Lead-free wide-band-gap double-perovskite solar cell, preparation method thereof and electronic price tag

Abstract

The invention relates to the technical field of application of perovskite solar cells, and discloses a lead-free wide-band-gap double-perovskite solar cell, a preparation method thereof and an electronic price tag. According to the lead-free wide-band-gap double-perovskite solar cell provided by the invention, the optical band gap of the lead-free double-metal perovskite layer is in the range of 1.8 eV to 2.2 eV. Therefore, the lead-free wide-band-gap double-perovskite solar cell can be ensured to effectively absorb visible light and an indoor light source with a specific wavelength, not only can the energy of the indoor light source be utilized to the greatest extent, but also a relatively high open-circuit voltage can be maintained under low light intensity, and further relatively high photoelectric conversion efficiency of the lead-free wide-band-gap double-perovskite solar cell in an indoor weak light environment can be ensured. In addition, by adopting the non-lead perovskite material, the risk of heavy metal pollution is reduced, the method is green and environment-friendly, and large-scale production is easier.

Description

Technical Field

[0001] The invention belongs to the technical field of perovskite solar cell applications, and in particular relates to a lead-free wide-bandgap double perovskite solar cell and a preparation method thereof, and an electronic price tag. Background Art

[0002] Electronic price tags, also known as electronic shelf labels (ESL), are electronic display devices with information receiving and sending functions. They are mainly used in supermarkets, convenience stores, pharmacies, etc. to display price information. They are placed on shelves and can replace traditional paper price tags. Each electronic shelf label is connected to the computer database of the mall through a wired or wireless network, and the latest product information is displayed on the screen of the electronic shelf label.

[0003] At present, there are many ways to power electronic price tags, such as using button batteries or solar cells. Figure 1 As shown, float TCO glass 8 is usually selected as a substrate, and a hole transport layer 7, a perovskite layer 6, an electron transport layer 5 and an electrode 4 are sequentially deposited on the TCO glass 8, and then laminated with butyl rubber 2, POE film 3 and cover glass 1 for packaging, and then tempered glass 9 is laminated on the back of the TCO glass 8 to prepare a perovskite solar cell.

[0004] However, traditional silicon-based solar cells and lead-based perovskite cells have low photoelectric conversion efficiency under low illumination of indoor ambient light sources (such as fluorescent lamps and LED lamps), and use toxic heavy metal lead, which poses potential hazards to human health and the environment. Summary of the invention

[0005] The purpose of the present invention is to overcome the above problems and provide a lead-free wide-bandgap double perovskite solar cell and a preparation method thereof, and an electronic price tag. The lead-free wide-bandgap double perovskite solar cell provided by the present invention can not only maximize the use of the energy of the indoor light source, but also maintain a high open-circuit voltage under low light intensity, thereby ensuring that its photoelectric conversion efficiency is high in an indoor weak light environment.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a lead-free wide bandgap double perovskite solar cell, which comprises, from bottom to top, a transparent conductive substrate, a first carrier transport layer, a lead-free double metal perovskite layer, a second carrier transport layer and an electrode layer;

[0008] The lead-free bimetallic perovskite layer is obtained by spin coating a lead-free bimetallic perovskite precursor solution and then annealing; the lead-free bimetallic perovskite precursor solution comprises: a lead-free bimetallic perovskite precursor material and a lead-free bimetallic perovskite precursor solvent; the general structural formula of the lead-free bimetallic perovskite precursor material is A2B'B"X' y X” 6-y , A is an organic monovalent cation or an inorganic monovalent cation, B' is a monovalent metal cation, B" is a trivalent metal cation, X' is a halogen anion, and X" is a halogen anion; the range of y is 0<y<6;

[0009] Wherein, the optical band gap of the lead-free bimetallic perovskite layer ranges from 1.8 eV to 2.2 eV.

[0010] A further improvement of the present invention is that the A position is Cs + , FA + and MA + One of the following, wherein the B' position is Ag + 、Na + and Cu + One of the two, B" is Bi 3+ 、V 3+ andIn 3+ One of the above, wherein the X' position is Cl - Br - and I - One of the above, wherein the X" position is Cl - Br - and I - One of them.

[0011] A further improvement of the present invention is that the lead-free bimetallic perovskite precursor material includes: an inorganic compound formed by a monovalent metal element and a halogen element, and an inorganic compound formed by a trivalent metal element and a halogen element.

[0012] A further improvement of the present invention is that the lead-free bimetallic perovskite precursor solvent includes: N,N-dimethylformamide, and / or dimethyl sulfoxide.

[0013] A further improvement of the present invention is that the thickness of the lead-free wide bandgap double perovskite solar cell ranges from 0.3 mm to 0.6 mm.

