Perovskite solar cells based on piperazine halide additives and their fabrication method

Abstract

This invention discloses a perovskite solar cell based on piperazine halide additives and its preparation method. By introducing piperazine halide additives into the bulk phase of the perovskite active layer, a perovskite bulk phase stabilization system is constructed. This additive increases the rotational entropy of cations while suppressing unfavorable entropy increases associated with octahedral disorder, thereby significantly improving the phase transition energy barrier of the photoactive α-phase perovskite and effectively suppressing its transformation to the photoelectric inert δ-phase under external stress. This avoids the defect of sacrificing photocurrent density due to bandgap widening caused by ion doping. The perovskite thin film prepared by this invention exhibits significantly suppressed formation of the photoelectric inert δ-phase under humid heat aging conditions, with excellent phase purity. This achieves a comprehensive improvement in the photoelectric conversion efficiency and long-term stability of the perovskite solar cell, while also possessing excellent photoelectric conversion efficiency and significantly improved operational and humid heat stability.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, and more specifically, relates to a perovskite solar cell based on piperazine halide additives and its preparation method. Background Technology

[0002] In recent years, the power conversion efficiency of perovskite solar cells (PSCs) has been significantly improved. Among them, formamidinium-containing halide perovskite materials have become one of the key photovoltaic materials for achieving high efficiency and industrialization potential due to their near-ideal band gap, long carrier diffusion distance, low exciton binding energy, and solution processability. However, this type of photoactive perovskite phase is thermodynamically metastable and readily transforms spontaneously into the photoelectric inert δ phase at room temperature. Humid and oxygen environments further accelerate this phase transition process.

[0003] To suppress the α→δ phase transition, some studies have disclosed the introduction of smaller cations (such as Cs). + and MA + ) or mixed halide ions (such as Br) - To stabilize the α phase, patent CN118368952A proposes a two-step method for preparing α-FAPbI3 thin films followed by treatment with methylamine ethanol solution. While this method can suppress δ phase formation to some extent, ion doping typically leads to a widening of the material's band gap, sacrificing some photocurrent density and limiting further improvements in device performance. Another approach involves introducing interface materials between the perovskite layer and the transport layer to modulate energy levels and passivate surface defects. For example, patent CN121226286A discloses a technique using N-acetylpiperazine halide / N-formylpiperazine halide as passivating molecules, utilizing an "ammonium-carbonyl" dual-site synergistic anchoring of the perovskite surface. However, this technique is functionally positioned for interface passivation rather than bulk α-phase stabilization, making it difficult to fundamentally suppress phase transitions. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a perovskite solar cell based on piperazine halide additives and its preparation method. By introducing piperazine halide additives into the bulk phase of the perovskite active layer, a perovskite bulk phase stabilization system is constructed. This additive increases the rotational entropy of cations while suppressing unfavorable entropy increases associated with octahedral disorder, thereby significantly improving the phase transition energy barrier of the photoactive α-phase perovskite and effectively suppressing its transformation to the photoelectric inert δ-phase under external stress. This avoids the defect of sacrificing photocurrent density due to bandgap widening caused by ion doping. The perovskite thin film prepared by this invention exhibits significantly suppressed formation of the photoelectric inert δ-phase under humid heat aging conditions, demonstrating excellent phase purity. This achieves a comprehensive improvement in the photoelectric conversion efficiency and long-term stability of the perovskite solar cell, while also possessing excellent photoelectric conversion efficiency and significantly improved operational and humid heat stability.

