Efficient and stable perovskite solar cell based on internal packaging strategy and preparation method and application of efficient and stable perovskite solar cell

Abstract

The invention discloses an efficient and stable perovskite solar cell based on an internal packaging strategy and a preparation method and application thereof. The invention belongs to the field of photovoltaic devices. The invention aims to provide an efficient and stable perovskite solar cell based on an internal packaging strategy and a preparation method and application thereof. According to the perovskite solar cell, the polydopamine and chitosan composite layer serves as the packaging layer of the perovskite thin film and is used for passivating a large number of defects existing in the perovskite thin film and in the grain boundary and capturing lead element leakage caused by degradation of the perovskite thin film, and meanwhile the structural stability of the packaged perovskite thin film is remarkably improved; the composite film is not easy to degrade or crack in extreme environments (such as strong acid, strong alkali and humid environments), so that the mechanical strength and chemical stability of the interface passivation layer are enhanced, and the problem of degradation or performance reduction caused by environmental factors is avoided. And environmental pollution caused by internal lead element leakage after the device is broken can be avoided.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaic devices, and particularly relates to an efficient and stable perovskite solar cell with an internal encapsulation strategy, a preparation method thereof, and an application thereof. Background Art

[0002] As a new type of solar cell technology, metal halide perovskite solar cells (PSCs) have received extensive attention from researchers in the past few years. This kind of battery has attracted much attention and developed rapidly due to its advantages such as high carrier mobility, wide light absorption range, adjustable optical bandgap, long carrier diffusion length, and simple process preparation technology. Due to the high PCE of PSCs and relatively low manufacturing cost, it is expected to replace the mature silicon-based solar cells in the market and is one of the important development directions in the future solar cell field. However, due to the soft lattice structure of the perovskite material, it is sensitive to water, heat, oxygen, and light soaking. And currently, the preparation of high-performance perovskite solar cells usually contains lead elements. When the battery degrades, the lead elements have a high solubility in water, so the resulting lead leakage problem seriously threatens the ecological environment and human health.

[0003] Chinese Patent CN202420719142.2 discloses a packaging structure for a perovskite solar cell. The packaging component of this patent includes a first packaging adhesive, a buffer structure adhesive, and a second packaging adhesive with different viscosities (all composed of resin); wherein, the first packaging adhesive is arranged between the transparent conductive layer and the packaging cover plate to form a sealed space. A passivation layer covers the perovskite functional layer, and both are located in this sealed space; the buffer structure adhesive and the second packaging adhesive are filled in the remaining sealed space, and the buffer structure adhesive is located between the passivation layer and the first packaging adhesive. However, in actual applications, when this kind of physical packaging is broken due to severe damage (such as hail, strong wind, flood, etc.) to the perovskite solar cell, it will lose its packaging effect.

[0004] Chinese Patent CN202411394353.4 discloses an antireflection polymer film for perovskite batteries with lead ion sequestration function, its preparation and application. Mix PVA with water, heat and dissolve it to obtain a transparent and clear PVA solution; under continuous heating, add phosphoric acid solution, disodium hydrogen phosphate, and a transparent plasticizer to the PVA solution in sequence, and react for more than 1 hour respectively. The obtained modified polymer solution is poured on a substrate with a micro-nano structure, naturally cured, and peeled off to obtain an antireflection polymer film PFPF with lead ion sequestration. Applying PFPF to the light-receiving surface of a perovskite solar cell can not only reduce the Pb ions leaked from PSCs when the light-receiving surface is damaged, but also reduce the Fresnel reflection of the light-receiving surface, thereby reducing light energy loss and improving the photoelectric conversion efficiency of PSCs. However, this material has problems such as complex preparation process, high cost, and low yield. Summary of the Invention

[0005] The object of the present invention is to provide an efficient and stable perovskite solar cell based on an internal encapsulation strategy, and its preparation method and application.