[0014] A further improvement of the present invention is that the lead-free wide bandgap double perovskite solar cell further comprises: a thin film encapsulation layer

[0015] In a second aspect, the present invention further provides a method for preparing a lead-free wide bandgap double perovskite solar cell, comprising the following steps:

[0016] Step S1, pre-treating the transparent conductive substrate;

[0017] Step S2, preparing a first carrier transport layer on one side of the transparent conductive substrate;

[0018] Step S3, preparing a lead-free bimetallic perovskite layer on a side of the first carrier transport layer away from the transparent conductive substrate;

[0019] Step S4, sequentially preparing a second carrier transport layer, an electrode layer and a thin film encapsulation layer on a side of the lead-free bimetallic perovskite layer away from the transparent conductive substrate.

[0020] A further improvement of the present invention is that in step S3, a lead-free bimetallic perovskite layer is prepared on a side of the first carrier transport layer away from the transparent conductive substrate, comprising:

[0021] The lead-free bimetallic perovskite precursor solution is filtered, and the lead-free bimetallic perovskite precursor solution is dropped onto the side of the first carrier transport layer away from the transparent conductive substrate, and spin-coated at a rotation speed of 4000rpm / s to 6000rpm / s for 30s to 60s. After the spin coating, the solution is annealed at a temperature of 60°C to 120°C for 1min to 30min, and then annealed at a temperature of 100°C to 150°C for 10min to 30min. The solution is cooled to room temperature to obtain a lead-free bimetallic perovskite layer.

[0022] In a third aspect, the present invention further provides an electronic price tag, comprising the above-mentioned lead-free wide-bandgap double perovskite solar cell.

[0023] A further improvement of the present invention is that the electronic price tag further comprises: a connecting electrode, and the connecting electrode is used to be electrically connected to the lead-free wide-bandgap double perovskite solar cell.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] By using the lead-free bimetallic perovskite precursor solution of the present invention to prepare a wide bandgap perovskite film, the non-lead material is combined with the bimetallic perovskite system, so that the optical bandgap of the lead-free bimetallic perovskite layer can be in the range of 1.8eV to 2.2eV. In this way, it can be ensured that the lead-free wide bandgap double perovskite solar cell can efficiently capture and utilize indoor visible light, especially achieve excellent conversion of blue light and green light. This bandgap design can not only maximize the energy of indoor light sources, but also maintain a high open circuit voltage under low light intensity, thereby improving the photoelectric conversion efficiency of lead-free wide bandgap double perovskite solar cells. Compared with traditional solar cells, under this bandgap optimization design, higher photoelectric response sensitivity and better energy conversion efficiency can be shown under indoor weak light conditions.

[0026] At the same time, the use of non-lead materials also reduces the risk of heavy metal pollution, is green and environmentally friendly, and is easier to mass produce; in addition, the perovskite layer uses a bimetallic system, which can form a more stable crystal structure, improve the thermal stability and moisture resistance of the material, thereby extending the service life of perovskite solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings described herein are only for explanation purposes and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the various components in the drawings are only schematic, used to help understand the present invention, and are not intended to specifically limit the shapes and proportional dimensions of the various components of the present invention.

[0028] Figure 1 A schematic diagram of the film structure of a current perovskite solar cell;

[0029] Figure 2 A schematic diagram of the film structure of a lead-free wide-bandgap double perovskite solar cell provided in this application;

[0030] Figure 3 An absorbance curve of a lead-free wide-bandgap double perovskite layer provided in this application;

[0031] Figure 4 A Tauc bandgap curve diagram provided for this application;

[0032] Figure 5 A current density-voltage curve of a lead-free wide-bandgap double perovskite solar cell provided in this application under common indoor scenes (1000 lux);

[0033] Figure 6 Absorbance curve of another lead-free wide bandgap double perovskite layer provided in this application;

[0034] Figure 7 Another Tauc bandgap curve graph provided for this application;

[0035] Figure 8 A current density-voltage curve of another lead-free wide bandgap double perovskite solar cell provided in this application under common indoor scenes (1000 lux);

[0036] Fig. 9 A schematic diagram of connecting a lead-free wide-bandgap double perovskite solar cell and an electronic price tag provided in this application;

[0037] Fig.10 A schematic diagram of connecting another lead-free wide bandgap double perovskite solar cell provided in this application to an electronic price tag;

[0038] Fig.11A schematic diagram of connecting another lead-free wide-bandgap double perovskite solar cell to an electronic price tag provided in the present application.

[0039] Among them: 1. cover glass; 2. butyl rubber; 3. POE film; 4. electrode; 5. electron transport layer; 6. perovskite layer; 7. hole transport layer; 8. TCO glass; 9. tempered glass; 10. transparent conductive substrate; 11. first carrier transport layer; 12. lead-free bimetallic perovskite layer; 13. second carrier transport layer; 14. electrode layer; 15. thin film encapsulation layer; 100. non-display area; 101. display area; 000. lead-free wide-bandgap bimetallic perovskite solar cell. DETAILED DESCRIPTION

[0040] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] It should be noted that in indoor photovoltaic applications, the spectral distribution of indoor light sources is usually narrow and the light intensity is relatively low. For example, the spectrum of common indoor light sources such as LEDs and fluorescent lamps is mainly concentrated in the visible light range of 400nm to 700nm, especially the blue light and green light parts dominate, and the near-infrared light component is relatively small. Therefore, the band gap of perovskite solar cell materials must be optimized to match the spectrum of indoor light sources.

