A phenoxazine ester derivative, a preparation method and application thereof

Abstract

The present application relates to the technical field of perovskite solar cells, and particularly relates to a phenoxazine ester derivative, a preparation method and application thereof. The molecular structure of the phenoxazine ester derivative is shown in the general formula; wherein L1 is methyl, ethyl or isopropyl. The present application uses the phenoxazine ester derivative with a specific structure as a passivation material, so that the photoelectric conversion efficiency of the battery is significantly improved, and the problems of the existing perovskite solar cell passivator, such as limited passivation effect, poor thermal stability, poor film forming property, and insufficient compatibility with perovskite and charge transport layer, are solved.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, specifically to a phenazine ester derivative, its preparation method, and its application. Background Technology

[0002] Perovskite solar cells (PSCs) have become a research hotspot in the photovoltaic field due to their low cost, high efficiency, and ease of processing. Since their development, the energy conversion efficiency of PSCs has been continuously improved. However, the perovskite light-absorbing layer is prone to grain boundary defects and point defects due to insufficient crystallization. Furthermore, under high temperature, high humidity, and high local electric fields, they are susceptible to chemical degradation, escape of organic components, or ion migration. These defects accelerate charge recombination and significantly reduce carrier lifetime. Simultaneously, interface defects and insufficient transport performance between the charge transport layer and the perovskite light-absorbing layer jointly restrict the efficiency improvement and long-term stability of PSCs, becoming a key bottleneck hindering their industrialization. Defect passivation is one of the core methods to improve the quality of perovskite thin films and enhance device performance.

[0003] For mainstream nip-type perovskite solar cells, the hole transport layer (HTL), as one of the core functional layers, plays a crucial role in extracting holes from the perovskite absorber layer and transporting them to the electrodes. Its performance directly affects the energy conversion efficiency and stability of the cell. Currently, commonly used hole transport materials mainly include two categories: molecular semiconductors and polymer semiconductors. Among them, spiro-OMeTAD is a widely used molecular semiconductor model material with suitable HOMO energy levels. It can achieve a certain hole concentration and conductivity through doping. However, its glass transition temperature is less than 85℃, the diffusion coefficient of exogenous species in the solid is relatively high, and the amorphous film is prone to crystallization and cracking when heated, resulting in poor high-temperature stability of the cell.

[0004] Polymer semiconductors such as PTAA, while possessing longer charge transport persistence and superior thin film mechanical properties, have deep HOMO levels, making it difficult to achieve sufficiently high conductivity through air oxidation doping. Existing passivators are mostly single-function materials, with either limited passivation effects or poor compatibility with perovskites and charge transport layers, failing to fundamentally solve the charge recombination problem caused by defects. Furthermore, the combined use of these two materials can easily lead to interface compatibility issues, hindering the improvement of device performance. Summary of the Invention

[0005] To address the problems of limited passivation effect, poor thermal stability, unsatisfactory film formation, and insufficient compatibility with perovskite and charge transport layers in existing perovskite solar cell passivators, this invention provides a phenazine ester derivative, its preparation method, and its application.

[0006] This invention utilizes the unique conjugated fused-ring structure of phenazine compounds. The nitrogen atoms and ester groups in the molecule can provide lone pairs of electrons, forming stable coordination with perovskite defect sites to achieve efficient passivation. Simultaneously, the nitrogen atoms and benzene ring sites can undergo diverse substitution reactions, providing a structural basis for optimizing the material's stability, film-forming properties, and interfacial compatibility. Therefore, this invention provides a perovskite passivating agent that combines efficient passivation capability, excellent thermal stability, good film-forming properties, and interfacial compatibility, which is crucial for promoting the industrialization of perovskite solar cells.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows.

[0008] A first aspect of this invention provides a phenazine ester derivative, the general molecular structural formula of which is shown below: ; L1 is methyl, ethyl, or isopropyl.

[0009] Preferably, the phenazine ester derivative is any one of the following compounds: .