[0006] One of the objects of the present invention is to provide an efficient and stable perovskite solar cell based on an internal encapsulation strategy, and the perovskite solar cell includes a substrate sequentially arranged from bottom to top;

[0007] Electron transport layer;

[0008] Perovskite layer;

[0009] Hole transport layer;

[0010] Electrode;

[0011] Among them, the perovskite layer is composed of a perovskite thin film and a chitosan layer and a polydopamine layer sequentially spin-coated on the surface of the thin film.

[0012] Further defined, the perovskite thin film is formed by spin-coating a perovskite precursor solution, and the perovskite precursor is Cs 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb(I 0.83 Br 0.17 ) 3 。

[0013] Further defined, the polydopamine layer is formed by spin-coating a 0.8 - 1.2 g / L polydopamine isopropanol solution.

[0014] Further defined, the chitosan layer is formed by spin-coating a 0.8 - 1.2 g / L chitosan isopropanol solution.

[0015] Another object of the present invention is to provide a preparation method of an efficient and stable perovskite solar cell based on an internal encapsulation strategy, and the method is carried out according to the following steps:

[0016] S1: Sequentially prepare an electron transport layer solution, a perovskite precursor solution, a chitosan isopropanol solution, a polydopamine isopropanol solution, and a hole transport layer solution;

[0017] S2: Sequentially form an electron transport layer, a perovskite thin film, a chitosan layer, a polydopamine layer, and a hole transport layer on the substrate by spin-coating, wherein the perovskite thin film is spin-coated by one-step anti-solvent assisted spin-coating, and annealing treatment is carried out respectively after each spin-coating;

[0018] S3: Deposit the electrode by vacuum evaporation method.

[0019] Further defined, the preparation of the perovskite precursor solution in S1: First, PbI 2, formamidinium iodide (FAI), PbBr 2 and methylammonium bromide (MABr) are dissolved in a mixed solvent composed of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) to obtain a main solution; secondly, CsI is dissolved in DMSO to obtain a CsI solution, and then it is mixed with the main solution according to a volume ratio of 5:95 to obtain a perovskite precursor solution.

[0020] Furthermore, it is further defined that PbI in the main solution 2 , FAI, PbBr 2 and MABr have a molar ratio of 1.1:1:0.2:0.2.

[0021] Furthermore, it is further defined that the concentration of PbI in the main solution 2 is 1 - 1.2 mol / L.

[0022] Furthermore, it is further defined that the concentration of CsI in the CsI solution is 1.5 - 1.8 mol / L.

[0023] The third object of the present invention is to provide an application of the above-mentioned highly efficient and stable perovskite solar cell based on the internal encapsulation strategy as a photovoltaic power generation device in the fields of aerospace and architecture.

[0024] The remarkable effects of the present invention compared with the prior art:

[0025] The present invention selects low-cost polydopamine (PDA) and chitosan as the internal encapsulation layer of the perovskite film to passivate a large number of defects existing inside the perovskite film and at the grain boundaries and capture the lead element leakage caused by the degradation of the perovskite film. The encapsulation effect is remarkable, and the specific advantages are as follows:

[0026] (1) By combining chitosan and polydopamine, the present invention constructs a tight complex by using the strong intermolecular interaction formed between the two, significantly improving the mechanical strength and chemical stability of the perovskite film after encapsulation, thereby more effectively isolating external environmental factors such as moisture, acids and alkalis, realizing a more solid interface, making the composite film less likely to degrade or break in extreme environments (such as strong acids, strong alkalis, humid environments, etc.). The combined use of the two can achieve a more lasting lead ion capture and interface repair function, avoiding the problems of degradation or performance decline due to environmental factors.

