Self-assembled monolayers for trans- perovskite cells and methods of making and use thereof

Abstract

The application relates to a self-assembled monolayer for a trans-perovskite battery and a preparation method and application thereof. The self-assembled monolayer is arranged between a perovskite layer and a hole transport layer; the self-assembled monolayer is composed of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl] phosphonic acid molecules doped with tryptophan; the doping amount of the tryptophan is 0.1-10 mol%. The technical problem to be solved is how to provide a self-assembled monolayer which can optimize the interface performance of a trans-perovskite solar cell, so as to improve the photoelectric conversion efficiency and stability of the device.

Description

Technical Field

[0001] This invention belongs to the field of perovskite battery technology, and in particular relates to a self-assembled monolayer for inverted perovskite batteries, its preparation method, and its application. Background Technology

[0002] Perovskite solar cells, with their outstanding advantages in photoelectric conversion efficiency, manufacturing cost, and material availability, have become a prominent research focus in the field of solar cells. However, in the process of promoting practical applications, perovskite solar cells have encountered many challenging problems, among which the performance bottlenecks related to the cell interface are particularly prominent.

[0003] Specifically, the interface between the perovskite layer and the electron selection layer is poor, commonly exhibiting band mismatch and interface defects. These problems directly lead to low electron and hole extraction efficiency, negatively impacting the overall performance of the cell. Simultaneously, the poor interface condition also causes nonradiative recombination losses; electrons and holes readily recombine during transport, resulting in a significant reduction in photoelectric conversion efficiency. Furthermore, the interface stability of perovskite solar cells is also unsatisfactory, easily eroded by environmental factors such as moisture and oxygen, leading to material degradation, interface structural instability, and a series of other problems that severely affect the long-term stability and reliability of the cell. Summary of the Invention

[0004] The main objective of this invention is to provide a self-assembled monolayer for inverted perovskite solar cells, its preparation method, and its application. The technical problem to be solved is how to provide a self-assembled monolayer that can optimize the interface performance of inverted perovskite solar cells, thereby improving the photoelectric conversion efficiency and stability of the device.

[0005] The objective of this invention and the technical problem it solves are achieved by the following technical solution. According to this invention, a self-assembled monolayer for an inverted perovskite solar cell is provided, wherein the self-assembled monolayer is disposed between a perovskite layer and a hole transport layer; the self-assembled monolayer is composed of tryptophan-doped [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid molecules; the doping amount of tryptophan is 0.1–10 mol.

[0006] In one possible implementation, the doping amount of tryptophan is 5 mol.

[0007] The objective of this invention and the technical problem it solves are further achieved by the following technical solution. A method for preparing a self-assembled monolayer for an inverted perovskite solar cell, according to this invention, includes the following steps: S1. Dissolve tryptophan and [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid in isopropanol to obtain a mixed solution; S2. The mixed solution is coated onto the substrate surface and heated to obtain the self-assembled monolayer.

[0008] In one possible implementation, the concentration of the mixed solution is 0.5–1.5 mg / mL.

[0009] In one possible implementation, in step S2, the mixed solution is coated onto the substrate surface using spin coating or dip coating.

[0010] In one possible implementation, the mixed solution is coated onto the substrate surface using a spin coating method; the spin coating speed is 2000–3000 rpm; and the spin coating time is 25–35 s.

[0011] In one possible implementation, the heating temperature is 95–100°C; the heating time is 8–12 minutes.

[0012] The objective of this invention and the technical problem it solves are further achieved by the following technical solution. According to this invention, a trans-perovskite solar cell comprises, from bottom to top: a substrate, a hole transport layer, a perovskite layer, an electron transport layer, and an electrode; a self-assembled monolayer is disposed on the contact surface between the hole transport layer and the perovskite layer; the self-assembled monolayer is composed of tryptophan-doped [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid molecules; the doping amount of tryptophan is 0.1–10 mol.

[0013] In one possible implementation, the doping amount of tryptophan is 5 mol.

[0014] In one possible implementation, the self-assembled monolayer is the self-assembled monolayer for inverted perovskite solar cells as described in claim 1 or 2.

[0015] By employing the above technical solution, the self-assembled monolayer for inverted perovskite solar cells proposed in this invention, its preparation method, and its application have at least the following advantages: This application discloses a self-assembled monolayer for inverted perovskite solar cells. It primarily utilizes tryptophan-doped ME-4PACz molecules to construct a co-self-assembled monolayer, thereby improving the performance and stability of perovskite solar cells. By introducing the natural amino acid tryptophan into the ME-4PACz molecular structure for doping, this application constructs a composite molecular system with various intermolecular interactions such as π–π stacking and hydrogen bonding. This structure not only effectively improves the interface matching in perovskite solar cells but also enhances the electronic selectivity of the interface and suppresses non-radiative recombination losses.

