Passivation molecule and perovskite solar cell

Abstract

The invention discloses a passivation molecule, the passivation molecule is N-acetyl piperazine halide and N-formyl piperazine halide, the two ends of the passivation molecule respectively contain ammonium cations and carbonyl functional groups, and the passivation molecule shows stable plane orientation preference due to the double-site geometric synergistic anchoring effect of'ammonium-carbonyl '. Therefore, synchronous passivation of double defects can be realized on the surface of the perovskite, and the photoelectric conversion efficiency and the stability of the perovskite solar cell can be improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optoelectronic materials and devices, and particularly relates to a passivation molecule and a perovskite solar cell. BACKGROUND

[0002] Perovskite solar cells have rapidly climbed from an initial efficiency of 3.8% to about 27% in just over a decade due to their excellent optoelectronic performance, becoming a strong contender for the next generation of photovoltaic technology. However, there are still many challenges to commercialization of the device, among which non-radiative recombination caused by interfacial defects is a key bottleneck limiting efficiency and stability. Vacancy defects (such as organic cations FA + ) and uncoordinated Pb 2+ sites on the perovskite grain boundaries and surfaces can act as deep level trap centers, accelerating carrier recombination and inducing material degradation.

[0003] To suppress the adverse effects of the above interfacial defects, researchers have proposed various passivation strategies. Among them, single-function ammonium salt passivation agents are widely used, such as phenethylammonium iodide (PEAI), 1,4-butanediamine iodide (BDAI2), and ethylenediamine diiodide (EDAI2), which can bond with ionic defects on the perovskite surface, repair lattice vacancies, and thus reduce non-radiative recombination loss.

[0004] The patent document with publication number CN116193872A discloses a perovskite solar cell and a passivation method thereof. The electron blocking layer is generated after modification by a passivation agent solution containing an acyl chloride group. The carbonyl group in the acyl chloride group forms a Lewis acid-base pair with uncoordinated Pb 2+ ions on the perovskite surface, significantly reducing the defect state density on the perovskite surface. However, this application only works on a certain type of defect in the perovskite, and the passivation effect is limited, unable to passivate different types of defects simultaneously.

[0005] There are also synergistic passivation strategies that deposit two or more passivation molecules together in order to passivate different types of defects simultaneously. However, multi-molecular co-passivation often faces the problem of mutual competition for adsorption, which may lead to uneven surface coverage and disordered interfacial energy levels.

[0006] Recent research has shown that multifunctional single-molecule passivators with "one agent, multiple effects" have become a new research direction. By introducing multiple coordinating functional groups into a single molecule, simultaneous passivation of various defects can be achieved. Patent document CN120322097A discloses an interface passivation layer, a perovskite solar cell, its preparation method, and electrical devices. The passivation layer material in this application includes 3-fluoro-4-aminobenzoic acid, which possesses multiple functional groups, including fluoride ions, amino groups, benzene rings, and carboxylic acid groups. This allows for precise passivation modification of the perovskite solar cell surface. Through the passivation effect of these multiple functional groups, energy loss at the cell interface is significantly reduced. However, this application does not address the influence of the adsorption orientation of the passivation molecules on the perovskite passivation effect.

[0007] Studies have shown that when passivating molecules adsorb parallel to the surface (i.e., "face-on"), multiple functional groups can simultaneously point towards the perovskite surface, achieving dual-site coordination. This face-on orientation enhances chemical anchoring, improves interfacial coupling, and thus more effectively passivates defects and promotes charge extraction. Conversely, if molecules adsorb vertically (edge-on), typically only one functional group interacts with the surface, limiting the passivation effect. Therefore, the adsorption orientation of passivating molecules has a decisive influence on the passivation effect of multifunctional molecules.

[0008] However, existing publicly available single-molecule multifunctional passivators capable of stably achieving face-oriented orientation with a significant orientation preference on perovskite surfaces remain relatively limited, and there are few reports on the systematic design and quantitative relationships between orientation, coordination, and device performance. Therefore, designing single-molecule multifunctional passivation molecular structures with strong face-oriented orientation preference is of great significance for achieving more efficient and stable dual passivation effects. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the first aspect of this invention provides a passivating molecule that has a face orientation preference and multiple passivation effects.