[0042] like Figure 2 As shown, the present invention provides a lead-free wide bandgap double perovskite solar cell, which includes, from bottom to top, a transparent conductive substrate 10, a first carrier transport layer 11, a lead-free bimetallic perovskite layer 12, a second carrier transport layer 13 and an electrode layer 14.

[0043] Here, the first carrier transport layer 11 can be one of the hole transport layer and the electron transport layer, and the second carrier transport layer 13 can be the other of the hole transport layer and the electron transport layer, that is, according to the structural type of the lead-free wide bandgap double perovskite solar cell 000 (normal structure nip type or inverted structure pin type), the preparation order and position of the electron transport layer and the hole transport layer will be different, and the embodiments of the present application are not limited to this. And the embodiments of the present application are schematically illustrated by taking the inverted structure pin type as an example, that is, the first carrier transport layer 11 in the embodiments of the present application can be a hole transport layer, and the second carrier transport layer 13 can be an electron transport layer.

[0044] In the present application, the lead-free wide bandgap double perovskite solar cell 000 may further include: a thin film encapsulation layer 15. The thin film encapsulation layer 15 may encapsulate the first carrier transport layer 11, the lead-free bimetallic perovskite layer 12, the second carrier transport layer 13 and the electrode layer 14. In this case, the thin film encapsulation layer 15 can isolate moisture, oxygen and other substances that may corrode or damage the internal layer structure, thereby reducing the interference of the external environment on the internal layer structure, thereby improving the life and stability of the lead-free wide bandgap double perovskite solar cell 000.

[0045] It should be noted that the thin film encapsulation layer 15 can be a single-layer structure or a multi-layer stacked structure, that is, the thin film encapsulation layer 15 can be a single-layer inorganic thin film encapsulation layer, or the thin film encapsulation layer 15 includes a first inorganic encapsulation layer, a first organic encapsulation layer and a second inorganic encapsulation layer from bottom to top, and the embodiments of the present application are not limited to this.

[0046] In the embodiment of the present application, the lead-free bimetallic perovskite layer 12 in the lead-free wide bandgap bimetallic perovskite solar cell 000 can be obtained by spin coating a lead-free bimetallic perovskite precursor solution and then annealing. Here, the lead-free bimetallic perovskite precursor solution may include: a lead-free bimetallic perovskite precursor material and a lead-free bimetallic perovskite precursor solvent.

[0047] Here, the optical band gap of the lead-free bimetallic perovskite layer 12 can be in the range of 1.8 eV to 2.2 eV. It should be noted that the optical band gap of the lead-free bimetallic perovskite layer 12 can be regulated by changing the type and proportion of ions in the perovskite compound. The optical band gap of the lead-free bimetallic perovskite layer 12 is a core parameter that affects the photoelectric conversion efficiency of the lead-free wide-bandgap bimetallic perovskite solar cell, and is directly related to its responsiveness to different light sources. In this case, it can be ensured that the lead-free wide-bandgap bimetallic perovskite solar cell is more suitable for indoor spectral absorption, thereby being able to maintain a high light conversion efficiency in an indoor low-light intensity environment.

[0048] The general structural formula of the lead-free bimetallic perovskite precursor solution is A2B'B"X' y X” 6-y , y is in the range of 0<y<6. Here, the A position is generally an organic monovalent cation or an inorganic monovalent cation. For example, the A position can be cesium (Cs + ), formamidine (FA + ) and methylamine (MA + )

[0049] The B' position is generally a monovalent metal cation, specifically Ag. + 、Na + and Cu +The B" position is generally a trivalent metal cation, specifically Bi 3+ 、V 3+ andIn 3+ One of the following; X' is a halogen anion, specifically Cl - Br - and I - One of the following, X" is a halogen anion, specifically Cl - Br - and I - One of them.

[0050] In the present application, the lead-free bimetallic perovskite precursor material may include: an inorganic compound formed by a monovalent metal element and a halogen element, and an inorganic compound formed by a trivalent metal element and a halogen element. For example, the lead-free bimetallic perovskite precursor material may include: AgCl, AgI, BiBr3, etc.

[0051] The lead-free bimetallic perovskite precursor solvent may include: N, N dimethylformamide, and / or dimethyl sulfoxide. That is, the lead-free bimetallic perovskite precursor solvent may be N, N dimethylformamide, or the lead-free bimetallic perovskite precursor solvent may be dimethyl sulfoxide, or the lead-free bimetallic perovskite precursor solvent may be a mixture of N, N dimethylformamide and dimethyl sulfoxide. The embodiments of the present application are not limited to this.

