Co-adsorption hole transport layer material and perovskite solar cell

Abstract

The invention belongs to the technical field of perovskite solar cells, particularly provides a co-adsorption hole transport layer material and a perovskite solar cell, and aims to solve the problems of energy level mismatch, high defect state density, serious non-radiative recombination loss and the like of a buried interface in an existing trans-broadband gap perovskite solar cell. Therefore, the technical bottlenecks of device open-circuit voltage attenuation, filling factor reduction and poor performance and stability are overcome. According to the invention, aromatic co-adsorption molecules are introduced and form the co-adsorption hole transport layer material together with carbazolyl phosphonic acid self-assembly hole transport layer molecules, so that the characteristics of a buried interface can be optimized, the comprehensive performance of a device can be improved, and meanwhile, a perovskite solar cell containing the material is provided.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, specifically providing a co-adsorption hole transport layer material and a perovskite solar cell. Background Technology

[0002] As a core carrier of clean and renewable energy, solar energy's efficient conversion technology is a key direction for addressing the global energy crisis and environmental problems. Under this premise, perovskite solar cells (PSCs), with their advantages such as tunable bandgap, high light absorption coefficient, long carrier diffusion length, and low-temperature solution fabrication, have become a research hotspot in the photovoltaic field over the past decade. Compared to traditional upright structures, inverted perovskite solar cells have significant advantages in performance stability, fabrication process, compatibility, and application scenarios. Currently, the publicly reported photoelectric conversion efficiency of inverted single-junction perovskite solar cells has reached 27.0%.

[0003] In inverted perovskite solar cells, the bandgap of wide-bandgap perovskite solar cells is between 1.65 and 2.0 eV. This allows them to be combined with silicon and narrow-bandgap perovskite solar cells to form tandem cells, achieving full-spectrum absorption of the solar spectrum and enabling more efficient energy conversion. However, the buried interface of wide-bandgap perovskite solar cells generally suffers from critical problems such as severe nonradiative recombination losses due to energy level mismatch and high defect state density. These problems directly cause open-circuit voltage decay and reduced fill factor, severely impacting the performance and stability of wide-bandgap perovskite solar cells. In existing technologies, single interface modification or transport layer material optimization often fails to simultaneously address both issues. Therefore, developing a novel interface material or strategy that can synergistically solve energy level mismatch and interface defects is crucial for unlocking the full potential of wide-bandgap perovskite solar cells. Summary of the Invention

[0004] The purpose of this invention is to provide a co-adsorbed hole transport layer material and a perovskite solar cell to address the problems of energy level mismatch, high defect state density, and severe non-radiative recombination loss at the buried interface in existing inverted wide-bandgap perovskite solar cells. This overcomes the technical bottlenecks of device open-circuit voltage decay, reduced fill factor, and poor performance and stability. This invention introduces aromatic co-adsorbed molecules to form a co-adsorbed hole transport layer material with carbazole-phosphonic acid self-assembled hole transport layer molecules. This optimizes the buried interface characteristics, improves the overall device performance, and proposes a perovskite solar cell incorporating this material.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A co-adsorbed hole transport layer material, characterized in that the co-adsorbed hole transport layer material comprises carbazole phosphonic acid self-assembled hole transport layer molecules and aromatic co-adsorbed molecules, wherein:

[0007] The carbazolylphosphonic acid self-assembled hole transport molecule is one of (2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl)phosphonic acid (MeO-2PACz) and (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz);

[0008] The aromatic co-adsorbent molecule is one of 4-methoxybenzoic acid (4-MBA) and (4-methoxyphenyl)trimethoxysilane (MPTS).

[0009] Furthermore, the weight ratio of the carbazophosphonic acid self-assembled hole transport layer molecule to the aromatic co-adsorbed molecule is 9:1-6:4.

[0010] Furthermore, the weight ratio of the carbazophosphonic acid self-assembled hole transport layer molecule to the aromatic co-adsorbed molecule is 8:2.

[0011] Meanwhile, based on the aforementioned co-adsorbed hole transport layer material, the present invention also provides a perovskite solar cell, comprising: a transparent conductive glass 1, a hole transport layer 2, a perovskite light-absorbing layer 3, an electron transport layer 4, and a metal electrode 5 stacked sequentially from bottom to top, characterized in that the hole transport layer is a co-adsorbed hole transport layer formed from the aforementioned co-adsorbed hole transport layer material.

[0012] Furthermore, the thickness of the co-adsorbed hole transport layer is 3-10 nm.

[0013] Furthermore, the co-adsorbed hole transport layer is prepared by the following steps:

[0014] The co-adsorption hole transport layer material was mixed with anhydrous ethanol to prepare a co-adsorption hole transport layer solution.

