Doping molecules for sam-based hole transport layer and perovskite solar cell

Abstract

The application relates to the technical field of perovskite solar cells, in particular to a doped molecule of a SAMs-based hole transport layer and a perovskite solar cell, and the structure formula of the doped molecule is a compound shown in the following structure formula. The application does not change the structure of the SAM molecule itself, but physically introduces a doped molecule in the existing self-assembled monolayer, uses intermolecular pi-pi stacking to improve the film quality and realizes p-type doping; meanwhile, with the help of specific functional groups of the doped molecule, the interface wettability is improved, the energy level alignment is optimized, the interface defects are passivated, and the performance of the perovskite solar cell is improved.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, specifically to doped molecules in SAMs-based hole transport layers and perovskite solar cells. Background Technology

[0002] Self-assembled monolayers (SAMs), as hole transport layers in pin perovskite solar cells, significantly improve the photoelectric conversion efficiency of devices due to their advantages such as precise energy level control, nanoscale thickness, low fabrication cost, and high optical transmittance.

[0003] However, the following problems still exist in SAMs-based hole transport layers: (1) Film quality and uniformity: The inherent steric hindrance effect and amphiphilic molecular characteristics of carbazole derivatives easily lead to non-uniform aggregation of molecules on the surface of oxide substrates such as ITO, forming discontinuous island structures or micro-pinholes. This morphological defect not only increases the interfacial contact resistance, but also becomes a non-radiative recombination center for charge carriers, which seriously restricts the performance of the device. (2) Interfacial wettability and crystallization control: The terminal groups of most high-performance SAMs are hydrophobic aromatic ring structures, which have significant interfacial energy differences with polar perovskite precursor solutions (such as DMF / DMSO systems), causing severe dewetting. This directly hinders the uniform nucleation and epitaxial growth of perovskite films, resulting in insufficient coverage of the final active layer, small grain size, and excessively high grain boundary density, which significantly increases the concentration of bulk and interfacial defects. (3) Energy level alignment and charge transport: Imperfect energy level matching between SAMs and the perovskite layer will form a hole injection barrier at the interface, inhibiting efficient charge extraction, increasing series resistance, and causing significant open-circuit voltage loss, thereby limiting the final photoelectric conversion efficiency of the device. (4) Interface chemistry and defect passivation: A large amount of uncoordinated Pb exists at the perovskite buried interface. 2+ Ion and halogen vacancy defects are difficult to passivate due to the lack of effective Lewis base coordination groups in traditional SAMs molecules. This deficiency not only exacerbates nonradiative recombination at the interface, but may also induce halogen phase separation, ultimately impairing the operational stability and lifespan of the device.

[0004] Currently, the mainstream technical approach to improving the performance of SAMs-based hole transport layers focuses on chemical structural modification and alteration of the SAM molecules themselves. For example, introducing conjugated structures between the anchoring group and the functional head group of the molecule, synthesizing terminal groups with different electron-donating or electron-withdrawing capabilities (such as carbazole, triphenylamine, phosphonates, and other derivatives) to improve the energy level matching between them and the top of the valence band of the perovskite layer, and designing SAM molecules with specific molecular skeletons or side chains in order to form a more compact and ordered monolayer arrangement on the substrate, thereby improving interfacial contact and charge transport pathways.

[0005] However, there are many problems with modifying and altering the chemical structure of SAM molecules: (1) Complex synthesis and high cost: The synthesis route is long, the purification is difficult, and the overall yield is low, resulting in extremely high material costs. This runs counter to the commercial goal of reducing the cost of PSCs. Moreover, the synthesis process may use hazardous reagents and generate a large amount of waste liquid, which is not environmentally friendly. (2) Limited performance improvement: The performance improvement of the modification of a single molecular structure is usually limited to the framework of the molecular structure. The single SAM molecule mainly provides energy level matching and dipole regulation functions, but the ability to simultaneously passivate common defect states (such as lead vacancies and halogen vacancies) at the perovskite interface is limited. The complex multifunctional molecular design further exacerbates the difficulty of synthesis. (3) Process compatibility and reproducibility challenges: New SAM molecules may require a lot of re-exploration of deposition conditions to form high-quality monolayer films. This increases the uncertainty and complexity of process development and is not conducive to the stable continuation of existing mature processes. This has become a bottleneck restricting the further improvement of SAM performance. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a doped molecule for a SAM-based hole transport layer and a perovskite solar cell. This invention does not alter the structure of the SAM molecule itself, but rather physically introduces dopant molecules into an existing self-assembled monolayer. This utilizes the π-π stacking between molecules to improve film quality and achieve p-type doping. Simultaneously, by leveraging the specific functional groups of the doped molecules, it synergistically improves interface wettability, optimizes energy level alignment, and passivates interface defects, thereby enhancing the performance of the perovskite solar cell.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a doped molecule for a SAMs-based hole transport layer, said doped molecule being a compound with the following structural formula:

