MAPbI3-papain perovskite device and preparation method thereof

Abstract

The invention is applicable to the technical field of perovskite photovoltaic devices, and provides an MAPbI3-papain perovskite device and a preparation method thereof, and the device structurally comprises a conductive substrate, an electron transport layer, a papain modification layer, a perovskite active layer, a hole transport layer and a metal electrode which are stacked in sequence. The papain modification layer is introduced between the electron transport layer and the perovskite active layer, surface and grain boundary defects of the perovskite layer are effectively passivated by amino, carboxyl and hydroxyl functional groups in molecules of the papain modification layer, and the flexible protein chain structure of the papain modification layer can buffer interface stress. According to the technology, the tolerance of the device to environmental moisture, oxygen and high temperature is remarkably improved. The method is simple in process, low in cost and environment-friendly, and a novel and reliable solution is provided for preparing efficient and long-life perovskite solar cells and photoelectric detectors.

Description

A MAPbI3-papain perovskite device and its fabrication method Technical Field

[0001] This invention belongs to the field of perovskite photovoltaic device technology, and particularly relates to a MAPbI3-papain perovskite device and its preparation method. Background Technology

[0002] Organic-inorganic hybrid perovskite materials (such as MAPbI3) have shown great potential in the fields of photovoltaics and photoelectric detection due to their excellent photoelectric properties, such as high absorption coefficient, tunable band gap and long carrier diffusion length. Their device efficiency has approached or even exceeded that of traditional silicon-based solar cells.

[0003] However, the inherent ionic properties of perovskite materials make them extremely sensitive to the external environment, which severely restricts their industrialization and long-term application. The main problems include: (1) In a humid environment, moisture and oxygen can easily cause perovskite materials to decompose; (2) At higher temperatures, the materials are prone to phase transitions or decomposition; (3) There are a large number of defects (such as vacancies) on the surface and at the grain boundaries, which not only serve as non-radiative recombination centers to reduce photoelectric conversion efficiency, but also provide channels for water and oxygen erosion, accelerating material degradation; (4) The different thermal expansion coefficients of the materials in the functional layers of the device generate interfacial stress during the preparation and operation process, which may damage the integrity of the thin film.

[0004] Therefore, developing a technology that can effectively passivate defects, block water and oxygen erosion, and alleviate interfacial stress is crucial for the fabrication of efficient and stable perovskite optoelectronic devices. Summary of the Invention

[0005] The purpose of this invention is to provide a MAPbI3-papain perovskite device and its preparation method, thereby addressing the problems mentioned in the background art.

[0006] The present invention is implemented as follows: a MAPbI3-papain perovskite device, which has a stacked structure and includes, from bottom to top: a conductive substrate; an electron transport layer disposed on the conductive substrate; a papain-modified layer disposed on the electron transport layer; a perovskite active layer disposed on the papain-modified layer, using MAPbI3; a hole transport layer disposed on the perovskite active layer; and a metal electrode disposed on the hole transport layer.

[0007] In a further technical solution, the conductive substrate is made of FTO conductive glass, with the following dimensions: length and width 2cm × 2cm, etching width 5mm, and depth 500nm.

[0008] In a further technical solution, the papain-modified layer is formed by spin-coating and annealing an aqueous solution of papain.

[0009] Another objective of this invention is to provide a method for fabricating a MAPbI3-papain perovskite device, based on the aforementioned MAPbI3-papain perovskite device, comprising the following steps: Step 1: providing and processing a conductive substrate; Step 2: fabricating an electron transport layer on the conductive substrate; Step 3: forming a papain-modified layer on the electron transport layer; Step 4: forming a perovskite active layer on the papain-modified layer in an inert gas atmosphere; Step 5: fabricating a hole transport layer on the perovskite active layer; Step 6: forming a metal electrode on the hole transport layer.

[0010] In a further technical solution, in step 3, a papain aqueous solution with a concentration of 0.5 mg / mL is spin-coated onto the electron transport layer, and then annealed and cured to form a papain-modified layer.

[0011] In a further technical solution, in step 4, the MAPbI3 precursor solution is spin-coated onto the papain-modified layer, and an antisolvent is added dropwise during the spin-coating process. Subsequently, a gradient annealing treatment is performed to crystallize the perovskite into a film, forming a perovskite active layer.

[0012] In a further technical solution, the MAPbI3 precursor solution is prepared by dissolving PbI2 (lead iodide) and MAI (methyl ammonium iodide) in a mixed solvent of DMSO (dimethyl sulfoxide) and DMF (N,N-dimethylformamide).

[0013] The MAPbI3-papain perovskite device and its preparation method provided in this embodiment of the invention have the following advantages: (1) Significantly improves stability: The functional groups such as amino (-NH2), carboxyl (-COOH), and hydroxyl (-OH) in papain can coordinate or bond with the defect sites (such as iodine vacancies) in the perovskite material, effectively passivating surface and grain boundary defects, blocking the intrusion path of water molecules and oxygen, thereby greatly improving the device's tolerance to water, oxygen and high temperature.