[0052] In the present application, the thickness of the lead-free wide bandgap double perovskite solar cell 000 can range from 0.3 mm to 0.6 mm. In this case, it can be ensured that after the lead-free wide bandgap double perovskite solar cell is integrated on the electronic price tag, the overall thickness of the electronic price tag is low.

[0053] It should be noted that the present invention has no particular restrictions on the material selection, thickness and preparation process of the transparent conductive substrate 10, the first carrier transport layer 11, the second carrier transport layer 13 and the electrode layer 14, as long as the purpose of the present invention can be achieved.

[0054] For example, the transparent conductive substrate 10 can be a flexible conductive substrate or a rigid conductive substrate, wherein the flexible conductive substrate can be a fluorine-doped tin oxide FTO flexible conductive substrate or an indium-doped tin oxide ITO flexible conductive substrate, and the rigid conductive substrate can be a FTO conductive glass substrate or an ITO conductive glass substrate.

[0055] The first carrier transport layer 11 can be any layered structure prepared by nickel oxide, doped nickel oxide, cuprous iodide, cuprous thiocyanate, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), PEDOT:PSS or Spiro-OMeTAD, and can be prepared by solution spin coating, solution scraping, slit coating or vapor phase method.

[0056] The second carrier transport layer 13 can be made of materials such as titanium dioxide TiO2, tin dioxide SnO2, fullerene, C60 or zinc oxide ZnO, and can be prepared by solution spin coating, solution scraping, solution spraying, slit coating or hydrothermal growth.

[0057] The electrode layer 14 can be made of one of gold Au, silver Ag, aluminum Al and copper Cu electrodes, and can be prepared by thermal evaporation. Those skilled in the art can adjust and optimize the material selection, thickness and preparation process according to specific needs and experimental conditions.

[0058] The present invention also provides a method for preparing a lead-free wide bandgap double perovskite solar cell, comprising the following steps:

[0059] Step S1, pre-treating the transparent conductive substrate;

[0060] For example, the transparent conductive substrate 10 may be subjected to ultrasonic treatment for 10 to 20 minutes, and then the ultrasonically treated transparent conductive substrate 10 may be baked for 1 to 2 hours;

[0061] It should be noted that before pretreatment, the transparent conductive substrate 10 is placed in an ultraviolet ozone apparatus for treatment to remove organic impurities on the surface and adjust the work function and affinity of the substrate surface, which is helpful for the subsequent film forming process.

[0062] Step S2, preparing a first carrier transport layer on one side of the transparent conductive substrate;

[0063] For example, a PEDOT:PSS solution can be dropped onto one side of the transparent conductive substrate 10 and spin coated at a speed of 4000-6000 rpm for 30-60 s. After the spin coating, the substrate is annealed at a temperature of 150-200° C. for 10-30 min to obtain a first carrier transport layer.

[0064] Step S3, preparing a lead-free bimetallic perovskite layer on a side of the first carrier transport layer away from the transparent conductive substrate;

[0065] For example, the lead-free bimetallic perovskite precursor solution can be filtered, and then the lead-free bimetallic perovskite precursor solution can be dropped onto the side of the first carrier transport layer 11 away from the transparent conductive substrate 10, and spin coated at a rotation speed of 4000rpm / s to 6000rpm / s for 30s to 60s. After the spin coating, annealing is performed at a temperature of 60°C to 120°C for 1min to 30min, and then annealing is performed at a temperature of 100°C to 150°C for 10min to 30min, and then cooled to room temperature to obtain the lead-free bimetallic perovskite layer 12.

[0066] Step S4, sequentially preparing a second carrier transport layer, an electrode layer and a thin film encapsulation layer on a side of the lead-free bimetallic perovskite layer away from the transparent conductive substrate;

[0067] For example, the second carrier transport layer 13 and the electrode layer 14 can be evaporated in a vacuum chamber, and after the evaporation is completed, thin film packaging is performed to form a thin film packaging layer 15, and after packaging, the electrodes are led out to finally complete the preparation of the lead-free wide bandgap double perovskite solar cell.

[0068] The present invention also provides an electronic price tag, which may include the above-mentioned lead-free wide-bandgap double perovskite solar cell.

[0069] In the present application, the electronic price tag may further include: a connecting electrode, wherein the connecting electrode may be used to electrically connect to the lead-free wide bandgap double perovskite solar cell 000, so that the lead-free wide bandgap double perovskite solar cell 000 may better power the electronic price tag, thereby ensuring that the electronic price tag may realize the corresponding function.

[0070] Please refer to Figures 9 to 11 The lead-free wide band gap double perovskite solar cell 000 in the present application can be electrically connected to the electronic price tag and provide power for the electronic price tag. The application scenarios of the lead-free wide band gap double perovskite solar cell 000 in the electronic price tag are as follows, but are not limited to the following distribution methods: the lead-free wide band gap double perovskite solar cell 000 can be distributed in the non-display area 100 at the front edge of the electronic price tag, the lead-free wide band gap double perovskite solar cell 000 can be distributed in the non-display area 100 on the back of the electronic price tag, or the lead-free wide band gap double perovskite solar cell 000 can be distributed on the side of the front display area 101 of the electronic price tag.