[0008] R1 to R8 are each independently selected from hydrogen or halogen.

[0009] Preferably, the structure of the doped molecule is any one of Formula 1 and Formula 2:

[0010] Formula 1

[0011] Formula 2.

[0012] Preferably, the SAMs material is selected from any one or more of Meo-2PACz, Me-4PACz, Me-2PACz, Meo-4PACz, and CBZPH.

[0013] Preferably, the mass ratio of the doped molecules to the SAMs material is 1:1.

[0014] In a second aspect, the present invention provides a SAMs-based hole transport layer comprising the doped molecules.

[0015] Thirdly, the present invention provides a perovskite solar cell, wherein the perovskite solar cell includes the aforementioned SAMs-based hole transport layer.

[0016] Preferably, the perovskite solar cell further includes a transparent conductive substrate layer, a lower interface passivation layer, a perovskite absorption layer, an upper interface passivation layer, an electron transport layer, a buffer layer, and a back electrode layer.

[0017] Preferably, the oxide material of the transparent conductive substrate is selected from any one or more of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), and aluminum-doped zinc oxide (AZO).

[0018] Preferably, the material of the lower interface passivation layer is aluminum oxide.

[0019] Preferably, the perovskite absorber layer has the structural formula ABX3, where A is an organic cation or metal ion selected from CH(NH2). 2+ CH3NH 3+ Cs + 、Rb + One or more of the following; B is selected from Pb 2+ Sn 2+ Any one or more of them; X is I - ,Br - Cl - Or hybridized halide ions.

[0020] Preferably, the material of the upper interface passivation layer is selected from any one or more of 2-phenylethylamine hydroiodate, 1,3-propanediamine hydroiodate (propanediamine iodide), and phenylethylamine iodide.

[0021] Preferably, the material of the electron transport layer is selected from PCBM, C 60 Any one or more of SnO2.

[0022] Preferably, the material of the buffer layer is BCP.

[0023] Preferably, the material of the metal back electrode layer is selected from any one or more of Ag, Au, Al, Cu, and Ni.

[0024] Preferably, the perovskite solar cell is an inverted perovskite solar cell.

[0025] Fourthly, the present invention provides a method for preparing a perovskite solar cell, comprising: preparing a hole transport layer, preparing a lower interface passivation layer, preparing a perovskite absorber layer, preparing an upper interface passivation layer, preparing an electron transport layer, preparing a buffer layer, and preparing a back electrode layer; wherein, the process of preparing the hole transport layer is as follows: preparing SAMs material into a solution, adding the doping molecules, mixing, spin-coating onto a substrate, and annealing to obtain the final product.

[0026] Preferably, the mass ratio of the doped molecules to the SAMs material is 1:1.

[0027] Preferably, the spin coating parameters are 3500 rpm, acceleration 3500 rpm / s, and spin coating for 30 s.

[0028] Preferably, the annealing parameters are annealing at 100°C for 10 minutes.