[0014] (2) Improve photoelectric performance: Passivation defects reduce the nonradiative recombination probability of charge carriers and improve charge transport efficiency, thereby obtaining higher photocurrent response and specific detectivity.

[0015] (3) Relieve interfacial stress: Papain has a flexible protein chain structure, which can act as a buffer layer to absorb and release interfacial stress caused by the mismatch between the thermal expansion coefficients of the electron transport layer and the perovskite layer. This helps to form a denser and smoother perovskite film and reduce cracks and pinholes.

[0016] (4) Simple and environmentally friendly process: Papain is a natural biological enzyme that can be extracted from papaya, which is environmentally friendly. The process of introducing its modification layer is simple, has good compatibility with existing spin coating processes, does not require complex equipment, and is low in cost. Attached Figure Description

[0017] Figure 1 is a schematic diagram of the structure of a MAPbI3-papain perovskite device provided in an embodiment of the present invention; Figure 2 is a surface microstructure diagram of intrinsic MAPbI3 (left) and MAPbI3-papain (right); Figure 3 is a stability test diagram of intrinsic MAPbI3 (top) and MAPbI3-papain (bottom).

[0018] In the attached figure: 1. Conductive substrate; 2. Electron transport layer; 3. Papain modified layer; 4. Perovskite active layer; 5. Hole transport layer; 6. Metal electrode. Detailed Implementation

[0019] 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.

[0020] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0021] Figure 1 shows a MAPbI3-papain perovskite device provided in an embodiment of the present invention. The device has a stacked structure and includes, from bottom to top: a conductive substrate 1, made of FTO conductive glass; an electron transport layer 2 disposed on the conductive substrate 1; a papain-modified layer 3 disposed on the electron transport layer 2; a perovskite active layer 4 disposed on the papain-modified layer 3, wherein the material of the perovskite active layer 4 is an organic-inorganic hybrid perovskite, preferably MAPbI3; a hole transport layer 5 disposed on the perovskite active layer 4; and a metal electrode 6 disposed on the hole transport layer 5.

[0022] An embodiment of the present invention provides a method for preparing a MAPbI3-papain perovskite device, based on the above-mentioned MAPbI3-papain perovskite device, comprising the following steps: Step 1: Preparation of MAPbI3 precursor and papain-modified layer 3; First, prepare an intrinsic MAPbI3 precursor by placing 1 mmol of PbI2 and 1 mmol of MAI into a 5 ml bottle, and using polar solvents DMSO and DMF in a 3:7 ratio to prepare 1 ml of MAPbI3 precursor solution. After thoroughly shaking to ensure complete solvent dissolution, filter the precursor using a 0.45 μm filter plug; Prepare papain aqueous solution by preparing 5 ml solutions of 0.5 mg / ml, 0.75 mg / ml, 1 mg / ml, 1.5 mg / ml, and 2 mg / ml respectively. The MAPbI3 and papain films are prepared by hot casting (using a spin coater to uniformly disperse the solution on the substrate and then transferring it to a baking stage for heating and annealing to form a dense film).

[0023] Papain films and MAPbI3 films were sequentially prepared on conductive substrate 1. The emission spectra of these films were tested using 530 nm excitation light. The test results showed that the structure using 0.5 mg / ml papain had the weakest luminescence intensity. This indicates that the addition of papain modifies the vacancies and other defects in MAPbI3, thereby improving the efficiency of electron transport and reducing the number of charge carriers used for radiative recombination. This results in a higher response speed for the photovoltaic device fabricated using this structure.

[0024] Step 2: Synthesis of MAPbI3-papain perovskite device; First, commercially etched FTO conductive glass (2cm x 2cm, 5mm etching width, 500nm depth) was placed in a beaker for cleaning. Detergent and water were added to the beaker to remove surface dust and debris. Plastic wrap was then placed over the beaker to prevent dust from falling into the beaker and causing recontamination. After ultrasonically vibrating the beaker for 20 minutes, the cleaning solvent was changed to acetone. Acetone was used to remove water and oil stains from the FTO conductive glass. After vibrating for 30 minutes, acetone was changed to ethanol to remove any acetone residue. After vibrating for another 30 minutes, deionized water was added to cover the top of the FTO conductive glass to remove any remaining ethanol and acetone cleaning solvents. After vibrating for 30 minutes, the deionized water was discarded. Holes were punched in the plastic wrap, and the beaker was placed in a 60℃ oven for 4 hours to dry the surface moisture for use.