[0005] To achieve the above objectives, according to one aspect of the present invention, a perovskite solar cell based on piperazine halide additive is provided, comprising, from bottom to top, a transparent conductive oxide substrate, a hole transport layer, a lower interface modification layer, a perovskite active layer, an upper interface modification layer, an electron transport layer, a buffer layer and an electrode layer. The perovskite active layer is made of APbX3, where A is formamidinium (HC(NH2)2). + FA + ), Methylamine (CH3NH3) + MA + ) or cesium ions (Cs + At least one of the following: X is or At least one of them; The perovskite active layer is introduced with piperazine halide additives, which are hydrochloride, hydrobromide or hydroiodide salts of piperazine derivatives as shown in Formula 1, and their parent molecular structures are shown in Formula 1, where n takes the value of an integer from 1 to 8. In the parent molecule structure, the nitrogen atom at the 1-position of the piperazine ring is denoted by -(CH2). n - Connected to an Ar group; Ar is selected from phenyl, pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl, benzenesulfonic acid, benzoic acid, phenylphosphoric acid, and the alkylene group is connected to Ar through 19 sites shown in Formula 2; Formula 1 Equation 2.

[0006] Preferably, the amount of piperazine halide additive in the perovskite active layer is 0.08 to 0.5 mol% relative to the molar amount of the perovskite precursor solute; the solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide, or N-methyl-2-pyrrolidone; and the antisolvent is one or more of ethyl acetate, chlorobenzene, anisole, or diethyl ether.

[0007] Preferably, the transparent conductive substrate is selected from either FTO conductive glass or ITO conductive glass.

[0008] Preferably, the material of the hole transport layer is selected from one or more organic or inorganic hole transport materials; the organic hole transport material is selected from carbazole phosphate or triphenylamine hole transport materials, including one or more of 2PACz, MeO-2PACz, Me-4PACz, MeO-4PACz, Ph-2PACz, 4PADCB, Ph-4PACz, 4,4',4''-triphenylamine tricarboxylate, PTAA, Poly-4PACz or Poly-2PACz; the inorganic hole transport material includes one or more of nickel oxide, doped nickel oxide, cuprous chromate or cuprous gallate.

[0009] Preferably, the lower interface modification layer material includes one or more of phenylethyl iodide, phenylethyl ammonium chloride, phenylethyl ammonium bromide, 2-thiophene ethylamine hydrochloride, 1,3-propanediamine hydroiodide, and ethylenediamine hydroiodide.

[0010] Preferably, the upper interface modification layer material includes one or more of PEAI, PEACl, PEABr, 2-ThEACl, PDADI, EDADI and 3-PMPI.

[0011] Preferably, the electron transport layer material is selected from PC. 61 One or a combination of BM and fullerene.

[0012] Preferably, the buffer layer material is selected from one or more of copper bath, tin oxide, cerium oxide, or titanium oxide.

[0013] Preferably, the electrode layer is a single-layer structure or a double-layer structure, wherein the material of the single-layer structure is selected from silver, gold, copper, chromium, bismuth, indium tin oxide, aluminum-doped zinc oxide, and tungsten-doped indium oxide; the material of the double-layer structure is selected from bismuth-copper double-layer structure, bismuth-gold double-layer structure, bismuth-silver double-layer structure, chromium-copper double-layer structure, chromium-gold double-layer structure, and chromium-silver double-layer structure; and the thickness of the electrode layer is 20–1000 nm.

[0014] According to a second aspect of the present invention, a method for preparing a perovskite solar cell based on a piperazine halide additive is provided, comprising the following steps: Step 1, Pretreatment of transparent conductive substrate: The transparent conductive substrate is ultrasonically cleaned sequentially with glass cleaning solution, deionized water, anhydrous ethanol and acetone, dried with nitrogen, and then treated with ultraviolet ozone for 20~30 min. Step 2, prepare hole transport layer: spin coat the precursor solution of hole transport layer on the surface of the pretreated transparent conductive substrate at a spin speed of 4000~6000 rpm for 10~50 s, and anneal at 100~150 ℃ for 10~40 min after coating. Step 3, prepare the lower interface modification layer: spin coat the precursor solution of the lower interface modification layer onto the surface of the hole transport layer at a spin speed of 5000~7000 rpm for 10~30 s. After coating, anneal at 90~110 ℃ for 1~3 min. Step 4, Preparation of perovskite light absorption layer: APbX3 and piperazine halide are dissolved together in a solvent, mixed to obtain a precursor solution, and then coated as a perovskite wet film. The spin coating speed is 7000~9000 rpm, and the total time is 30~50 s. During the spin coating process, the anti-solvent is added dropwise, and the film is annealed at 100~130 ℃ for 5~15 min. Step 5, prepare the upper interface modification layer: spin-coat the precursor solution on the surface of the perovskite light absorption layer at a spin speed of 2000~4000 rpm for 20~40s. After coating, anneal at 90~110 ℃ for 5~15 min. Step 6, prepare the electron transport layer: spin-coat the precursor solution onto the surface of the upper interface modification layer at a spin speed of 2000~4000 rpm for 20~30 s. After coating, anneal at 60~80 ℃ for 5~15 min. Step 7, prepare the buffer layer: spin-coat the precursor solution on the surface of the electron transport layer at a speed of 5000~7000 rpm for 10~30 s. After coating, anneal at 60~80 ℃ for 5~15 min. Step 8, Electrode layer preparation: Silver electrodes are deposited on the surface of the buffer layer using a thermal evaporation device. The thickness is 100~150nm.

