Semitransparent perovskite solar cell and preparation method thereof

Abstract

The invention discloses a semitransparent perovskite solar cell and a preparation method thereof, and belongs to the technical field of perovskite solar cells. The semitransparent perovskite solar cell sequentially comprises a substrate, a transparent conductive glass anode, an anode transmission layer, a perovskite layer, a cathode transmission layer, a protective layer and an ITO (Indium Tin Oxide) electrode from bottom to top, wherein the protective layer is a PEI (at) M (M = Ti, Zr, Hf) protective layer; and the PEI (at) M (M = Ti, Zr, Hf) protective layer is formed by spin-coating a mixed solution of PEI and TiCl4, ZrCl4 or HfCl4 on the surface of the cathode transmission layer and drying. Through coordination interaction of metal ions Ti, Zr and Hf and amino groups in PEI, PEI (at) M (M = Ti, Zr and Hf) is used as a protective layer to realize effective buffer protection of a perovskite layer and a functional layer under relatively high sputtering power, and meanwhile, the charge transfer performance of a device interface is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite solar cells, and particularly to a semi-transparent perovskite solar cell and a preparation method thereof. Background Art

[0002] Perovskite solar cells have gradually become a research hotspot in the photovoltaic field due to their excellent photoelectric conversion efficiency, low cost, and solution processability. However, in order to further improve the utilization rate of sunlight, the preparation of high-efficiency semi-transparent perovskite solar cells has become an important research direction. Such cells can not only be used as sub-cells in perovskite / silicon heterojunction solar cells, but also be widely applied in fields such as building integrated photovoltaics (BIPV), such as photovoltaic power generation windows or curtain walls. These applications are of great significance for accelerating the realization of the "dual carbon" goal. In the preparation of semi-transparent perovskite solar cells, the transparent electrode needs to have excellent optoelectronic properties and stability. Indium tin oxide (ITO) has become the first choice for transparent electrodes due to its high transmittance and conductivity. However, ITO films are usually deposited by magnetron sputtering, and high-energy sputtering particles may cause serious damage to the underlying functional materials of the cell (such as the perovskite layer and charge transport layer), significantly affecting the optoelectronic properties and stability of the device. Although some studies have introduced protective layers to reduce sputtering damage, there are still deficiencies.

[0003] Figure 1 (a) is a schematic diagram of the device structure of a typical p-i-n structured opaque perovskite solar cell. The device structure from bottom to top is conductive glass glass / ITO, hole transport layer PTAA, perovskite with a bandgap of 1.66 eV, electron transport layer C 60 , buffer layer BCP, and opaque metal electrode Ag. When preparing a semi-transparent cell, the opaque metal electrode Ag needs to be replaced with a transparent electrode ITO. During the ITO sputtering preparation process, high-energy particles will damage the device, and BCP cannot provide good protection. Therefore, a new protective layer material needs to be introduced to replace BCP in semi-transparent perovskite solar cells.

[0004] Some researchers have placed SnO2 prepared by atomic layer deposition (ALD) on top of the ITO top electrode and the electron transport layer C 60 instead of the conventional buffer layer material BCP, such as Figure 1(b). SnO₂ serves as both a protective layer to buffer high-energy sputtering damage and an electron transport layer, providing excellent chemical and thermal stability and extending the working life of the battery. This technical solution usually adopts a low-temperature ALD process (such as below 150 °C) to adapt to the sensitivity of perovskite materials to high temperatures. The thickness of the SnO₂ thin film can be precisely controlled within the nanometer range (generally 10 - 20 nm) to provide sufficient protection while maintaining light transmittance. However, this method has the following disadvantages: 1. High cost and equipment requirements: The ALD technology has high requirements for equipment and processes, and the preparation cycle is long, resulting in a significant increase in production costs. This high cost limits the large-scale commercial production of perovskite solar cells; 2. Low time efficiency: ALD is a layer-by-layer deposition process, and the growth of a single atomic layer requires multiple gas-phase reaction cycles, resulting in a low deposition rate. When a thicker protective layer needs to be prepared, the time cost is high. 3. Material matching problems: Although SnO₂ has a high electron mobility, the interfacial contact between it and the perovskite layer or the electron transport layer (such as C 60 ) is not perfect, and interface defects or discontinuities may occur, thus limiting the further improvement of device performance. The above disadvantages indicate that although the SnO₂ protective layer improves the performance and stability of perovskite cells to a certain extent, its high cost and process complexity make this solution difficult to meet the large-scale production requirements.

