at 150°C for 8 h to obtain a WO3 nanoparticle mother liquor;

[0041] S4. The WO3 nanoparticle mother solution was dialyzed into water through a dialysis bag (molecular weight 1000), and then freeze-dried into powder to obtain alcohol-soluble WO3 nanoparticles;

[0042] S5. The WO3 nanoparticles can be dispersed in an isopropanol solvent to prepare a tungsten oxide isopropanol dispersion with a concentration of 30 mg / ml.

[0043] Embodiment 2

[0044] S1. At 3°C, 1.8 g of sodium tungstate dihydrate was mixed with 100 ml of methanol and stirred evenly to form a first reaction system;

[0045] S2. 100 ml of 30 wt % hydrogen peroxide was added to the first reaction system at a drip rate of 100 ml / h and reacted for 15 h to obtain a transparent tungsten precursor solution;

[0046] S3. Mix 40 ml of tungsten precursor, 1.5 ml of acetic acid and 40 ml of ethylene glycol, place in a hydrothermal reactor, the temperature is 160 ° C, react for 8 hours, and obtain WO3 nanoparticle mother liquor;

[0047] S4. The WO3 nanoparticle mother solution was dialyzed into water through a dialysis bag (molecular weight 1000), and then freeze-dried into powder to obtain alcohol-soluble WO3 nanoparticles;

[0048] S5. The WO3 nanoparticles can be dispersed in an isopropanol solvent to prepare a tungsten oxide isopropanol dispersion with a concentration of 20 mg / ml.

[0049] Embodiment 3

[0050] S1. At 10°C, 17 g of ammonium tungstate pentahydrate was mixed with 100 ml of ethanol and stirred to form a first reaction system;

[0051] S2. 100 ml of 30 wt % hydrogen peroxide was added to the first reaction system at a drip rate of 100 ml / h and reacted for 18 h to obtain a transparent tungsten precursor solution;

[0052] S3. 100 ml of tungsten precursor, 5 ml of 5 wt% PVP ethanol solution and 100 ml of ethylene glycol were mixed and placed in a hydrothermal reactor at 180°C for 12 h to obtain a WO3 nanoparticle mother solution;

[0053] S4. The WO3 nanoparticle mother solution was dialyzed into water through a dialysis bag (molecular weight 5000), and then freeze-dried into powder to obtain alcohol-soluble WO3 nanoparticles;

[0054] S5. The WO3 nanoparticles can be dispersed in an isopropanol solvent to prepare a tungsten oxide isopropanol dispersion with a concentration of 25 mg / ml.

[0055] The first electron transport layer of the device is made from the tungsten oxide isopropanol dispersion of the above embodiment and applied to an inverted perovskite solar cell. The inverted perovskite solar cell comprises an ITO anode, a NiO x Hole transport layer, perovskite absorption layer, tungsten oxide electron transport layer, SnO2 electron transport layer and cathode gold.

[0056] Comparative Example 1

[0057] Ammonium tungstate is used to prepare a 2.5wt% tungsten precursor aqueous solution, which is spin-coated on an ITO substrate as an electron transport layer, and then a perovskite absorption layer, a nickel oxide electron transport layer and a cathode gold are prepared in sequence.

[0058] Comparative Example 2

[0059] The electron transport layer of the device is made from the tungsten oxide isopropanol dispersion of the first embodiment and applied to the inverse perovskite solar cell. The inverse perovskite solar cell comprises an ITO anode, a NiO x Hole transport layer, perovskite absorption layer, tungsten oxide electron transport layer and cathode gold.

[0060] The preparation method of an inverse perovskite solar cell comprises the following steps: spin coating an aqueous solution of nickel oxide on an IT0 anode layer, and then annealing at 100° C. for 10 min to form a hole transport layer; spin coating a perovskite solution on the hole transport layer as a carrier to form an absorption layer; spin coating an isopropanol dispersion of tungsten oxide nanomaterials in Example 1 on the absorption layer, and forming a first electron transport layer after drying; spin coating an isopropanol solution of SnO2 on the first electron transport layer to form a second electron transport layer; and finally vapor depositing an Au cathode electrode layer and encapsulating to form a perovskite solar cell device.