[0029] The beneficial effects of this invention are: This invention effectively enhances the performance of self-assembled monolayers (SAMs) in hole transport layers by physically introducing specific dopant molecules without altering the molecular structure of the SAMs themselves. This process is primarily based on three synergistic mechanisms: First, functional molecules form stable charge-transfer complexes with SAMs molecules through π–π stacking interactions, which not only enhances the molecular coverage density and interfacial potential uniformity of the SAMs film but also synergistically fills uncovered areas on the ITO substrate surface, thereby improving the overall film quality. Second, these conjugated molecules act as p-type dopants, effectively increasing the work function of the SAMs layer and optimizing the energy level matching between it and the perovskite active layer, thus promoting efficient hole extraction and transport. Finally, rationally designed functional groups in the molecular structure comprehensively improve the interfacial wettability of the SAMs film, enhance the interaction with the perovskite layer, and passivate perovskite surface defects at the buried interface, synergistically improving crystallinity and interfacial stability.

[0030] This invention systematically enhances the device performance of perovskite solar cells by introducing specific functionalized dopants into self-assembled monolayers (SAMs). These molecule optimizes the uniformity and coverage of the SAM film through π–π stacking interactions, and acts as a p-type dopant to improve work function and conductivity, effectively improving energy level matching and hole extraction efficiency, resulting in a significant increase in open-circuit voltage and fill factor. Simultaneously, its functional groups improve interfacial wettability, promote high-quality perovskite crystal formation, enhance light absorption and carrier transport, passivate interfacial defects, and suppress ion migration, thereby improving short-circuit current density and long-term device stability. Furthermore, this strategy combines low-temperature solution process compatibility with excellent reproducibility, providing an innovative interface engineering solution for developing high-efficiency and stable inverted perovskite solar cells. Attached Figure Description

[0031] Figure 1 Infrared spectra of powder materials containing doped molecules, self-assembled monolayer molecules, or mixtures thereof (a. Infrared spectra of Meo-2pacz, doped molecules described in Formula 1, and mixtures thereof; c. Infrared spectra of Meo-2pacz, doped molecules described in Formula 2, and mixtures thereof; b and d are magnified views of a and c, respectively).

[0032] Figure 2 XPS spectra of the hole transport layers prepared in Examples 1, 2 and Comparative Example 1.

[0033] Figure 3 XPS images of the buried interface of the perovskite absorber layer prepared in Examples 1, 2 and Comparative Example 1.

[0034] Figure 4 The contact angle test diagrams are for the hole transport layers prepared in Example 1, Example 2 and Comparative Example 1.

[0035] Figure 5 The images show the XRD patterns of the buried interfaces of the perovskite absorber layers prepared in Examples 1, 2, and 1.

[0036] Figure 6 SEM images of the buried interface of the perovskite absorber layer prepared in Examples 1, 2 and Comparative Example 1.

[0037] Figure 7 The image shows the KPFM diagrams of the buried interface of the perovskite absorber layer prepared in Examples 1, 2, and Comparative Example 1.

[0038] Figure 8 The UV-Vis absorption spectra of the buried interface of the perovskite absorption layer prepared in Examples 1, 2 and Comparative Example 1 are shown.

[0039] Figure 9 Steady-state photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra of the buried interface of the perovskite absorber layer prepared in Examples 1, 2 and Comparative Example 1.

[0040] Figure 10 Box plots showing the photovoltaic performance parameters of perovskite solar cells prepared in Examples 1-2 and Comparative Example 1.

[0041] Figure 11 The JV characteristic curves are for the perovskite solar cells prepared in Examples 1-2 and Comparative Example 1.

[0042] Figure 12 The external quantum efficiency (EQE) spectra of the perovskite solar cells prepared in Examples 1-2 and Comparative Example 1 are shown.

[0043] Figure 13The graphs show the stability test results of the perovskite solar cells prepared in Examples 1, 2, and 1. Detailed Implementation

[0044] To enable those skilled in the art to better understand the technical solution of the invention, the invention will be further described in detail below with reference to specific embodiments.

[0045] Example 1 This embodiment provides a method for fabricating an inverted perovskite solar cell, comprising the following steps: (1) Preparation of hole transport layer A clear solution was prepared by adding 0.5 mg of the dopant molecule (2,7-dibromo-9-vinyl-9H-carbazole) shown in Formula 1 to 1 mL of a 0.5 mg / mL solution of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (Meo-2PACz). This solution was then dropped onto a clean indium tin oxide (ITO) substrate that had been treated with UV radiation and spin-coated at a speed of 3500 rpm and an acceleration of 3500 rpm / s for 30 s. After spin-coating, the substrate was annealed at 100 °C for 10 min.

