2D perovskite solar cell with high-entropy structure and preparation method thereof

Abstract

The application provides a 2D perovskite solar cell with a high-entropy structure and a preparation method thereof, and comprises a high-entropy perovskite film as a 2D perovskite absorption layer; wherein large-size A-site organic spacer cations of the high-entropy perovskite film are composed of five kinds of linear alkyl dimethylammonium cations with carbon chain lengths of 2, 3, 4, 5 and 6 respectively in an equimolar ratio. Through an entropy-driven crystallization process, the application promotes the occupation of large-size A-site cations in disorder, effectively eliminates the low n value impurities commonly existing in conventional 2D perovskite, and induces the preferential growth of the crystal along the direction perpendicular to the substrate. The open-circuit voltage of the battery breaks through 1050 mV, the indoor efficiency is more than 35%, and the battery has excellent environmental stability, and is very suitable for self-powered applications of indoor micro-power-consumption electronic equipment such as Internet of Things sensors.

Description

Technical Field

[0001] This invention proposes a 2D perovskite solar cell with a high-entropy structure and its fabrication method, which relates to the field of thin-film solar cells. Background Technology

[0002] The explosive growth of the Internet of Things (IoT) and portable electronic devices urgently requires efficient indoor solar energy harvesting technologies. These devices typically need to operate stably for extended periods (years or even decades) under low light intensities (100-1000 lux), placing stringent demands on the photovoltaic (PV) equipment powering them. Specifically, such systems must achieve high low-light conversion efficiency, robust long-term environmental stability, and precise spectral matching, with an optimal bandgap shift of approximately 1.7-1.9 eV to the indoor spectrum. In this context, 2D organic-inorganic hybrid perovskites have emerged as ideal candidates for efficient and stable indoor PV. Compared to 3D perovskites, 2D perovskites exhibit superior intrinsic environmental stability, including excellent moisture / heat resistance and photostability, while suppressing ion migration and halide phase separation. Furthermore, the bandgap characteristics of 2D perovskites can be flexibly tuned through n-value engineering, making them ideal for optimizing performance under low-light conditions.

[0003] While 2D perovskites hold immense potential for photovoltaic applications, their actual performance remains limited by intrinsic material defects and insufficient control over phase distribution during thin film fabrication. The significant size difference between large A-site organic spacer cations (such as alkylammonium chains) and formamidinium cations often leads to poor film crystallinity and difficulty in controlling phase distribution. Specifically, this manifests as the simultaneous coexistence of multiple quantum well structures with different numbers of layers (i.e., different n values, such as n = 2, 3, 4, 5) within the film. This non-uniformity in phase distribution increases the bulk defect state density, thereby exacerbating trap-assisted nonradiative recombination under weak light conditions, becoming a key bottleneck restricting the improvement of indoor photoelectric conversion efficiency in 2D perovskite devices. Summary of the Invention

[0004] In view of this, in order to fill the gaps and deficiencies in the existing technology, this invention proposes a 2D perovskite solar cell with a high-entropy structure and its preparation method. The preparation method of this invention replaces the conventional single alkyl chain 2D perovskite structure with a high-entropy strategy of mixing multiple alkyl chains, effectively inducing the formation of a better crystal orientation of 2D perovskite, reducing the bulk defect density of perovskite, thereby improving the photovoltaic performance of 2D perovskite devices under indoor lighting conditions.

[0005] This invention proposes a 2D perovskite solar cell with a high-entropy structure and its fabrication method, comprising the following:

[0006] According to a first aspect of the present invention, a 2D perovskite solar cell with a high-entropy structure is provided, characterized in that the 2D perovskite solar cell uses a high-entropy state perovskite thin film as a 2D perovskite absorber layer; wherein the large-size A-site organic spacer cation of the high-entropy state perovskite thin film is composed of five straight-chain alkyl diammonium cations with carbon chain lengths of 2, 3, 4, 5 and 6 in an equimolar ratio.

[0007] Furthermore, the configurational entropy of the 2D perovskite absorber layer satisfies:

[0008] ΔS config ≥ 1.61R;

[0009] Where ΔS config Let R be the configuration entropy, and R be the ideal gas constant.

[0010] Furthermore, the high-entropy perovskite film does not contain the characteristic exciton absorption peaks corresponding to the n=2, n=3, or n=4 quantum well structures in the ultraviolet to visible absorption spectrum.

[0011] Furthermore, the high-entropy perovskite thin film is characterized by a preferred growth orientation perpendicular to the substrate direction within its crystal interior.