[0010] This invention provides a passivation molecule, wherein the passivation molecule is an N-acetylpiperazine halide or an N-formylpiperazine halide, and the structural formulas are shown in formulas (1) and (2), respectively:

[0011] Equation (1)

[0012] Equation (2); In this case, the substituent X is a halogen element.

[0013] Compared to existing single-molecule multifunctional passivating agents, which suffer from unstable face orientation and limited passivation effect, the passivating molecules N-acetylpiperazine halide and N-formylpiperazine halide designed in this invention contain ammonium cations and carbonyl functional groups (C=O) at their respective ends. The ammonium cations can react with FA... + Vacancies are attracted by electrostatic attraction, filling the cation FA. + Vacancy defects, while carbonyl oxygen can interact with uncoordinated Pb on the perovskite surface. 2+ Lewis acid-base coordination occurs, leading to a dual-site synergistic anchoring of an "ammonium-carbonyl" group. Driven by this dual-site geometric synergy, the passivated molecules on the perovskite surface tend to adopt a face-on orientation parallel to the surface. The adsorption energy difference between the face-on and edge-on orientations of the passivated molecules is... ΔE ads = E face-on - E edge-on <0 indicates a preference for facing orientation.

[0014] Passivation molecules with a face orientation preference have more significant advantages in chemical anchoring and interfacial coupling, enabling simultaneous passivation of multiple defects on the perovskite surface. When these passivation molecules are applied to the preparation of perovskite passivation layers, the simultaneous passivation effect of dual defects is superior, which can reduce the defect density of perovskite, enhance interfacial band bending and charge extraction, and thus improve the efficiency and stability of perovskite solar cells.

[0015] Organic cations with conjugated π systems and rigid pyridine rings tend to form quasi-two-dimensional phases via cation exchange due to strong π–π stacking. These phases are non-uniformly distributed along the normal in three-dimensional perovskite films, thus hindering charge extraction. Introducing low-rigidity alicyclic ammonium cations (such as piperazine ammonium) can weaken intermolecular interactions and enhance their coordination to defect centers, thereby effectively suppressing the formation of quasi-two-dimensional phases.

[0016] More preferably, the X - For I - ,Br - or Cl - .

[0017] Preferably, the passivating molecules ΔE ads ≤−0.05eV, corresponding to an orientation ratio of ≥80% at 25-150℃.

[0018] Preferably, the passivating molecule is an N-formylpiperazine halide, wherein the N-formylpiperazine halide... ΔE ads ≤−0.20eV, corresponding to an orientation ratio of ≥99% at 25-150℃.

[0019] The N-formylpiperazine halide provided by this invention has a formyl group (-CHO) as its carbonyl group, which is smaller and less sterically hindered than an acetyl group (-COCH3), and exhibits a more negative carbonyl group. ΔE ads The more negative ΔE ads This indicates a stronger preference for face orientation, resulting in a higher proportion of face orientation in the adsorption orientation selection of the passivated molecules, thus leading to better performance and stability of perovskite solar devices.

[0020] Use the above-mentioned range ΔE ads This can thermodynamically ensure statistical dominance of face orientation, thereby improving the effectiveness of dual-site synergistic passivation.

[0021] Preferably, the passivating molecule is N-acetylpiperazine iodide (NAPI) or N-formylpiperazine iodide (NFPI).

[0022] Secondly, the present invention also provides a perovskite solar cell, including an inverted pin structure: The following layers are arranged sequentially from bottom to top: anode, hole transport layer, perovskite light absorption layer, passivation layer made according to the passivation molecule, electron transport layer, and cathode.

[0023] More preferably, the electron transport layer is C 60 A BCP buffer layer is provided between the electron transport layer and the cathode. The hole transport layer is NiOx. An organic self-assembled monolayer, Me4PACz, is provided between NiOx and the perovskite light absorption layer.