[0016] The tryptophan-doped ME-4PACz molecules disclosed in this application can self-assemble into a monolayer on the NiOx surface. This monolayer has an ordered and dense structure, which can significantly improve the surface smoothness of the perovskite layer, improve crystal growth, reduce surface defects, and optimize the extraction efficiency of electrons and holes, thereby improving the performance and stability of perovskite solar cells.

[0017] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the inverse perovskite solar cell of the present invention, as well as the structural formula of tryptophan doping and ME-4PACz. Figure 2 This is a SEM image of the perovskite buried interface in Comparative Example 1 of the present invention. Figure 3 This is a SEM image of the perovskite buried interface in Example 1 of the present invention; Figure 4 This is a schematic diagram of the JV curves of the perovskite solar cells of Embodiment 1 and Comparative Example 1 of this invention. Figure 5 The images show the EIS test results of the perovskite solar cells of Example 1 and Comparative Example 1 of this invention. Detailed Implementation

[0019] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a self-assembled monolayer for inverted perovskite solar cells proposed according to the present invention, its preparation method, and its application. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable manner.

[0020] This invention proposes a self-assembled monolayer for inverted perovskite solar cells, wherein the self-assembled monolayer is disposed between a perovskite layer and a hole transport layer; the self-assembled monolayer is composed of tryptophan-doped [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid molecules; the doping amount of tryptophan is 0.1-10 mol.

[0021] This application discloses a self-assembled monolayer. This monolayer, disposed between the perovskite layer and the hole transport layer in an inverted perovskite solar cell, optimizes the interface matching between the two layers, reduces the interface energy barrier, suppresses non-radiative recombination losses, and thus improves the extraction efficiency of electrons and holes.

[0022] The self-assembled monolayer disclosed in this application is composed of tryptophan-doped [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid molecules. By introducing this monolayer, the interface matching can be significantly optimized, the selective extraction capability of electrons and holes can be effectively enhanced, and the non-radiative recombination loss at the interface can be greatly reduced, thereby improving the power conversion efficiency of inverted perovskite solar cells.

[0023] The tryptophan-doped ME-4PACz self-assembled monolayer disclosed in this application optimizes the crystal growth process of perovskite, resulting in more uniform grain size and higher crystal quality. This improves the flatness of the buried interface of the perovskite layer, fills surface defects and rough areas, and thus enhances the cell efficiency of inverted perovskite solar cells. Furthermore, the modified interface structure effectively promotes the extraction of holes from the perovskite layer to the electron-selective layer, thereby improving the cell's output current and power conversion efficiency.

[0024] In one possible implementation, the doping amount of tryptophan is 5 mol.

[0025] The 5 mol% doping amount of tryptophan mentioned in this application refers to: the tryptophan doping amount is 5% (molar ratio) of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (ME-4PACz).

[0026] This invention also proposes a method for preparing a self-assembled monolayer for inverted perovskite solar cells, the steps of which include: S1. Dissolve tryptophan and [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid in isopropanol to obtain a mixed solution; S2. The mixed solution is coated onto the substrate surface and heated to obtain the self-assembled monolayer.

[0027] In one possible implementation, the concentration of the mixed solution is 0.5–1.5 mg / mL.

[0028] In one possible implementation, in step S2, the mixed solution is coated onto the substrate surface using spin coating or dip coating.

[0029] In one possible implementation, the mixed solution is coated onto the substrate surface using a spin coating method; the spin coating speed is 2000–3000 rpm; and the spin coating time is 25–35 s.

[0030] In one possible implementation, the heating temperature is 95–100°C; the heating time is 8–12 minutes.

[0031] During the preparation process, the substrate is heat-treated, which induces ME-4PACz molecules and tryptophan-doped molecules to self-assemble into an ordered monolayer on the perovskite surface through intermolecular interactions such as hydrogen bonding and π-π stacking. This ordered structure helps reduce surface defects and significantly improves the smoothness of the perovskite layer.

[0032] This invention also proposes an inverse perovskite solar cell, such as... Figure 1 As shown, from bottom to top, it comprises: a substrate (ITO), a hole transport layer (HTL), a perovskite layer, an electron transport layer (ETL), and an electrode; a self-assembled monolayer is disposed on the contact surface between the hole transport layer and the perovskite layer; the self-assembled monolayer is composed of tryptophan-doped [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid molecules; the doping amount of tryptophan is 0.1–10 mol.