[0015] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1. This invention constructs a perovskite bulk phase stabilization system by introducing piperazine halide additives into the perovskite active layer bulk phase. In this system, the piperazine halide additives improve the FA (fatal efficiency). +The rotational entropy of cations simultaneously suppresses the unfavorable entropy increase associated with octahedral disorder, thereby significantly improving the phase transition energy barrier of photoactive α-phase perovskite and effectively suppressing its transformation to photoelectric inert δ-phase under external stress, thus avoiding the defect of sacrificing photocurrent density due to band gap widening caused by ion doping.

[0016] 2. This invention utilizes aryl or heteroaryl alkylpiperazine halides with specific linkage sites to establish a perovskite bulk phase stabilization strategy based on finely controlled molecular structure. Specifically, the formation of the photoelectric inert δ-phase in the perovskite thin film is significantly suppressed under damp-heat aging conditions, resulting in excellent phase purity. This invention achieves a comprehensive improvement in the photoelectric conversion efficiency and long-term stability of perovskite solar cells, combining excellent photoelectric conversion efficiency with significantly improved operational and damp-heat stability, providing a stable and scalable material and process foundation for efficient and stable perovskite photovoltaic technology. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the perovskite solar cell of Embodiment 1 of the present invention; Figure 2 The perovskite solar cell of Embodiment 1 of the present invention J - V curve; Figure 3 This is a perovskite solar cell of Comparative Example 1 of the present invention. J - V curve; Figure 4 Box plots showing the photoelectric conversion efficiency of perovskite solar cells with different amounts of 3-PMPCl added according to the present invention. Figure 5 These are the deuterated proton NMR spectra of the perovskite active layers of Example 1 and Comparative Example 1 of the present invention. Figure 6 The extended X-ray absorption fine structure spectra of the perovskite active layers of Example 1 and Comparative Example 1 of this invention are shown. Figure 7 This is a schematic diagram of grazing incidence wide-angle X-ray scattering of the perovskite active layer described in Embodiment 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0019] Example 1 In this embodiment, the PIN perovskite solar cell is prepared by spin coating. All spin coating operations are performed in a nitrogen glove box, and the specific steps include: (1) Pretreatment of transparent conductive substrate: The ITO conductive glass was ultrasonically cleaned in sequence with glass cleaning solution, deionized water, anhydrous ethanol and acetone, dried with nitrogen, and then treated with ultraviolet ozone for 25 min.

[0020] (2) Preparation of hole transport layer: A nickel oxide solution with a concentration of 5 mg / mL was spin-coated onto the pretreated ITO conductive glass surface. The solvent was a mixture of deionized water and isopropanol in a volume ratio of 3:1. The spin-coating speed was 5000 rpm and the time was 30 s. After coating, the solution was annealed at 140 ℃ for 20 min. A mixed solution of Me-4PACz and NA was spin-coated onto the nickel oxide layer surface. The concentration of both solutions was 1 mmol / mL. The solvent was anhydrous ethanol. The spin-coating speed was 3000 rpm and the time was 20 s. After coating, the solution was annealed at 100 ℃ for 10 min.