[0005] Previously, the inventors used alcohol-soluble polyethylenimine (PEI) as a protective layer to replace BCP, effectively weakening the damage to the device during ITO sputtering. The device structure is as Figure 1 (c). PEI is a polymer rich in amino groups and has the following characteristics and functions: 1. Optimization of charge transport performance: The interfacial interaction between the amino groups of PEI and the transparent electrode ITO can adjust the energy level arrangement, thereby improving the charge transport ability at the device interface and enhancing the photoelectric conversion efficiency; 2. Buffering high-energy particle impact: As a buffer layer, PEI can effectively absorb and disperse the energy of high-energy particles during the magnetron sputtering process, thus reducing the damage to the underlying functional materials (such as the perovskite layer or C 60 electron transport layer); 3. Ultra-thin and efficient: The PEI protective layer is usually nanometer-thick (2 - 5 nm). While maintaining high light transmittance, it can provide sufficient protection performance and will not significantly affect the optical performance of the battery. The semi-transparent battery based on PEI exhibits excellent photovoltaic performance. Under the conventional ITO sputtering power condition (100 W), the efficiency and stability of the device have been significantly improved.

[0006] Although PEI shows good protection effect under conventional sputtering conditions, its protective effect will be weakened when the ITO sputtering power increases (from 100 W to 300 W) to shorten the device fabrication time. This is because the impact intensity of high-energy particles increases with the power, and pure PEI is difficult to meet the requirements under higher power conditions for the following reasons. Its disadvantages are as follows: 1. The anti-impact ability shows insufficiency in a more severe environment: The mechanical strength of PEI is limited and may not be able to fully buffer the impact of high-energy particles under high-power sputtering conditions, resulting in damage to the underlying perovskite material; 2. The charge transport performance is limited: As an insulating material, PEI itself has a low charge mobility; 3. The stability decreases: Under high-power conditions, PEI may suffer from structural damage due to heating or stronger sputtering particle impact, leading to a further weakening of its protective effect. Based on the above deficiencies, there is a current need to introduce more powerful protective materials to achieve efficient protection and better performance under high-power sputtering conditions. Summary of the Invention

[0007] To solve the problems existing in the prior art, the present invention provides a semi-transparent perovskite solar cell and a preparation method thereof. The present invention uses PEI@M (M = Ti, Zr, Hf) as a buffer protection layer to solve the damage caused by ITO sputtering to the semi-transparent perovskite solar cell; at the same time, it improves the charge transport performance of the device interface to ensure that the device still has excellent photovoltaic performance and long-term stability under efficient preparation conditions.

[0008] To solve the above technical problems, the present invention provides the following technical solutions:

[0009] On the one hand, the present invention provides a semi-transparent perovskite solar cell, which successively comprises a substrate, a transparent conductive glass anode, an anode transport layer, a perovskite layer, a cathode transport layer, a protection layer and an ITO electrode from bottom to top; wherein, the protection layer is a PEI@M (M = Ti, Zr, Hf) protection layer;

[0010] The PEI@M (M = Ti, Zr, Hf) protection layer is formed by uniformly mixing a polyethyleneimine (PEI) solution with a TiCl4, ZrCl4 or HfCl4 solution to form a PEI@M solution, and spin-coating the PEI@M solution on the surface of the cathode transport layer and drying it;

[0011] The average molecular weight of the polyethyleneimine is 1200 - 20000 and has the following structure

[0012] ;

[0013] wherein, n is 3 - 35 nm.

[0014] Further, the concentration of the PEI solution is 1-2 mg / ml; the TiCl4, ZrCl4 or HfCl4 solution is a solution dissolved in methanol or isopropanol, and the concentration of the TiCl4, ZrCl4 or HfCl4 solution is 100-200 mg / ml.

[0015] Preferably, the mass ratio of PEI to MCl4 is 10:1-40:1, and the preferred mass ratios are 19:1, 16:1, 13:1, 10:1. The dosage of the PEI@M solution is 30 μl / cm 2 .