[0010] A second aspect of this invention provides a method for preparing the phenazine ester derivative described in the first aspect, comprising the following steps: Using compounds of Formula 1 and Formula 2 as starting materials, the compound of Formula 1 was reacted with NaH in a reaction solvent at 5℃–10℃. Then, the compound of Formula 2 was added at 5℃–10℃, and a substitution reaction occurred at 20℃–25℃, attaching an ester group to the phenazine N atom of the compound of Formula 1 to obtain the phenazine ester derivative shown in Formula 3. The synthetic route for the phenazine ester derivative is as follows: .

[0011] The preparation process of the phenazine ester derivative of the present invention is simple. The phenazine ester derivative is prepared from commercially available inexpensive phenazine-1-carboxylic acid through esterification and acylation reactions. The reaction conditions are mild and the yield is high. Moreover, the prepared phenazine ester derivative can be used as a passivation layer by solution spin coating. The process is simple and low-cost, suitable for large-area device processing, and does not require additional adjustments to the existing battery preparation process, which is conducive to promoting its industrial application.

[0012] Preferably, the molar ratio of the compound shown in Formula 1 to the compound shown in Formula 2 is 1:2.5 to 2.6.

[0013] Preferably, the molar ratio of the compound shown in Formula 1 to NaH is 1:3 to 3.1.

[0014] In this invention, NaH acts as a highly reactive non-nucleophilic strong base to abstract the active hydrogen atom from the methylene group in the compound shown in Formula 1, generating a highly reactive carbanion intermediate. This carbanion intermediate then undergoes an SN2 nucleophilic substitution reaction with the acetate group in the compound shown in Formula 2, thereby introducing an acetate group onto the phenazine skeleton and constructing a new C-C bond, thus obtaining the phenazine ester derivative shown in Formula 3.

[0015] Preferably, the reaction solvent is N,N-dimethylformamide.

[0016] Preferably, the ratio of the compound shown in Formula 1 to the organic solvent is 1 mmol: 1.8 mL to 2 mL.

[0017] The third aspect of the present invention provides an application of a phenazine ester derivative as a passivation material for a perovskite light-absorbing layer in the fabrication of a perovskite solar cell, wherein the phenazine ester derivative is the phenazine ester derivative described in the first aspect.

[0018] This invention uses phenazine ester derivatives with specific structures as passivating agents to achieve efficient passivation of perovskite defects, reduce the probability of charge recombination, and thus improve the energy conversion efficiency and long-term stability of perovskite solar cells.

[0019] The beneficial effects of this invention are: 1. In the phenazine ester derivative provided by this invention, the lone pair electrons on the carbonyl group (C=O) of the ester group (-COOCH3) interact with the undercoordinated Pb on the perovskite surface. 2+ Forming coordinate bonds to fill Pb 2+ The electron vacancy is eliminated, thus removing the deep-level defect state; the lone pair electrons on the nitrogen atom of the phenazine ring can also interact with Pb. 2+ Coordination occurs, further enhancing the passivation effect; the phenazine conjugated ring has good electron transport characteristics, which can promote the separation of interfacial charges and form energy level matching with perovskite, reducing charge recombination loss. The synergistic effect of multiple aspects ultimately achieves a significant improvement in the photoelectric conversion efficiency of the battery, solving the problems of limited passivation effect, poor thermal stability, poor film formation, and insufficient compatibility with perovskite and charge transport layer of existing perovskite solar cell passivators.

[0020] 2. The phenazine ester derivative obtained by the present invention through specific molecular structure design can be used as a passivation material for the perovskite light absorption layer, which can significantly improve the photoelectric conversion efficiency of perovskite solar cells. Attached Figure Description

[0021] Figure 1 These are the current density-voltage curves of the inverted perovskite solar cells used in Examples 1 to 4 and Comparative Example 1.

[0022] Figure 2The result is the 1H NMR spectrum of compound 1 in Example 1.

[0023] Figure 3 The result is the 1H NMR spectrum of compound 2 in Example 2.

[0024] Figure 4 The result is the 1H NMR spectrum of compound 3 in Example 3.

[0025] Figure 5 The result is the 1H NMR spectrum of compound 4 in Example 4. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. The technical solutions of this invention will be further described below through specific embodiments. In the following embodiments, unless otherwise specified, the methods are conventional methods; the reagents and materials, unless otherwise specified, are commercially available. N,N-Dimethylformamide, abbreviated as DMF. Dimethyl sulfoxide, abbreviated as DMSO. Methylammonium bromide, abbreviated as MABr.