[0021] (3) Preparation of the lower interface modification layer: Spin-coating a PEACl solution with a concentration of 1 mg / mL onto the surface of the hole transport layer. The solvent is isopropanol. The spin-coating speed is 6000 rpm and the time is 20 s. After coating, anneal at 100 ℃ for 2 min.

[0022] (4) Preparation of perovskite light-absorbing layer: Prepare perovskite precursor solution. Based on FAPbI3, add 0.12 mol% of 1-(pyridin-3-ylmethyl)piperazine hydrochloride (i.e., a molecule with n=1 in the general formula and Ar connection point 2, 3-PMPCI) to 2 M FAPbI3 solution. Then add 3.5 mol% of PbI2 and 15 mol% of MACl. The solvent of the precursor solution is a mixed solution of DMF and DMSO in a volume ratio of 4:1. Coat the prepared solution as a perovskite wet film. Spin coat at 8000 rpm for a total time of 40 s. When the spin coat reaches 12-13 seconds, continuously and rapidly add 150 μL of ethyl acetate as an antisolvent. After coating, quickly transfer to an air environment with a relative humidity of 20% and anneal at 100 ℃ for 5 min. Then anneal at 130 ℃ for 15 min to obtain perovskite light-absorbing layer.

[0023] (5) Preparation of the upper interface modification layer: Spin-coating a 1-(pyridin-3-ylmethyl)piperazine iodate solution with a concentration of 0.4 mg / mL onto the surface of the perovskite light absorption layer. The solvent is a mixture of isopropanol and chlorobenzene in a volume ratio of 1:1. The spin-coating speed is 3000 rpm and the time is 30 s. After coating, anneal at 100 ℃ for 10 min.

[0024] (6) Preparation of electron transport layer: Spin-coat a PCBM solution with a concentration of 23 mg / mL on the surface of the upper interface modified layer. The solvent is chlorobenzene. The spin-coating speed is 3000 rpm and the time is 25 s. After coating, anneal at 70 ℃ for 10 min.

[0025] (7) Preparation of hole blocking layer: Spin-coat a supersaturated BCP solution with isopropanol on the surface of the electron transport layer at a speed of 6000 rpm for 20 s. After coating, anneal at 70 ℃ for 10 min.

[0026] (8) Preparation of electrode layer: Silver electrode is deposited on the surface of hole blocking layer using thermal evaporation equipment. The thickness is 125 nm.

[0027] Example 2 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1, except that in the 2 M FAPbI3 solution, 0.12 mol% of 1-(3-phenylphosphonoethyl)piperazine hydrochloride (i.e., a molecule with n=2 in the general formula and Ar connection point 18) is used as the piperazine halide additive.

[0028] Example 3 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light absorption layer, 0.12 mol% of 1-(3-benzoylpropyl)piperazine hydrochloride (i.e., a molecule with n=3 in the general formula and Ar connection point 12) is used as the piperazine halide additive in a 2 M FAPbI3 solution.

[0029] Example 4 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light-absorbing layer, 0.12 mol% of 1-(4-benzenesulfonylbutyl)piperazine hydrochloride (i.e., a molecule with n=4 in the general formula and Ar connection point 16) is used as the piperazine halide additive in a 2 M FAPbI3 solution.

[0030] Example 5 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light absorption layer, 0.12 mol% of 1-(4-pyridazinylpentyl)piperazine hydrochloride (i.e., a molecule with n=5 in the general formula and Ar connection point 10) is used as the piperazine halide additive in a 2 M FAPbI3 solution.

[0031] Example 6 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light absorption layer, 0.12 mol% of 1-(2-pyrimidinylhexyl)piperazine hydrochloride (i.e., a molecule with n=6 in the general formula and Ar connection point 4) is used as the piperazine halide additive in a 2 M FAPbI3 solution.

[0032] Example 7 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light absorption layer, 0.12 mol% of 1-(4-pyrimidinylheptyl)piperazine hydrochloride (i.e., a molecule with n=7 and Ar connection point 6 in the general formula) is used as the piperazine halide additive in a 2 M FAPbI3 solution.