[0016] On the other hand, the present invention also provides a method for preparing a semi-transparent perovskite solar cell, comprising:

[0017] (1) Pretreatment of the ITO glass substrate; the ITO glass substrate includes a glass substrate and a transparent conductive glass anode provided thereon; the thickness of the transparent conductive glass anode is 150 nm; the thickness of the glass substrate is 1.1 mm;

[0018] Specifically: sequentially ultrasonic clean the ITO glass substrate in detergent (dishwashing liquid, any commercially available dishwashing liquid), water, deionized water, acetone and isopropanol solvent for 15 minutes; then place the cleaned ITO substrate in an oven at 150 °C and dry for 5 minutes, and then place the substrate in an ultraviolet ozone (UVO) machine for treatment for 15 min;

[0019] (2) Prepare an anode transport layer on the transparent conductive glass anode. Specifically: spin-coat a 2 mg / ml solution of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA) dissolved in toluene on the surface of the transparent conductive glass anode at a speed of 4000 rpm, and then anneal it on a heating table at 150 °C for 10 min to prepare the anode transport layer;

[0020] (3) Deposit a perovskite layer on the anode transport layer. Specifically: coat 70 μl of the perovskite precursor solution on the substrate at a speed of 5000 rpm; then drop 300 ul of the antisolvent chlorobenzene at the 25th s during the spin-coating process, and then anneal at 100 °C for 30 min to obtain a perovskite layer with a thickness of 450 nm;

[0021] The perovskite precursor solution is formed by dissolving 77.62 mg of CsI, 162.15 mg of formamidinium hydroiodide (FAI), 112.13 mg of PbBr2, 2.83 mg of methylammonium chloride (MACl), 11.68 mg of PbCl2, and 425.15 mg of PbI2 in 1 mL of a mixed solution of DMSO:DMF; the volume ratio of DMSO:DMF is 1:3;

[0022] (4) Deposit the cathode transport layer on the perovskite layer by vacuum evaporation, specifically: vacuum evaporate 15 nm of C on the prepared perovskite layer 60 ; The conditions for vacuum evaporation are that the evaporation current starts from 6 A and slowly increases, reaching about 25 A within 10 minutes. Open the substrate baffle to start evaporation. When it evaporates to 15 nm, turn off the substrate baffle and reduce the evaporation current to 0 A;

[0023] (5) Prepare the PEI@M protective layer on the surface of the cathode transport layer: Add TiCl4, ZrCl4, or HfCl4 solution to the PEI solution and mix evenly to form the PEI@M solution. Spin-coat the PEI@M solution on the surface of the cathode transport layer, and then dry it;

[0024] (6) Deposit the ITO electrode on the surface of the protective layer by vacuum sputtering. During the vacuum sputtering process, the sputtering power is 300 W, the sputtering time is 20 min, the argon gas flow rate is 60 sccm, and the working pressure is 2 Pa; then the perovskite solar cell can be obtained.

[0025] The novel anti-sputtering buffer layer material of the present invention combines good anti-impact performance, high-efficiency electron transport ability, and is highly compatible with the perovskite battery preparation process, thus realizing the preparation of high-performance semi-transparent perovskite solar cells; and the method of the present invention further improves the device efficiency and reduces the manufacturing difficulty, providing an innovative solution for the development of semi-transparent solar cells.

[0026] In the present invention, a large number of amino active groups on the PEI molecule produce a coordination effect with metal ions Ti, Zr, and Hf, which can cause a certain degree of interlacing between different molecular chains of PEI, thus forming a polymer network structure with a larger and more closely packed structure to resist the magnetron sputtering high-energy particles at higher powers. The prepared PEI@M (M = Ti, Zr, Hf) has great advantages in charge transport compared with a simple PEI polymer with a higher molecular weight. This is because the coordination effect can form an electron transfer channel between the metal and the polymer, promoting the movement of electrons, thereby improving the conductive properties of the material.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) Higher sputtering resistance

[0029] In the present invention, by using the coordination interaction between metal ions Ti, Zr, Hf and amino groups in PEI, a metal coordination polymer material PEI@M (M = Ti, Zr, Hf) with a larger polymer network and certain charge transport properties is generated through reaction. PEI@M (M = Ti, Zr, Hf) is used as a protective layer to achieve effective buffer protection for the perovskite layer and functional layers under a relatively high sputtering power (i.e., a shorter preparation cycle), while improving the charge transport performance at the device interface, ensuring that the device still has excellent photovoltaic performance and long-term stability under efficient preparation conditions.