[0012] Furthermore, the high-entropy perovskite thin film comprises:

[0013] A type of (EDA) 0.2 PDA 0.2 BDA 0.2 PentDA 0.2 HDA 0.2 (FA)4Pb5I 16 The thickness of the high-entropy perovskite thin film is 340~350 nm.

[0014] Furthermore, the 2D perovskite solar cell also includes an FTO conductive substrate; wherein the thickness of the FTO conductive substrate is 190~200nm.

[0015] Furthermore, the 2D perovskite solar cell has an open-circuit voltage greater than 1050 mV and a photoelectric conversion efficiency greater than 35% during operation.

[0016] According to a second aspect of the present invention, the present invention provides a method for fabricating a 2D perovskite solar cell with a high-entropy structure, used to fabricate a 2D perovskite solar cell with a high-entropy structure as described in any one of the present invention, characterized in that the method for fabricating a 2D perovskite solar cell with a high-entropy structure includes the following:

[0017] The preparation method of 2D perovskites with high-entropy structures is as follows:

[0018] Under a nitrogen atmosphere, five organic salts—ethylenediamine dihydroiodate, propylenediamine dihydroiodate, butylamine dihydroiodate, pentanediamine dihydroiodate, and hexamethylenediamine dihydroiodate—were mixed with formamidinium hydroiodate and lead iodide in a precise molar ratio of 0.2:0.2:0.2:0.2:0.2:4:5 and dissolved in a 4:1 mixture of N,N-dimethylformamide and dimethyl sulfoxide to obtain Pb. 2+ A 1.0 mol / L solution of a 2D perovskite precursor with a high-entropy structure.

[0019] Furthermore, the method for fabricating a 2D perovskite solar cell with a high-entropy structure further includes the following:

[0020] The 2D perovskite precursor solution with high entropy structure was spin-coated onto the hole transport layer. Chlorobenzene was added dropwise as an antisolvent for extraction before the spin-coating was completed. The spin-coated film was annealed at 110°C for 20 minutes. The high configurational entropy effect induced by the mixing of multiple alkyl chains was used to promote the spontaneous formation of a single high n-value phase distribution and vertical orientation structure in the film.

[0021] The present invention has the following advantages:

[0022] This invention constructs a high-entropy structure by introducing mixed alkyl chains. Compared to conventional single-alkyl-chain 2D perovskites, this invention fundamentally reconstructs the microstructure of the A-site spacer layer in 2D perovskite films using the high-entropy effect. This high-entropy 2D perovskite film not only reduces bulk defects that restrict low-light performance but also establishes efficient vertical charge transport channels. Under 1000 lux indoor LED illumination, the device achieves an indoor efficiency exceeding 35% and an open-circuit voltage exceeding 1055 mV, while also exhibiting excellent environmental stability. This invention provides a simple and easy-to-implement control approach for the material design of high-performance indoor photovoltaic devices. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the device structure of the 2D perovskite solar cell with a high-entropy structure according to the present invention.

[0024] Figure 2 This is a SEM schematic diagram of the conventional 2D perovskite structure and the surface of a 2D perovskite solar cell with a high-entropy structure according to the present invention.

[0025] Figure 3 This is an XRD diagram of a conventional 2D perovskite solar cell and a 2D perovskite solar cell with a high-entropy structure according to the present invention.

[0026] Figure 4This is a schematic diagram of the ultraviolet-visible absorption spectra of the conventional 2D perovskite device and the 2D perovskite solar cell with a high-entropy structure of the present invention.

[0027] Figure 5 This is a schematic diagram of the JV curves of a conventional 2D perovskite device and a 2D perovskite solar cell with a high-entropy structure according to the present invention.

[0028] Figure 6 This is a schematic diagram of the device stability test of conventional 2D perovskite solar cells and 2D perovskite solar cells with high entropy structure of the present invention under conditions of 25°C and 30±5% RH. Detailed Implementation

[0029] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0030] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention; as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise; furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0032] like Figures 1 to 6 As shown, this invention proposes a 2D perovskite solar cell with a high-entropy structure and its fabrication method, including the following:

[0033] According to a first aspect of the present invention, a 2D perovskite solar cell with a high-entropy structure is provided, characterized in that the 2D perovskite solar cell uses a high-entropy state perovskite thin film as a 2D perovskite absorber layer; wherein the large-size A-site organic spacer cation of the high-entropy state perovskite thin film is composed of five straight-chain alkyl diammonium cations with carbon chain lengths of 2, 3, 4, 5 and 6 in an equimolar ratio.