[0033] Example 8 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light absorption layer, 0.12 mol% of 1-(phenyloctyl)piperazine hydrochloride (i.e., a molecule with n=8 in the general formula and Ar connection point 8) is used as the piperazine halide additive in a 2 M FAPbI3 solution.

[0034] Example 9 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light absorption layer, 0.12 mol% of 1-(2-benzenesulfonic acid propyl)piperazine hydrochloride (i.e., a molecule with n=3 in the general formula and Ar connection point 14) is used as the piperazine halide additive in a 2 M FAPbI3 solution.

[0035] Example 10 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light absorption layer, 0.12 mol% of 1-(4-benzoylpentyl)piperazine hydrochloride (i.e., a molecule with n=5 in the general formula and Ar connection point 13) is used as the piperazine halide additive in a 2 M FAPbI3 solution.

[0036] Example 11 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light-absorbing layer, 0.08 mol% of 1-(pyridin-3-ylmethyl)piperazine hydrochloride is added to a 2 M FAPbI3 solution based on FAPbI3.

[0037] Example 12 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light-absorbing layer, 0.10 mol% of 1-(pyridin-3-ylmethyl)piperazine hydrochloride is added to a 2 M FAPbI3 solution based on FAPbI3.

[0038] Example 13 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light-absorbing layer, 0.14 mol% of 1-(pyridin-3-ylmethyl)piperazine hydrochloride is added to a 2 M FAPbI3 solution based on FAPbI3.

[0039] Example 14 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light-absorbing layer, 0.16 mol% of 1-(pyridin-3-ylmethyl)piperazine hydrochloride is added to a 2 M FAPbI3 solution based on FAPbI3.

[0040] Example 15 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light-absorbing layer, 0.20 mol% of 1-(pyridin-3-ylmethyl)piperazine hydrochloride is added to a 2 M FAPbI3 solution based on FAPbI3.

[0041] Example 16 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light-absorbing layer, 0.30 mol% of 1-(pyridin-3-ylmethyl)piperazine hydrochloride is added to a 2 M FAPbI3 solution based on FAPbI3.

[0042] Example 17 The preparation steps of the perovskite solar cell in this embodiment are the same as those in Example 1. The difference is that in the step of preparing the perovskite light-absorbing layer, 0.50 mol% of 1-(pyridin-3-ylmethyl)piperazine hydrochloride is added to a 2 M FAPbI3 solution based on FAPbI3.

[0043] Comparative Example 1 The preparation steps of the perovskite solar cell in this comparative example are the same as those in Example 1, except that piperazine halide additives are not added to the 2 M FAPbI3 solution in the step of preparing the perovskite light-absorbing layer.

[0044] Performance testing of perovskite solar cells The performance of the perovskite solar cells prepared in Examples 1-17 and Comparative Example 1 was tested. The current density-voltage ratio of the devices was measured under standard illumination conditions. JV Characteristic curves are used to obtain the open-circuit voltage ( V OC ), short-circuit current density ( J SC The fill factor (FF) and photoelectric conversion efficiency (PCE) were measured, with the test results of Examples 1-10 shown in Table 1. The current density-voltage ratios of Example 1 and Comparative Example 1 were compared. JV Characteristic curves as follows Figure 2 and Figure 3 As shown in the figure, 3-PMPCl is used to represent the case of Example 1, and control is used to represent the case of Comparative Example 1. To investigate the effect of different 3-PMPCl addition amounts (Examples 1 and 11-17, Comparative Example 1) on the device, at least 10 parallel samples were prepared for testing in each example. The photoelectric conversion efficiency of the device is shown in the figure. Figure 4 As shown.

[0045] Table 1. Battery performance parameters of each embodiment and comparative example.

[0046] As shown in Table 1, compared to Comparative Example 1 without the addition of piperazine halide additive, Examples 1-10... V OC 、J SC All three parameters (FF and PCE) were improved. Among them, Example 10 showed the best performance.