[0046]

[0047] Formula 1 (2) Preparation of the lower interface passivation layer A 50 μL solution of alumina isopropanol IPA with a volume ratio of 1:50 was spin-coated onto the hole transport layer cooled to room temperature at a speed of 4000 rpm and an acceleration of 4000 rpm / s for 35 s, and then annealed at 100°C for 10 minutes.

[0048] (3) Preparation of perovskite absorber layer 1.5 mmol lead iodide (PbI2), 1.5 mmol formamidin hydroiodide (FAI), 0.1 mmol methylamine hydrobromide (MABr), 0.15 mmol rubidium chloride (RbCl), 0.1 mmol cesium iodide (CsI), and 0.1 mmol lead bromide (PbBr2) were mixed and dissolved in 1 mL of a mixture of DMSO and DMF (volume ratio 1:4) and stirred for 3–6 h. After filtering with an organic filter with a pore size of 0.22 μm, the mixture was spin-coated onto the lower interface passivation layer at 1000 rpm, 1500 rpm / s acceleration, and 10 s spin-coating time, and at 3000 rpm, 1500 rpm / s acceleration, and 40 s spin-coating time. 120 μL of 10 μL / mL anisole was added dropwise 10 s before the end of the second spin-coating step, and then annealed at 110 °C for 20 min.

[0049] (4) Preparation of the upper interface passivation layer A 50 μL solution of 1 mg / mL 2-phenylethylamine hydroiodide isopropanol IPA was spin-coated onto a perovskite absorber layer cooled to room temperature at a spin speed of 5000 rpm and an acceleration of 5000 rpm / s for 40 s, and then annealed at 100°C for 5 minutes.

[0050] (5) Fabrication of electron transport layer 50 μL of PC at 20 mg / mL 61 BM chlorobenzene solution was spin-coated onto the upper interface passivation layer cooled to room temperature at a speed of 1500 rpm and an acceleration of 1500 rpm / s for 30 s, and then annealed at 100°C for 10 minutes.

[0051] (6) Preparation of the buffer layer A 60 μL solution of BCP isopropanol IPA with a concentration of 0.5 mg / mL was spin-coated onto the electron transport layer cooled to room temperature at a speed of 6000 rpm and an acceleration of 6000 rpm / s for 35 s.

[0052] (7) Preparation of the back electrode layer A 100 nm silver Ag layer was deposited on the buffer layer as the back electrode, with a vacuum degree <1×10⁻⁶. -4 Pa, velocity 0.2 Å / s.

[0053] Example 2 Same as Example 1, except that the dopant molecule in step (1) is replaced with (3,6-dibromo-9-vinyl-9H-carbazole), with the structural formula shown in Formula 2.

[0054]

[0055] Formula 2 Comparative Example 1 Same as Example 1, except that no dopant molecules were added in step (1).

[0056] Example 1: Interaction between doped molecules and self-assembled monolayer (SAM) molecules In the characterization diagram, BrV-Cz-2,7 represents the dopant molecule described in Formula 1 (2,7-dibromo-9-vinyl-9H-carbazole); BrV-Cz-3,6 represents the dopant molecule described in Formula 2 (3,6-dibromo-9-vinyl-9H-carbazole); Mix-2,7 represents a mixture of the dopant molecule described in Formula 1 and Meo-2pacz; Mix-3,6 represents a mixture of the dopant molecule described in Formula 2 and Meo-2pacz.