[0034] In one embodiment of the present invention, the configurational entropy of the 2D perovskite absorber layer satisfies:

[0035] ΔS config ≥ 1.61R;

[0036] Where ΔS config Let R be the configuration entropy, and R be the ideal gas constant.

[0037] In one embodiment of the present invention, the high-entropy perovskite thin film does not contain characteristic exciton absorption peaks corresponding to quantum well structures of n = 2, n = 3, or n = 4 in the ultraviolet to visible absorption spectrum.

[0038] In one embodiment of the present invention, the high-entropy perovskite thin film is characterized by a preferred growth orientation perpendicular to the substrate direction within its crystal.

[0039] In one embodiment of the present invention, the high-entropy perovskite thin film comprises:

[0040] A type of (EDA) 0.2 PDA 0.2 BDA 0.2 PentDA 0.2 HDA 0.2 (FA)4Pb5I 16 The thickness of the high-entropy perovskite thin film is 340~350 nm.

[0041] Furthermore, the 2D perovskite solar cell also includes an FTO conductive substrate; wherein the thickness of the FTO conductive substrate is 190~200nm.

[0042] Furthermore, the 2D perovskite solar cell has an open-circuit voltage greater than 1050 mV and a photoelectric conversion efficiency greater than 35% during operation.

[0043] According to a second aspect of the present invention, the present invention provides a method for fabricating a 2D perovskite solar cell with a high-entropy structure, used to fabricate a 2D perovskite solar cell with a high-entropy structure as described in any one of the present invention, characterized in that the method for fabricating a 2D perovskite solar cell with a high-entropy structure includes the following:

[0044] The preparation method of 2D perovskites with high-entropy structures is as follows:

[0045] Under a nitrogen atmosphere, five organic salts—ethylenediamine dihydroiodide (EDADI), propylenediamine dihydroiodide (PDADI), butylamine dihydroiodide (BDADI), pentanediamine dihydroiodide (PentDADI), and hexamethylenediamine dihydroiodide (HDADI)—were mixed with formamidinium hydroiodide (FAI) and lead iodide (PbI₂) in a precise molar ratio of 0.2:0.2:0.2:0.2:0.2:4:5 and dissolved in a 4:1 mixture of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to obtain Pb. 2+ A 1.0 mol / L solution of a 2D perovskite precursor with a high-entropy structure.

[0046] In one embodiment of the present invention, the method for fabricating a 2D perovskite solar cell with a high-entropy structure further includes the following:

[0047] The 2D perovskite precursor solution with high entropy structure was spin-coated onto the hole transport layer. Chlorobenzene was added dropwise as an antisolvent for extraction before the spin-coating was completed. The spin-coated film was annealed at 110°C for 20 minutes. The high configurational entropy effect induced by the mixing of multiple alkyl chains was used to promote the spontaneous formation of a single high n-value phase distribution and vertical orientation structure in the film.

[0048] In addition to the above, the present invention also has related embodiments, including the following:

[0049] Fabrication of a 2D perovskite absorber layer with a high-entropy structure, including the following:

[0050] Perovskite absorber layers were prepared using a solution spin-coating method. First, a conventional perovskite precursor solution BDA(FA)4Pb5I with a molar ratio of 1:4:5 was prepared with n = 5. 16 The raw materials used were 1,4-butanediamine hydroiodate (BDADI), formamidinium hydroiodate (FAI), and PbI₂ in a molar ratio of 1:4:5. The solvent was a mixture of DMF and DMSO (volume ratio 4:1), in which Pb 2+ The concentration was 1.0 mol / L. High-entropy 2D perovskite layers were prepared by equimolar mixing of five alkylammonium iodides. The raw materials used were ethylenediamine dihydroiodate (EDADI), propylenediamine dihydroiodate (PDADI), butylamine dihydroiodate (BDADI), pentanediamine dihydroiodate (PentDADI), hexamethylenediamine dihydroiodate (HDADI), FAI, and PbI₂ in a molar ratio of 0.2:0.2:0.2:0.2:0.2:4:5, and the solvent was a mixture of DMF and DMSO (volume ratio 4:1), wherein Pb... 2+ The concentration was 1.0 mol / L. Subsequently, 15 mol% of methylammonium chloride (MACl) was added to the precursor solution to control the growth of the perovskite film. The perovskite solution was stirred at 70 °C for 2 hours and then cooled to room temperature for later use.