[0033] This application discloses an inverse perovskite solar cell containing the aforementioned self-assembled monolayer. The substrate is an ITO substrate; the hole transport layer is made of NiO. x The perovskite layer is made of normal bandgap perovskite, such as Cs. 0.05 FA 0.95 Pb(I 0.70 Br 0.30 )3, etc.; the material of the electron transport layer is C 60 The electrodes are made of gold or silver.

[0034] In one possible implementation, the doping amount of tryptophan is 5 mol.

[0035] In one possible implementation, the self-assembled monolayer is the self-assembled monolayer for inverted perovskite solar cells as described in claim 1 or 2.

[0036] This application discloses a trans-perovskite solar cell, the structure of which is as follows: Figure 1 As shown, its preparation method is as follows: 1. Substrate treatment: The ITO glass substrate was ultrasonically cleaned to remove potential surface contaminants such as residual solvents and dust. It was then cleaned with a cleaning agent (ethanol and deionized water) and dried with nitrogen. The dried ITO glass substrate was then subjected to ultraviolet light irradiation for 20 minutes and set aside for later use.

[0037] 2. Fabrication of the hole transport layer: Spin coating was used at a speed of 2000–3000 rpm for 30 seconds to coat 10 mg / ml NiO. x An aqueous solution was spin-coated onto the ITO surface and annealed for 10 minutes to obtain a hole transport layer.

[0038] 3. Preparation of self-assembled monolayers: 3.1 Preparation of self-assembled monolayer solutions: Tryptophan (Trp) and [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (ME-4PACz) were dissolved in isopropanol (IPA) to obtain a self-assembled monolayer solution; the concentration of the self-assembled monolayer solution was 0.5–1.5 mg / mL; preferably, the concentration of the self-assembled monolayer solution was 1 mg / mL.

[0039] 3.2 Spin-coated self-assembled monolayers: The self-assembled monolayer solution obtained in step 3.1 was uniformly coated onto the surface of the hole transport layer using spin coating or dip coating methods. Then, heating was applied to promote the self-assembly process at a temperature of 95–100 °C for 8–12 min, allowing ME-4PACz molecules to assemble on NiO. x An ordered monolayer is formed on the surface. Preferably, the coating is performed using a spin coating method; the spin coating speed is 2000-3000 rpm and the coating time is 30 s; preferably, the heating temperature is 100℃ and the heating time is 10 min.

[0040] 4. Then, the perovskite layer, electron transport layer, and electrodes are prepared using conventional techniques.

[0041] The present invention will be further described below with reference to specific embodiments, but this should not be construed as a limitation on the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention still fall within the scope of protection of the present invention.

[0042] Unless otherwise specified, all materials and reagents mentioned below are commercially available products well known to those skilled in the art; unless otherwise specified, all methods described are methods known in the art. Unless otherwise defined, the technical or scientific terms used should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0043] Example 1 A self-assembled monolayer for inverted perovskite solar cells is composed of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid molecules (ME-4PACz) doped with tryptophan (Trp). The doping amount of tryptophan is 0.1 mol%.

[0044] Its preparation method is as follows: Trp and ME-4PACz were dissolved in isopropanol (IPA) to obtain a self-assembled monolayer solution with a concentration of 1 mg / mL. Then, the self-assembled monolayer solution was spin-coated onto the surface of the hole transport layer using a spin-coating method with a spin-coating speed of 2500 rpm and a spin-coating time of 30 s. The solution was then heated to a temperature of 95–100 °C for 8–12 min to obtain the self-assembled monolayer.

[0045] Example 2 A self-assembled monolayer for inverted perovskite solar cells is composed of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid molecules (ME-4PACz) doped with tryptophan (Trp). The doping amount of tryptophan is 5 mol%.

[0046] Its preparation method is as follows: Trp and ME-4PACz were dissolved in isopropanol (IPA) to obtain a self-assembled monolayer solution with a concentration of 1 mg / mL. Then, the self-assembled monolayer solution was spin-coated onto the surface of the hole transport layer using a spin-coating method with a spin-coating speed of 2500 rpm and a spin-coating time of 30 s. The solution was then heated to a temperature of 95–100 °C for 8–12 min to obtain the self-assembled monolayer.

[0047] Example 3 A self-assembled monolayer for inverted perovskite solar cells is composed of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid molecules (ME-4PACz) doped with tryptophan (Trp). The doping amount of tryptophan is 10 mol%.

[0048] Its preparation method is as follows: Trp and ME-4PACz were dissolved in isopropanol (IPA) to obtain a self-assembled monolayer solution with a concentration of 1 mg / mL. Then, the self-assembled monolayer solution was spin-coated onto the surface of the hole transport layer using a spin-coating method with a spin-coating speed of 2500 rpm and a spin-coating time of 30 s. The solution was then heated to a temperature of 95–100 °C for 8–12 min to obtain the self-assembled monolayer.