[0057] Figure 1Infrared spectra of powder materials containing doped molecules, self-assembled monolayer molecules, or mixtures thereof (a. Infrared spectra of Meo-2pacz, doped molecules described in Formula 1, and mixtures thereof; c. Infrared spectra of Meo-2pacz, doped molecules described in Formula 2, and mixtures thereof; b and d are magnified views of a and c, respectively). Figure 1 It can be seen that the pure MeO-2PACZ molecule at 1210 cm⁻¹ -1 and 949 cm -1 The dopant molecules exhibit distinct P=O and P-OH characteristic absorption peaks in the vicinity, respectively, while the dopant molecules described in Formula 1 and Formula 2 show peaks at 1640 cm⁻¹. -1 Approximately 1222 cm -1 The presence of corresponding C=C and C-Br characteristic vibrational peaks indicates that the two doped molecular structures are complete and successfully introduced. When the doped molecules are mixed with MeO-2PACZ, characteristic absorption signals from both components can still be observed in the mixed materials (Mix-2,7 and Mix-3,6), but the P-OH vibrational peak in MeO-2PACZ changes from 949 cm⁻¹. -1 Moved to 943 cm respectively -1 and 843 cm -1 Meanwhile, the local peak shape and peak intensity also changed to some extent, which indicates that there is a significant intermolecular interaction (including π-π stacking) between the dopant molecule and the phosphonic acid group of MeO-2PACZ, thereby changing the chemical environment around the phosphonic acid group.

[0058] Figure 2 XPS spectra of the hole transport layers prepared in Examples 1, 2, and Comparative Example 1. Figure 2 It can be seen that the In-OP / In-OH peak area ratio of the samples in Example 1 and Example 2 is significantly higher than that of the sample in Comparative Example 1, indicating that the doped molecules suppress the aggregation of SAMs through steric hindrance and π-π stacking, fill the uncovered area on the ITO surface, and the SAMs are more densely arranged and more stably anchored.

[0059] Example 2: Characterization of the performance of the perovskite absorber layer at the buried interface Figure 3 XPS spectra of the buried interface of the perovskite absorber layer prepared in Examples 1, 2, and Comparative Example 1. As can be seen from the figures, compared with Comparative Example 1, the addition of dopant molecules resulted in varying degrees of negative shifts in the characteristic peaks of Pb 4f and I 3d. Specifically, Pb 4f... 5 / 2 The peaks shifted from 143.35 eV to 143.20 eV and 143.02 eV, respectively. 3 / 2The peaks shifted from 630.60 eV to 630.50 eV and 630.45 eV, respectively. This result indicates that the introduction of dopant molecules effectively altered the local chemical environment of the perovskite buried interface and caused a redistribution of the interface electron cloud density. In contrast, the sample in Example 2 exhibited a larger binding energy shift, indicating a stronger regulatory effect on the interface electronic structure. This interface optimization effect is expected to reduce nonradiative recombination induced by interface defects, promote interface charge extraction and transport, and thus improve device performance.

[0060] Figure 4 The figures show the contact angle test results of the hole transport layers prepared in Examples 1, 2, and Comparative Example 1. As can be seen from the figures, the contact angle of Comparative Example 1 is 80.77°, while after the introduction of dopant molecules, the contact angles of the samples in Examples 1 and 2 decreased to 70.077° and 55.494°, respectively. The significant decrease in contact angle indicates that the introduction of dopant molecules effectively improved the surface energy and hydrophilicity of the SAM film. This is because the dopant molecules altered the arrangement and exposure state of the terminal groups in the SAM layer, enhancing surface polarity and thus improving the interfacial compatibility between the SAM layer and the polar perovskite precursor solution. This suppressed dewetting during film formation and provided a good interfacial foundation for uniform nucleation and high-quality crystallization of the perovskite film.

[0061] Figure 5 The figures show the XRD patterns of the buried interfaces of the perovskite absorber layers prepared in Examples 1, 2, and Comparative Example 1. As can be seen from the figures, compared with Comparative Example 1, the intensity of the characteristic diffraction peaks of the perovskite in Examples 1 and 2 is significantly enhanced, and the intensity ratio of the (100) / (110) peaks is significantly increased, indicating that the crystallinity of the perovskite is significantly improved and the grain orientation is more favorable after the introduction of dopant molecules. Combined with the water contact angle results, it can be seen that the dopant molecules improve the surface wettability of SAMs, promote the uniform spreading and nucleation of the perovskite precursor, and reduce the density of grain boundaries and defects; at the same time, the dopant molecules passivate the uncoordinated Pb at the buried interface through interfacial coordination. 2+ Defects are eliminated, ion migration and lattice distortion are suppressed, and the growth quality of perovskite crystals is further optimized to form dense, highly crystalline perovskite thin films, laying a good structural foundation for improving light absorption capacity and carrier transport efficiency.