[0027] (2) In the present invention, by combining chitosan and polydopamine as the internal encapsulation layer of the perovskite thin film, on the one hand, it can effectively passivate the defects inside the perovskite thin film and at the grain boundaries, reduce the non-radiative recombination during the carrier transport process inside the device, and reduce energy loss, which can improve the power conversion efficiency of the perovskite solar cell to a certain extent. On the other hand, a large number of Pb capture sites are provided. The combination of chitosan and polydopamine can interact with the empty orbitals of Pb ions to form a stable complex. In addition, the aromatic ring structure can not only have π-π interaction with metal ions, but also have a weak interaction with Pb ions through π-metal coordination, further enhancing the adsorption ability of lead ions. Therefore, under the synergistic effect of chitosan and polydopamine in the present invention, the efficiency of capturing lead ions is greatly improved. When the perovskite solar cell is damaged when facing extreme environments (such as hail, strong wind, flood, etc.) during actual application, it can effectively capture the free Pb ions contained inside the device, prevent the leakage of Pb ions into the surrounding environment and cause serious environmental pollution, and ensure the safe use of the device.

[0028] (3) The preparation process of this application is simple and the preparation cost is low, which is more suitable for popularization and application. Description of the Drawings

[0029] Figure 1 is the top-view scanning electron microscope (SEM) image of the surface morphology of the perovskite thin films obtained in Example 1 and Comparative Examples 1-2 of the present invention; where a is Comparative Example 1, b is Comparative Example 2, and c is Example 1;

[0030] Figure 2 is the XRD test image of the perovskite thin films obtained in Example 1 and Comparative Examples 1-2 of the present invention;

[0031] Figure 3 is the visible light band absorption test image of the perovskite thin films obtained in Example 1 and Comparative Examples 1-2 of the present invention;

[0032] Figure 4 is the conductivity test image of the perovskite solar cell devices obtained in Example 1 and Comparative Examples 1-2 of the present invention;

[0033] Figure 5 is the internal carrier transport dynamics test and efficiency test of the perovskite solar cell devices obtained in Example 1 and Comparative Examples 1-2 of the present invention; where a is the logarithmic J-V characteristic curve of the electronic device, b is the Nyquist curve diagram and equivalent circuit, c is the logarithmic dark state J-V analysis curve, and d is the J-V curve;

[0034] Figure 6 is the stability test of the perovskite solar cells obtained in Example 1 and Comparative Examples 1-2 of the present invention;

[0035] Figure 7 Ion mobility spectrometry (IMS) tests were performed on the perovskite solar cells obtained in Example 1 and Comparative Examples 1-2 of the present invention;

[0036] Figure 8 Inductively coupled plasma optical emission spectrometry (ICP-OES) tests for Pb leakage management of the perovskite solar cells obtained in Example 1 and Comparative Examples 1-2 of the present invention;

[0037] Figure 9 Biological activity tests were performed on the perovskite solar cells obtained in Example 1 and Comparative Examples 1-2 of the present invention; where a is a bar graph of cell viability, b is a confocal fluorescence image of L-929 cells before treatment, c is a confocal fluorescence image of L-929 cells after treatment with Comparative Example 1, d is a confocal fluorescence image of L-929 cells after treatment with Comparative Example 2, and e is a confocal fluorescence image of L-929 cells after treatment with Example 1;

[0038] Figures 2 - 8 Among them, Control represents Comparative Example 1, Chitosan represents Comparative Example 2, and PDA represents Example 1 of the present invention. Detailed implementation manners

[0039] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] The experimental methods used in the following examples are all conventional methods unless otherwise specified. The materials, reagents, methods and instruments used, unless otherwise specified, are all conventional materials, reagents, methods and instruments in the art, and those skilled in the art can obtain them through commercial channels.

[0041] Example 1

[0042] The preparation method of the high-efficiency and stable perovskite solar cell based on the internal encapsulation strategy in this example is carried out according to the following steps:

[0043] Step 1: Preparation of the electron transport layer SnO 2 Solution preparation: Use a pipette to take SnO 2 Colloidal solution (colloid with a concentration of 15 wt.% dispersed in water) and deionized water are filled into a small bottle in a volume ratio of 1:1, sealed, and placed in an ultrasonic machine for 4 h. The liquid in the ultrasonic machine is kept at a temperature of 35 °C until evenly dispersed;