[0024] Because the passivation molecules N-acetylpiperazine halide and N-formylpiperazine halide provided by this invention can simultaneously passivate multiple defects in perovskites, the passivation layer treated with these passivation molecules has a lower defect density, and the interfacial band bending and charge extraction are also enhanced, thus achieving efficient and stable interfacial passivation. Perovskite solar cells fabricated based on these passivation layers show a significant improvement in photoelectric conversion efficiency (PCE) and open-circuit voltage (OPV). V OC Both the fill factor (FF) and efficiency retention factor (FFF) were improved. Under unencapsulated dark storage and thermal aging conditions, the efficiency retention of the solar cell was enhanced, and the encapsulated device's lifetime (T) was improved during maximum power point tracking under continuous illumination. 80 () Significantly prolonged.

[0025] Thirdly, the present invention also provides a perovskite solar cell, comprising a conventional structure (nip): The layers arranged from bottom to top are: cathode, electron transport layer, perovskite light absorption layer, passivation layer made according to the passivation molecules, hole transport layer, and anode.

[0026] More preferably, the electron transport layer is SnO2, and the hole transport layer is Spiro-OMeTAD.

[0027] Preferably, the method for preparing the passivation layer includes: The passivating molecule is dissolved in isopropanol solvent to prepare a passivating agent isopropanol solution of 0.1-10 mg / mL. Then, it is spin-coated on a perovskite film at 2000-6000 rpm for 10-60 s, and then baked at 80-120 °C for 2-10 min to obtain the passivation layer.

[0028] This invention prepares a passivation layer of moderate thickness by controlling the concentration of the passivating agent isopropanol solution and the spin-coating parameters, which helps to improve the passivation effect. At the same time, it avoids the passivation layer being too thick, which would cause the passivation layer to tend to become an insulator and be detrimental to interfacial transport.

[0029] More preferably, the concentration of the passivating agent isopropanol solution is 0.2–2 mg / mL.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: The passivation molecules N-acetylpiperazine iodide and N-formylpiperazine iodide provided by this invention have ammonium cations and carbonyl functional groups at their respective ends, and the ammonium cations can fill the cation FA. + Vacancy defects, while carbonyl functional groups can interact with uncoordinated Pb. 2+ Coordination and passivation of metal cation defects, along with the geometric synergistic anchoring effect of the "ammonium-carbonyl" dual-site, enable the passivated molecules to exhibit a stable orientation preference, thereby achieving simultaneous passivation of dual defects on the perovskite surface. This helps to improve the photoelectric conversion efficiency and stability of perovskite solar cells. Attached Figure Description

[0031] Figure 1 The structural formula of N-acetylpiperazine iodide (NAPI) obtained in Example 1 of this invention is shown below. Figure 2 The structural formula of N-formylpiperazine iodide NFPI obtained in Example 2 of this invention is shown below; Figure 3 The structural formula of N-methylpiperazine iodide (NMPI) provided in Comparative Example 1 is used in this invention; Figure 4 This is a schematic diagram of the passivation process for the passivation molecules provided in Application Example 1 of the present invention; Figure 5A schematic diagram illustrating the face orientation and edge orientation provided by the present invention; Figure 6 The N-acetylpiperazine iodide (NAPI) prepared in Example 1 of this invention 1 H NMR spectrum; Figure 7 The N-formylpiperazine iodide NFPI prepared in Example 2 of this invention 1 H NMR spectrum. Detailed Implementation

[0032] Example 1 NAPI synthesis: 1.0754 g (8.4 mmol) of acetylpiperazine was added to a 100 mL flask and dissolved in 20 mL of ethanol. 2.22 mL (16.8 mmol) of 57% HI was added dropwise under ice bath conditions. The reaction was allowed to proceed for 30 min. The solvent was removed by rotary evaporation, and the solution was washed three times with diethyl ether to obtain white crystalline NAPI (1.55 g, 75%), with the structural formula shown below. Figure 1 As shown. Figure 6 NMR data for NAPI: ¹H NMR (400 MHz, CD3OD) δ: 2.29 (t, 4H), 1.79 (t, 2H), 1.71 (t, 2H), 0.62 (s, 3H).

[0033] Example 2 Synthesis of NFPI: 1.107 g (9.7 mmol) of formylpiperazine was added to a 100 mL flask and dissolved in 20 mL of ethanol. 2.56 mL (19.4 mmol) of 57% HI was added dropwise under ice bath conditions. The reaction was allowed to proceed for 30 min. The solvent was removed by rotary evaporation, and the mixture was washed three times with diethyl ether to obtain NFPI (1.84 g, 82%), with the structural formula shown below. Figure 2 As shown. Figure 7 NMR data for NFPI: ¹H NMR (400 MHz, CD3OD) δ: 8.12 (s, 1H), 3.79 (t, 4H), 3.26 (t, 4H).