[0030] (2) Improvement of photovoltaic performance

[0031] Compared with traditional protective layer materials (such as PEI or BCP), PEI@M (M = Ti, Zr, Hf) exhibits higher electron mobility and excellent interfacial charge extraction ability. Based on this technology, the PCE of the semi-transparent perovskite solar cell is increased to 20.14% (when PEI@Hf is used as the protective layer).

[0032] (3) Acceleration of production rhythm

[0033] By supporting a higher ITO sputtering power, the present invention significantly shortens the preparation time of the ITO thin film, improves the production efficiency of the device, and paves the way for the commercial application of semi-transparent solar cells and tandem solar cells.

[0034] (4) Wide applicability

[0035] As a protective layer, PEI@M (M = Ti, Zr, Hf) combines high performance and low cost, can be seamlessly compatible with the preparation processes of existing perovskite solar cells and tandem cells, and has broad application prospects. Description of the drawings

[0036] Figure 1 In the figure, (a) is a schematic diagram of the device structure of an opaque perovskite solar cell; (b) is a schematic diagram of the device structure of a semi-transparent perovskite solar cell with SnO2 as the protective layer; (c) is a schematic diagram of the device structure of a semi-transparent perovskite solar cell with PEI as the protective layer; (d) is a schematic diagram of the device structure of a semi-transparent perovskite solar cell with PEI@M (M = Ti, Zr, Hf) as the protective layer in the present invention;

[0037] Figure 2 It is a schematic diagram of the complete reaction of PEI with TiCl4, ZrCl4 or HfCl4 to generate the coordination compound PEI@M (M = Ti, Zr, Hf) in the present invention;

[0038] Figure 3 Schematic diagram of the device disassembly structure of Embodiment 1 of the present invention;

[0039] Figure 4 Current density - voltage (J - V) curve of the semi - transparent perovskite solar cell provided in Embodiment 1 of the present invention under illumination with an intensity of 100 mW / cm²;

[0040] Figure 5 Current density - voltage (J - V) curve of the semi - transparent perovskite solar cell provided in Embodiment 2 of the present invention under illumination with an intensity of 100 mW / cm²;

[0041] Figure 6 Current density - voltage (J - V) curve of the semi - transparent perovskite solar cell provided in Embodiment 3 of the present invention under illumination with an intensity of 100 mW / cm². Detailed implementation manners

[0042] To make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the drawings and specific embodiments.

[0043] In the present invention, materials and reagents used without special instructions can be obtained from commercial channels. Among them, the ITO glass substrate is purchased from South China Xiangcheng Technology Co., Ltd., the thickness of the transparent conductive glass anode is 150 nm, and the thickness of the glass substrate is 1.1 mm; PTAA is purchased from Xi'an Baolaitai Optoelectronic Technology Co., Ltd., with an average molecular weight of 25000; C 60 is purchased from Xi'an Baolaitai Optoelectronic Technology Co., Ltd.; polyethyleneimine is purchased from Shanghai Yuanye Bio - Technology Co., Ltd., with model numbers S24086 (molecular weight 600), S31375 (molecular weight 1200 - 1300), S24087 (molecular weight 1800), S28081 (molecular weight 5000), S24088 (molecular weight 10000), S24467 (molecular weight 20000 - 30000); PEI is a PEI aqueous solution with a concentration of 1 mg / ml; the TiCl₄ solution is a TiCl₄ methanol solution with a concentration of 150 mg / ml; the ZrCl₄ solution is a ZrCl₄ methanol solution with a concentration of 150 mg / ml; the HfCl₄ solution is a HfCl₄ methanol solution with a concentration of 150 mg / ml.

[0044] The present invention provides a method using PEI@M (M = Ti, Zr, Hf) as a buffer protection layer to solve the damage caused by ITO sputtering to semi - transparent perovskite solar cells, and the specific embodiments are as follows.