[0044] Step 2: Preparation of the perovskite precursor solution: First, 1.1 mmol of PbI 2, 1 mmol formamidinium iodide (FAI), 0.2 mmol PbBr 2 and 0.2 mmol methylammonium bromide (MABr) were dissolved in a mixed solvent of 200 μL dimethyl sulfoxide (DMSO) and 800 μL N,N-dimethylformamide (DMF) to obtain a main solution. Secondly, 1.5 mmol CsI was dissolved in 900 μL DMSO to obtain a CsI solution, and then it was mixed with the main solution according to a volume ratio of 5:95 to obtain Cs 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb(I 0.83 Br 0.17 ) 3 , abbreviated as CsFAMA, can regulate the perovskite lattice stress and inhibit non-radiative recombination by the incorporation of cesium ions;

[0045] Step 3: Preparation of the hole transport layer Spiro-OMeTAD solution: 72.3 mg of Spiro-OMeTAD, 28.8 μL of 4-tert-butylpyridine (TBP), and 17.5 μL of a lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) dopant solution (prepared by dissolving 520 mg of Li-TFSI in 1 mL of acetonitrile) were dissolved together in 1 mL of chlorobenzene solvent and left to stand until the solution became clear and transparent, indicating uniform mixing;

[0046] Step 4: Preparation of the Chitosan solution: Weigh 1.0 g of Chitosan in a 500 mL clean beaker, add 400 mL of isopropanol, stir for 30 min, then transfer it to a 1000 mL volumetric flask and dilute it to the mark with isopropanol to obtain a 1.0 g / L Chitosan dispersion. The prepared Chitosan dispersion was placed in an ultrasonic machine and ultrasonicated for 30 min to further disperse it;

[0047] Step 5: Preparation of the PDA solution: Take 10 mg of PDA powder and dissolve it in 10 mL of isopropanol solvent, stir at room temperature for 30 min until completely dissolved to obtain a 1.0 g / L PDA solution;

[0048] Step 6: First, clean the FTO substrate, and then spin-coat the SnO 2 precursor solution prepared in Step 1 as the electron transport layer. During the spin-coating process, a spin coater was used to spin-coat at a high speed of 4000 rpm for 30 s. After spin-coating, the sample was placed on a heating stage at 150 °C for annealing treatment for 30 minutes. To prepare an SnO 2 electron transport layer with a thickness of about 100 nm.

[0049] Then, the prepared SnO 2 film was transferred to a chamber filled with N2 The perovskite film was deposited in a glove box with an inert atmosphere. The film deposition adopted a one-step anti-solvent assisted spin-coating method: specifically, the perovskite precursor solution prepared in Step 2 was spin-coated at a low speed of 600 rpm for 6 s, and then switched to a high speed of 4000 rpm for 50 s. At the 26th second of spin-coating, 500 μL of diethyl ether was added dropwise as an anti-solvent. After film formation, the sample was placed at 150 °C for annealing for 15 minutes. The thickness of the prepared perovskite film was 500 nm.

[0050] Subsequently, a pipette was used to separately aspirate the prepared Chitosan solution and PDA solution in Step 4 and Step 5. First, the Chitosan solution was spin-coated on the surface of the perovskite film at 5000 rpm for 30 s and annealed at 70 °C for 5 minutes to obtain a Chitosan layer with a thickness of 100 nm. Then, the PDA solution was spin-coated on the surface of the Chitosan layer at 4000 rpm for 30 s and annealed at 70 °C for 5 minutes to obtain a PDA layer with a thickness of 100 nm.

[0051] Next, the prepared Spiro-OMeTAD solution in Step 3 was dropped on the perovskite layer to prepare a hole transport layer, and spin-coated at 3000 rpm for 30 s on the surface of the encapsulation layer to form a Spiro-OMeTAD film with a thickness of 200 nm. Finally, a 100-nm-thick silver electrode was deposited by vacuum evaporation to obtain a complete device, labeled as PDA.

[0052] Comparative Example 1:

[0053] The difference between this comparative example and Example 1 is that the Chitosan layer and PDA layer were omitted, and a device with a perovskite layer as a bare perovskite film was prepared, labeled as Control.