[0034] Application Example 1 Fabrication and passivation of perovskite solar cells: ① Substrate treatment: The glass substrate coated with ITO was sequentially cleaned in an ultrasonic cleaner with 2% detergent, deionized water and ethanol for 20 min, then dried in a vacuum drying oven at 80 ℃, and then subjected to UV ozone treatment for 20 min to obtain the conductive transparent electrode substrate.

[0035] ② Preparation of NiOx: Ni(NO3)2·6H2O (290.79 mg), EDA (67 μL) and KCl (3.7 mg) were dissolved in 2 mL of ethylene glycol to obtain a NiOx precursor solution. The precursor solution was spin-coated onto the conductive transparent electrode substrate at 4000 rpm for 30 s to form a film, and then dried in a vacuum drying oven at 115 ℃ for 30 min. After that, it was calcined on a hot stage at 315 ℃ for 60 min and cooled in a rotating oven at 155 ℃.

[0036] ③ Self-assembled monolayer: Dissolve Me4PACz (0.5 mg) in 1 mL of ethanol to prepare an ethanol solution of Me4PACz of 0.5 mg / mL. Spin-coat the ethanol solution of Me4PACz on the surface of the NiOx substrate at 5000 rpm for 30 s, and anneal at 100 °C for 10 min on a hot plate to obtain the NiOx substrate modified with Me4PACz.

[0037] ④ Perovskite thin films: CsI (38.97 mg), FAI (232.15 mg), PbI2 (760.65 mg), and MACl (11.14 mg) were prepared. 0.1 FA 0.9 PbI3 (containing 10% MACl and 10% excess PbI2) was dissolved in 1 mL of DMF / DMSO solution, wherein the volume ratio of DMF to DMSO was 4:1, to obtain the perovskite precursor solution. The perovskite precursor solution was first spin-coated on the Me4PACz-modified NiOx substrate at 1000 rpm for 5 s, and then spin-coated at 5000 rpm for 30 s. At the 17th s of spin-coating, 150 μL of chlorobenzene was added dropwise as an antisolvent, and then annealed at 120 °C for 20 min to obtain the perovskite film.

[0038] ⑤ Passivation layer: The NAPI passivation molecules obtained in Example 1 were dissolved in isopropanol solution to prepare a 1 mg / mL passivating agent isopropanol solution containing NAPI passivation molecules. The passivating agent isopropanol solution was then spin-coated onto the perovskite film at 5000 rpm for 30 s, and then annealed at 100 °C for 5 min on a hot plate to obtain the passivation layer.

[0039] ⑥ Top Layer: Apply C sequentially using a vacuum evaporation apparatus. 60 The perovskite solar cell is obtained by vapor deposition of (25 nm) / BCP (5 nm) / Ag (100 nm) onto the passivation layer.

[0040] The passivation process of the passivation molecule NAPI in step ⑤ is illustrated in the diagram below. Figure 4 As shown.

[0041] Application Example 2 The only difference from Application Example 1 is that the passivation layer in Application Example 2 is the NFPI prepared in Example 2.

[0042] Application Comparative Example 1 The only difference from Application Example 1 is that Comparative Example 1 does not perform passivation treatment on the perovskite.

[0043] Application Comparative Example 2 The only difference from Application Example 1 is that the passivation layer in Comparative Example 2 uses N-methylpiperazine iodide (NMPI), the structural formula of which is as follows: Figure 3 As shown.

[0044] The application embodiments and comparative examples provided by this invention are illustrated in the following schematic diagrams showing the face and edge orientations of the passivated molecules. Figure 5 As shown.

[0045] Performance testing: The passivation molecules used in Application Examples 1-2 and Comparative Example 2 were applied to the FAI termination surface. ΔE ads and the perovskite solar cells prepared using Examples 1-2 and Comparative Examples 1-2. V OC FF and PCE are shown in Table 1.

