Hole transport layer, preparation method and perovskite solar cell

Abstract

The invention relates to a hole transport layer, a preparation method and a perovskite solar cell. The preparation method of the hole transport layer comprises the following steps: adding ethanol into an aqueous solution of nickel oxide to obtain a nickel oxide blade coating solution; performing blade coating on the nickel oxide blade coating solution in a nitrogen atmosphere to obtain the hole transport layer; the volume ratio of water to ethanol in the nickel oxide blade coating solution is 1: (1.5-2.2); the concentration of nickel oxide in the nickel oxide blade coating solution is 4-6 mg / mL. Ethanol is added into an aqueous solution of nickel oxide, the surface tension of the solution is reduced by breaking a hydrogen bond network of water through the ethanol, the wettability of the nickel oxide blade coating solution on a conductive glass substrate is improved, the obtained hole transport layer is good in uniformity, defects are reduced, and a film can be uniformly formed in large-area blade coating; and a more efficient and stable perovskite solar cell can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic material preparation, and particularly relates to a hole transport layer, a preparation method, and a perovskite solar cell. Background Art

[0002] As an emerging technology in the photovoltaic field, perovskite solar cells have outstanding advantages such as simple preparation process, low cost, and high photoelectric conversion efficiency. Therefore, they have become a current research hotspot in the photovoltaic field. Currently, the highest efficiency of perovskite solar cells can already be comparable to that of traditional silicon-based solar cells. Perovskite solar cells are divided into three types: mesoporous structure, normal (n-i-p) planar structure, and inverted (p-i-n) planar structure. Among them, the inverted structure adopts the preparation sequence of a hole transport layer, a perovskite light-absorbing layer, and an electron transport layer. For inverted perovskite solar cells, nickel oxide is a common hole transport layer, which has energy levels that match well with perovskite. However, most of the current preparation processes of nickel oxide are spin coating. The traditional spin coating method wastes a lot of materials, has poor uniformity, and cannot be applied to large-area components. Summary of the Invention

[0003] Aiming at the above problems existing in the prior art, the present invention provides a hole transport layer, a preparation method, and a perovskite solar cell, which can ensure the uniformity and coverage rate of the hole transport layer on the substrate to prepare a large-area and highly efficient inverted perovskite solar cell.

[0004] To achieve the above object, the technical solutions provided by the present invention are as follows:

[0005] In a first aspect, the present application provides a preparation method of a hole transport layer, including the following steps:

[0006] Adding ethanol to an aqueous solution of nickel oxide to obtain a nickel oxide doctor blade coating solution; doctor blade coating the nickel oxide doctor blade coating solution under a nitrogen atmosphere to obtain the hole transport layer;

[0007] The volume ratio of water to ethanol in the nickel oxide doctor blade coating solution is 1:(1.5 - 2.2); the concentration of nickel oxide in the nickel oxide doctor blade coating solution is 4 - 6 mg / mL.

[0008] Optionally, the doctor blade coating process parameters are as follows: Gap 60 - 100μm, wire bar moving speed 3 - 5mm / s, nickel oxide solution dropping amount 180 - 200μL.

[0009] Optionally, the nickel oxide doctor blade coating solution is doctor blade coated and then subjected to an annealing process to obtain the hole transport layer.

[0010] Optionally, the annealing process is treatment at 110 - 120°C for 15 min.

[0011] In a second aspect, the present application provides a hole transport layer obtained by the preparation method described in the first aspect.

[0012] In a third aspect, the present application provides a perovskite solar cell including the hole transport layer described in the second aspect.

[0013] Optionally, it further includes: a conductive glass substrate, a perovskite light-absorbing layer, an electron transport layer, and a metal electrode;

[0014] The conductive glass substrate is used to collect the holes transported by the hole transport layer and convey the holes to the external circuit;

[0015] The hole transport layer is obtained by spin-coating an oxidation nickel spin-coating solution on the conductive glass substrate, and is used to transport the holes generated by the perovskite light-absorbing layer to the conductive glass substrate;

[0016] The perovskite light-absorbing layer covers the hole transport layer and is used to absorb sunlight and generate electron-hole pairs;

[0017] The electron transport layer covers the perovskite light-absorbing layer and is used to transport the electrons generated by the perovskite light-absorbing layer to the metal electrode;

[0018] The metal electrode is disposed on the electron transport layer and is used to collect the electrons transported by the electron transport layer and is connected to the conductive glass substrate through an external circuit.