[0062] Figure 6 SEM images of the buried interface of the perovskite absorber layers prepared in Examples 1, 2, and Comparative Example 1 are shown. As can be seen from the images, the perovskite film of Comparative Example 1 exhibits obvious pores, loose grain boundaries, and poor density on its surface; while the films of Examples 1 and 2 show smooth and dense surfaces, significantly reduced pores, increased grain size, and clear grain boundaries. This is because the doped molecules improve the interfacial wettability of the SAMs substrate, promote the uniform spreading and orderly nucleation and growth of the perovskite precursor, and passivate the Pb at the buried interface. 2+Defects are suppressed, and defect aggregation and nonradiative recombination at grain boundaries are inhibited, ultimately forming a dense, uniform, and high-quality perovskite thin film with few defects, which is beneficial to improving carrier transport efficiency and device stability.

[0063] Figure 7 The KPFM images show the buried interfaces of the perovskite absorber layers prepared in Examples 1, 2, and Comparative Example 1. As can be seen from the images, Comparative Example 1 has a higher interface roughness. However, after introducing dopant molecules, the interface roughness of the samples in Examples 1 and 2 is significantly reduced, and the surfaces are smoother and more uniform. This indicates that the dopant molecules, through π-π stacking, make the SAMs more orderly assembled and the interface potential distribution more uniform. These results demonstrate that the dopant molecules improve the wettability of the SAMs substrate and inhibit molecular aggregation, enabling the perovskite precursor to spread uniformly and grow orderly at the interface, reducing interface micro-undulations and defect sites. Simultaneously, the interface passivation effect of the dopant molecules further reduces the interface defect density, optimizes the interface energy level distribution, and reduces carrier scattering loss. This provides a smooth, low-defect interface environment for efficient hole extraction and transport at the interface, which is beneficial for improving the open-circuit voltage and stability of the device.

[0064] Figure 8 The figures show the UV-Vis absorption spectra of the buried interfaces of the perovskite absorber layers prepared in Examples 1, 2, and Comparative Example 1. As can be seen from the figures, compared to Comparative Example 1, the absorption intensity of the samples in Examples 1 and 2 in the visible light region is significantly enhanced, and the absorption edge positions remain basically consistent, indicating that the SAMs substrate modified with doped molecules did not change the intrinsic bandgap structure of the perovskite material. Considering the mechanisms of interface wetting, defect passivation, and improved crystallinity, it can be seen that the doped molecules effectively improve the compactness and light-harvesting ability of the perovskite film by optimizing interface compatibility, promoting uniform crystallization of the perovskite, and reducing interface defects, thereby enhancing the absorption and utilization rate of visible light and providing strong support for improving the short-circuit current density of the device.

[0065] Figure 9 The figures show the steady-state photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra of the buried interface of the perovskite absorber layer prepared in Examples 1, 2, and Comparative Example 1. As can be seen from the figures, compared to Comparative Example 1, the PL emission intensity of the samples in Examples 1 and 2 is significantly enhanced, the emission peak shape is more symmetrical, and the TRPL fluorescence lifetime is significantly prolonged. These results confirm that the dopant molecules improve interfacial wettability, promote high-quality crystallization of perovskite, and efficiently passivate uncoordinated Pb at the buried interface through the Lewis base coordination of carbazole nitrogen atoms and bromine atoms. 2+ These defects significantly reduce non-radiative recombination centers at the interface, lower carrier recombination losses, and extend carrier lifetime, thereby promoting efficient hole extraction and transport and providing direct evidence for improving device open-circuit voltage, short-circuit current density, and stability.