[0054] Comparative Example 2:

[0055] The difference between this comparative example and Example 1 is that the PDA layer was omitted, and a device with a perovskite layer composed of a bare perovskite film and a Chitosan layer was prepared, labeled as Chitosan.

[0056] As Figure 1As shown in the figure, (a) is the top-view SEM image of the bare perovskite film without internal encapsulation material obtained in Comparative Example 1 (Control) and the statistical grain size distribution thereof; (b) is the top-view SEM image of the improved perovskite film with internal chemical encapsulation using Chitosan obtained in Comparative Example 2 (Chitosan) and the statistical grain size distribution thereof; (c) is the top-view SEM image of the perovskite film with internal chemical encapsulation using PDA / Chitosan obtained in Example 1 (PDA) of the present invention and the statistical grain size distribution thereof. It can be found from the figure that the introduction of the polymers Chitosan and PDA can play a role in regulating the crystallization of perovskite. The average grain size of the original perovskite film is 288.5 nm. After the introduction of Chitosan, the grain size increases to 323.8 nm. After the introduction of PDA, the perovskite grain size increases to 356.3 nm, and after the introduction of PDA, the perovskite grain size distribution is more uniform and concentrated. In addition, a large number of holes can be significantly observed at the grain boundaries in the SEM image of the original perovskite film (the area circled in red in the figure). The lattice arrangement changes in these areas, resulting in the discontinuity of the crystal structure, and this discontinuity will lead to a large number of carrier defects in this area, acting as non-radiative recombination on the carrier transport path and the center of perovskite film degradation, severely limiting the PCE and operating stability of PSCs. However, after the modification with PDA / Chitosan, a significant reduction in the number of holes is observed. This result indicates that the introduction of the passivation material has a significant impact on the perovskite crystallization process, "stitching" the grain boundaries and significantly improving the crystallinity at the grain boundaries.

[0057] Figure 2 XRD patterns of perovskite films before and after encapsulation with PDA and Chitosan. Obvious diffraction peaks can be observed at 14.24° and 28.25° for all three curves, corresponding to the (110) and (220) crystal planes of CsFAMA perovskite, respectively. In addition, an additional characteristic peak corresponding to the residual PbI 2 crystal plane can be clearly observed at 12.8°. To measure the quality of the film crystallization, the ratio of the peak intensity value of the main perovskite diffraction peak (110) to the PbI 2 diffraction peak intensity is calculated. The higher the value, the better the perovskite crystallization quality, the more concentrated the crystal plane orientation, and the lower the content of residual PbI 2 at the interface. Through calculation, this value increases from 2.28 of the pure perovskite film in Comparative Example 1 to 2.35 after the introduction of Chitosan in Comparative Example 2 and 3.81 after the further introduction of PDA in Example 1 of the present invention. After the introduction of PDA / Chitosan, the XRD diffraction peak value of the perovskite film and PbI 2The increase in the ratio of the standard peak indicates that the crystallization quality of the perovskite film has been effectively improved. This improvement can be attributed to the formation of a dense encapsulation layer of PDA / Chitosan on the surface of the perovskite, filling the defects and pores at the grain boundaries and promoting the ordered growth of perovskite crystals, thereby improving the crystal morphology.

[0058] Figure 3 For the ultraviolet-visible absorption spectra (UV-vis) tests of the three films, the spectrum of the sample encapsulated with PDA / Chitosan shows higher absorbance in the visible light wavelength range. The inset in the figure shows the absorption values of the three perovskite films in the wavelength range of 500 nm - 600 nm. The absorption values of the samples modified in Comparative Example 2 and Example 1 of the present invention are both stronger than that of the sample in Comparative Example 1 (Control), and the sample further modified with PDA in Example 1 of the present invention has the highest absorption spectrum value. It is further confirmed that the modification with PDA / Chitosan can significantly regulate the perovskite crystallization. The improvement of the crystallinity optimizes the lattice structure, thereby increasing the optical absorption cross-section. In addition, the improvement of the crystallinity means better consistency in crystal morphology and size, further reducing light scattering and refraction, and thus increasing the light absorption amount.