[0027] Example 1 A phenazine ester derivative has the following molecular structural formula: .

[0028] A method for preparing phenazine ester derivatives includes the following steps: Synthesis of Compound 1: Under nitrogen protection, 74.08 mmol of NaH and 20 mL of anhydrous DMF were added to a reaction flask, and the temperature was lowered to 10 °C. 24.69 mmol of 5,10-dihydrophenazine was weighed and dissolved in 25 mL of DMF, which was then added dropwise to the reaction flask at a controlled temperature of 5 °C–10 °C. After the addition was complete, the reaction was maintained at 10 °C for 1.5 h. Then, 61.74 mmol of methyl bromoacetate was added dropwise at a controlled temperature of 5 °C–10 °C. After the addition was complete, the reaction was carried out at room temperature (20 °C) for 3 h. The reaction mixture was extracted with water and ethyl acetate, dried over anhydrous sodium sulfate, and the solvent was removed by concentration under reduced pressure. Finally, the reaction product was separated by column chromatography using a mixed solvent of n-hexane and ethyl acetate in a volume ratio of 10:1 as the eluent, yielding Compound 1. The product yield was 82.4%. The synthetic route of Compound 1 is as follows: .

[0029] The detection results of the proton NMR spectrum of compound 1 are as follows: Figure 2As shown.

[0030] Example 2 A phenazine ester derivative has the following molecular structural formula: .

[0031] A method for preparing phenazine ester derivatives includes the following steps: Synthesis of Compound 2: Under nitrogen protection, 98.78 mmol of NaH and 25 mL of anhydrous DMF were added to a reaction flask, and the temperature was lowered to 10 °C. 32.93 mmol of 5,10-dihydrophenazine was weighed and dissolved in 35 mL of DMF, which was then added dropwise to the reaction flask at a controlled temperature of 5 °C–10 °C. After the addition was complete, the reaction was maintained at 10 °C for 1.5 h. Then, 82.32 mmol of ethyl bromoacetate was added dropwise at a controlled temperature of 5 °C–10 °C. After the addition was complete, the reaction was carried out at room temperature (20 °C) for 3 h. The reaction mixture was extracted with water and ethyl acetate, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to remove the solvent. Finally, the reaction product was separated by column chromatography using a mixture of n-hexane and ethyl acetate in a volume ratio of 10:1 as the eluent, yielding Compound 2. The product yield was 65.7%. The synthetic route of Compound 2 is as follows: .

[0032] The detection results of the proton NMR spectrum of compound 2 are as follows: Figure 3 As shown.

[0033] Example 3 A phenazine ester derivative has the following molecular structural formula: .

[0034] A method for preparing phenazine ester derivatives includes the following steps: Synthesis of Compound 3: Under nitrogen protection, 82.32 mmol of NaH and 20 mL of anhydrous DMF were added to a reaction flask, and the temperature was lowered to 10 °C. 27.44 mmol of 5,10-dihydrophenazine was weighed and dissolved in 30 mL of DMF, which was then added dropwise to the reaction flask at a controlled temperature of 5 °C–10 °C. After the addition was complete, the reaction was maintained at 10 °C for 1.5 h. Then, 68.60 mmol of tert-butyl bromoacetate was added dropwise at a controlled temperature of 5 °C–10 °C. After the addition was complete, the reaction was carried out at room temperature (20 °C) for 3 h. The reaction mixture was extracted with water and ethyl acetate, dried over anhydrous sodium sulfate, and the solvent was removed by concentration under reduced pressure. Finally, the reaction product was separated by column chromatography using a mixture of n-hexane and ethyl acetate in a volume ratio of 10:1 as the eluent to obtain Compound 3. The product yield was 78.10%. The synthetic route of Compound 3 is as follows: .

[0035] The detection results of the proton NMR spectrum of compound 3 are as follows: Figure 4 As shown.

[0036] Example 4 A phenazine ester derivative has the following molecular structural formula: .

