A quasi-two-dimensional / three-dimensional heterojunction perovskite solar cell

Abstract

This invention discloses a quasi-two-dimensional / three-dimensional heterojunction perovskite solar cell. The cell structure, from the light-receiving front side to the light-receiving back side, sequentially includes a transparent conductive substrate, a hole transport layer, a wide-bandgap perovskite layer, a quasi-two-dimensional perovskite layer, an electron transport layer, and grid electrodes. The fabrication process of the quasi-two-dimensional perovskite layer involves: first, evaporating a lead iodide layer onto the wide-bandgap perovskite layer; then, forming a methylamine iodide layer onto the lead iodide layer; and finally, forming a two-dimensional perovskite organic ligand layer onto the methylamine iodide layer. This invention, by employing evaporation-assisted multi-step fabrication of the two-dimensional perovskite, can adjust the n-value of the two-dimensional perovskite, thereby regulating the surface energy level and avoiding charge blocking.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a quasi-two-dimensional / three-dimensional heterojunction perovskite solar cell prepared using evaporation-assisted fabrication. Background Technology

[0002] Organic-inorganic hybrid perovskites have become a promising new photovoltaic material due to their excellent photoelectric properties, such as tunable bandgap, long carrier lifetime, and low defect state density, combined with low-cost solution-based preparation. Perovskite / perovskite (or "all-perovskite") tandem solar cells, constructed by connecting wide / narrow bandgap perovskite sub-cells in series, offer the outstanding advantages of high efficiency and low cost, and are an effective way to overcome the Shockley-Queisser limit of single-junction perovskite solar cells. In perovskite / perovskite tandem solar cells, using a wide-bandgap perovskite as the top cell to absorb short-wavelength sunlight and a narrow-bandgap perovskite as the bottom cell to absorb long-wavelength sunlight improves the utilization of the solar spectrum and reduces the thermal relaxation loss of carriers in single-junction cells, thereby increasing the photoelectric conversion efficiency.

[0003] In recent years, the photoelectric conversion efficiency of all-perovskite tandem solar cells has surpassed the highest certified efficiency of 25.7% for single-junction perovskite solar cells. Currently, one of the main challenges in further developing all-perovskite tandem solar cells is achieving higher open-circuit voltages in wide-bandgap cells. In recent years, with advancements in quantitative analysis methods and in-depth research, the open-circuit voltage loss in wide-bandgap cells is more generally considered to be caused by non-radiative recombination, especially in perovskite / C0 series cells. 60 interface.

[0004] Another challenge limiting the development of perovskite tandem solar cells is the significant gap between current stability and commercialization standards. For ideally bandgap-matched perovskite tandem devices, wide-bandgap cells typically contain high levels of bromides, leading to severe photoinduced phase separation under continuous illumination. Furthermore, compared to bottom-narrow-bandgap cells, wide-bandgap cells are exposed to the entire incident spectrum, and their photostability has a considerable impact on the operating lifetime of the tandem cells.

[0005] In recent years, two-dimensional / three-dimensional (2D / 3D) heterojunction perovskites have been considered an effective method to improve efficiency and stability. In formal perovskite (nip) structures, 2D / 3D heterojunction structures deposited by spin-coating organic two-dimensional ligands onto the surface of three-dimensional perovskites can mitigate interfacial nonradiative recombination and promote hole transport. However, at the interface of inverted (pin) perovskites, 2D / 3D heterojunctions prepared by conventional spin-coating methods can actually hinder electron transport in the 3D perovskite at energy levels.

[0006] Therefore, developing a 2D / 3D heterojunction interface that can adjust energy levels, promote electron transport, and reduce nonradiative recombination at the interface is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a quasi-two-dimensional / three-dimensional heterojunction perovskite solar cell.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A quasi-two-dimensional / three-dimensional heterojunction perovskite solar cell, from the light-receiving front side to the light-receiving back side, comprises: a transparent conductive substrate, a hole transport layer, a wide-bandgap perovskite layer, a quasi-two-dimensional perovskite layer, an electron transport layer, and grid electrodes. The preparation process of the quasi-two-dimensional perovskite layer is as follows: first, a lead iodide layer is evaporated on the wide-bandgap perovskite layer, then a methyl iodide layer is formed on the lead iodide layer, and then a two-dimensional perovskite organic ligand layer is formed on the methyl iodide layer. The two-dimensional perovskite organic ligand is a long-chain alkylammonium cation or an arylammonium cation, selected from: ethylenediamine hydroiodide (EDAI2), n-butylammonium bromide (BABr), octylamine iodide (OAI), phenylethylamine iodide (PEAI), 4-fluorophenylethylamine iodide (4F-PEAI), benzylamine chloride (PMACl), or guanidine hydroiodide (GuaI).