[0047] like Figure 2 As shown, the device obtained in Example 1 JV The characteristic curve shows: Under reverse scanning conditions, the open-circuit voltage V OC The short-circuit current density is 1.21 V. J SC It is 26.5 The fill factor (FF) is 86.5%, and the photoelectric conversion efficiency (PCE) reaches 27.6%; under forward scanning conditions, V OC It is 1.21 V. J SC It is 26.5 FF was 86.3%, and PCE reached 27.6%.

[0048] like Figure 3 As shown, the device obtained in Comparative Example 1 JV The characteristic curves show that under reverse scan conditions, VOC It is 1.19 V. J SC It is 26.4 The FF was 85.6%, and the PCE reached 26.9%; under forward scanning conditions, V OC It is 1.19 V. J SC It is 26.4 FF was 85.3%, and PCE reached 26.8%.

[0049] like Figure 4 As shown, 3-PMPCl additive can effectively improve the power conversion efficiency (PCE) of perovskite solar cells. There is an optimal addition concentration, with 0.12 mol% representing the optimal amount of 3-PMPCl. At this concentration, the PCE of the device reaches its peak, with small data dispersion and excellent device repeatability. Excessive addition leads to a gradual decrease in the PCE and may even degrade device performance. This indicates that the additive must be controlled within a reasonable concentration range to achieve the optimal passivation effect.

[0050] The above results show that after introducing piperazine halide additives into the perovskite active layer, the performance parameters of the device are all superior to those of the unadded comparative example, especially the PCE, which is improved from 26.9% to over 27.6%, and no problem of sacrificing photocurrent density for stability has occurred. J SC Maintain at 26.5 The above figures are comparable to or even higher than the comparative figures.

[0051] Characterization tests of perovskite thin films To further investigate the effect of additives on perovskite thin films, solid-state nuclear magnetic resonance (NMR), extended X-ray absorption fine structure (EPXS), and grazing-incidence wide-angle X-ray scattering (GISS) tests were performed on the perovskite thin films prepared in Example 1 and Comparative Example 1, respectively. The results are shown in [Figure 1]. Figure 5 , Figure 6 and Figure 7 In the figure, 3-PMPC1 is used to represent the case of Example 1, and control is used to represent the case of Comparative Example 1.

[0052] Figure 5 Solid-state NMR spectroscopy of deuterated proton NMR was performed on the perovskite films obtained in Example 1 and Comparative Example 1. It can be clearly observed that both sets of peaks exhibit symmetrical single peaks centered at 0 ppm, with peak shape and position highly overlapping, and no additional impurity peaks appearing. This indicates that the addition of the 3-PMPCl additive in this invention did not alter the FA... +The chemical environment of the cation does not damage the main crystal structure of the perovskite; it exists only as a functional additive and does not affect the bulk phase of the perovskite.

[0053] Figure 6 Extended X-ray absorption fine structure spectroscopy (EPXS) was performed on the perovskite films obtained in Example 1 and Comparative Example 1 before and after aging in a nitrogen atmosphere for 15 days. The left figure shows the Pb-I bond length changes of the perovskite samples in the fresh and aged states. It can be observed that the Pb-I bond lengths of the Control group and the 3-PMPCl group are almost identical in the fresh sample. After aging, the Pb-I bond length of the Control group expands significantly, while the Pb-I bond length of the 3-PMPCl group only increases slightly, showing a significant difference between the two groups. This indicates that in this invention, 3-PMPCl can effectively suppress the distortion of the perovskite lattice during the aging process, significantly improving the lattice stability of the perovskite. The right figure shows the DW (Debye-Waller) factor changes of the perovskite samples in the fresh and aged states. It can be observed that the DW factor values ​​of the Control group and the 3-PMPCl group are close in the fresh sample. After aging, the DW factor of the Control group increases significantly, while the DW factor of the 3-PMPCl group only increases slightly, with the increase in the Control group being much greater than that of the 3-PMPCl group. This indicates that, in this invention, 3-PMPCl can effectively suppress the increase of perovskite lattice disorder, passivate perovskite defects, and improve the structural stability of perovskite.