[0066] Example 3: Performance Testing of Perovskite Solar Cells Figure 10 Box plots show the photovoltaic performance parameters of the perovskite solar cells prepared in Examples 1-2 and Comparative Example 1. As can be seen from the figures, compared with Comparative Example 1, the perovskite solar cells prepared in Examples 1 and 2 show significantly improved open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and power conversion efficiency (PCE), with more concentrated performance data distribution and less dispersion. This result stems from the multiple synergistic effects of the doping molecules: improving interface wettability, enhancing perovskite crystal quality, passivating interface defects, and optimizing energy level matching, effectively reducing interface recombination losses, promoting efficient carrier extraction and transport, and ultimately achieving a systematic improvement in the overall photovoltaic performance of the device, while also enhancing the repeatability and stability of device fabrication.

[0067] Figure 11 These are the JV characteristic curves of the perovskite solar cells prepared in Examples 1-2 and Comparative Example 1. Figure 12 The figures show the external quantum efficiency (EQE) spectra of the perovskite solar cells prepared in Examples 1-2 and Comparative Example 1. As can be seen from the figures, the perovskite solar cells prepared in Examples 1 and 2 exhibit superior JV curves, with power conversion efficiencies (PCE) reaching 25.23% and 25.42%, respectively. Furthermore, both sets of devices demonstrate higher EQE response intensity in the visible light region, and the integrated short-circuit current density shows a high degree of agreement with the measured value, with an error of less than 5%. These results further confirm that doping molecules significantly enhance the light-harvesting capability and carrier transport efficiency of perovskite thin films by improving interface wettability, passivating interface defects, and optimizing energy level matching, thus achieving a high-efficiency improvement in the photoelectric performance of the devices and providing strong support for the development of high-performance perovskite solar cells.

[0068] Figure 13 The figures show the stability test results of the perovskite solar cells prepared in Examples 1, 2, and 1 (Comparative Example 1). As can be seen from the figures, under N2, 60℃, and unencapsulated conditions, the device in Comparative Example 1 retained only 76% of its initial PCE after 1000 h. However, the stability of the device was significantly enhanced after the introduction of dopant molecules. The devices in Examples 1 and 2 maintained 94% and 95% of their initial efficiencies, respectively, after 1200 h. This indicates that the dopant molecules can effectively stabilize the SAM / perovskite buried interface, not only improving the photovoltaic performance of the device but also significantly enhancing the thermal stability of the inverted perovskite solar cell.

[0069] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A doped molecule for a SAMs-based hole transport layer, characterized in that, The doped molecule is a compound with the following structural formula: R1 to R8 are each independently selected from hydrogen or halogen.

2. The doped molecule of the SAMs-based hole transport layer according to claim 1, characterized in that, The structure of the doped molecule is either one of the following formulas 1 and 2: Formula 1 Formula 2.

3. The doped molecule of the SAMs-based hole transport layer according to claim 1, characterized in that, The SAMs material is selected from any one or more of Meo-2PACz, Me-4PACz, Me-2PACz, Meo-4PACz, and CBZPH.

4. The doped molecule of the SAMs-based hole transport layer according to any one of claims 1 to 3, characterized in that, The mass ratio of the doped molecules to the SAMs material is 1:

1.

5. A SAMs-based hole transport layer comprising the doped molecules according to any one of claims 1 to 4.

6. A perovskite solar cell, characterized in that, The perovskite solar cell includes the SAMs-based hole transport layer as described in claim 5.

7. The perovskite solar cell according to claim 6, characterized in that, The perovskite solar cell further includes a transparent conductive substrate layer, a lower interface passivation layer, a perovskite absorption layer, an upper interface passivation layer, an electron transport layer, a buffer layer, and a back electrode layer.

8. The perovskite solar cell according to claim 7, characterized in that, The material of the lower interface passivation layer is aluminum oxide.

9. The perovskite solar cell according to claim 7, characterized in that, The material of the upper interface passivation layer is selected from any one or more of 2-phenylethylamine hydroiodate, 1,3-propanediamine hydroiodate, and phenylethylamine iodide.

10. A method for fabricating a perovskite solar cell, comprising: The process involves preparing a hole transport layer, a lower interface passivation layer, a perovskite absorption layer, an upper interface passivation layer, an electron transport layer, a buffer layer, and a back electrode layer. The hole transport layer is prepared by: preparing SAMs material into a solution, adding the dopant molecules described in any one of claims 1 to 4, mixing, spin-coating onto a substrate, and annealing.

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