[0046] Table 1. The passivation molecules used in Application Examples 1-2 and Comparative Example 2 on the FAI termination surface. ΔE ads and the perovskite solar cells prepared using Examples 1-2 and Comparative Examples 1-2. V OC FF and PCE

[0047] In summary, using Examples 1-2 and Comparative Examples 1-2, it can be seen that compared to NMPI containing methyl substitution and without a passivation layer, the NAPI and NFPI provided by this invention, due to the introduction of carbonyl substitutions (acetyl-COCH3 and formyl-CHO, respectively) at the other end of the molecule, under the dual-site geometric synergy, achieve better performance on the FAI termination surface. ΔE ads All values ​​are negative, indicating a stable face orientation preference, which is more stable and has a stronger interface anchoring ability compared to edge orientation configurations. The photoelectric conversion efficiency of the fabricated perovskite solar cells is significantly improved, and both the open-circuit voltage and fill factor are increased.

[0048] Furthermore, the passivated molecules on the FAI termination surface ΔE adsLet's look at NAPI's ΔE ads The value is -0.09 eV, which is the value of NFPI. ΔE ads With a value of -0.29 eV, compared to NAPI, NFPI exhibits a more negative value due to the presence of smaller, less sterically hindered formyl functional groups. ΔE ads They have a higher percentage of face orientation orientations and a stronger face orientation preference.

[0049] The efficiency retention rates of the perovskite solar cells prepared in the above application examples 1-2 and comparative examples 1-2 after 65°C thermal aging for 1500 hours were 90%, 90%, 30%, and 3%, respectively. The efficiency retention rates of the encapsulated devices under illumination were also measured. 80 The results were 169 h, 477 h, 26 h, and 26 h, respectively.

[0050] It can be seen that the perovskite solar cells fabricated using the passivation molecules provided by this invention exhibit improved efficiency retention under unencapsulated dark storage and thermal aging conditions. In continuous illumination maximum power point tracking, the operating lifetime (T...) of the encapsulated device is significantly improved. 80 The lifespan of perovskite solar cells is significantly extended, the rate of performance degradation is significantly slowed down, the lifespan is greatly extended, the performance is excellent, and the stability is also improved.

Claims

1. A passivated molecule, characterized in that, The passivation molecule is N-acetyl piperazine halide or N-formyl piperazine halide, and the structural formulae are shown in formula (1) and (2) respectively. , formula (1); , formula (2); The substituent group X is a halogen element.

2. The passivated molecule of claim 1, wherein, The X - is I - , Br - or Cl - .

3. The passivated molecule of claim 1, wherein, The passivation molecules ΔE ads ≤ -0.05 eV, corresponding to a face-on orientation fraction ≥ 80% at 25-150 °C.

4. The passivated molecule of claim 1, wherein, The passivation molecule is N-formylpiperazine halide, the N-formylpiperazine halide has ΔE ads ≤-0.20eV, corresponding to 25-150℃, the proportion of face-up orientation ≥99%.

5. The passivated molecule of claim 1, wherein, The passivation molecule is N-acetyl piperazine iodide or N-formyl piperazine iodide.

6. A perovskite solar cell, comprising: The anode, the hole transport layer, the perovskite light absorption layer, the passivation layer prepared from the passivation molecule according to any one of claims 1-5, the electron transport layer and the cathode are sequentially arranged from bottom to top.

7. A perovskite solar cell, comprising: The cathode, the electron transport layer, the perovskite light absorption layer, the passivation layer prepared from the passivation molecule according to any one of claims 1-5, the hole transport layer and the anode are sequentially arranged from bottom to top.

8. The perovskite solar cell according to claim 6 or 7, characterized in that, The preparation method of the passivation layer comprises: The passivation molecule is dissolved in an isopropanol solvent to prepare a passivation agent isopropanol solution with a concentration of 0.1-10 mg / mL, then the passivation agent isopropanol solution is spin-coated on the perovskite film at 2000-6000 rpm for 10-60 s, and then baking is performed at 80-120 ℃ for 2-10 min to obtain the passivation layer.

9. The perovskite solar cell according to claim 8, characterized in that, The concentration of the passivation agent isopropanol solution is 0.2-2 mg / mL.

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