[0059] Figure 4 Current-voltage (I-V) tests were carried out on the electrical properties of the three perovskite films. After adding the internal encapsulation layer of PDA and Chitosan, the electrical properties of the device did not decline because the spin-coated internal encapsulation layer was relatively thin and would not cause a decline in the electrical properties of the device.

[0060] Figure 5 For the test of the influence of internal encapsulation on the internal carrier transport dynamics and efficiency test of the perovskite solar cell device provided in this application, among them: the SCLC curve was obtained under the pure electronic structure of FTO / SnO 2 / CsFAMA(PDA / Chitosan) / PCBM / Ag, as shown in Figure 5 a. At low bias voltages, the SCLC curve shows a linear Ohmic region. As the applied bias voltage increases, the injected carriers begin to fill the bulk and interface carrier traps. The bias voltage at this time is called the trap filling voltage (V TFL ). When the bias voltage is further increased, resulting in a large number of carrier traps being filled, the SCLC curve begins to rise rapidly. V TFL is related to the density of trap states (N t) ) inside the device and can be estimated and calculated by the following formula:

[0061]

[0062] where ε and ε 0represents the dielectric constant and the permittivity of vacuum, e and L represent the elementary charge and the film thickness respectively. The Control device has a higher density of defect states inside the device due to its poor crystallization quality, with a V TFL value of 0.248 V. After using Chitosan encapsulation in Comparative Example 2, this value decreased to 0.215 V. After using PDA / Chitosan co-encapsulation in Example 1 of the present invention, due to its obvious defect passivation effect, this value further decreased to 0.186 V. The device in Example 1 of the present invention using PDA / Chitosan co-encapsulation has the lowest density of carrier defect states calculated according to formula (1), with its N t value being 1.76×10 16 cm -3 . For the device encapsulated with Chitosan obtained in Comparative Example 2, the N t value is 2.03×10 16 cm -3 , both are lower than 2.34×10 16 cm -3 of the Control device.

[0063] EIS was measured under dark conditions, and the Nyquist impedance plot of the PSCs as shown in Figure 5 b was obtained. The measured data was fitted through the equivalent circuit diagram ( Figure 5 b inset). The semi-circle in the high-frequency region corresponds to the transfer impedance (Rct), and the semi-circle in the low-frequency region corresponds to the recombination impedance (Rrec). Figure 5 b shows an obvious increase in Rrec and a decrease in Rct after using PDA / Chitosan encapsulation. For the device co-modified with PDA / Chitosan in Example 1 of the present invention, Rct is only 1.028 kΩ, lower than 1.338 kΩ of the Control device, while Rrec increased from 21.705 kΩ of the Control device to 23.181 kΩ of the PDA / Chitosan co-encapsulated device. The lower Rct and higher Rrec indicate that after using PDA / Chitosan encapsulation, the extraction and transport of carriers are significantly improved and the non-radiative recombination of carriers is inhibited, thereby reducing the energy loss during the transport of charges inside the device and further improving the PCE of the overall device. In Figure 5 c, it can be clearly seen that compared with the Control device, the device after being decorated with PDA / Chitosan encapsulation shows a lower leakage current. A lower leakage current often means higher quality perovskite crystals, fewer internal lattice defects and impurities, because these impurities and defects usually act as recombination centers and leakage paths of charge carriers, resulting in a higher dark current. Figure 5d shows the J-V curves of PSCs before and after PDA / Chitosan encapsulation. The device structure adopted is FTO / SnO 2 / CsFAMA(PDA / Chitosan) / Spir-OMeTAD / Ag. The tests were carried out under standard sunlight intensity (AM 1.5G, 100mW cm -2 ). In comparison, introducing the PDA / Chitosan encapsulation layer significantly improves the power conversion efficiency (PCE) of PSCs. Specifically, the open-circuit voltage (V OC ) of the PDA / Chitosan co-encapsulated device in Example 1 of the present invention is 1.21V, and the short-circuit current density (J SC ) is 24.35mAcm -2 , and the fill factor (FF) is 81.41, thus achieving a PCE of 24.09%. This PCE is 2.98% and 1.02% higher than that of Control (21.11%) and the Chitosan encapsulation group (23.07%) respectively.