[0071] Here, since the lead-free bimetallic perovskite layer 12 has an adjustable bandgap range, and the optical bandgap of the lead-free bimetallic perovskite layer 12 has a value range of 1.8eV to 2.2eV. In this case, it can be ensured that the lead-free wide bandgap bimetallic perovskite solar cell 000 can effectively absorb visible light and light sources of specific wavelengths indoors, so that the lead-free wide bandgap bimetallic perovskite solar cell 000 can also maintain a high photoelectric conversion efficiency in indoor weak light environments. For example, its photoelectric conversion efficiency in indoor weak light can reach 20%-35%. In this case, the stable display of the electronic price tag can be ensured, thereby extending the service life and reducing the frequency of maintenance and replacement.

[0072] Embodiment 1:

[0073] In this embodiment, the lead-free bimetallic perovskite precursor material is Cs2AgBiBr3Cl3 as an example, and the method for preparing Cs2AgBiBr3Cl3 lead-free wide bandgap bimetallic perovskite solar cell includes the following steps:

[0074] Step S11, the FTO conductive glass substrate is sequentially subjected to KOH solution, ITO detergent (1:50 v / v dilution), acetone, ethanol (1:1 v / v) and deionized water ultrasound for 15 minutes each, and then the FTO conductive glass substrate is taken out and baked under a baking lamp for 1 hour. Before use, the FTO conductive glass substrate is placed in an ultraviolet ozone meter for treatment for 10 minutes to remove organic impurities on the surface while adjusting the work function and affinity of the substrate surface, which is helpful for the subsequent film formation process.

[0075] Step S21, using a pipette to measure the PEDOT:PSS solution and drop it onto the FTO conductive glass substrate, maintaining the rotation speed at 5000 rpm for 60 seconds, and then annealing on a hot stage at 170° C. for 20 minutes.

[0076] Step S31, dissolving CsCl, AgCl and BiBr3 in dimethyl sulfoxide at a ratio of 2:1:1, stirring at 100°C until the salt is completely dissolved, to prepare a lead-free bimetallic perovskite precursor solution Cs2AgBiBr3Cl3, with a solution concentration of 1.2 mol / L;

[0077] The lead-free bimetallic perovskite precursor solution Cs2AgBiBr3Cl3 was filtered using a 0.22um polytetrafluoroethylene filter, and then the lead-free bimetallic perovskite precursor solution Cs2AgBiBr3Cl3 was dropped onto the FTO / PEDOT:PSS substrate and spin coated at 4000rpm for 50s. At the 20th second of spinning, 400μL of chlorobenzene was dropped onto the film, followed by annealing at a 60°C hot stage for 1min, and then transferred to a 100°C hot stage for annealing for 20min to obtain a Cs2AgBiBr3Cl3 lead-free bimetallic perovskite layer.

[0078] Step S42, transfer the film to a vacuum chamber, evaporate a 40nm C60 electron transport layer and a 6nm electron blocking layer BCP respectively at a gas pressure of 10-5mbar, then replace the mask to evaporate a 120nm Ag electrode, and then perform thin film encapsulation on the surface of the formed functional layer to form a thin film encapsulation layer 15, and then lead out the electrodes after encapsulation, and finally complete the preparation of the Cs2AgBiBr3Cl3 lead-free wide bandgap double perovskite solar cell.

[0079] Embodiment 2:

[0080] In this embodiment, the lead-free bimetallic perovskite precursor material is Cs2AgBiBr3I3 as an example, and the method for preparing Cs2AgBiBr3I3 lead-free wide bandgap bimetallic perovskite solar cell includes the following steps:

[0081] Step S12, the FTO conductive glass substrate is sequentially subjected to KOH solution, ITO detergent (1:50 v / v dilution), acetone, ethanol (1:1 v / v) and deionized water ultrasound for 15 minutes each, and then the FTO conductive glass substrate is taken out and baked under a baking lamp for 1 hour. Before use, the FTO conductive glass substrate is placed in an ultraviolet ozone meter for treatment for 10 minutes to remove organic impurities on the surface while adjusting the work function and affinity of the substrate surface, which is helpful for the subsequent film formation process.

[0082] Step S22, using a pipette to measure the PEDOT:PSS solution and drop it onto the FTO conductive glass substrate, maintaining the rotation speed at 5000 rpm for 60 seconds, and then annealing on a hot stage at 170° C. for 20 minutes.