[0051] During the spin-coating of 2D perovskite films, the substrate was first rotated at 1000 rpm for 5 seconds, then the speed was increased to 6000 rpm for 30 seconds. 150 μL of chlorobenzene was dropped onto the center of the film 15 seconds before the end of the spin-coating. Immediately after spin-coating, the substrate was transferred to a hot plate and annealed at 110°C for 20 minutes to transform the film from an intermediate state into a highly crystalline black perovskite phase with vertical orientation.

[0052] like Figure 1 In one embodiment of the present invention, a high-entropy 2D perovskite solar cell is provided, which, along the incident light direction, sequentially includes an FTO substrate, a hole transport layer, a 2D perovskite high-entropy absorption layer, an electron transport layer, and an electrode.

[0053] In this embodiment, a conventional perovskite device (BDA(FA)4Pb5I) is prepared using a large-size A-site cation as an alkyl chain with a carbon chain length of 4. 16 A comparative experiment was conducted, and the following results were obtained:

[0054] High-entropy 2D perovskite morphology analysis: such as Figure 2 As shown, Figure 2 This is a schematic SEM image of the surface of a conventional 2D perovskite solar cell (left) and a 2D perovskite solar cell with a high-entropy structure (right) according to the present invention.

[0055] Compared to 2D-Control perovskites with a single alkyl chain structure, 2D-highentropy (2D-HE) perovskites form denser grains and reduce a large number of pores. This morphological change can be attributed to the good crystal orientation of the high-entropy structure.

[0056] Orientation analysis of high-entropy 2D perovskite crystals: Figure 3 XRD patterns of 2D-Control and 2D-HE perovskite films. Figure 3 The horizontal axis 2θ degree represents the diffraction angle, and the vertical axis Intensity (au) represents the diffraction intensity.

[0057] XRD revealed two main diffraction peaks at approximately 14.2° and 28.4°, corresponding to the (111) and (202) crystal planes, respectively. The 2D-HE perovskite exhibited higher diffraction peak intensities and a narrower full width at half maximum (FWHM) compared to the control group, indicating that the introduction of the high-entropy structure improved the crystallinity of the 2D perovskite. Furthermore, the ratio of the (202) to (111) crystal plane diffraction peak intensities in the 2D-Control was only 0.73, indicating a relatively random crystal orientation. In contrast, the high-entropy 2D perovskite film of this invention achieved a ratio of 0.84, demonstrating that the high-entropy effect induced preferred crystal growth along the direction perpendicular to the substrate, which significantly reduced carrier scattering during longitudinal transport.

[0058] High-entropy 2D perovskite phase purity analysis: Figure 4 The UV-Vis absorption spectra of 2D-Control and 2D-HE perovskite films are shown. Figure 4 The horizontal axis represents wavelength, and the vertical axis represents absorbance.

[0059] The 2D-Control film exhibits low-dimensional phase exciton absorption peaks at 580 nm, 630 nm, and 680 nm, corresponding to n = 2, n = 3, and n = 4, indicating severe phase separation within the film. These highly disordered low-n-value phases severely hinder carrier transport. However, in the 2D-HE perovskite film of this invention, these low-n-phase characteristic peaks completely disappear, retaining only a single absorption edge of the high-n-value phase. This demonstrates that introducing mixed alkyl chains can effectively suppress the random nucleation of phases with different n-values, thereby promoting a more uniform n-value distribution.

[0060] Performance testing of high-entropy 2D perovskite devices: such as Figure 5 As shown, the photovoltaic performance of the device was evaluated using indoor LED illumination (3000 K, @1000 lux), with an effective illumination area of ​​0.059 cm². 2 .in Figure 5 The horizontal axis represents voltage, and the vertical axis represents current density.

[0061] JV curve data were collected at a scan rate of 50 mV / s during both the forward scan (-0.05 to 1.2 V) and the reverse scan (1.2 to -0.05 V). In this embodiment, the open-circuit voltage of the original 2D perovskite device (comparative experiment) was 896 mV, and the short-circuit current was 0.137 mA cm⁻¹. -2 The fill factor is 71.3%, and the photoelectric conversion efficiency is 25.14%. In comparison, the open-circuit voltage of the high-entropy 2D perovskite device increases to 1055 mV, and the short-circuit current increases to 0.141 mA cm⁻¹. -2 The fill factor reaches 82.0%, and the photoelectric conversion efficiency is improved to 35.06%. Compared with the original conventional 2D perovskite device, the high-entropy junction perovskite device of the present invention has achieved a significant improvement in indoor photovoltaic performance.