[0009] like Figure 2-3 As shown, evaporated lead iodide (PbI2) and methylamine iodide (MAI) react completely to form MAPbI3 perovskite, which then reacts with a two-dimensional perovskite organic ligand (phenylethylamine iodide PEAI) to generate a quasi-two-dimensional perovskite layer with multiple n values. The methylamine iodide layer plays a crucial role in regulating the n value of the quasi-two-dimensional perovskite. Compared to traditional methods, directly spin-coating two-dimensional perovskite organic ligands onto the surface of a wide-bandgap perovskite can only form a wide-bandgap two-dimensional perovskite layer with n=1.

[0010] In one specific embodiment of the present invention, both the methyl iodide layer and the two-dimensional perovskite organic ligand layer are formed by a solution method (such as spin coating), and the annealing conditions are 100 degrees Celsius for 5 minutes. The methyl iodide layer and the two-dimensional perovskite organic ligand layer can also be formed by physical vapor deposition (such as evaporation), controlling the thickness until the reaction is complete to generate the two-dimensional perovskite.

[0011] Furthermore, the transparent conductive substrate is selected from indium tin oxide (ITO) substrate, indium tungsten oxide (IWO) substrate, fluorine-doped tin oxide (FTO) substrate, indium zinc oxide (IZO) substrate or aluminum-doped zinc oxide (AZO) substrate.

[0012] Furthermore, the hole transport layer is composed of a p-type semiconductor material. Specifically, the p-type semiconductor material is selected from nickel oxide (NiO), molybdenum oxide (MoO3), cuprous oxide (Cu2O), copper iodide (CuI), copper phthalocyanine (CuPc), cuprous thiocyanate (CuSCN), reduced graphene oxide, poly(triaryl amine) (PTAA), 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), poly(3,4-ethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS), poly(4-phenyl)(4-butylphenyl)amine (Ploy-TPD), or a monolayer.

[0013] Furthermore, the electron transport layer is composed of an n-type semiconductor material. Specifically, the n-type semiconductor material is selected from fullerenes (C... 60 ), graphene or fullerene derivative [6,6]-phenyl-C61-butyrate methyl ester (PCBM).

[0014] Furthermore, the material of the gate electrode is selected from gold, palladium, silver, titanium, chromium, nickel, aluminum or copper.

[0015] Compared with existing technologies, the two-dimensional / three-dimensional heterojunction wide-bandgap solar cell of the present invention has the following advantages: 1) By using evaporation-assisted multi-step preparation of two-dimensional perovskites, the n-value of the two-dimensional perovskites can be adjusted, thereby regulating the surface energy level and avoiding charge blockage; 2) Avoid the influence of the composition of three-dimensional perovskites on the formation of two-dimensional structures; 3) Reduced three-dimensional perovskite / C 60 Nonradiative recombination at the interface enables higher photoelectric conversion efficiency; 4) The acceleration of charge extraction and the reduction of nonradiative recombination have led to a significant improvement in stability. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the device structure of the quasi-two-dimensional / three-dimensional heterojunction wide-bandgap solar cell in Example 1.

[0017] Figure 2 This is a flowchart illustrating the fabrication process of the evaporation-assisted quasi-two-dimensional / three-dimensional heterojunction wide-bandgap solar cell in Example 1.

[0018] Figure 3 The images show the steady-state fluorescence spectra of the evaporation-assisted quasi-two-dimensional / three-dimensional heterojunctions and the two-dimensional / three-dimensional heterojunctions prepared by the conventional spin-coating method in Example 1. The laser wavelength was 532 nm and the intensity was 100 mW / cm².2 .