[0037] A method for preparing phenazine ester derivatives includes the following steps: Synthesis of Compound 4: Under nitrogen protection, 90.55 mmol of NaH and 25 mL of anhydrous DMF were added to a reaction flask, and the temperature was lowered to 10 °C. 30.18 mmol of 5,10-dihydrophenazine was weighed and dissolved in 30 mL of DMF, which was then added dropwise to the reaction flask at a controlled temperature of 5 °C–10 °C. After the addition was complete, the reaction was maintained at 10 °C for 1.5 h. Then, 75.46 mmol of isopropyl bromoacetate was added dropwise at a controlled temperature of 5 °C–10 °C. After the addition was complete, the reaction was carried out at room temperature (20 °C) for 3 h. The reaction mixture was extracted with water and ethyl acetate, dried over anhydrous sodium sulfate, and the solvent was removed by concentration under reduced pressure. Finally, the reaction product was separated by column chromatography using a mixture of n-hexane and ethyl acetate in a volume ratio of 10:1 as the eluent, yielding Compound 4. The product yield was 50.6%. The synthetic route of Compound 4 is as follows: .

[0038] The detection results of the proton NMR spectrum of compound 4 are as follows: Figure 5 As shown.

[0039] Application Example 1 An application of the phenazine ester derivative from Example 1 as a passivation material in the fabrication of an inverted perovskite solar cell. The passivation material in the perovskite solar cell is compound 1. The device structure of the perovskite solar cell is: FTO substrate / hole transport layer / titanium oxide light absorption layer / passivation modification layer / electron transport layer / Ag electrode. The FTO is fluorine-doped tin oxide; the FTO substrate is a fluorine-doped tin oxide transparent glass substrate.

[0040] The method for fabricating an inverted perovskite solar cell includes the following steps: Step 1, FTO glass substrate treatment: The FTO glass was sequentially immersed in an ultrasonic cleaning tank containing deionized water, anhydrous ethanol, and isopropanol. Each step of the ultrasonic cleaning process lasted 15 minutes, with the ultrasonic power set to 100W. The ultrasonic vibration was used to remove inorganic particles and residual organic matter adhering to the surface of the FTO glass. After the ultrasonic cleaning was completed, the FTO glass was removed, and the surface residual solvent was slowly blown dry in one direction with a high-purity nitrogen gun to avoid water stains or secondary contamination caused by back-and-forth blowing.

[0041] After drying, the FTO glass was placed in an ultraviolet ozone cleaner with a power of 30W and a treatment time of 20 minutes. The trace organic matter on the surface was removed by ultraviolet degradation and ozone oxidation. After the treatment was completed, the glass was immediately transferred to a nitrogen glove box (water and oxygen content <0.1 ppm) for later use.

[0042] Step 2, Hole transport layer fabrication: In a nitrogen glove box, 15 mg of Me-4PACz powder (4,4',4'',4'''-(benzo[1,2-b:4,5-b']dithiophene-4,8-diyl)tetra(triphenylamine)) was weighed and added to 1 mL of anhydrous chlorobenzene. The mixture was magnetically stirred at 500 rpm for 1 h until the powder was completely dissolved, forming a transparent solution. The solution was then filtered through a 0.22 μm organic filter membrane to remove agglomerated particles. The pretreated FTO glass was fixed on the spin coater suction cup, and 40 μL of Me-4PACz solution was added. The spin coater parameters were set as follows: spin speed 4000 rpm, time 30 s, acceleration 1500 rpm / s. Spin coater was started to form a uniform thin film. After spin coater operation, the device was annealed at 100 °C for 10 min to form a hole transport layer on the surface of the FTO glass substrate.

[0043] Step 3, Preparation of the perovskite light-absorbing layer: In a nitrogen glove box, the following raw materials were weighed in sequence: 616.8 mg PbI₂, 31.6 mg MABr, 73.2 mg PbBr₂, 571.6 mg FAI, and 15.8 mg CsI. These were then placed into a 20 mL sample vial. 1250 μL of a 4:1 DMF / DMSO mixed solvent was added to the vial. The mixture was magnetically stirred at 600 rpm for 3 hours at room temperature until the solids were completely dissolved, yielding a clear, transparent, and precipitate-free perovskite precursor solution. The perovskite precursor solution was filtered through a 0.22 μm organic filter membrane to remove undissolved microparticles and agglomerates. After standing for 10 minutes to ensure the solution was free of bubbles, it was ready for use.