[0045] Embodiment 1

[0046] A semi-transparent perovskite solar cell using PEI@Ti as a buffer protection layer, as shown in Figure 3 shown in Figure 3 , the semi-transparent perovskite solar cell comprises, from bottom to top in sequence, a substrate 1, a transparent conductive glass anode 2, an anode transport layer 3, a perovskite layer 4, a cathode transport layer 5, a protection layer 6, and an ITO electrode 7; wherein, the protection layer 6 is a PEI@Ti protection layer;

[0047] The preparation method of the above semi-transparent perovskite solar cell comprises:

[0048] (1) Cleaning of the ITO glass substrate (length and width are 1.5×1.5 cm 2 , thickness is 1.1 mm; the thickness of the transparent conductive glass anode 2 is 150 nm): ultrasonically clean the glass substrate in dishwashing liquid, water, deionized water, acetone, and isopropanol solvents for 15 minutes in sequence. Then place the cleaned ITO substrate in an oven at 150 °C for 5 minutes to dry it, and then place the substrate in an ultraviolet ozone machine (UVO) for 15 min;

[0049] (2) Preparation of the anode transport layer on the ITO transparent conductive layer. Spin-coat 70 μl of a 2 mg / ml PTAA solution dissolved in toluene on the transparent conductive glass anode at a speed of 4000 rpm for 30 s, and then anneal it on a heating table at 150 °C for 10 min to prepare the anode transport layer;

[0050] (3) Deposit the perovskite layer on the substrate of the previous step by a one-step deposition method: First, spin-coat 70 μl of a perovskite precursor solution (77.62 mg CsI, 162.15 mg FAI, 112.13 mg PbBr2, 2.83 mg MACl, 11.68 mg PbCl2, 425.15 mg PbI2 dissolved in 1 mL of a mixed solution of DMSO:DMF (volume ratio of DMSO:DMF is 1:3)) on the anode transport layer at a speed of 5000 rpm for 50 s; then, drip 300 μl of the antisolvent chlorobenzene on the perovskite film at the 25th s of the spin-coating process; then anneal it at 100 °C for 30 min to obtain a perovskite film with a thickness of 450 nm;

[0051] (4) Deposit the cathode transport layer on the perovskite layer by vacuum evaporation. Vacuum-evaporate 15 nm of C 60 on the prepared perovskite film. During the vacuum evaporation process, the evaporation current starts from 6 A and slowly increases, and is increased to about 25 A within 10 minutes. Open the substrate baffle to start evaporation, and turn off the substrate baffle when the evaporation reaches 15 nm, and reduce the evaporation current to 0 A;

[0052] (5) Spin-coating the PEI@Ti solution to form a PEI@Ti protective layer: Mix and stir evenly the PEI (1 ml of 1 mg / ml PEI solution (PEI is S24087 with a molecular weight of 1800)) and the TiCl4 methanol solution (concentration 150 mg / ml, dosage 1 μl) to obtain the PEI@Ti solution. Then spin-coat the PEI@Ti solution on the surface of the cathode transport layer. The dosage of the PEI@Ti solution is 30 μl / cm 2 , the spin-coating speed is 5000 rpm. After 30 s, the spin-coating stops and it is immediately placed on a heating table at 100 °C for annealing for 5 min to form the PEI@Ti protective layer, and then the next operation is carried out;

[0053] (6) Finally, deposit the ITO electrode by vacuum sputtering to obtain the perovskite solar cell; among them, the sputtering conditions of ITO are: sputtering power 300 W, sputtering time 20 min, argon gas flow rate 60 sccm, working pressure 2 Pa, and the thickness of the sputtered ITO electrode is 100 nm.

[0054] Example 2

[0055] In step (5) of this example, the TiCl4 solution is replaced with a ZrCl4 solution of the same concentration and the same volume, and the other conditions are the same as those in Example 1.

[0056] Example 3

[0057] In step (5) of this example, the TiCl4 solution is replaced with an HfCl4 solution of the same concentration and the same volume, and the other conditions are the same as those in Example 1.

[0058] To further illustrate the beneficial effects of the present invention, the following comparative examples are constructed.