[0064] Figure 6 This is the test on the influence of internal encapsulation on the stability of perovskite solar cells provided by the present invention. The Control device and the device after internal encapsulation with PDA / Chitosan were placed in a dark environment, and the PCE evolution of the devices was recorded in an environment with RH of 85% and temperature of 20 - 30 °C, obtaining the curve as shown in the figure. After 500h of aging, the Chitosan internal encapsulation device retained nearly 84.5% of the initial PCE, while the PDA / Chitosan co-encapsulated device in Example 1 of the present invention retained nearly 87.6% of the initial PCE. The Control device only retained 50.5% of the initial PCE. The enhanced stability is attributed to the enhanced hydrophobicity of the internal encapsulation layer. After introducing the PDA / Chitosan encapsulation layer on the surface of the perovskite film, it prevents water molecules from penetrating into the perovskite film, thus significantly enhancing the moisture resistance of PSCs.

[0065] Figure 7 This is the ion mobility spectrometry (IMS) test on the influence of internal encapsulation on ion migration in perovskite solar cells provided by the present invention. The results show that: the device without the encapsulation layer in Comparative Example 1 provides additional ion migration channels due to the higher defect density, resulting in a higher initial current density (29.56×10 -5 mA / cm 2 ). After introducing the PDA / Chitosan encapsulation layer, it significantly passivates the carrier defects, improves the crystallization quality of the perovskite film, suppresses ion migration to a certain extent, making it have a lower initial current density and a shorter decay time. The initial current density is 15×10-5 mA / cm 2 or so, only about half of the initial current density of the device without the encapsulation layer in Comparative Example 1, indicating that the introduction of the PDA / Chitosan internal encapsulation layer can effectively inhibit ion migration and is effective in improving the long-term operation stability of the device.

[0066] Figure 8 For the inductively coupled plasma optical emission spectrometry (ICP-OES) test of Pb leakage management in perovskite solar cells based on internal encapsulation provided by the present invention, the bare perovskite thin film and the perovskite thin film encapsulated with PDA / Chitosan internally were immersed in deionized water with a pH value of 5.5 to simulate the Pb leakage situation when PSCs were severely damaged in an acidic rainfall environment. The results showed that: after soaking in deionized water with a pH of 5.5 for 3 hours, the perovskite thin film underwent severe degradation. The Pb content of the degraded pure perovskite thin film reached 13.2 mg / L at RT, indicating that the device had basically completely degraded. For the device encapsulated with Comparative Example 2 (Chitosan) internally, the monitored Pb concentration was significantly reduced to 7.7 mg / L. For the device co-encapsulated with Example 1 (PDA / Chitosan) of the present invention, the monitored Pb concentration was further reduced to 7.2 mg / L, indicating that the successful introduction of the PDA / Chitosan internal encapsulation layer can firmly anchor Pb ions inside the perovskite thin film and effectively inhibit the perovskite degradation rate and Pb leakage.