[0054] Figure 7 The perovskite films obtained in Example 1 and Comparative Example 1 were aged at 85 °C and 85% relative humidity, and then subjected to GIWAXS testing. The left image shows the GIWAXS two-dimensional pattern of the perovskite film with the 3-PMPCl additive group. It can be observed that the sample exhibits a clear and complete perovskite α-phase main diffraction ring, with no additional stray diffraction signals, uniform diffraction rings, and no abnormal crystal orientation. This indicates that in this invention, the addition of the 3-PMPCl additive did not destroy the crystallinity of the perovskite, did not change the preferred orientation of the crystal, and effectively suppressed the formation of harmful non-perovskite phases, resulting in excellent film phase purity. The right image shows the GIWAXS two-dimensional pattern of the perovskite film in the control group. It can be observed that, in addition to the perovskite α-phase main diffraction ring, the sample showed obvious δ-phase (harmful non-perovskite phase) diffraction signals next to the main ring. This indicates that the perovskite film without the addition of 3-PMPCl contains a harmful non-perovskite δ-phase, with insufficient phase purity, prone to phase decomposition, and poor structural stability.

[0055] Based on the above performance tests and characterization analysis results, it can be seen that this invention, by introducing piperazine halide additives, achieves the desired effect without sacrificing photocurrent density and bandgap width. J SC Maintain ≥26.3 (PCE increased to over 27.6%), while simultaneously achieving: enhanced FA + The additives in this invention significantly reduce cation rotational disorder, inhibit Pb-I bond expansion and octahedral disorder, and suppress δ-phase formation under humid and hot conditions. This demonstrates that the additives fundamentally stabilize the perovskite α-phase through a bulk phase regulation mechanism, overcoming the shortcomings of existing technologies where interface passivation makes it difficult to suppress bulk phase transitions or where ion doping leads to bandgap widening and sacrifices photocurrent.

[0056] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A perovskite solar cell based on piperazine halide additives, characterized in that... It includes, from bottom to top, a transparent conductive oxide substrate, a hole transport layer, a lower interface modification layer, a perovskite active layer, an upper interface modification layer, an electron transport layer, a buffer layer, and an electrode layer. The perovskite active layer is made of APbX3, where A is formamidinium (HC(NH2)2). + FA + ), Methylamine (CH3NH3) + MA + ) or cesium ions (Cs + At least one of the following: X is I − or Br − At least one of them; The perovskite active layer is introduced with piperazine halide additives, which are hydrochloride, hydrobromide or hydroiodide salts of piperazine derivatives as shown in Formula 1, and their parent molecular structures are shown in Formula 1, where n takes the value of an integer from 1 to 8. In the parent molecule structure, the nitrogen atom at the 1-position of the piperazine ring is denoted by -(CH2). n - Connected to an Ar group; Ar is selected from phenyl, pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl, benzenesulfonic acid, benzoic acid, phenylphosphoric acid, and the alkylene group is connected to Ar through 19 sites shown in Formula 2; Formula 1 Formula 2.

2. A perovskite solar cell based on piperazine halide additives according to claim 1, characterized in that, The amount of piperazine halide additive in the perovskite active layer is 0.08 to 0.5 mol% relative to the molar amount of the perovskite precursor solute; the solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide, or N-methyl-2-pyrrolidone; the antisolvent is one or more of ethyl acetate, chlorobenzene, anisole, or diethyl ether.

3. A perovskite solar cell based on piperazine halide additives according to claim 2, characterized in that, The transparent conductive oxide substrate is selected from either FTO conductive glass or ITO conductive glass.

4. A perovskite solar cell based on piperazine halide additives according to any one of claims 1-3, characterized in that, The material of the hole transport layer is selected from one or more organic or inorganic hole transport materials; the organic hole transport material is selected from carbazole phosphate or triphenylamine hole transport materials, including one or more of 2PACz, MeO-2PACz, Me-4PACz, MeO-4PACz, Ph-2PACz, 4PADCB, Ph-4PACz, 4,4',4''-triphenylamine tricarboxylate, PTAA, Poly-4PACz or Poly-2PACz. The inorganic hole transport material includes one or more of nickel oxide, doped nickel oxide, cuprous chromate, or cuprous gallate.