[0062] Figure 6 Stability testing was conducted on 2D-Control and 2D-HE perovskite solar cells. Figure 5 The horizontal axis, Time, represents time, and the vertical axis, Normalized PCE, represents the normalized photoelectric conversion efficiency.

[0063] Under ambient conditions (25°C and 30±5% RH), the 2D-Control device retained only 82% of its initial efficiency after approximately 2100 hours, while the 2D-HE device retained 96% of its initial efficiency. The superior humidity stability of the 2D-DJ / RP device is attributed to a high-entropy strategy that effectively suppresses moisture erosion by enhancing the interaction between the organic spacer layer and the inorganic framework, thereby improving the long-term stability of the device.

[0064] The above are preferred embodiments of the present invention. Any changes made to the technical solution of the present invention that do not exceed the scope of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A 2D perovskite solar cell with a high-entropy structure, characterized in that, The 2D perovskite solar cell uses a high-entropy perovskite thin film as the 2D perovskite absorber layer; wherein the large-size A-site organic spacer cation of the high-entropy perovskite thin film is composed of five straight-chain alkyl diammonium cations with carbon chain lengths of 2, 3, 4, 5 and 6 in an equimolar ratio.

2. A 2D perovskite solar cell with a high-entropy structure according to claim 1, characterized in that, The configurational entropy of the 2D perovskite absorber layer satisfies: ΔS config ≥ 1.61R; Where ΔS config Let R be the configuration entropy, and R be the ideal gas constant.

3. A 2D perovskite solar cell with a high-entropy structure according to claim 1, characterized in that, The high-entropy perovskite film described herein does not contain characteristic exciton absorption peaks corresponding to quantum well structures of n = 2, n = 3, or n = 4 in its ultraviolet to visible absorption spectrum.

4. A 2D perovskite solar cell with a high-entropy structure according to claim 1, characterized in that, The high-entropy perovskite thin film is characterized by a preferred growth orientation perpendicular to the substrate direction within the crystal.

5. A 2D perovskite solar cell with a high-entropy structure according to claim 1, characterized in that, The high-entropy perovskite thin film includes a thin film as follows: (EDA) 0.2 PDA 0.2 USA 0.2 PentDA 0.2 HDA 0.2 )(FA)4Pb5I 16 thin film The thickness of the high-entropy perovskite film is 340~350 nm.

6. A 2D perovskite solar cell with a high-entropy structure according to claim 1, characterized in that, The 2D perovskite solar cell also includes an FTO conductive substrate; wherein the thickness of the FTO conductive substrate is 190~200nm.

7. A 2D perovskite solar cell with a high-entropy structure according to claim 1, characterized in that, The 2D perovskite solar cell described above has an open-circuit voltage greater than 1050 mV and a photoelectric conversion efficiency greater than 35% when in operation.

8. A method for fabricating a 2D perovskite solar cell with a high-entropy structure, used to fabricate a 2D perovskite solar cell with a high-entropy structure as described in any one of claims 1 to 7, characterized in that, The method for fabricating a 2D perovskite solar cell with a high-entropy structure includes the following: The preparation method of 2D perovskites with high-entropy structures is as follows: Under a nitrogen atmosphere, five organic salts—ethylenediamine dihydroiodate, propylenediamine dihydroiodate, butylamine dihydroiodate, pentanediamine dihydroiodate, and hexamethylenediamine dihydroiodate—were mixed with formamidinium hydroiodate and lead iodide in a precise molar ratio of 0.2:0.2:0.2:0.2:0.2:4:5 and dissolved in a 4:1 mixture of N,N-dimethylformamide and dimethyl sulfoxide to obtain Pb. 2+ A 1.0 mol / L solution of a 2D perovskite precursor with a high-entropy structure.

9. The method for fabricating a 2D perovskite solar cell with a high-entropy structure according to claim 8, characterized in that, The method for fabricating a 2D perovskite solar cell with a high-entropy structure further includes the following: The 2D perovskite precursor solution with high entropy structure was spin-coated onto the hole transport layer. Chlorobenzene was added dropwise as an antisolvent for extraction before the spin-coating was completed. The spin-coated film was annealed at 110°C for 20 minutes. The high configurational entropy effect induced by the mixing of multiple alkyl chains was used to promote the spontaneous formation of a single high n-value phase distribution and vertical orientation structure in the film.

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