[0067] Figure 9 For the test of the influence of internal encapsulation on the biological activity of perovskite solar cells provided by the present invention, in order to further evaluate the Pb leakage situation in perovskite solar cells, a cell activity experiment was carried out. The cells were: L-929 cells (purchased from Shanghai Institute of Cellular Biology, Chinese Academy of Sciences), and the incubator conditions were: 37 °C + 5% CO 2 , and the culture medium was: DMEM medium containing 1% penicillin-streptomycin (100 U·mL -1 penicillin and 100 g·mL -1 streptomycin) and 10% fetal bovine serum (FBS, Clark) (purchased from Gibco). At 1×10 4Density of cells / well: L-929 cells were seeded on a 96-well plate and cultured for 24 hours. Then, the cultured cell medium was exposed to a PDA / Chitosan-encapsulated perovskite solar cell that had been acid-treated (soaked in deionized water at pH 5.5 for 3 hours), and the cell viability and growth were measured. Subsequently, the CCK-8 method was used to evaluate cell activity with an enzyme-linked immunosorbent assay reader. As shown in Figure (a). Due to significant Pb leakage, the unencapsulated perovskite solar cell resulted in a cell viability of only 57.55%. In contrast, after encapsulation in Comparative Example 2 and Example 1 of the present invention, Pb ions were effectively captured, and cell activity was significantly improved. The viability reached 83.78% after internal encapsulation with Chitosan in Comparative Example 2, and further increased to 84.26% after co-encapsulation with Example 1 (PDA / Chitosan) of the present invention. Confocal fluorescence spectroscopy further demonstrated that after PDA / Chitosan encapsulation, the overall environmental friendliness of the device was significantly improved, as shown in Figures (b)-(e). The perovskite solar cell device was degraded in the L-929 cell medium, and after 5 hours, cell activity was observed by confocal fluorescence imaging. Living cells were stained green, while red staining indicated dead cells. After PDA / Chitosan encapsulation, the toxicity of the degraded cell device to cells was greatly reduced, and most L-929 cells remained viable. In contrast, the unencapsulated control device showed severe cytotoxicity. This indicates that PDA / Chitosan encapsulation effectively captures Pb ions and greatly enhances the environmental safety of perovskite solar cells.

[0068] As described above, the above are only the preferred specific embodiments of the present invention. These specific embodiments are all different implementation manners based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A highly efficient and stable perovskite solar cell based on an internal packaging strategy, characterized in that: The perovskite solar cell comprises substrates arranged sequentially from bottom to top; Electron transport layer; Perovskite layer; hole transport layer; electrode; The perovskite layer consists of a perovskite film and a chitosan layer and a polydopamine layer which are sequentially spin-coated on the surface of the film.

2. The perovskite solar cell according to claim 1, characterized in that The perovskite film is spin-coated from a perovskite precursor solution. The perovskite precursor is Cs 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb(I 0.83 Br 0.17 )3.

3. The perovskite solar cell according to claim 1, characterized in that The polydopamine layer is formed by spin coating a 0.8-1.2 g / L polydopamine isopropanol solution.

4. The perovskite solar cell according to claim 1, characterized in that: The chitosan layer is formed by spin coating a 0.8-1.2 g / L chitosan isopropanol solution.

5. The method for preparing a perovskite solar cell according to any one of claims 1 to 4, characterized in that: The method: S1: sequentially prepare an electron transport layer solution, a perovskite precursor solution, a chitosan isopropanol solution, a polydopamine isopropanol solution and a hole transport layer solution; S2: forming an electron transport layer, a perovskite film, a chitosan layer, a polydopamine layer and a hole transport layer on the substrate in sequence by spin coating, wherein the perovskite film is spin coated with the aid of a one-step anti-solvent, and annealing is performed after each spin coating step; S3: Depositing electrodes using vacuum evaporation.

6. The method according to claim 5, characterized in that Preparation of the perovskite precursor solution in S1: First, PbI2, FAI, PbBr2 and MABr are dissolved in a mixed solvent consisting of DMSO and DMF to obtain a main solution; secondly, CsI is dissolved in DMSO to obtain a CsI solution, which is then mixed with the main solution in a volume ratio of 5:95 to obtain a perovskite precursor solution.

7. The method according to claim 6, characterized in that The molar ratio of PbI2, FAI, PbBr2 and MABr in the main solution is 1.1:1:0.2:0.

2.

8. The method according to claim 6, characterized in that The concentration of PbI2 in the main solution is 1-1.2 mol / L.

9. The method according to claim 6, characterized in that The concentration of CsI in the CsI solution is 1.5-1.8 mol / L.

10. Application of the perovskite solar cell according to any one of claims 1 to 4 as a photovoltaic power generation device in the fields of aerospace and construction.

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