[0059] Comparative Example 1

[0060] This comparative example provides a semi-transparent perovskite battery. Compared with Example 3, the difference lies in: the different selection of the protective layer material. This comparative example uses BCP as the protective layer. The preparation method of BCP is:

[0061] Evaporate 8 nm of BCP (Chinese name 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, manufacturer Xi'an Baolaitai Optoelectronic Technology Co., Ltd.) by vacuum evaporation. The evaporation current is slowly increased from 0 A to 3 A and then the baffle is opened for evaporation. After the BCP thickness reaches 8 nm, the evaporation stops.

[0062] Comparative Example 2

[0063] This comparative example provides a semi-transparent perovskite solar cell. Compared with Example 3, the difference lies in the different selection of the protective layer material. This comparative example uses pure PEI as the protective layer. The preparation method of the PEI layer is as follows:

[0064] Spin-coat a PEI solution with a concentration of 1 mg / ml, and the dosage is 30 μl / cm 2 , the spin-coating speed is 5000 rpm. Immediately after the spin-coating stops, place it on a heating table at 100 °C for annealing for 5 min, and then proceed to the next step.

[0065] Comparative Example 3

[0066] In this comparative example, the sputtering conditions in step (6) are as follows: the sputtering power is 100 W, the sputtering time is 50 min, the argon gas flow rate is 60 sccm, the working pressure is 2 Pa, and the thickness of the sputtered ITO electrode is 100 nm. The other conditions are the same as those in Comparative Example 2.

[0067] Comparative Example 4

[0068] The difference between this comparative example and Example 3 lies in that in step (6), the sputtering conditions are as follows: the sputtering power is 100 W, the sputtering time is 50 min, the argon gas flow rate is 60 sccm, the working pressure is 2 Pa, and the thickness of the sputtered ITO electrode is 100 nm.

[0069] Perform performance tests on the semi-transparent perovskite solar cells obtained in the above Examples 1-3 and Comparative Examples 1-4. The current density-voltage (J-V) curves measured under illumination with an intensity of 100 mW / cm² are as shown in Figures 4 - 6 , and the specific test results are shown in Table 1.

[0070] Table 1

[0071]

[0072] As can be seen from Table 1, there are significant differences in the device performance between Comparative Example 1 and Examples 1-3, indicating that the effect of BCP is very poor and it cannot protect the device from the damage of ITO sputtering; the device performance of Comparative Example 2 is much higher than that of Comparative Example 1, indicating that PEI still has a certain protective effect under the ITO sputtering conditions of 300 W, but there are still some gaps compared with the device performance of Examples 1-3, indicating that when PEI is used as the protective layer at a sputtering power of 300 W, the device still has a certain degree of damage. There is little difference among Examples 1-3, indicating that the strategy of using metal ions Ti, Zr or Hf coordinated with PEI to form PEI@M (M = Ti, Zr, Hf), as shown in Figure 2 , as a buffer protective layer to solve the damage caused by ITO sputtering to the semi-transparent perovskite solar cell is very successful, and the device performance based on PEI@Hf is the highest.

[0073] The device performance of Comparative Example 2 has a certain gap compared with that of Comparative Example 3. It can be seen that the protection of the device by PEI is very effective at 100 W, but the effect becomes worse when the sputtering power increases to 300 W. In Comparative Example 3, with PEI as the buffer layer and the sputtering power of 100 W, although both the energy conversion efficiency and the fill factor are relatively high, the electrode preparation time is much longer than that of Example 3. The device performances of Comparative Example 4 and Example 3 are very similar, which indicates that when the sputtering power of ITO increases from 100 W to 300 W, the protective effect of PEI@Hf is still obvious, showing very good buffer protection performance. The application of PEI@Hf not only ensures the excellent performance of the semi-transparent perovskite solar cell but also greatly reduces the electrode preparation time.

[0074] The present invention further optimizes the specific parameters in the preparation process. The specific examples and comparative examples are as follows.

[0075] Example 4

[0076] In this example, PEI is S31375 with a molecular weight of 1200 - 1300, and the other conditions are the same as those in Example 3.

[0077] Example 5

[0078] In this example, PEI is S28081 with a molecular weight of 5000, and the other conditions are the same as those in Example 3.

[0079] Example 6

[0080] In this example, PEI is S24088 with a molecular weight of 10000, and the other conditions are the same as those in Example 3.

[0081] Example 7

[0082] In this example, the mass ratio of PEI to HfCl4 is 10:1, and the other conditions are the same as those in Example 3.