[0015] The co-adsorbed hole transport layer solution is spin-coated onto the surface of a conductive glass substrate, and then annealed at 100-200 °C for 10-20 min to form the co-adsorbed hole transport layer.

[0016] Based on the above technical solution, the beneficial effects of the present invention are as follows:

[0017] This invention creatively proposes a co-adsorption strategy, introducing aromatic co-adsorbed molecules and carbazole phosphonic acid-based hole transport molecules to form a co-adsorbed hole transport layer material. On one hand, the aromatic co-adsorbed molecules can dissociate into micelles or clusters of carbazole phosphonic acid-based hole transport molecules in solution, thereby increasing the single-molecule concentration of carbazole phosphonic acid-based hole transport molecules in solution and improving their coverage on the substrate. On the other hand, the aromatic co-adsorbed molecules can fill the sites on the substrate not covered by carbazole phosphonic acid-based hole transport molecules, achieving dense deposition of the hole transport layer, reducing direct contact between the perovskite light-absorbing layer and the conductive glass substrate, optimizing the energy level alignment at the buried interface, passivating interface defects, reducing defect density at the buried interface, and reducing non-radiative recombination losses. Ultimately, this improves the problems of energy level mismatch, high defect state density, and severe non-radiative recombination losses at the buried interface in existing inverted wide-bandgap perovskite solar cells, effectively improving the voltage output and charge collection efficiency of the corresponding perovskite solar cells, and increasing the photoelectric conversion efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a perovskite solar cell in the embodiments and comparative examples of the present invention, wherein 1-transparent conductive glass, 2-hole transport layer, 3-perovskite light-absorbing layer, 4-electron transport layer, and 5-metal electrode.

[0019] Figure 2 These are morphology images of the hole transport layer thin film surface in Embodiment 1 and Comparative Example 1 of the present invention, wherein... Figure 2 Image (a) is a Kelvin probe force microscope (KPFM) image. Figure 2 (b) is an atomic force microscope (AFM) image.

[0020] Figure 3 These are photographs of the water contact angle on the surface of the hole transport layer film in Embodiment 1 and Comparative Example 1 of the present invention.

[0021] Figure 4 These are morphological images of the buried interface of the perovskite thin film in Example 1 and Comparative Example 1 of the present invention, taken under a scanning electron microscope (SEM).

[0022] Figure 5 These are morphological images of the buried interface of the perovskite thin film in Example 1 and Comparative Example 1 of the present invention, taken under an atomic force microscope (AFM).

[0023] Figure 6 The images show the photoluminescence spectrum (PLmapping) of the buried interface of the perovskite thin film in Example 1 and Comparative Example 1 of this invention.

[0024] Figure 7Box plots showing the photovoltaic performance of perovskite solar cells in Example 1 and Comparative Example 1 of this invention.

[0025] Figure 8 The figures show the current-voltage (JV) curves of the perovskite solar cells in Embodiment 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. In addition, unless otherwise defined, the technical terms used in this invention have the same meaning as commonly understood by those skilled in the art; all raw materials, reagents, instruments, and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0027] Example 1

[0028] This embodiment provides a perovskite solar cell, the structure of which is as follows: Figure 1 As shown, the perovskite solar cell includes, from bottom to top, a transparent conductive glass 1 (ITO), a hole transport layer 2, a perovskite light-absorbing layer 3, and an electron transport layer 4 (lithium fluoride LiF, C). 60 With BCP) and metal electrode layer 5 (Ag); wherein, the hole transport layer is a co-adsorbed hole transport layer, composed of 2PACz and MPTS in a weight ratio of 8:2; furthermore, in order to achieve good current matching between the perovskite light-absorbing layer and the silicon heterojunction bottom cell, the composition of the perovskite light-absorbing layer is FA. 0.80 MA 0.15 CS 0.05 Pb(Br 0.23 I 0.77 )3, the band gap of the perovskite light-absorbing layer film prepared by it is 1.68eV.

[0029] The preparation process of the co-adsorbed hole transport layer is as follows: 0.8 mg 2PACz and 0.2 mg MPTS are dissolved in 1 ml anhydrous ethanol and magnetically stirred for 30 min at room temperature to obtain a co-adsorbed hole transport layer solution; the co-adsorbed hole transport layer solution is spin-coated onto the surface of the conductive glass substrate, and then annealed at 100-200 °C for 10-20 min to form a co-adsorbed hole transport layer with a thickness of 3-10 nm.

[0030] Furthermore, the preparation process of the perovskite light-absorbing layer is as follows: FA 0.80 MA 0.15 CS 0.05 Pb(Br 0.23 I0.77 )3 was mixed with N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) and magnetically stirred at room temperature for 12 h to obtain a perovskite precursor solution. The perovskite precursor solution was spin-coated onto the upper surface of the co-adsorbed hole transport layer and annealed on a hot stage at 100 °C for 20 min to obtain a perovskite light-absorbing layer film with a thickness of about 500 nm.