[0049] Example 4 An inverted perovskite solar cell has a self-assembled monolayer for inverted perovskite solar cells, prepared in Example 2, disposed on the contact surface between the hole transport layer and the perovskite layer; specifically, it comprises, from bottom to top: an ITO substrate, a NiO layer, and a NiO layer. x Hole transport layer, self-assembled monolayer for inverted perovskite solar cells prepared in Example 2, material is Cs 0.05 FA 0.95 Pb(I 0.70 Br 0.30 The perovskite layer of 3 is made of C. 60 It has an electron transport layer and electrodes made of gold.

[0050] Comparative Example 1 Compared to Example 1, Comparative Example 1 is a conventional inverse perovskite solar cell, which does not contain a self-assembled monolayer. Its structure, from bottom to top, includes: an ITO substrate, a NiO layer, and so on. x Hole transport layer, material is Cs 0.05 FA 0.95 Pb(I 0.70 Br 0.30 The perovskite layer of 3 is made of C. 60 It has an electron transport layer and electrodes made of gold.

[0051] The perovskite buried interface in the inverse perovskite solar cells prepared in Example 4 and Comparative Example 1 was observed, and the results are as follows: Figure 2 and Figure 3 As shown, through Figure 2 It can be seen that the perovskite at the buried interface in Comparative Example 1 has poor crystal quality and a rougher surface. Through... Figure 3 It can be seen that the crystal quality of the perovskite buried interface in Example 1 is better than that in Comparative Example 1, with a smoother surface. This is because the tryptophan-doped ME-4PACz self-assembled monolayer introduced in this application optimizes the crystal growth process of the perovskite layer, resulting in more uniform grains and higher crystal quality. This improves the smoothness of the perovskite buried interface, fills surface defects and rough areas, and thus improves the cell efficiency of the inverted perovskite solar cell.

[0052] The photovoltaic performance and ESI of the inverted perovskite solar cells prepared in Example 4 and Comparative Example 1 were tested, and the results are as follows: Figure 4 and Figure 5 As shown, it can be seen that the inverted perovskite solar cell prepared in Example 4 outperforms the one prepared in Comparative Example 1 in all aspects of performance. This is due to the introduction of the tryptophan-doped ME-4PACz molecule self-assembled monolayer, which optimizes interface matching, effectively improves the selective extraction of electrons and holes, and significantly reduces the non-radiative recombination loss of electrons and holes at the interface, thus achieving superior electrical performance compared to Comparative Example 1.

[0053] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A self-assembled monolayer for inverted perovskite solar cells, characterized in that, The self-assembled monolayer is disposed between the perovskite layer and the hole transport layer; the self-assembled monolayer is composed of tryptophan-doped [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid molecules; the doping amount of tryptophan is 0.1-10 mol.

2. The self-assembled monolayer for inverted perovskite solar cells according to claim 1, characterized in that, The doping amount of tryptophan is 5 mol.

3. A method for preparing a self-assembled monolayer for inverted perovskite solar cells, characterized in that, The steps include: S1. Dissolve tryptophan and [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid in isopropanol to obtain a mixed solution; S2. The mixed solution is coated onto the substrate surface and heated to obtain the self-assembled monolayer.

4. The method for preparing a self-assembled monolayer for an inverted perovskite solar cell according to claim 3, characterized in that, The concentration of the mixed solution is 0.5–1.5 mg / mL.

5. The method for preparing a self-assembled monolayer for an inverted perovskite solar cell according to claim 3, characterized in that, In step S2, the mixed solution is coated onto the substrate surface using spin coating or dip coating.

6. The method for preparing a self-assembled monolayer for an inverted perovskite solar cell according to claim 5, characterized in that, The mixed solution is coated onto the substrate surface using a spin coating method; the spin coating speed is 2000-3000 rpm; the spin coating time is 25-35 s.

7. The method for preparing a self-assembled monolayer for an inverted perovskite solar cell according to claim 3, characterized in that, The heating temperature is 95–100°C; the heating time is 8–12 minutes.

8. A trans-perovskite solar cell, characterized in that, From bottom to top, it comprises: a substrate, a hole transport layer, a perovskite layer, an electron transport layer, and an electrode; a self-assembled monolayer is disposed on the contact surface between the hole transport layer and the perovskite layer; the self-assembled monolayer is composed of tryptophan-doped [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid molecules; the doping amount of tryptophan is 0.1–10 mol.

9. The inverse perovskite solar cell according to claim 8, characterized in that, The doping amount of tryptophan is 5 mol.

10. The inverse perovskite solar cell according to claim 8, characterized in that, The self-assembled monolayer is the self-assembled monolayer for inverted perovskite solar cells as described in claim 1 or 2.

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