[0083] Step S32, dissolving CsI, AgI and BiBr3 in dimethyl sulfoxide at a ratio of 2:1:1, stirring at 100°C until the salt is completely dissolved, to prepare a lead-free bimetallic perovskite precursor solution Cs2AgBiBr3I3, with a solution concentration of 1.2 mol / L;

[0084] The lead-free bimetallic perovskite precursor solution Cs2AgBiBr3I3 was filtered using a 0.22um polytetrafluoroethylene filter, and then the lead-free bimetallic perovskite precursor solution Cs2AgBiBr3I3 was dropped onto the FTO / PEDOT:PSS substrate and spin coated at 4000rpm for 50s. At the 20th second of spinning, 400μL of chlorobenzene was dropped onto the film, followed by annealing at a 60°C hot stage for 1min, and then transferred to a 100°C hot stage for annealing for 20min to obtain a Cs2AgBiBr3I3 lead-free bimetallic perovskite layer.

[0085] Step S42: Transfer the film to a vacuum chamber, and evaporate a 40nm C60 electron transport layer and a 6nm electron blocking layer BCP at a gas pressure of 10-5mbar. Then, replace the mask to evaporate a 120nm Ag electrode. Then, perform thin film encapsulation on the surface of the formed functional layer to form a thin film encapsulation layer 15. After encapsulation, the electrodes are led out to finally complete the preparation of the Cs2AgBiBr3I3 lead-free wide bandgap double perovskite solar cell.

[0086] In the examples of this application, please refer to Figure 3 , Figure 3 An absorbance curve of a lead-free wide bandgap double perovskite layer provided in the present application. The horizontal axis is the wavelength value range, and the vertical axis is the absorbance value. Here, the larger the absorbance value, the stronger the light absorption capacity of the lead-free wide bandgap double perovskite layer within a certain wavelength range. It can be seen from the figure that within the wavelength range of 400nm-700nm, the light absorption capacity of the Cs2AgBiBr3Cl3 lead-free wide bandgap double perovskite layer and the Cs2AgBiBr3I3 lead-free wide bandgap double perovskite layer are both strong.

[0087] In this application, please refer to Figure 4 , Figure 4 It is a Tauc bandgap curve provided by this application. It should be noted that there is no clear definition of the bandgap of the perovskite layer, and the definition method with a clearer physical meaning for the optical bandgap of the perovskite layer is the Tauc bandgap. Here, (ahv) 1 / 2 The value obtained from the -hv relationship curve is called the Tauc band gap. Figure 4 The horizontal axis is the binding energy, and the vertical axis is the square of the product of the absorption coefficient and the energy. Figure 4 It can be concluded that the band gap of the Cs2AgBiBr3I3 lead-free wide-bandgap double perovskite layer is 1.78 eV, and the band gap of the Cs2AgBiBr3Cl3 lead-free wide-bandgap double perovskite layer is 1.98 eV.

[0088] Table 1 Parameters of Cs2AgBiBr3Cl3 and Cs2AgBiBr3I3 lead-free wide bandgap double perovskite solar cells

[0089] Light(lux) PVK Pin(uW) Pin(uW) PCE(%) 1000 <![CDATA[Cs2AgBiBr3Cl3]]> 301 97.36 32.35 1000 <![CDATA[Cs2AgBiBr3I3]]> 301 85.86 28.52

[0090] In the examples of this application, please refer to Figure 5 , Figure 5This is a current density-voltage curve of a lead-free wide bandgap double perovskite solar cell provided by the present application under common indoor scenes (1000 lux). Combined with Table 1, it can be obtained that the Cs2AgBiBr3Cl3 lead-free wide bandgap double perovskite solar cell and the Cs2AgBiBr3I3 lead-free wide bandgap double perovskite solar cell can maintain a photoelectric conversion efficiency of about 25%-35% under a light intensity of 1000 lux, which is sufficient to meet the working needs of electronic price tags in weak light.

[0091] Embodiment 3:

[0092] In this embodiment, the lead-free bimetallic perovskite precursor material is Cs2AgBiBr5I1 as an example, and the method for preparing Cs2AgBiBr5I1 lead-free wide bandgap bimetallic perovskite solar cell includes the following steps:

[0093] Step S13, the FTO conductive glass substrate is sequentially subjected to KOH solution, ITO detergent (1:50 v / v dilution), acetone, ethanol (1:1 v / v) and deionized water ultrasound for 15 minutes each, and then the FTO conductive glass substrate is taken out and baked under a baking lamp for 1 hour. Before use, the FTO conductive glass substrate is placed in a UV ozone instrument for 10 minutes to remove organic impurities on the surface and adjust the work function and affinity of the substrate surface, which is helpful for the subsequent film formation process.

[0094] Step S23, using a pipette to measure the PEDOT:PSS solution and dripping it onto the FTO conductive glass substrate, maintaining the rotation speed at 5000 rpm for 60 seconds, and then annealing on a hot stage at 170° C. for 20 minutes.