[0031] Furthermore, in a vacuum evaporation coating system, at 1×10 -4 1 nm LiF and 10 nm C were sequentially deposited under a vacuum of Pa. 60 A 1.5 nm BCP is deposited to form an electron transport layer, followed by the deposition of a 120 nm Ag layer as a metal electrode layer, thus obtaining a complete perovskite solar cell device.

[0032] Example 2

[0033] This embodiment provides a perovskite solar cell, which is prepared according to the method described in Example 1, except that the amounts of 2PACz and MPTS are adjusted to 0.9 mg and 0.1 mg respectively during the preparation of the co-adsorbed hole transport layer, that is, the weight ratio of 2PACz to MPTS is adjusted to 9:1.

[0034] Example 3

[0035] This embodiment provides a perovskite solar cell, which is prepared according to the method described in Example 1, except that the amounts of 2PACz and MPTS are adjusted to 0.7 mg and 0.3 mg respectively during the preparation of the co-adsorbed hole transport layer, that is, the weight ratio of 2PACz to MPTS is adjusted to 7:3.

[0036] Example 4

[0037] This embodiment provides a perovskite solar cell, implemented according to the method described in Embodiment 1, except that MPTS is replaced with 4-MBA of the same weight.

[0038] Comparative Example 1

[0039] This embodiment provides a perovskite solar cell. The preparation process is the same as that in Example 1, except that the hole transport layer solution uses only 2 PACz with a concentration of 1 mg / mL.

[0040] The beneficial effects of the present invention will be described in detail below with reference to the analysis and testing of Example 1 and Comparative Example 1.

[0041] To more intuitively illustrate the influence of the co-adsorbed hole transport layer provided by this invention on the characteristics of the buried interface, the hole transport layer films prepared in Example 1 and Comparative Example 1 were characterized, such as... Figure 2 As shown. Figure 2 As shown in (a), the Kelvin probe force microscopy results indicate that the surface potential distribution of the co-adsorbed self-assembled hole transport layer film in Example 1 is significantly more uniform than that in Comparative Example 1. This suggests that the introduction of MPTS molecules effectively fills the ITO substrate sites that were not covered by 2PACz molecules, forming a denser and more uniform monolayer and reducing interfacial charge traps. Simultaneously, the film in Example 1 exhibits a lower average surface potential, a change that helps optimize the energy level structure and create a built-in electric field more conducive to hole extraction and transport. Figure 2 As shown in (b), the co-adsorbed self-assembled hole transport layer film of Example 1 exhibits lower surface roughness, as revealed by atomic force microscopy. The smooth interface facilitates the subsequent deposition of higher-quality perovskite crystal films and reduces non-radiative recombination centers at the interface. Furthermore, as... Figure 3 As shown in the contact angle test results, the contact angle of Example 1 (51.3°) is higher than that of Comparative Example 1 (42.1°). The increase in contact angle proves that MPTS molecules effectively fill the gaps of 2PACz molecules, significantly improving the coverage and density of the hole transport layer on the ITO substrate. The more complete coverage can effectively block the direct contact between the perovskite layer and the substrate, which is crucial for reducing interfacial recombination.

[0042] Meanwhile, the buried interface of the perovskite light-absorbing layer film prepared in Example 1 and Comparative Example 1 was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and photoluminescence (PL). First, the buried interface after the perovskite layer was peeled off (i.e., the exposed hole transport layer and the bottom of the perovskite crystal attached thereon) was characterized by SEM, as shown below. Figure 4 As shown, in the sample of Comparative Example 1, numerous incompletely covered blank areas and fine grains were observed at the interface, indicating incomplete coverage of the 2PACz monolayer, leading to uneven perovskite nucleation. In contrast, the sample of Example 1 exhibited significantly improved coverage, with larger and more uniformly distributed perovskite grains and a continuous and dense interface. This demonstrates that the co-adsorption of MPTS molecules effectively filled the gaps between 2PACz molecules, forming a more complete template, thereby guiding the formation of high-quality buried interface crystallization of perovskite. Furthermore, the three-dimensional morphology and roughness of the buried interface were quantitatively analyzed using atomic force microscopy (AFM), such as... Figure 5As shown, the AFM images and SEM results corroborate each other. The perovskite buried interface of Example 1 has a lower surface roughness (RMS), while the interface of Comparative Example 1 shows more protrusions and pits, corresponding to the non-uniform coverage observed in SEM. The smoother interface morphology means fewer interface charge recombination centers, which is beneficial for the efficient extraction and transport of charge carriers.