[0019] Optionally, the thickness of the hole transport layer is 20 - 40 nm; the thickness of the perovskite light-absorbing layer is 400 - 600 nm; the thickness of the electron transport layer is 20 - 80 nm; and the thickness of the metal electrode is 100 - 140 nm.

[0020] Optionally, the preparation method of the perovskite light-absorbing layer includes: spin-coating a perovskite precursor solution onto the hole transport layer by spin-coating; obtaining the perovskite light-absorbing layer after vacuum-assisted crystallization and annealing treatment; the perovskite precursor solution uses lead iodide, formamidinium iodide, and methylammonium chloride as solutes and N,N-dimethylformamide and N-methyl-2-pyrrolidone as solvents.

[0021] Optionally, the solute concentration in the perovskite precursor solution is 1 - 1.5 mol / L, and the molar ratio of lead iodide, formamidinium iodide, and methylammonium chloride is (2 - 3):1:(0.1 - 0.15).

[0022] Optionally, the electron transport layer is prepared by spin-coating a material including [6,6]-phenyl-C61-butyric acid isomethyl ester onto the perovskite light-absorbing layer.

[0023] Compared with the prior art, the present application has at least the following beneficial effects:

[0024] In the present invention, ethanol is added to an aqueous solution of nickel oxide. Ethanol disrupts the hydrogen bond network of water, reducing the surface tension of the solution and improving the wettability of the solution by nickel oxide when spin-coated on a conductive glass substrate. The obtained hole transport layer has good uniformity and fewer defects, and can form a uniform film during spin-coating over a large area (exceeding 100 cm 2 ).). By the method of the present invention, the hysteresis effect in perovskite solar cells can be effectively improved, thereby obtaining a more efficient and stable perovskite solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of a perovskite solar cell in an embodiment of the present invention;

[0026] Figure 2 is a comparison chart of JV curves of perovskite solar cells obtained in an embodiment of the present invention and a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0027] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] Embodiment:

[0029] The preparation of a perovskite solar cell is as follows:

[0030] Step 1: Prepare a nickel oxide spin-coating solution. The structural composition of the nickel oxide spin-coating solution is: nickel oxide, water, and ethanol, where the volume ratio of water to ethanol is 1:2, and the concentration of nickel oxide nanoparticles is 5 mg / ml.

[0031] Step 2: Spin-coat the nickel oxide spin-coating solution obtained in Step 1 onto a conductive glass substrate in a nitrogen glove box using a spin coater to prepare a hole transport layer. The spin-coating parameters are Gap 60 μm, the moving speed of the wire bar is 5 mm / s, and the dropping amount of the nickel oxide solution is 180 μL.

[0032] Step 3: Prepare a perovskite light-absorbing layer: The perovskite precursor solution is spin-coated (Gap is 200 microns) onto the hole transport layer obtained in Step 2;

[0033] Among them, the perovskite precursor solution: The solute is lead iodide, formamidinium iodide, and methylammonium chloride, and the solvent is a mixed solution of N,N-dimethylformamide and N-methyl-2-pyrrolidone (volume ratio 7:1);

[0034] The solute concentration of the perovskite precursor solution is 1.2 M; among them, the molar ratio of lead iodide, formamidinium iodide, and methylammonium chloride is 3:1:0.1.

[0035] Step 4: Use a doctor blade to scrape a 50-nm layer of [6,6]-phenyl-C61-butyric acid isopropyl ester on the surface of the perovskite light-absorbing layer obtained in Step 3, and then grow a 10-nm-thick SnO2 layer on the surface of [6,6]-phenyl-C61-butyric acid isopropyl ester to obtain an electron transport layer.