[0095] Step S33, dissolving CsBr, CsI, AgBr and BiBr3 in dimethyl sulfoxide at a ratio of 1:1:1:1, stirring at 100° C. until completely dissolved, to prepare a lead-free bimetallic perovskite precursor solution Cs2AgBiBr5I1, with a solution concentration of 1.2 mol / L;

[0096] The lead-free bimetallic perovskite precursor solution Cs2AgBiBr5I1 was filtered using a 0.22um polytetrafluoroethylene filter, and then the lead-free bimetallic perovskite precursor solution Cs2AgBiBr5I1 was dropped onto the FTO / PEDOT:PSS substrate and spin coated at 4000rpm for 50s. At the 20th second of spinning, 400μL of chlorobenzene was dropped onto the film, followed by annealing at a 60°C hot stage for 1min, and then transferred to a 100°C hot stage for annealing for 20min to obtain a Cs2AgBiBr5I1 lead-free bimetallic perovskite layer.

[0097] Step S43, transfer the film to a vacuum chamber, and evaporate a 40nm C60 electron transport layer and a 6nm electron blocking layer BCP respectively at a gas pressure of 10-5mbar, then replace the mask to evaporate a 120nm Ag electrode, and then perform thin film encapsulation on the surface of the formed functional layer to form a thin film encapsulation layer 15. After encapsulation, the electrodes are led out to finally complete the preparation of the Cs2AgBiBr5I1 lead-free wide bandgap double perovskite solar cell.

[0098] Embodiment 4:

[0099] In this embodiment, the lead-free bimetallic perovskite precursor material is Cs2CuBiBr5I1 as an example, and the method for preparing Cs2CuBiBr5I1 lead-free wide bandgap bimetallic perovskite solar cell includes the following steps:

[0100] Step S14, the FTO conductive glass substrate is sequentially subjected to KOH solution, ITO detergent (1:50 v / v dilution), acetone, ethanol (1:1 v / v) and deionized water ultrasound for 15 minutes each, and then the FTO conductive glass substrate is taken out and baked under a baking lamp for 1 hour. Before use, the FTO conductive glass substrate is placed in a UV ozone instrument for 10 minutes to remove organic impurities on the surface and adjust the work function and affinity of the substrate surface, which is helpful for the subsequent film formation process.

[0101] Step S24, using a pipette to measure the PEDOT:PSS solution and dripping it onto the FTO conductive glass substrate, maintaining the rotation speed at 5000 rpm for 60 seconds, and then annealing on a hot stage at 170° C. for 20 minutes.

[0102] Step S34, dissolving CsBr, CsI, CuBr and BiBr3 in dimethyl sulfoxide at a ratio of 1:1:1:1, stirring at 100° C. until completely dissolved, to prepare a lead-free bimetallic perovskite precursor solution Cs2CuBiBr5I1, with a solution concentration of 1.2 mol / L;

[0103] The lead-free bimetallic perovskite precursor solution Cs2CuBiBr5I1 was filtered using a 0.22um polytetrafluoroethylene filter, and then the lead-free bimetallic perovskite precursor solution Cs2CuBiBr5I1 was dropped onto the FTO / PEDOT:PSS substrate and spin coated at 4000rpm for 50s. At the 20th second of spinning, 400μL of chlorobenzene was dropped onto the film, followed by annealing at a 60°C hot stage for 1min, and then transferred to a 100°C hot stage for annealing for 20min to obtain a Cs2CuBiBr5I1 lead-free bimetallic perovskite layer.

[0104] Step S44, transfer the film to a vacuum chamber, evaporate a 40nm C60 electron transport layer and a 6nm electron blocking layer BCP respectively at a gas pressure of 10-5mbar, then replace the mask to evaporate a 120nm Ag electrode, and then perform thin film encapsulation on the surface of the formed functional layer to form a thin film encapsulation layer 15, and then lead out the electrodes after encapsulation, and finally complete the preparation of the Cs2CuBiBr5I1 lead-free wide bandgap double perovskite solar cell.

[0105] In the examples of this application, please refer to Figure 6 , Figure 6 This is another absorbance curve of a lead-free wide bandgap double perovskite layer provided by the present application. The horizontal axis is the wavelength value range, and the vertical axis is the absorbance value. The larger the absorbance value, the stronger the light absorption capacity of the lead-free wide bandgap double perovskite layer within a certain wavelength range. It can be seen from the figure that within the wavelength range of 400nm-700nm, the light absorption capacity of the Cs2AgBiBr5I1 lead-free wide bandgap double perovskite layer and the Cs2CuBiBr5I1 lead-free wide bandgap double perovskite layer are both strong.

[0106] In this application, please refer to Figure 7 , another Tauc bandgap curve provided by the present application. The horizontal axis is the binding energy, and the vertical axis is the square of the product of the absorption coefficient and the energy. It can be concluded from the figure that the band gap of the Cs2AgBiBr5I1 lead-free wide bandgap double perovskite layer is 1.85eV, and the band gap of the Cs2CuBiBr5I1 lead-free wide bandgap double perovskite layer is 1.80eV.