[0083] Example 8

[0084] In this example, the mass ratio of PEI to HfCl4 is 16:1, and the other conditions are the same as those in Example 3.

[0085] Example 9

[0086] In this example, the mass ratio of PEI to HfCl4 is 19:1, and the other conditions are the same as those in Example 3.

[0087] Example 10

[0088] In this example, the mass ratio of PEI to HfCl4 is 30:1, and the other conditions are the same as those in Example 3.

[0089] Example 11

[0090] In this example, the mass ratio of PEI to HfCl4 is 40:1, and the other conditions are the same as in Example 3.

[0091] Comparative Example 4

[0092] In this comparative example, PEI is S24467 with a molecular weight of 20,000 - 30,000, and the other conditions are the same as in Example 3.

[0093] Comparative Example 5

[0094] In this comparative example, PEI is S24086 with a molecular weight of 600, and the other conditions are the same as in Example 3.

[0095] Comparative Example 6

[0096] In this comparative example, the mass ratio of PEI to HfCl4 is 5:1, and the other conditions are the same as in Example 3.

[0097] Comparative Example 7

[0098] In this comparative example, the mass ratio of PEI to HfCl4 is 50:1, and the other conditions are the same as in Example 3.

[0099] Comparative Example 8

[0100] In this comparative example, HfCl4 is replaced with SnCl4, and the other conditions are the same as in Example 3.

[0101] The performance of the above Examples 4 - 11 and Comparative Examples 4 - 8 was detected, and the results are shown in Table 2.

[0102] Table 2

[0103]

[0104] As can be seen from Table 2, the change in the molecular weight of PEI in Examples 4 - 6 may cause a change in the energy conversion efficiency of the fabricated device. However, when the molecular weight is between 1200 - 10000, the impact on the performance of the fabricated device is not significant. In Examples 7 - 11, the mass ratio of PEI to HfCl4 is regulated within a specific range, and the impact on the performance of the fabricated device is not significant. However, when the molecular weight of PEI is too large (Comparative Example 4) or too small (Comparative Example 5), the energy conversion efficiency of the fabricated device will decrease. This may be because when the molecular weight of PEI is too large, the number of PEI chains is small, and the network structure formed by coordination with metal ions is relatively simple, corresponding to poor toughness or impact resistance of the film. When the molecular weight is too small, the network structure formed by the combination of PEI and metal ions is also relatively fragmented, corresponding to poor toughness or impact resistance of the film layer.

[0105] When the mass ratio of PEI to HfCl4 is too small (Comparative Example 6) or too large (Comparative Example 7), it will also lead to a decrease in the energy conversion efficiency of the fabricated device. This may be because when the mass ratio is too small, a trace amount of the product of the complete coordination reaction between PEI and HfCl4 is generated. This product is insoluble in alcohol solvents, and the film prepared by spin-coating using the solution method will have a poor morphology, affecting the film structure of other functional layer materials in the upper layer and ultimately affecting the performance of the device. When the mass ratio is too large, there is more PEI, and the coordination effect is not obvious, tending to only have the protective effect of PEI.

[0106] Replacing HfCl4 with SnCl4 (Comparative Example 8), PEI@Sn may have poorer mechanical properties than PEI@Hf, resulting in a decrease in energy conversion efficiency.

[0107] Meanwhile, the inventors also regulated the concentration of the PEI solution. When the PEI concentration is lower than 1 mg / ml, the prepared PEI@M buffer layer is thinner, and the anti-sputtering performance is reduced; when the PEI solution concentration is too high, it will lead to an excessive thickness of the prepared PEI@M buffer layer, resulting in a decrease in conductivity and affecting the battery performance.

[0108] In summary, the present invention utilizes the coordination interaction between metal ions Ti, Zr, Hf and the amino groups in PEI, and uses PEI@M (M = Ti, Zr, Hf) as a protective layer to effectively buffer and protect the perovskite layer and functional layers under a relatively high sputtering power (i.e., a shorter preparation cycle), ensuring that the device still has excellent photovoltaic performance and long-term stability under efficient preparation conditions.