[0036] Step 5: Evaporate a 120-nm-thick Cu layer on the surface of the electron transport layer as the cathode electrode.

[0037] Comparative example:

[0038] The difference between this comparative example and the example is that water is used to replace an equal volume of ethanol in the nickel oxide doctor blade solution.

[0039] Perform reverse-scan current-voltage characteristic detection on the perovskite solar cell samples prepared in the examples (adding ethanol) and comparative examples (not adding ethanol) of the present invention.

[0040] The results are as Figure 2 shown. The perovskite solar cells prepared according to the method of the embodiments of the present application exhibit the best performance. The photoelectric conversion efficiency of a perovskite solar cell module with an area of 81 square centimeters reaches 18.6%, which is higher than 14.2% of the comparative example.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a hole transport layer, characterized in that It includes the following steps: Add ethanol to an aqueous solution of nickel oxide to obtain a nickel oxide spin-coating solution; spin-coat the nickel oxide spin-coating solution under a nitrogen atmosphere to obtain the hole transport layer; The volume ratio of water to ethanol in the nickel oxide spin-coating solution is 1:(1.5 - 2.2); the concentration of nickel oxide in the nickel oxide spin-coating solution is 4 - 6 mg / mL.

2. The preparation method of the hole transport layer according to claim 1, wherein The parameters of the spin-coating process are as follows: Gap 60 - 100μm, wire bar moving speed 3 - 5mm / s, nickel oxide solution dropping volume 180 - 200μL.

3. The preparation method of the hole transport layer according to claim 1, wherein The nickel oxide spin-coating solution is spin-coated and then annealed to obtain the hole transport layer.

4. A hole transport layer, characterized in that, Obtained by the preparation method according to any one of claims 1 - 3.

5. A perovskite solar cell, characterized in that, It includes the hole transport layer according to claim 4.

6. The perovskite solar cell according to claim 5, characterized in that It further includes: A conductive glass substrate, a perovskite light-absorbing layer, an electron transport layer, and a metal electrode; The conductive glass substrate is used to collect the holes transported by the hole transport layer and convey the holes to the external circuit; The hole transport layer is obtained by spin-coating the nickel oxide spin-coating solution on the conductive glass substrate, and is used to transport the holes generated by the perovskite light-absorbing layer to the conductive glass substrate; The perovskite light-absorbing layer covers the hole transport layer and is used to absorb sunlight and generate electron-hole pairs; The electron transport layer covers the perovskite light-absorbing layer and is used to transport the electrons generated by the perovskite light-absorbing layer to the metal electrode; The metal electrode is arranged on the electron transport layer and is used to collect the electrons transported by the electron transport layer and is connected to the conductive glass substrate through an external circuit.

7. The perovskite solar cell according to claim 6, wherein, The thickness of the hole transport layer is 20 - 40nm; the thickness of the perovskite light-absorbing layer is 400 - 600nm; the thickness of the electron transport layer is 20 - 80nm; the thickness of the metal electrode is 100 - 140nm.

8. The perovskite solar cell according to claim 6, wherein The preparation method of the perovskite light-absorbing layer includes: spin-coating the perovskite precursor solution onto the hole transport layer by spin-coating; obtaining the perovskite light-absorbing layer after vacuum-assisted crystallization and annealing treatment; the perovskite precursor solution uses lead iodide, formamidinium iodide, and methylammonium chloride as solutes, and N,N-dimethylformamide and N-methyl-2-pyrrolidone as solvents.

9. The perovskite solar cell according to claim 6, wherein The solute concentration in the perovskite precursor solution is 1 - 1.5mol / L, and the molar ratio of lead iodide, formamidinium iodide, and methylammonium chloride is (2 - 3):1:(0.1 - 0.15).

10. The perovskite solar cell according to claim 6, wherein The electron transport layer is prepared by spin-coating a material including [6,6]-phenyl-C61-butyric acid isopropyl ester on the perovskite light-absorbing layer.

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