5. A perovskite solar cell based on piperazine halide additives according to any one of claims 1-3, characterized in that, The lower interface modification layer material includes one or more of phenylethyl iodide, phenylethyl ammonium chloride, phenylethyl ammonium bromide, 2-thiophene ethylamine hydrochloride, 1,3-propanediamine hydroiodide, and ethylenediamine hydroiodide.

6. A perovskite solar cell based on piperazine halide additives according to any one of claims 1-3, characterized in that, The upper interface modification layer material includes one or more of PEAI, PEACl, PEABr, 2-ThEACl, PDADI, EDADI, and 3-PMPI.

7. A perovskite solar cell based on piperazine halide additives according to any one of claims 1-3, characterized in that, The electron transport layer material is selected from PC. 61 One or a combination of BM or fullerene.

8. A perovskite solar cell based on piperazine halide additives according to any one of claims 1-3, characterized in that, The buffer layer material is selected from one or more of bath copper, tin oxide, cerium oxide, or titanium oxide.

9. A perovskite solar cell based on piperazine halide additives according to any one of claims 1-3, characterized in that, The electrode layer can be a single-layer structure or a double-layer structure. The single-layer structure is made of a material selected from silver, gold, copper, chromium, bismuth, indium tin oxide, aluminum-doped zinc oxide, and tungsten-doped indium oxide. The double-layer structure is selected from a bismuth-copper double-layer structure, a bismuth-gold double-layer structure, a bismuth-silver double-layer structure, a chromium-copper double-layer structure, a chromium-gold double-layer structure, and a chromium-silver double-layer structure. The thickness of the electrode layer is 20–1000 nm.

10. A method for preparing a perovskite solar cell based on a piperazine halide additive as described in any one of claims 1-9, comprising the following steps: Step 1, Pretreatment of transparent conductive substrate: The transparent conductive substrate is ultrasonically cleaned sequentially with glass cleaning solution, deionized water, anhydrous ethanol and acetone, dried with nitrogen, and then treated with ultraviolet ozone for 20~30 min. Step 2, prepare hole transport layer: spin coat the precursor solution of hole transport layer on the surface of the pretreated transparent conductive substrate at a spin speed of 4000~6000 rpm for 10~50 s, and anneal at 100~150 ℃ for 10~40 min after coating. Step 3, prepare the lower interface modification layer: spin coat the precursor solution of the lower interface modification layer onto the surface of the hole transport layer at a spin speed of 5000~7000 rpm for 10~30 s. After coating, anneal at 90~110 ℃ for 1~3 min. Step 4, Preparation of perovskite light absorption layer: APbX3 and piperazine halide are dissolved together in a solvent, mixed to obtain a precursor solution, and then coated as a perovskite wet film. The spin coating speed is 7000~9000 rpm, and the total time is 30~50 s. During the spin coating process, the anti-solvent is added dropwise, and the film is annealed at 100~130 ℃ for 5~15 min. Step 5, prepare the upper interface modification layer: spin-coat the precursor solution on the surface of the perovskite light absorption layer at a spin speed of 2000~4000 rpm for 20~40 s. After coating, anneal at 90~110 ℃ for 5~15 min. Step 6, prepare the electron transport layer: spin-coat the precursor solution onto the surface of the upper interface modification layer at a spin speed of 2000~4000 rpm for 20~30 s. After coating, anneal at 60~80 ℃ for 5~15 min. Step 7, prepare the buffer layer: spin-coat the precursor solution onto the surface of the electron transport layer at a spin speed of 5000~7000 rpm for 10~30 s. After coating, anneal at 60~80 ℃ for 5~15 min. Step 8, prepare the electrode layer: use a thermal evaporation device to deposit a silver electrode on the surface of the buffer layer with a thickness of 100~150 nm.

Images