[0043] To verify the improvement in interface quality from the perspective of optoelectronic performance, this invention conducted photoluminescence (PL mapping) spectroscopy testing, and the results are as follows: Figure 6 As shown, the PL intensity of the perovskite film deposited on the co-adsorption hole transport layer of Example 1 is significantly higher than that of the film deposited on the single hole transport layer of Comparative Example 1. The significant enhancement of the PL mapping image intensity indicates a reduction in non-radiative recombination channels in the film. The combined results of SEM and AFM strongly confirm that the co-adsorption strategy effectively passivates defects on the substrate surface by forming a denser and flatter interface and optimizes the crystallization process of perovskite, thereby significantly reducing the defect density of the perovskite light-absorbing layer, especially at its buried interface, and greatly suppressing the non-radiative recombination loss of photogenerated carriers.

[0044] In summary, through the mutual corroboration of SEM, AFM, and PL characterization methods, it can be concluded that the introduction of MPTS as a co-adsorbed molecule to form a co-adsorbed hole transport layer significantly improves the physical coverage and morphology of the buried interface through synergistic self-assembly effects, resulting in a denser and smoother interface contact and effectively reducing the interface defect density. This lays a solid foundation for reducing interface recombination and improving the optoelectronic performance of the device. Furthermore, data from Examples 1-3 show that when the mass ratio of 2PACz to MPTS is in the range of 9:1 to 7:3, the device maintains excellent performance, with 8:2 being the optimal ratio. Moreover, Example 4, using 4-MBA as a co-adsorbed molecule, also achieved good results, demonstrating the universality of the aromatic co-adsorbed molecule selection in this invention.

[0045] Based on this, the current density-voltage (JV) characteristics of the perovskite solar cells prepared in Example 1 and Comparative Example 1 were tested, and the results are as follows: Figure 7 and Figure 8 As shown.

[0046] like Figure 7 The figure shows the key performance parameters of the device (V). OC J SC The statistical distribution of (FF, PCE) shows that the parameters of the device in Example 1 not only have higher average values, but also more concentrated data distribution, which proves the dual advantages of the co-adsorption strategy of the present invention in improving performance and ensuring batch stability.

[0047] like Figure 8 The JV curves of Example 1 and Comparative Example 1 are shown in the comparison. The test results show that Example 1, which uses a co-adsorption hole transport layer, is significantly better than Comparative Example 1 in terms of open-circuit voltage and fill factor. Specifically, the open-circuit voltage increases from 1.26 V to 1.28 V, the fill factor increases from 80.27% to 81.60%, and the short-circuit current density increases from 21.15 mA·cm⁻¹. -2 Increased to 21.31 mA·cm -2 This performance characteristic indicates that the co-adsorbed hole transport layer material effectively improves the voltage output and charge collection efficiency of the device by optimizing the interface energy level alignment and reducing charge recombination loss, ultimately increasing the photoelectric conversion efficiency from 21.49% to 22.35%.

[0048] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A co-adsorbed hole transport layer material, characterized in that, The co-adsorption hole transport layer material comprises carbazole phosphonic acid self-assembled hole transport layer molecules and aromatic co-adsorption molecules, wherein: The carbazolylphosphonic acid self-assembled hole transport molecule is one of (2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl)phosphonic acid (MeO-2PACz) and (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz); The aromatic co-adsorbent molecule is one of 4-methoxybenzoic acid (4-MBA) and (4-methoxyphenyl)trimethoxysilane (MPTS).

2. The co-adsorbed hole transport layer material according to claim 1, characterized in that, The weight ratio of the carbazophosphonic acid self-assembled hole transport layer molecule to the aromatic co-adsorbed molecule is 9:1-6:

4.

3. The co-adsorbed hole transport layer material according to claim 1, characterized in that, The weight ratio of the carbazole phosphonate self-assembled hole transport layer molecule to the aromatic co-adsorbed molecule is 8:

2.

4. A perovskite solar cell, comprising: The transparent conductive glass (1), hole transport layer (2), perovskite light-absorbing layer (3), electron transport layer (4) and metal electrode (5) are stacked sequentially from bottom to top, characterized in that the hole transport layer is a co-adsorption hole transport layer formed of the co-adsorption hole transport layer material as described in claim 1.

5. The perovskite solar cell according to claim 1, characterized in that, The thickness of the co-adsorbed hole transport layer is 3~10 nm.

6. The perovskite solar cell according to claim 1, characterized in that, The co-adsorption hole transport layer is prepared by the following steps: The co-adsorption hole transport layer material was mixed with anhydrous ethanol to prepare a co-adsorption hole transport layer solution. The co-adsorbed hole transport layer solution is spin-coated onto the surface of a conductive glass substrate, and then annealed at 100~200 °C for 10~20 min to form the co-adsorbed hole transport layer.

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