[0061] Inkjet printing method: In the above spin coating method, only the spin coating process is changed to inkjet printing into the perovskite light absorbing layer material, and the tungsten oxide layer material is annealed by a gradient temperature increase method under high vacuum conditions.

[0062] Table 1: Performance comparison of various embodiments

[0063]

[0064] Note: PCE: Power Conversion Efficiency.

[0065] The above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above descriptions. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the protection scope of the invention.

Claims

1. A perovskite solar cell using alcohol-soluble tungsten oxide as an electron transport layer, characterized in that: The invention comprises a transparent anode, a hole transport layer, a perovskite absorption layer, a first electron transport layer, a second electron transport layer, and a cathode layer stacked in sequence from bottom to top, wherein the first electron transport layer is prepared by spin coating, printing, and slit coating of an alcohol-soluble tungsten oxide dispersion, and the second electron transport layer is made of SnO2, ZnO, TiO2, C 60 , PC 61 One of BM, ZnSO4, CdS, and CdSe.

2. A method for preparing alcohol-soluble tungsten oxide, characterized in that: The following steps are involved: S1. Mixing the tungsten precursor and the first solvent at 0-10° C. and stirring evenly to form a first reaction system; S2. The hydrogen peroxide solution and the first reaction system are added dropwise at a uniform rate and mixed, and the mixture is reacted for 0.5-24 hours to obtain a transparent tungsten precursor solution; S3. Mix the tungsten precursor, the ligand and a certain amount of ethylene glycol to make the molar concentration of the tungsten element 0.05-0.5 mol / L, place it in a hydrothermal reactor, the temperature is 100-200°C, react for 0.5-24h, and obtain a mother solution of tungsten oxide nanoparticles; S4. The mother solution of tungsten oxide nanoparticles is dialyzed into water through a dialysis bag with a molecular weight of 1000-50000, and then freeze-dried into a powder to obtain alcohol-soluble tungsten oxide nanoparticles; S5. Dispersing the tungsten oxide nanoparticles in an organic alcohol solvent to obtain an alcohol-soluble tungsten oxide dispersion.

3. The method for preparing alcohol-soluble tungsten oxide according to claim 2, characterized in that: The tungsten precursor described in S1 is tungsten powder, one of sodium tungstate and its hydrate, ammonium tungstate and its hydrate, lithium tungstate, potassium tungstate or cesium tungstate; the first solvent described in S1 is one of water, methanol and ethanol.

4. The method for preparing alcohol-soluble tungsten oxide according to claim 2, characterized in that: The hydrogen peroxide described in S2 is a 10-30wt% hydrogen peroxide aqueous solution.

5. The method for preparing alcohol-soluble tungsten oxide according to claim 2, characterized in that: In terms of the amount of substance, the ratio of the tungsten precursor to hydrogen peroxide is 1:(1-10).

6. The method for preparing alcohol-soluble tungsten oxide according to claim 2, characterized in that: The ligand described in S3 is one or more of ethanolamine, acetic acid, glycolic acid, PEG200, PEG400, and PVP.

7. The alcohol-soluble tungsten oxide prepared by the preparation method according to any one of claims 2 to 6, characterized in that: It includes inorganic tungsten oxide and organic ligands on the surface of inorganic tungsten oxide.

8. The alcohol-soluble tungsten oxide according to claim 7, characterized in that: The weight of the organic ligand accounts for 3%-20% of the whole.

9. The alcohol-soluble tungsten oxide according to claim 7, characterized in that: The particle size is 3-10nm, the band gap is 2.5-3.5eV, and the empty electron mobility is 0.1-20cm 2 V -1 s -1 .

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