[0025] Before spin coating, the cleaned FTO conductive glass was subjected to ozone treatment for 1 hour to add hydrophilic groups to the surface and increase solution adhesion. The FTO conductive glass was then placed on a spin coater in air, and 150 µL of papain aqueous solution was placed on the FTO conductive glass and dispersed at 4000 rpm for 30 seconds. Afterward, it was annealed at 60°C for 30 minutes. The FTO conductive glass coated with the papain film and the synthesized precursor solution were then placed in a glove box to ensure an inert gas environment throughout the synthesis process. The FTO conductive glass was then placed on a spin coater, and 100 µL of MAPbI3 was placed on the FTO conductive glass and rotated at 1000 rpm for 12 seconds, followed by a high-speed rotation at 2500 rpm for 30 seconds. At the 15th second, 150 µL of chlorobenzene was spin-coated onto the surface. After spin coating, the surface was annealed at 60°C for 5 minutes, and then at 100°C for 10 minutes. This resulted in the growth of a 50 µm thick MAPbI3 perovskite film on the surface of the FTO conductive glass.

[0026] Step 3: Device structure design; This method aims to prepare a stable perovskite optoelectronic device. Electron transport layer 2, papain-modified layer 3, perovskite active layer 4 (MAPbI3), and hole transport layer 5 are spin-coated sequentially on FTO conductive glass. Finally, a 150nm thick silver electrode is deposited on the surface to form a conductive circuit. The MAPbI3 device of the control group and the MAPbI3 device with added papain are tested for photocurrent. While improving stability, papain also modifies defects through functional groups, reduces the probability of exciton recombination, and improves photocurrent response.

[0027] To investigate the stability enhancement of MAPbI3-papain perovskite, various characterization methods were employed. Scanning electron microscopy (SEM) was used to test both the control group MAPbI3 film and the papain / MAPbI3 film. The measured morphology is shown in Figure 2. The test results revealed significant differences. Rod-shaped PbI2 (lead iodide) crystals were found on the surface of the intrinsic MAPbI3 film on the left. In contrast, the papain-MAPbI3 film had a compact structure and no PbI2 was present. This indicates that water and oxygen have difficulty promoting the decomposition of MAPbI3 on ​​its surface.

[0028] The photoelectric performance stability of intrinsic MAPbI3 and MAPbI3-papain perovskite devices was tested separately. To confirm that the devices fabricated after adding papain could still maintain good stability, the MAPbI3-papain perovskite devices and intrinsic MAPbI3 devices were placed in an environment with 21% humidity without encapsulation for 30 days. Then, the two devices were subjected to 360 consecutive switching tests under 530nm excitation. As shown in Figure 3, it can be found that after the introduction of papain, the photocurrent of the device did not decrease significantly after continuous switching tests after a long period of storage, while the photocurrent of the intrinsic MAPbI3 device showed a significant downward trend after continuous testing.

[0029] The above description is only 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 protection scope of the present invention.

Claims

1. A MAPbI3-papain perovskite device, characterized in that, The device has a stacked structure, comprising, from bottom to top: a conductive substrate; an electron transport layer disposed on the conductive substrate; a papain-modified layer disposed on the electron transport layer; a perovskite active layer disposed on the papain-modified layer, using MAPbI3; a hole transport layer disposed on the perovskite active layer; and a metal electrode disposed on the hole transport layer.

2. The MAPbI3-papain perovskite device according to claim 1, characterized in that, The conductive substrate is made of FTO conductive glass, with the following dimensions: 2cm x 2cm (length x width), 5mm etching width, and 500nm depth.

3. The MAPbI3-papain perovskite device according to claim 1, characterized in that, The papain-modified layer is formed by spin coating and annealing of an aqueous papain solution.

4. A method for preparing a MAPbI3-papain perovskite device, based on the MAPbI3-papain perovskite device according to any one of claims 1-3, characterized in that, The steps include: Step 1: Providing and processing a conductive substrate; Step 2: Prepare an electron transport layer on the conductive substrate; Step 3: Form a papain-modified layer on the electron transport layer; Step 4: Form a perovskite active layer on the papain-modified layer in an inert gas atmosphere; Step 5: Prepare a hole transport layer on the perovskite active layer; Step 6: Form a metal electrode on the hole transport layer.

5. The method for preparing the MAPbI3-papain perovskite device according to claim 4, characterized in that, In step 3, a 0.5 mg / mL aqueous solution of papain is spin-coated onto the electron transport layer and then annealed and cured to form a papain-modified layer.

6. The method for preparing the MAPbI3-papain perovskite device according to claim 4, characterized in that, In step 4, the MAPbI3 precursor solution is spin-coated onto the papain-modified layer, and an antisolvent is added dropwise during the spin-coating process. Gradient annealing is then performed to crystallize the perovskite into a film, forming a perovskite active layer.

7. The method for preparing the MAPbI3-papain perovskite device according to claim 6, characterized in that, The MAPbI3 precursor solution was prepared by dissolving PbI2 and MAI in a mixed solvent of DMSO and DMF.

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