[0044] An FTO substrate with a hole transport layer was fixed on a spin coater, and 50 μL of perovskite precursor solution was added dropwise. A two-stage spin coating program was used: the first stage was 500 rpm / 5 s, and the second stage was 4000 rpm / 30 s. When the second stage of spin coating was 15 s, 200 μL of chlorobenzene antisolvent was rapidly added dropwise. After spin coating, the substrate was immediately transferred to a hot stage and annealed at 150 °C for 30 min under a nitrogen atmosphere. After natural cooling to room temperature, a Cs layer with a thickness of 550 nm was formed. 0.05 FA 0.95 PbI3 perovskite light-absorbing layer.

[0045] Step 4, preparation of passivation modification layer: Weigh 0.1 mmol of compound 1 as the passivation material and place it in a 10 mL brown sample vial. Add 4 mL of anhydrous isopropanol and stir magnetically at 500 rpm for 30 min until completely dissolved to prepare a passivation solution with a concentration of 1.0 mg / mL. Filter the passivation solution through a 0.22 μm organic filter membrane to remove undissolved trace impurities and transfer it to a nitrogen glove box for later use to avoid moisture affecting the stability of the solution and the passivation effect.

[0046] An FTO substrate with a perovskite light-absorbing layer was fixed on a spin coater, and 40 μL of passivation solution was added. The spin coating parameters were set as follows: spin speed 3000 rpm, time 30 s, and acceleration 1500 rpm / s, to ensure the solution uniformly covered the perovskite surface. After spin coating, the substrate was transferred to a hot stage and annealed at 110 °C for 10 min under a nitrogen atmosphere to promote the full bonding of phenazine ester molecules with the perovskite surface. After natural cooling to room temperature, a uniform passivation modification layer with a thickness of 1 nm to 3 nm was formed.

[0047] Step 5, Electron transport layer and Ag electrode deposition: The device was transferred to a thermal evaporation coating apparatus, the chamber was closed, and the vacuum pump was started. A C60 thin film and a BCP thin film were sequentially deposited on the passivation modification layer to obtain an electron transport layer with a thickness of 35 nm. An Ag electrode with a thickness of 100 nm was then deposited on the electron transport layer to obtain an inverse perovskite solar cell.

[0048] Application Example 2 An application of the phenazine ester derivative from Example 2 as a passivation material in the fabrication of an inverted perovskite solar cell. The inverted perovskite solar cell was fabricated according to the method described in Example 1, except that in step 4, compound 2 was used as the passivation material, and the concentration of the passivation solution was 1.4 mg / mL; annealing was performed at 130°C for 10 min under a nitrogen atmosphere.

[0049] Step 4 involves weighing 0.1 mmol of compound 2 as the passivation material and placing it in a 10 mL brown sample vial. Anhydrous isopropanol is added, and the mixture is magnetically stirred at 500 rpm for 30 minutes until completely dissolved, preparing a passivation solution with a concentration of 1.4 mg / mL. The passivation solution is then filtered through a 0.22 μm organic filter membrane to remove undissolved trace impurities and transferred to a nitrogen glove box for later use to prevent moisture from affecting the solution stability and passivation effect.

[0050] An FTO substrate with a perovskite light-absorbing layer was fixed on a spin coater, and 40 μL of passivation solution was added. The spin coating parameters were set as follows: spin speed 3000 rpm, time 30 s, and acceleration 1500 rpm / s, to ensure the solution uniformly covered the perovskite surface. After spin coating, the substrate was transferred to a hot stage and annealed at 130 °C for 10 min under a nitrogen atmosphere to promote the full bonding of phenazine ester molecules with the perovskite surface. After natural cooling to room temperature, a uniform passivation modification layer with a thickness of 1 nm to 3 nm was formed.

[0051] Application Example 3 An application of the phenazine ester derivative from Example 3 as a passivation material in the fabrication of an inverted perovskite solar cell. The inverted perovskite solar cell was fabricated according to the method described in Example 1, except that in step 4, compound 3 was used as the passivation material, and the concentration of the passivation solution was 1.8 mg / mL; annealing was performed at 150°C for 10 min under a nitrogen atmosphere.