[0107] Table 2 Parameters of Cs2AgBiBr5I1 and Cs2CuBiBr5I1 lead-free wide bandgap double perovskite solar cells

[0108] Light(lux) PVK Pin(uW) Pin(uW) PCE(%) 1000 <![CDATA[Cs2AgBiBr5I1]]> 301 95.18 31.62 1000 <![CDATA[Cs2CuBiBr5I1]]> 301 90.44 30.04

[0109] In the examples of this application, please refer to Figure 8 , Figure 8 It is a current density-voltage curve diagram of another lead-free wide band gap double perovskite solar cell in Example 3 and Example 4 of the present application under common indoor scenarios (1000 lux). Combined with Table 2, it can be obtained that the Cs2AgBiBr5I1 lead-free wide band gap double perovskite solar cell and the Cs2CuBiBr5I1 lead-free wide band gap double perovskite solar cell can maintain a photoelectric conversion efficiency of about 30% under a light intensity of 1000 lux, which is sufficient to meet the working requirements of electronic price tags under weak light.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A lead-free wide bandgap double perovskite solar cell, characterized in that: It includes, from bottom to top, a transparent conductive substrate, a first carrier transport layer, a lead-free bimetallic perovskite layer, a second carrier transport layer and an electrode layer; The lead-free bimetallic perovskite layer is obtained by spin coating a lead-free bimetallic perovskite precursor solution and then annealing; The lead-free bimetallic perovskite precursor solution comprises: a lead-free bimetallic perovskite precursor material and a lead-free bimetallic perovskite precursor solvent; the general structural formula of the lead-free bimetallic perovskite precursor material is A2B'B"X' y X” 6-y , A is an organic monovalent cation or an inorganic monovalent cation, B' is a monovalent metal cation, B" is a trivalent metal cation, X' is a halogen anion, and X" is a halogen anion; the range of y is 0<y<6; Wherein, the optical band gap of the lead-free bimetallic perovskite layer ranges from 1.8 eV to 2.2 eV.

2. A lead-free wide bandgap double perovskite solar cell according to claim 1, characterized in that: The A position is Cs + , FA + and MA + One of the following, wherein the B' position is Ag + 、Na + and Cu + One of the two, B" is Bi 3+ 、V 3+ andIn 3+ One of the above, wherein the X' position is Cl - Br - and I - One of the above, wherein the X" position is Cl - Br - and I - One of them.

3. A lead-free wide bandgap double perovskite solar cell according to claim 1, characterized in that: The lead-free bimetallic perovskite precursor material includes: an inorganic compound formed by a monovalent metal element and a halogen element and an inorganic compound formed by a trivalent metal element and a halogen element.

4. The lead-free wide bandgap double perovskite solar cell according to claim 1, characterized in that: The lead-free bimetallic perovskite precursor solvent includes: N,N-dimethylformamide, and / or dimethyl sulfoxide.

5. The lead-free wide bandgap double perovskite solar cell according to claim 1, characterized in that: The thickness of the lead-free wide bandgap double perovskite solar cell ranges from 0.3 mm to 0.6 mm.

6. The lead-free wide bandgap double perovskite solar cell according to claim 1, characterized in that: The lead-free wide bandgap double perovskite solar cell further includes a thin film encapsulation layer.

7. A method for preparing a lead-free wide bandgap double perovskite solar cell, characterized in that: The following steps are involved: Step S1, pre-treating the transparent conductive substrate; Step S2, preparing a first carrier transport layer on one side of the transparent conductive substrate; Step S3, preparing a lead-free bimetallic perovskite layer on a side of the first carrier transport layer away from the transparent conductive substrate; Step S4, sequentially preparing a second carrier transport layer, an electrode layer and a thin film encapsulation layer on a side of the lead-free bimetallic perovskite layer away from the transparent conductive substrate.

8. The lead-free wide bandgap double perovskite solar cell according to claim 7, characterized in that: The step S3 of preparing a lead-free bimetallic perovskite layer on a side of the first carrier transport layer away from the transparent conductive substrate comprises: The lead-free bimetallic perovskite precursor solution is filtered, and the lead-free bimetallic perovskite precursor solution is dropped onto the side of the first carrier transport layer away from the transparent conductive substrate, and spin-coated at a rotation speed of 4000rpm / s to 6000rpm / s for 30s to 60s. After the spin coating, the solution is annealed at a temperature of 60°C to 120°C for 1min to 30min, and then annealed at a temperature of 100°C to 150°C for 10min to 30min. The solution is cooled to room temperature to obtain a lead-free bimetallic perovskite layer.

9. An electronic price tag, characterized in that: A lead-free wide-bandgap double perovskite solar cell comprising any one of claims 1 to 6.

10. An electronic price tag according to claim 9, characterized in that: The electronic price tag further comprises: a connecting electrode, which is used to be electrically connected to the lead-free wide-bandgap double perovskite solar cell.

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