[0019] Figure 4 The current density-voltage curves are for the quasi-two-dimensional / three-dimensional heterojunction wide-bandgap solar cells prepared by evaporation assistance in Example 1. The tests were conducted at room temperature under full sunlight illumination (AM 1.5G, 100 mW cm⁻¹). -2 (This will be carried out under)

[0020] Figure 5 This is the long-term operational stability curve of the quasi-two-dimensional / three-dimensional heterojunction wide-bandgap solar cell prepared by evaporation assistance in Example 1. The test was conducted at room temperature under full sunlight illumination (AM 1.5G, 100 mW cm⁻¹). -2 Maximum power point tracking is performed on the packaged device. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but this should not be construed as limiting the present invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and substance of the invention are within the scope of the present invention. Experimental methods and reagents not specifically described in the embodiments are performed according to conventional conditions in the art. Example 1

[0022] The device structure in this embodiment is as follows: Figure 1 As shown, from the light-receiving front side to the light-receiving back side, it includes: a top electrode, a hole transport layer, a three-dimensional perovskite light-absorbing layer, a two-dimensional perovskite light-absorbing layer, an electron transport layer, and a back electrode.

[0023] The fabrication method of this device includes the following steps: 1. A layer of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) of about 20 nm was prepared on a cleaned ITO substrate as a hole transport layer.

[0024] 2. Deposit a wide-bandgap perovskite Cs layer on the prepared hole transport layer. 0.2 FA 0.8 Pb(I 0.6 Br 0.4 )3 serves as a three-dimensional perovskite light-absorbing layer with a thickness of approximately 400 nm.

[0025] 3. A layer of lead iodide (PbI2) with a thickness of about 10 nm is evaporated on the surface of a wide-bandgap perovskite.

[0026] 4. After depositing PbI2, spin-coat a layer of methylamine iodide (MAI) at a concentration of approximately 2 mg / ml and anneal at 100 degrees Celsius for 5 minutes.

[0027] 5. Spin-coat a layer of phenylethyl iodide (PEAI) at a concentration of approximately 2 mg / ml, and anneal at 100 degrees Celsius for 5 minutes.

[0028] 6. Preparation of a layer of fullerene (C1) using thermal evaporation. 60 As an electron transport layer, it is approximately 20 nm thick.

[0029] 7. Finally, a 150 nm thick Cu layer was deposited by thermal evaporation as the back gate electrode.

[0030] Introducing evaporation-assisted quasi-two-dimensional / three-dimensional heterojunction structures into wide-bandgap solar cells increases the photoelectric conversion efficiency from 16.7% to 19.0% (e.g., Figure 4 As shown in the figure, the device's turn-on voltage, current, and fill factor are significantly improved, which is the result of reduced non-radiative recombination at the interface and improved extraction; the operating stability (T 90 The time required for efficiency to decay to 90% of its initial value was increased from 385 hours to 1040 hours (e.g., Figure 5 As shown in the figure, this illustrates that the quasi-two-dimensional structure prepared by this method significantly enhances the operational stability of the device.

Claims

1. A quasi-two-dimensional / three-dimensional heterojunction perovskite solar cell, characterized in that: From the light-receiving front side to the light-receiving back side, the structure consists of: a transparent conductive substrate, a hole transport layer, a wide-bandgap perovskite layer, a quasi-two-dimensional perovskite layer, an electron transport layer, and a gate electrode. The preparation process of the quasi-two-dimensional perovskite layer is as follows: first, a lead iodide layer is evaporated on the wide-bandgap perovskite layer, then a methyl iodide layer is formed on the lead iodide layer, and then a two-dimensional perovskite organic ligand layer is formed on the methyl iodide layer. The two-dimensional perovskite organic ligands are selected from ethylenediamine hydroiodate, n-butylammonium bromide, octyl iodide, phenylethyl iodide, 4-fluorophenylethyl iodide, benzyl ammonium chloride, or guanidine hydroiodate.

2. The quasi-two-dimensional / three-dimensional heterojunction perovskite solar cell according to claim 1, characterized in that: The transparent conductive substrate is selected from indium tin oxide substrate, indium tungsten oxide substrate, fluorine-doped tin oxide substrate, indium zinc oxide substrate or aluminum-doped zinc oxide substrate.

3. The quasi-two-dimensional / three-dimensional heterojunction perovskite solar cell according to claim 1, characterized in that: The hole transport layer is made of a p-type semiconductor material.

4. The quasi-two-dimensional / three-dimensional heterojunction perovskite solar cell according to claim 1, characterized in that: The electron transport layer is made of an n-type semiconductor material.

5. The quasi-two-dimensional / three-dimensional heterojunction perovskite solar cell according to claim 1, characterized in that: The methyl iodide layer and the two-dimensional perovskite organic ligand layer are formed by solution method or physical vapor deposition method.

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