[0052] Application Example 4 An application of the phenazine ester derivative from Example 4 as a passivation material in the fabrication of an inverted perovskite solar cell. The inverted perovskite solar cell was fabricated according to the method described in Example 1, except that in step 4, compound 4 was used as the passivation material, and the concentration of the passivation solution was 1.6 mg / mL; annealing was performed at 140°C for 10 min under a nitrogen atmosphere.

[0053] Application Comparative Example 1 Inverted perovskite solar cell without passivation material: Except for not spin-coating the thiophene secondary urethane derivative material of Example 1 of the present invention on the surface of the perovskite light-absorbing layer, the other preparation steps are exactly the same as those in Application Example 1.

[0054] The performance of the inverted perovskite solar cells in the above application examples and comparative examples was tested. Performance testing was conducted under AM 1.5G simulated sunlight (100 mW / cm²), using a Keithley 2400 source meter to measure the JV curve of the device at a scan rate of 0.1 V / s. The test results are shown in Table 1.

[0055] Table 1 Performance test results of inverted perovskite solar cells Figure 1 These are the current density-voltage curves of the inverted perovskite solar cells used in Examples 1 to 4 and Comparative Example 1.

[0056] From the performance data in Table 1 and Figure 1As can be seen from the current density-voltage curve, through specific molecular structure design, the phenazine ester derivative of this invention, as a passivation material for the perovskite light absorption layer, can significantly improve the photoelectric conversion efficiency of perovskite solar cells.

[0057] In the phenazine ester derivatives of this invention, the lone pair electrons on the carbonyl group (C=O) of the ester group (-COOCH3) interact with the undercoordinated Pb on the perovskite surface. 2+ Forming coordinate bonds to fill Pb 2+ The electron vacancy is eliminated, thus removing the deep-level defect state; the lone pair electrons on the nitrogen atom of the phenazine ring can also interact with Pb. 2+ Coordination occurs, further enhancing the passivation effect; the phenazine conjugated ring has good electron transport characteristics, which can promote interfacial charge separation and form energy level matching with perovskite, reducing charge recombination loss. The synergistic effect of multiple aspects ultimately achieves a significant improvement in the photoelectric conversion efficiency of the battery.

[0058] The above are merely preferred embodiments of the present invention and are 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 protection scope of the present invention.

Claims

1. A phenazine ester derivative, characterized in that, The general molecular structural formula of the phenazine ester derivative is shown below: ； L1 is methyl, ethyl, or isopropyl.

2. A phenoxazine ester derivative, characterized by, The phenazine ester derivative is any one of the following compounds: 。 3. A method for producing the phenoxazine ester derivative according to any one of claims 1 to 2, characterized by, Includes the following steps: Using the compounds shown in Formula 1 and Formula 2 as raw materials, the compound shown in Formula 1 was reacted with NaH in a reaction solvent at 5℃~10℃. Then, the compound shown in Formula 2 was added at 5℃~10℃, and a substitution reaction was carried out at 20℃~25℃. An ester group was attached to the phenazine N atom of the compound shown in Formula 1 to obtain the phenazine ester derivative shown in Formula 3. The synthetic route for phenazine ester derivatives is as follows: 。 4. The method of claim 3, wherein the phenoxazine ester derivative is prepared by the reaction of a phenoxazine derivative of the following formula 1 with a compound of the following formula 2: ###0001### ###0002### 1 2 The molar ratio of the compound shown in Formula 1 to the compound shown in Formula 2 is 1:2.5 to 2.

6.

5. The method of claim 3, wherein the phenoxazine ester derivative is prepared by the reaction of a phenoxazine derivative of the following formula 1 with a compound of the following formula 2: ###00002### 1 2 The molar ratio of the compound shown in Formula 1 to NaH is 1:3 to 3.

1.

6. The method for preparing the phenazine ester derivative according to claim 3, characterized in that, The reaction solvent is N,N-dimethylformamide.

7. The method for preparing the phenazine ester derivative according to claim 6, characterized in that, The ratio of the compound shown in Formula 1 to the organic solvent is 1 mmol: 1.8 mL to 2 mL.

8. Use of a phenoxazine ester derivative as a passivation material for a perovskite light absorbing layer for the preparation of a perovskite solar cell, characterized in that, The phenazine ester derivative is any one of the phenazine ester derivatives described in claims 1 to 2.

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