[0109] The above is the preferred embodiment of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, making several improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A semi-transparent perovskite solar cell, wherein the semi-transparent perovskite solar cell comprises, from bottom to top, a substrate, a transparent conductive glass anode, an anode transport layer, a perovskite layer, a cathode transport layer, a protective layer, and an ITO electrode; characterized in that, The protective layer is a PEI@M protective layer, where M is Ti, Zr or Hf; The PEI@M protective layer is prepared by the following method: mixing a polyethyleneimine solution and an MCl4 solution evenly to form a PEI@M solution, and spin-coating the PEI@M solution on the surface of the cathode transport layer and drying it; The polyethyleneimine has the following structure: where n is 3 - 35.

2. The semi-transparent perovskite solar cell according to claim 1, characterized in that The concentration of the PEI solution is 1 - 2 mg / ml; the TiCl4, ZrCl4 or HfCl4 solution is a solution in which the three substances are dissolved in ultradry methanol, ethanol or isopropanol, and the concentration of the TiCl4, ZrCl4 or HfCl4 solution is 100 - 200 mg / ml.

3. The semi-transparent perovskite solar cell according to claim 2, wherein, The mass ratio of PEI to MCl4 is 10:1 - 40:

1.

4. The semi-transparent perovskite solar cell according to claim 3, characterized in that, The dosage of the PEI@M solution is 30 μl / cm 2 .

5. The preparation method of the semi-transparent perovskite solar cell according to any one of claims 1-4, characterized in that, It includes: (1) Pretreatment of the ITO glass substrate; The ITO glass substrate includes a glass substrate and a transparent conductive glass anode provided thereon; (2) Preparing an anode transport layer on the transparent conductive glass anode; (3) Depositing a perovskite layer on the anode transport layer; (4) Depositing a cathode transport layer on the perovskite layer by vacuum evaporation; (5) Preparing a PEI@M protective layer on the surface of the cathode transport layer: adding an MCl4 solution to the PEI solution, mixing evenly to form a PEI@M solution, spin-coating the PEI@M solution on the surface of the cathode transport layer, and then drying; (6) Depositing an ITO electrode on the surface of the protective layer by vacuum sputtering to obtain a perovskite solar cell.

6. The preparation method according to claim 5, characterized in that, The specific step (1) is: ultrasonically cleaning the ITO glass substrate in detergent, water, deionized water, acetone and isopropanol solvents for 15 minutes in sequence; then placing the cleaned ITO glass substrate in an oven at 150 °C for 5 minutes to dry, and then placing the substrate in an ultraviolet ozone machine for 15 minutes; The thickness of the transparent conductive glass anode is 150 nm; the thickness of the glass substrate is 1.1 mm.

7. The preparation method according to claim 5, characterized in that, The specific step (2) is: spin-coating a solution of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] dissolved in toluene at a concentration of 2 mg / ml on the surface of the transparent conductive glass anode at a speed of 4000 rpm, and then annealing it on a heating table at 150 °C for 10 minutes to prepare an anode transport layer.

8. The preparation method according to claim 5, characterized in that, The specific step (3) is: coating 70 μl of the perovskite precursor solution on the substrate at a speed of 5000 rpm; then dropping 300 μl of the antisolvent chlorobenzene at the 25th second during the spin-coating process, and then annealing at 100 °C for 30 minutes to obtain a perovskite layer with a thickness of 450 nm; The perovskite precursor solution is formed by dissolving 77.62 mg CsI, 162.15 mg FAI, 112.13 mg PbBr2, 2.83 mg MACl, 11.68 mg PbCl2 and 425.15 mg PbI2 in 1 ml of a mixed solution of DMSO:DMF; the volume ratio of DMSO:DMF is 1:

3.

9. The preparation method according to claim 5, wherein The specific step (4) is as follows: vacuum-evaporate 15 nm of C on the prepared perovskite layer 60 , and the conditions for the vacuum evaporation are that the evaporation current starts from 6 A and is slowly increased to 25 A within 10 minutes. Then, the substrate baffle is opened to start evaporation. When the evaporation reaches 15 nm, the substrate baffle is turned off, and the evaporation current is reduced to 0 A.

10. The preparation method according to claim 5, characterized in that, During the vacuum sputtering process of step (6), the sputtering power is 300 W, the sputtering time is 20 min, the argon gas flow rate is 60 sccm, and the working pressure is 2 Pa.

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